springMVC简单入门

快速搭建

pom.xml依赖

  <!-- 导入坐标 springmvc 与 servlet -->
  <dependencies>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.8.RELEASE</version>
    </dependency>

表现层控制类：springmvc\src\main\java\com\mercurows\controller\UserController.java

package com.mercurows.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

// 2.定义controller
// 2.1使用@Controller定义bean
@Controller
// 资源访问前缀
@RequestMapping("/user")
public class UserController {
    // 2.2设置当前操作的访问路径
    @RequestMapping("/save")
    // 2.3设置当前操作的返回值类型
    @ResponseBody
    // 当拦截到"/save"路径时就执行下面的save方法
    public String save() {
        System.out.println("user save .. ");
        // 将响应信息返回给浏览器
        return "{'module':'springmvc'}";
    }
}

springmvc配置类：springmvc\src\main\java\com\mercurows\config\SpringMvcConfig.java

package com.mercurows.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

// 3.创建springmvc的配置文件，加载controller对应的bean
@Configuration
@EnableWebMvc
@ComponentScan("com.mercurows.controller")
public class SpringMvcConfig {
}

这里需要知道的是，springmvc扫描相关的bean例如表现层bean；spring扫描相关的bean例如业务bean service，功能bean DataSource。

springmvc\src\main\java\com\mercurows\config\ServletContainersInitConfig.java

package com.mercurows.config;

import org.springframework.lang.Nullable;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
import org.springframework.web.servlet.support.AbstractDispatcherServletInitializer;

// // 如何让Tomcat启动时知道spring的配置类在哪里？就要继承下面的类
// // 4.定义一个servlet容器启动的配置类，在里面加载spring的配置
// public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer{

//     // 加载springMVC容器配置
//     @Override
//     protected WebApplicationContext createServletApplicationContext() {
//         AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
//         ctx.register(SpringMvcConfig.class);
//         return ctx;
//     }

//     // 设置那些请求归属springMVC处理
//     @Override
//     protected String[] getServletMappings() {
//         // 所有请求
//         return new String[] {"/"};
//     }

//     // 加载spring容器配置
//     @Override
//     @Nullable
//     protected WebApplicationContext createRootApplicationContext() {
//         return null;
//     }

// }

// 是上面的简化开发版本
public class ServletContainersInitConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
    protected Class<?>[] getServletConfigClasses() {
        return new Class[] { SpringMvcConfig.class };
    }
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }
    protected Class<?>[] getRootConfigClasses() {
        return new Class[0];
    }
}

这样简单的springmvc项目就搭建完毕了。在浏览器中输入：http://localhost:8080/springmvc/user/save 即可在后台控制端看到相关输出：user save ..

---

请求

get&post的参数传递

为解决post中文参数乱码问题，对文件springmvc\src\main\java\com\mercurows\config\ServletContainersInitConfig.java进行修改

package com.mercurows.config;

import org.springframework.lang.Nullable;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

// 简化开发版本
public class ServletContainersInitConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
    protected Class<?>[] getServletConfigClasses() {
        return new Class[] { SpringMvcConfig.class };
    }

    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

    protected Class<?>[] getRootConfigClasses() {
        return new Class[0];
    }

    // 处理post中文参数乱码问题
    @Override
    @Nullable
    protected javax.servlet.Filter[] getServletFilters() {
        CharacterEncodingFilter filter = new CharacterEncodingFilter();
        filter.setEncoding("UTF-8");
        return new javax.servlet.Filter[] { filter };
    }
}

五种参数类型传递

springmvc\src\main\java\com\mercurows\controller\UserController.java

package com.mercurows.controller;

import java.util.Arrays;
import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.mercurows.domain.Book;
import com.mercurows.domain.User;

// 2.定义controller
// 2.1使用@Controller定义bean
@Controller
// 资源访问前缀
@RequestMapping("/user")
public class UserController {
    // 2.2设置当前操作的访问路径
    @RequestMapping("/save")
    // 2.3设置当前操作的返回值类型
    @ResponseBody
    // 当拦截到"/save"路径时就执行下面的save方法
    public String save() {
        System.out.println("user save .. ");
        // 将响应信息返回给浏览器
        return "{'module':'springmvc'}";
    }

    // 普通参数
    @RequestMapping("/commonParam")
    @ResponseBody
    // 与mybatis中一样，这里加上@RequestParam注解
    // 当前端传入的名称为username时就可指定用name参数接受
    // 这里默认前端传的第二个名称为age
    public String commonParam(@RequestParam("username") String name, int age) {
        System.out.println("普通参数传递 name ==> " + name);
        System.out.println("普通参数传递 name ==> " + age);
        return "{'module':'conmmon param'}";
    }

    // POJO参数
    // 前端传入的参数名称与User成员变量的名称一样时
    // 这里为：name 与 age
    // 这些接收到的变量就会自动set进User类里面当成员变量
    @RequestMapping("/pojoParam")
    @ResponseBody
    public String pojoParam(User user) {
        System.out.println("pojo参数传递 user ==> " + user);
        return "{'module':'pojo param'}";
    }

