ok了家人们今天我们学习SpringMvc，之后学习SpringBoot，let‘s go

六.拦截器

6.1 拦截器概述

package com.cjx.Interceptor;

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

@Component
public class MyInterceptor implements HandlerInterceptor {
    //执行方法前执行
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        //false表示不执行该方法
        return true;
    }
    //执行方法后执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle");
    }

    //方法执行后(如果返回一个jsp页面执行)
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion");
    }
}

package com.cjx.config;

import com.cjx.Interceptor.MyInterceptor;
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;

//当前类需要设置为配置类，并被扫描加载
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {

    @Autowired
    private MyInterceptor myInterceptor;

    //配置加载拦截器
    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        super.addInterceptors(registry);
        //注册拦截器，可以注册多个
        registry.addInterceptor(myInterceptor).addPathPatterns("/emp","/emp/**");
    }

    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        //当访问/pages/xxxx时候，从/pages目录下查找内容
        //http://loclahost:8080/js/axios-0.18.0.js
        registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
        registry.addResourceHandler("/js/**").addResourceLocations("/js/");
        registry.addResourceHandler("/css/**").addResourceLocations("/css/");
        registry.addResourceHandler("/img/**").addResourceLocations("/img/");
        registry.addResourceHandler("/plugins/**").addResourceLocations("/plugins/");
    }
}

 使用RESTful操作资源：使用URL+请求方式确定具体的动作

http : //localhost:8080/springmvc02/user/1

查询 ,GET

http : //localhost:8080/springmvc02/user

新增 ,POST

http : //localhost:8080/springmvc02/user

更新 ,PUT

http : //localhost:8080/springmvc02/user/1

删除 ,DELETE

RESTFul风格好处：

• 安全：使用问号键值对的方式给服务器传递数据太明显，
  容易被人利用来对系统进行破坏。使用 REST 风格携带数
  据不再需要明显的暴露数据的名称。
• 风格统一： URL 地址整体格式统一，从前到后始终都使用

  斜杠划分各个单词，用简单一致的格式表达语义。
   
• 简洁：过去做增删改查操作需要设计 4 个不同的 URL ，现在
  一个就够了。

查询 / emp / editEmp ? empId = 2 / emp / 2 请求方式：GET

保存 / emp / saveEmp / emp 请求方式：POST

更新 / emp / updateEmp / emp 请求方式：PUT

删除 / emp / removeEmp ? empId = 2 / emp / 2 请求方式：DELETE

7.2 RESTFul案例

@Controller
public class EmpController {
//根据ID查询
@RequestMapping(value =
"/emp/{empId}",method = RequestMethod.GET)
@ResponseBody
public Result
findById(@PathVariable("empId") Integer empId){
Result result=new Result(20001,"查询成
功",empId);
return result;
}
//查询所有
@RequestMapping(value = "/emp",method =
RequestMethod.GET)
@ResponseBody
public Result findAll(){
Result result=new Result(20002,"查询成
功",null);
return result;
}
//保存
@RequestMapping(value = "/emp",method =
RequestMethod.POST)
@ResponseBody
public Result save(@RequestBody Emp emp){
Result result=new Result(20003,"保存成
功",emp);
return result;
}
//删除
@RequestMapping(value =
"/emp/{empId}",method = RequestMethod.DELETE)
@ResponseBody
public Result delete(@PathVariable("empId")
Integer empId){
Result result=new Result(20004,"删除成
功",empId);
return result;
}


//修改
@RequestMapping(value = "/emp",method =
RequestMethod.PUT)
@ResponseBody
public Result update(@RequestBody Emp emp){
Result result=new Result(20005,"修改成
功",emp);
return result;
}
}

 7.3 注解优化

@RestController
@RequestMapping("/emp")
public class EmpController {
//根据ID查询
@GetMapping("/{empId}")
@ResponseBody
public Result
findById(@PathVariable("empId") Integer empId){
Result result=new Result(20001,"查询成
功",empId);
return result;
}
//查询所有
@GetMapping
@ResponseBody
public Result findAll(){
Result result=new Result(20002,"查询成
功",null);
return result;
}
//保存
@PostMapping
@ResponseBody
public Result save(@RequestBody Emp emp){
Result result=new Result(20003,"保存成
功",emp);
return result;
}
//删除
@DeleteMapping("/{empId}")
@ResponseBody
public Result delete(@PathVariable("empId")
Integer empId){
Result result=new Result(20004,"删除成
功",empId);
return result;
}
//修改
@PutMapping
@ResponseBody
public Result update(@RequestBody Emp emp){
Result result=new Result(20005,"修改成
功",emp);
return result;
}
}

ok了家人们明天见byebye