    // 嵌套POJO参数
    // 思路与上面的一致，只不过这里对于嵌套的成员类而言
    // 前端传参时需要：user.age user.name 这样传
    @RequestMapping("/pojoContainPojoParam")
    @ResponseBody
    public String pojoContainPojoParam(Book book) {
        System.out.println("pojo嵌套pojo参数传递 book ==> " + book);
        return "{'module':'pojo contain pojo param'}";
    }

    // 数组参数
    // 前端参数传递时，需要确保传入的参数名称都为likes
    // 这样这些全部名为likes的参数都会被放到likes的数组里面
    @RequestMapping("/arrayParam")
    @ResponseBody
    public String arrayParam(String[] likes) {
        System.out.println("数组参数传递 likes ==> " + Arrays.toString(likes));
        return "{'module':'array param'}";
    }

    // 集合参数
    // 这里默认将List当成pojo并将前端的传入的参数当成其成员变量塞进去
    // 但是List里面的成员变量是length这样之类的属性
    // 因此正确的处理方式是将外面的数据作为集合里面的参数数据而非集合的属性出现
    // 所以需要在前面添加@RequestParam注解将前端的数据当成参数放到集合里面
    @RequestMapping("/listParam")
    @ResponseBody
    public String listParam(@RequestParam List<String> likes) {
        System.out.println("集合参数传递 likes ==> " + likes);
        return "{'module':'list param'}";
    }
}

JSON格式数据传递

pojo类

springmvc\src\main\java\com\mercurows\domain\User.java

package com.mercurows.domain;

public class User {
    private String name;
    private int age;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "User [name=" + name + ", age=" + age + "]";
    }
}

springmvc\src\main\java\com\mercurows\domain\Book.java

package com.mercurows.domain;

public class Book {
    private User user;
    private int id;
    public User getUser() {
        return user;
    }
    public void setUser(User user) {
        this.user = user;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    @Override
    public String toString() {
        return "Book [user=" + user + ", id=" + id + "]";
    }
}

springmvc\src\main\java\com\mercurows\controller\UserController.java

package com.mercurows.controller;

import java.util.Arrays;
import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.mercurows.domain.Book;
import com.mercurows.domain.User;

// 2.定义controller
// 2.1使用@Controller定义bean
@Controller
// 资源访问前缀
@RequestMapping("/user")
public class UserController {
    // 2.2设置当前操作的访问路径
    @RequestMapping("/save")
    // 2.3设置当前操作的返回值类型
    @ResponseBody
    // 当拦截到"/save"路径时就执行下面的save方法
    public String save() {
        System.out.println("user save .. ");
        // 将响应信息返回给浏览器
        return "{'module':'springmvc'}";
    }

    // 普通参数
    @RequestMapping("/commonParam")
    @ResponseBody
    // 与mybatis中一样，这里加上@RequestParam注解
    // 当前端传入的名称为username时就可指定用name参数接受
    // 这里默认前端传的第二个名称为age
    public String commonParam(@RequestParam("username") String name, int age) {
        System.out.println("普通参数传递 name ==> " + name);
        System.out.println("普通参数传递 name ==> " + age);
        return "{'module':'conmmon param'}";
    }

    // POJO参数
    // 前端传入的参数名称与User成员变量的名称一样时
    // 这里为：name 与 age
    // 这些接收到的变量就会自动set进User类里面当成员变量
    @RequestMapping("/pojoParam")
    @ResponseBody
    public String pojoParam(User user) {
        System.out.println("pojo参数传递 user ==> " + user);
        return "{'module':'pojo param'}";
    }

    // 嵌套POJO参数
    // 思路与上面的一致，只不过这里对于嵌套的成员类而言
    // 前端传参时需要：user.age user.name 这样传
    @RequestMapping("/pojoContainPojoParam")
    @ResponseBody
    public String pojoContainPojoParam(Book book) {
        System.out.println("pojo嵌套pojo参数传递 book ==> " + book);
        return "{'module':'pojo contain pojo param'}";
    }

    // 数组参数
    // 前端参数传递时，需要确保传入的参数名称都为likes
    // 这样这些全部名为likes的参数都会被放到likes的数组里面
    @RequestMapping("/arrayParam")
    @ResponseBody
    public String arrayParam(String[] likes) {
        System.out.println("数组参数传递 likes ==> " + Arrays.toString(likes));
        return "{'module':'array param'}";
    }

    // 集合参数
    // 这里默认将List当成pojo并将前端的传入的参数当成其成员变量塞进去
    // 但是List里面的成员变量是length这样之类的属性
    // 因此正确的处理方式是将外面的数据作为集合里面的参数数据而非集合的属性出现
    // 所以需要在前面添加@RequestParam注解将前端的数据当成参数放到集合里面
    @RequestMapping("/listParam")
    @ResponseBody
    public String listParam(@RequestParam List<String> likes) {
        System.out.println("集合参数传递 likes ==> " + likes);
        return "{'module':'list param'}";
    }

    // 集合参数：json格式
    // 与上面集合类型一样都需要添加参数注解
    // 不过由于json的数据是在请求体里面的所以要添加的是@RequestBody
    @RequestMapping("/listParamForJson")
    @ResponseBody
    public String listParamForJson(@RequestBody List<User> likes) {
        System.out.println("list commmon(json)参数传递 list ==> " + likes);
        return "{'module':'list common for json param'}";
    }

    // POJO参数：json格式
    @RequestMapping("/pojoParamForJson")
    @ResponseBody
    public String pojoParamForJson(@RequestBody Book book) {
        System.out.println("pojo(json)传递参数 book ==> " + book);
        return "{'module':'pojo for json param'}";
    }
}

// 普通参数

// POJO参数

// 嵌套POJO参数

// 数组参数

//集合参数

// 集合参数：json格式

// POJO参数：json格式

响应

springmvc\src\main\java\com\mercurows\controller\UserController.java

package com.mercurows.controller;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.mercurows.domain.Book;
import com.mercurows.domain.User;

@Controller
@RequestMapping("/user")
public class UserController {
    // 响应格式↓↓↓↓↓↓↓↓

    // 响应页面/跳转页面
    @RequestMapping("/toJumpPage")
    public String toJumpPage() {
        System.out.println("跳转页面");
        return "redirect:/page.jsp";
    }

    // 响应文本数据
    @RequestMapping("/toText")
    // 添加@ResponseBody注释说明返回的是String而不是页面
    @ResponseBody
    public String toText() {
        System.out.println("返回纯文本数据");
        return "response text";
    }

    // 响应pojo对象
    @RequestMapping("/toJsonPOJO")
    @ResponseBody
    public User toJsonPOJO() {
        System.out.println("返回json对象数据");
        User user = new User();
        user.setName("mercurows");
        user.setAge(15);
        return user;
    }

    // 响应pojo集合对象
    @RequestMapping("/toJsonList")
    @ResponseBody
    public List<User> toJsonList() {
        System.out.println("返回json集合数据");
        User user1 = new User();
        user1.setName("AAA");
        user1.setAge(11);

        User user2 = new User();
        user2.setName("BBB");
        user2.setAge(22);

        List<User> userList = new ArrayList<>();
        userList.add(user1);
        userList.add(user2);

        return userList;
    }
}

REST风格

springmvc\src\main\java\com\mercurows\domain\Brand.java

package com.mercurows.domain;

public class Brand {
    private int id;
    private String name;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "Brand [id=" + id + ", name=" + name + "]";
    }
}

springmvc\src\main\java\com\mercurows\controller\BrandController.java

package com.mercurows.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.mercurows.domain.Brand;

@Controller
public class BrandController {

    // 1.设定http的请求动作：method =
    @RequestMapping(value = "/brands",method = RequestMethod.POST)
    @ResponseBody
    public String save() {
        System.out.println("brand save... ");
        return "{'module':'brand save'}";
    }

    // 传入参数形式：1.后面value中的{}加上对应方法形参
    // 2.由于地址参数并不是id=这样的格式，所以方法不是加上注解@RequestParam而是加上@PathVariable
    @RequestMapping(value = "/brands/{id}" ,method = RequestMethod.DELETE)
    @ResponseBody
    public String delete(@PathVariable Integer id) {
        System.out.println("brand delete.. " + id);
        return "{'module':'brand delete'}";
    }

    // 引用对象使用RequestBody注解
    @RequestMapping(value = "/brands",method = RequestMethod.PUT)
    @ResponseBody
    public String update(@RequestBody Brand brand) {
        System.out.println("brand update.." + brand);
        return "{'module':'brand update'}";
    }

    @RequestMapping(value = "/brands/{id}",method = RequestMethod.GET)
    @ResponseBody
    public String getById(@PathVariable Integer id) {
        System.out.println("brand getById.." + id);
        return "{'module':'brand getById'}";
    }

    @RequestMapping(value = "/brands",method = RequestMethod.GET)
    @ResponseBody
    public String getAll() {
        System.out.println("brand getAll..");
        return "{'module':'brand getAll'}";
    }
}

REST简化开发

上面的REST代码有许多重复的部分，因此可以将其提取出来放到类名前面

springmvc\src\main\java\com\mercurows\controller\BrandController.java

package com.mercurows.controller;

import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.mercurows.domain.Brand;

// rest风格简化↓↓↓ 将公共部分提取出来放到类前面
// 例如方法前面都有@ResponseBody，可以提出来
// 注意：如果原本没有该注解的，在类前面写上这个注解则会报错
// @ResponseBody
// @Controller
// @RestController合并了：@ResponseBody与@Controller
@RestController
// 由于前面都有这个所以可以提取出来，但是参数格式得要保留：/{id}
@RequestMapping("/brands")
public class BrandController {

    // 1.设定http的请求动作：method =
    // @RequestMapping(value = "/brands",method = RequestMethod.POST)
    // 上面方法的简化
    @PostMapping
    public String save() {
        System.out.println("brand save... ");
        return "{'module':'brand save'}";
    }

    // 传入参数形式：1.后面value中的{}加上对应方法形参
    // 2.由于地址参数并不是id=这样的格式，所以方法不是加上注解@RequestParam而是加上@PathVariable
    // @RequestMapping(value = "/{id}" ,method = RequestMethod.DELETE)
    @DeleteMapping(value = "/{id}")
    public String delete(@PathVariable Integer id) {
        System.out.println("brand delete.. " + id);
        return "{'module':'brand delete'}";
    }

    // 引用对象使用RequestBody注解
    // @RequestMapping(method = RequestMethod.PUT)
    @PutMapping
    public String update(@RequestBody Brand brand) {
        System.out.println("brand update.." + brand);
        return "{'module':'brand update'}";
    }

    // @RequestMapping(value = "/{id}",method = RequestMethod.GET)
    @GetMapping("/{id}")
    public String getById(@PathVariable Integer id) {
        System.out.println("brand getById.." + id);
        return "{'module':'brand getById'}";
    }

    // @RequestMapping(method = RequestMethod.GET)
    @GetMapping
    public String getAll() {
        System.out.println("brand getAll..");
        return "{'module':'brand getAll'}";
    }
}

---

异常处理

Spring MVC的异常处理思想是将异常处理的职责从业务逻辑和数据层转移到控制层，以提供更好的用户体验和错误处理机制。

springmvc_ssm\src\main\java\com\mercurows\controller\Code.java

package com.mercurows.controller;

//错误代码
public class Code {
    public static final Integer SAVE_OK = 20011;
    public static final Integer DELETE_OK = 20021;
    public static final Integer UPDATE_OK = 20031;
    public static final Integer GET_OK = 20041;

    public static final Integer SAVE_ERR = 20010;
    public static final Integer DELETE_ERR = 20020;
    public static final Integer UPDATE_ERR = 20030;
    public static final Integer GET_ERR = 20040;

    public static final Integer SYSTEM_ERR = 50001;
    public static final Integer SYSTEM_TIMEOUT_ERR = 50002;
    public static final Integer SYSTEM_UNKNOW_ERR = 59999;

    public static final Integer BUSINESS_ERR = 60002;

}

自定义结果：前后端协议

springmvc_ssm\src\main\java\com\mercurows\controller\Result.java

package com.mercurows.controller;

public class Result {
    private Object data; // 数据
    private Integer code; // 状态码
    private String msg; // 出错时的信息

    public Result(Integer code, Object data, String msg) {
        this.data = data;
        this.code = code;
        this.msg = msg;
    }

    public Result(Integer code, Object data) {
        this.data = data;
        this.code = code;
    }

    public Result() {
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

}

控制层中对自定义异常类的处理类：

springmvc_ssm\src\main\java\com\mercurows\controller\ProjectExceptionAdvice.java

package com.mercurows.controller;

import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import com.mercurows.exception.BusinessException;
import com.mercurows.exception.SystemException;

// 处理异常类
@RestControllerAdvice
public class ProjectExceptionAdvice {
    // 定义当前类是用来处理异常的
    @ExceptionHandler(SystemException.class)
    public Result doSystemException(SystemException ex) {
        // 记录日志
        // 发送消息给运维
        // 发送邮件給开发人员

        // 规范统一结果
        return new Result(ex.getCode(), null, ex.getMessage());
    }

    @ExceptionHandler(BusinessException.class)
    public Result doBusinessException(BusinessException ex) {
        // 规范统一结果
        return new Result(ex.getCode(), null, ex.getMessage());
    }

    // 处理第三方异常
    @ExceptionHandler(Exception.class)
    public Result doException(Exception ex) {
        // 规范统一结果
        return new Result(Code.SYSTEM_UNKNOW_ERR, null, "捕获到异常");
    }
}
//SystemException 与 BusinessException为自定义异常类

自定义异常类

springmvc_ssm\src\main\java\com\mercurows\exception\BusinessException.java

package com.mercurows.exception;

public class BusinessException extends RuntimeException {
    private Integer code;

    public BusinessException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public BusinessException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

}

springmvc_ssm\src\main\java\com\mercurows\exception\SystemException.java

package com.mercurows.exception;

public class SystemException extends RuntimeException {
    private Integer code;

    public SystemException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public SystemException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

}

在业务层模拟的异常就会被打包成自定义的异常发送给控制层处理

springmvc_ssm\src\main\java\com\mercurows\service\impl\StudentServiceImpl.java

package com.mercurows.service.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.mercurows.controller.Code;
import com.mercurows.dao.StudentDao;
import com.mercurows.domain.Student;
import com.mercurows.exception.BusinessException;
import com.mercurows.exception.SystemException;
import com.mercurows.service.StudentService;

@Service
public class StudentServiceImpl implements StudentService {
    @Autowired
    StudentDao studentDao;

    @Override
    public Student getById(Integer id) {
        // 模拟异常
        if (id == 1) {
            //打包成自定义的类
            throw new BusinessException(Code.BUSINESS_ERR, "系统繁忙，请稍后重试");
        }
        try{
            int i = 1/0;
        } catch (Exception e) {
            //打包成自定义的类
            throw new SystemException(Code.SYSTEM_TIMEOUT_ERR, "服务器访问超时，请重试", e);
        }
        return studentDao.getById(id);
    }
}

拦截器

拦截器与过滤器的区别

• 归属不同：Filter属于Servlet技术，Interceptor属于SpringMVC技术
• 拦截内容不同：Filter对所有访问进行增强，Interceptor仅对SpringMVC访问进行增强

springmvc_ssm\src\main\java\com\mercurows\config\SpringMvcSupport.java

package com.mercurows.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

import com.mercurows.controller.interceptor.ProjectInterceptor;

// 此类需要SpringMvcConfig类ComponentScan扫描到
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    @Autowired
    private ProjectInterceptor projectInterceptor;

    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
    }

    // 配置拦截器
    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptor).addPathPatterns("/sudents", "/students/**");
		//这里的/sudents是StudentController.java里的资源访问前缀
        // 表示路径后面最后为/sudents或是包含/students之后的任意内容都将会被拦截器拦截
        // 别忘了要让SpringMvcConfig扫描ComponentScan加载该文件
    }
}

springmvc_ssm\src\main\java\com\mercurows\config\SpringMvcConfig.java

package com.mercurows.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration
@ComponentScan("com.mercurows.config" )
// 扫描config文件夹是为了扫描到：SpringMvcSupport文件
@EnableWebMvc
public class SpringMvcConfig {
}

springmvc_ssm\src\main\java\com\mercurows\controller\interceptor\ProjectInterceptor.java

package com.mercurows.controller.interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

// 使其受是springMVC管理，能让springmvc加载该类
@Component
public class ProjectInterceptor implements HandlerInterceptor {

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
            @Nullable Exception ex) throws Exception {
                System.out.println("afterCompletion");
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            @Nullable ModelAndView modelAndView) throws Exception {
                System.out.println("postHandle");
    }

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        // 获取请求头
        String contenType = request.getHeader("Content-Type");
        // 获取调用的方法
        HandlerMethod hm = (HandlerMethod) handler;
        System.out.println("preHandle==>" + contenType + hm);
        return true;
        // 如果是false，将终止原始操作
        // 只会执行preHandle方法，而postHandle与afterCompletion都不会执行
    }
}

springmvc_ssm\src\main\java\com\mercurows\controller\StudentController.java

package com.mercurows.controller;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.mercurows.domain.Student;
import com.mercurows.service.StudentService;

@RestController
@RequestMapping("/students")
public class StudentController {
    @Autowired
    StudentService studentService;

    @DeleteMapping("/{id}")
    public Result delete(@PathVariable Integer id) {
        boolean flag = studentService.delete(id);
        return new Result(flag ? Code.DELETE_OK : Code.DELETE_ERR, flag);
    }

    @GetMapping
    public Result getAll() {
        List<Student> students = studentService.getAll();
        Integer code = students == null ? Code.GET_ERR : Code.GET_OK;
        String msg = students == null ? "数据错误，请重试" : "";
        return new Result(code, students, msg);
    }

    @GetMapping("/{id}")
    public Result getById(@PathVariable Integer id) {
        // int i = 1 / 0;
        Student student = studentService.getById(id);
        Integer code = student == null ? Code.GET_ERR : Code.GET_OK;
        String msg = student == null ? "数据错误，请重试" : "";
        System.out.println(student);
        return new Result(code, student, msg);
    }

    @PostMapping
    public Result save(@RequestBody Student student) {
        boolean flag = studentService.save(student);
        return new Result(flag ? Code.SAVE_OK : Code.SAVE_ERR, flag);
    }

    @PutMapping
    public Result update(@RequestBody Student student) {
        boolean flag = studentService.update(student);
        return new Result(flag ? Code.UPDATE_OK : Code.UPDATE_ERR, flag);
    }
}

SpringMVC整合SSM

pom.xml依赖

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.13.1</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.8.RELEASE</version>
    </dependency>

    <!-- spring单元测试 -->
    <!-- https://mvnrepository.com/artifact/org.springframework/spring-test -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>5.2.8.RELEASE</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.2.8.RELEASE</version>
    </dependency>

  <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.6</version>
  </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.6</version>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.30</version>
    </dependency>

    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.1.16</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

    <!-- 导入jason的包 -->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.15.2</version>
    </dependency>
  </dependencies>

Spring配置部分

springmvc_ssm\src\main\java\com\mercurows\config\JdbcConfig.java

package com.mercurows.config;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;

import com.alibaba.druid.pool.DruidDataSource;

public class JdbcConfig {
    @Value("${jdbc.driver}")
    private String driver;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String userNaem;
    @Value("${jdbc.password}")
    private String passWord;

    @Bean
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(driver);
        dataSource.setUrl(url);
        dataSource.setUsername(userNaem);
        dataSource.setPassword(passWord);
        return dataSource;
    }

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
        DataSourceTransactionManager dstm = new DataSourceTransactionManager(dataSource);
        return dstm;
    }
}

springmvc_ssm\src\main\java\com\mercurows\config\MyBatisConfig.java

package com.mercurows.config;

import javax.sql.DataSource;

import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.context.annotation.Bean;

public class MyBatisConfig {

    @Bean
    public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource) {
        SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setTypeAliasesPackage("com.mercurows.domain");
        return sessionFactoryBean;
    }

    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer() {
        MapperScannerConfigurer msc = new MapperScannerConfigurer();
        msc.setBasePackage("com.mercurows.dao");
        return msc;
    }
}

springmvc_ssm\src\main\java\com\mercurows\config\Springconfig.java

package com.mercurows.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.PropertySource;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@ComponentScan({ "com.mercurows.service" })
@PropertySource("classpath:jdbc.properties")
@Import({ JdbcConfig.class, MyBatisConfig.class })
@EnableTransactionManagement

public class Springconfig {
}

springmvc_ssm\src\main\resources\jdbc.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/jdbc
jdbc.username=root
jdbc.password=5508769123

Servlet配置部分

Servlet和Spring MVC DispatcherServlet的配置

springmvc_ssm\src\main\java\com\mercurows\config\ServletConfig.java

package com.mercurows.config;

import org.springframework.lang.Nullable;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class ServletConfig extends AbstractAnnotationConfigDispatcherServletInitializer{

    @Override
    @Nullable
    protected Class<?>[] getRootConfigClasses() {
        // 根配置
        return new Class[] { Springconfig.class };
    }

    @Override
    @Nullable
    protected Class<?>[] getServletConfigClasses() {
        // web请求专门配置
        // SpringMvcConfig容器可以访问Springconfig的容器反之不行
        return new Class[] { SpringMvcConfig.class };
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

    // 处理post中文参数乱码问题
    protected javax.servlet.Filter[] getServletFilters() {
        CharacterEncodingFilter filter = new CharacterEncodingFilter();
        filter.setEncoding("UTF-8");
        return new javax.servlet.Filter[] { filter };
    }
}

SpringMVC配置部分

springmvc_ssm\src\main\java\com\mercurows\config\SpringMvcConfig.java

package com.mercurows.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration
@ComponentScan({ "com.mercurows.controller", "com.mercurows.config" })
// 扫描config文件夹是为了扫描到：SpringMvcSupport文件
@EnableWebMvc
public class SpringMvcConfig {
}

拦截器，资源处理

springmvc_ssm\src\main\java\com\mercurows\config\SpringMvcSupport.java

package com.mercurows.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

import com.mercurows.controller.interceptor.ProjectInterceptor;

// 此类需要SpringMvcConfig类ComponentScan扫描到
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    @Autowired
    private ProjectInterceptor projectInterceptor;

    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        // 设置放行路径：让tomcat管理而不是让mvc拦截
        registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
        registry.addResourceHandler("/css/**").addResourceLocations("/css/");
        registry.addResourceHandler("/js/**").addResourceLocations("/js/");
        registry.addResourceHandler("/plugins/**").addResourceLocations("/plugins/");

    }

    // 配置拦截器
    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptor).addPathPatterns("/sudents", "/students/**");
        // 表示路径后面最后为/sudents或是包含/students之后的任意内容都将会被拦截器拦截
        // 别忘了要让SpringMvcConfig扫描ComponentScan加载该文件
    }
}

数据层

springmvc_ssm\src\main\java\com\mercurows\dao\StudentDao.java

package com.mercurows.dao;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;

import com.mercurows.domain.Student;

public interface StudentDao {

    //返回更新的行数用于判断操作是否失败
    @Insert("insert into student (name_ch,sex,age,name_en) values(#{nameCh},#{sex},#{age},#{nameEn})")
    public int save(Student student);

    @Update("update student set name_ch = #{nameCh}, sex = #{sex}, age = #{age}, name_en = #{nameEn} where id = #{id}")
    public int update(Student student);

    @Delete("delete from student where id = #{id}")
    public int delete(Integer id);

    @Results({
        @Result(property = "nameCh", column = "name_ch"),
        @Result(property = "nameEn", column = "name_en")
        // property：成员变量名字，column：数据库列名
        // 按照类成员变量名和数据库列名的对应关系添加 @Result 注解
    })
    @Select("select * from student where id = #{id}")
    public Student getById(Integer id);

    // 对于变量名与数据库列名不一致的还可以直接用取相同别名的方式
    @Select("select id,name_ch as nameCh,sex,age,name_en as nameEn from student")
    public List<Student> getAll();
}

domain层

springmvc_ssm\src\main\java\com\mercurows\domain\Student.java

package com.mercurows.domain;

public class Student {
    private Integer id;
    private String nameCh;
    private String nameEn;
    private String sex;
    private Integer age;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getNameCh() {
        return nameCh;
    }
    public void setNameCh(String nameCh) {
        this.nameCh = nameCh;
    }
    public String getNameEn() {
        return nameEn;
    }
    public void setNameEn(String nameEn) {
        this.nameEn = nameEn;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "student [id=" + id + ", nameCh=" + nameCh + ", nameEn=" + nameEn + ", sex=" + sex + ", age=" + age
                + "]";
    }
}

数据访问层

springmvc_ssm\src\main\java\com\mercurows\dao\StudentDao.java

package com.mercurows.dao;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;

import com.mercurows.domain.Student;

public interface StudentDao {

    //返回更新的行数用于判断操作是否失败
    @Insert("insert into student (name_ch,sex,age,name_en) values(#{nameCh},#{sex},#{age},#{nameEn})")
    public int save(Student student);

    @Update("update student set name_ch = #{nameCh}, sex = #{sex}, age = #{age}, name_en = #{nameEn} where id = #{id}")
    public int update(Student student);

    @Delete("delete from student where id = #{id}")
    public int delete(Integer id);

    @Results({
        @Result(property = "nameCh", column = "name_ch"),
        @Result(property = "nameEn", column = "name_en")
        // property：成员变量名字，column：数据库列名
        // 按照类成员变量名和数据库列名的对应关系添加 @Result 注解
    })
    @Select("select * from student where id = #{id}")
    public Student getById(Integer id);

    // 对于变量名与数据库列名不一致的还可以直接用取相同别名的方式
    @Select("select id,name_ch as nameCh,sex,age,name_en as nameEn from student")
    public List<Student> getAll();
}

业务逻辑层

springmvc_ssm\src\main\java\com\mercurows\service\StudentService.java

package com.mercurows.service;

import java.util.List;

import org.springframework.transaction.annotation.Transactional;

import com.mercurows.domain.Student;

@Transactional
public interface StudentService {

    // 保存
    public boolean save(Student student);

    // 修改
    public boolean update(Student student);

    // 根据id删除
    public boolean delete(Integer id);

    // 根据id获取
    public Student getById(Integer id);

    // 获取全部
    public List<Student> getAll();
}

springmvc_ssm\src\main\java\com\mercurows\service\impl\StudentServiceImpl.java

package com.mercurows.service.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.mercurows.controller.Code;
import com.mercurows.dao.StudentDao;
import com.mercurows.domain.Student;
import com.mercurows.exception.BusinessException;
import com.mercurows.exception.SystemException;
import com.mercurows.service.StudentService;

@Service
public class StudentServiceImpl implements StudentService {
    @Autowired
    StudentDao studentDao;

    @Override
    public boolean delete(Integer id) {
        System.out.println("studentserviceImpl delete ...");
        return studentDao.delete(id) > 0;
    }

    @Override
    public List<Student> getAll() {
        return studentDao.getAll();
    }

    @Override
    public Student getById(Integer id) {
        // 模拟异常
       // if (id == 1) {
       //     throw new BusinessException(Code.BUSINESS_ERR, "系统繁忙，请稍后重试");
      //  }
        // try{
        //     int i = 1/0;
        // } catch (Exception e) {
        //     throw new SystemException(Code.SYSTEM_TIMEOUT_ERR, "服务器访问超时，请重试", e);
        // }
        return studentDao.getById(id);
    }

    @Override
    public boolean save(Student student) {
        return studentDao.save(student) > 0;
    }

    @Override
    public boolean update(Student student) {
        return studentDao.update(student) > 0;
    }
}

表现层

拦截器层

springmvc_ssm\src\main\java\com\mercurows\controller\interceptor\ProjectInterceptor.java

package com.mercurows.controller.interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

// 使其受是springMVC管理，能让springmvc加载该类
@Component
public class ProjectInterceptor implements HandlerInterceptor {

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
            @Nullable Exception ex) throws Exception {
                System.out.println("afterCompletion");
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            @Nullable ModelAndView modelAndView) throws Exception {
                System.out.println("postHandle");
    }

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        // 获取请求头
        String contenType = request.getHeader("Content-Type");
        // 获取调用的方法
        HandlerMethod hm = (HandlerMethod) handler;
        System.out.println("preHandle==>" + contenType + hm);
        return true;
        // 如果是false，将终止原始操作
        // 只会执行preHandle方法，而postHandle与afterCompletion都不会执行
    }
}

控制器层

springmvc_ssm\src\main\java\com\mercurows\controller\Code.java

package com.mercurows.controller;

public class Code {
    public static final Integer SAVE_OK = 20011;
    public static final Integer DELETE_OK = 20021;
    public static final Integer UPDATE_OK = 20031;
    public static final Integer GET_OK = 20041;

    public static final Integer SAVE_ERR = 20010;
    public static final Integer DELETE_ERR = 20020;
    public static final Integer UPDATE_ERR = 20030;
    public static final Integer GET_ERR = 20040;

    public static final Integer SYSTEM_ERR = 50001;
    public static final Integer SYSTEM_TIMEOUT_ERR = 50002;
    public static final Integer SYSTEM_UNKNOW_ERR = 59999;

    public static final Integer BUSINESS_ERR = 60002;

}

springmvc_ssm\src\main\java\com\mercurows\controller\Result.java

package com.mercurows.controller;

public class Result {
    private Object data; // 数据
    private Integer code; // 状态码
    private String msg; // 出错时的信息

    public Result(Integer code, Object data, String msg) {
        this.data = data;
        this.code = code;
        this.msg = msg;
    }

    public Result(Integer code, Object data) {
        this.data = data;
        this.code = code;
    }

    public Result() {
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

}

springmvc_ssm\src\main\java\com\mercurows\controller\ProjectExceptionAdvice.java

package com.mercurows.controller;

import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import com.mercurows.exception.BusinessException;
import com.mercurows.exception.SystemException;

// 处理异常类
@RestControllerAdvice
public class ProjectExceptionAdvice {
    // 定义当前类是用来处理异常的
    @ExceptionHandler(SystemException.class)
    public Result doSystemException(SystemException ex) {
        // 记录日志
        // 发送消息给运维
        // 发送邮件給开发人员

        // 规范统一结果
        return new Result(ex.getCode(), null, ex.getMessage());
    }

    @ExceptionHandler(BusinessException.class)
    public Result doBusinessException(BusinessException ex) {
        // 规范统一结果
        return new Result(ex.getCode(), null, ex.getMessage());
    }

    // 处理第三方异常
    @ExceptionHandler(Exception.class)
    public Result doException(Exception ex) {
        // 规范统一结果
        ex.printStackTrace();
        return new Result(Code.SYSTEM_UNKNOW_ERR, null, "捕获到异常");
    }
}

springmvc_ssm\src\main\java\com\mercurows\controller\StudentController.java

package com.mercurows.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.mercurows.domain.Student;
import com.mercurows.service.StudentService;

@RestController
@RequestMapping("/students")
public class StudentController {
    @Autowired
    StudentService studentService;

    @DeleteMapping("/{id}")
    public Result delete(@PathVariable Integer id) {
        boolean flag = studentService.delete(id);
        return new Result(flag ? Code.DELETE_OK : Code.DELETE_ERR, flag);
    }

    @GetMapping
    public Result getAll() {
        List<Student> students = studentService.getAll();
        Integer code = students == null ? Code.GET_ERR : Code.GET_OK;
        String msg = students == null ? "数据错误，请重试" : "";
        return new Result(code, students, msg);
    }

    @GetMapping("/{id}")
    public Result getById(@PathVariable Integer id) {
        // int i = 1 / 0;
        Student student = studentService.getById(id);
        Integer code = student == null ? Code.GET_ERR : Code.GET_OK;
        String msg = student == null ? "数据错误，请重试" : "";
        System.out.println(student);
        return new Result(code, student, msg);
    }

    @PostMapping
    public Result save(@RequestBody Student student) {
        boolean flag = studentService.save(student);
        return new Result(flag ? Code.SAVE_OK : Code.SAVE_ERR, flag);
    }

    @PutMapping
    public Result update(@RequestBody Student student) {
        boolean flag = studentService.update(student);
        return new Result(flag ? Code.UPDATE_OK : Code.UPDATE_ERR, flag);
    }
}

异常处理层

springmvc_ssm\src\main\java\com\mercurows\exception\BusinessException.java

package com.mercurows.exception;

public class BusinessException extends RuntimeException {
    private Integer code;

    public BusinessException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public BusinessException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }
}

springmvc_ssm\src\main\java\com\mercurows\exception\SystemException.java

package com.mercurows.exception;

public class SystemException extends RuntimeException {
    private Integer code;

    public SystemException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public SystemException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }
}

测试

springmvc_ssm\src\test\java\service\StudentServiceTest.java

package service;
import java.util.List;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import com.mercurows.config.Springconfig;
import com.mercurows.domain.Student;
import com.mercurows.service.StudentService;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = Springconfig.class)
public class StudentServiceTest {
    @Autowired
    private StudentService service;

    @Test
    public void testGetById() {
        Student student = service.getById(1);
        System.out.println(student);
    }

    @Test
    public void testGetAll() {
        List<Student> all = service.getAll();
        System.out.println(all);
    }
}

项目结构