Java 小项目开发日记 01（注册接口的开发）

1.项目需求

完成注册接口

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2.项目目录

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3. 配置文件（pom.xml）

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <!--继承父工程-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.6</version>
    </parent>
    <groupId>com.zhong</groupId>
    <artifactId>big-event</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>big-event</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!--web 依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--MyBatis 依赖-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>

        <!--MySQL 依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.29</version>
        </dependency>
        <!--lombok 依赖-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <!--参数校验依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
    </dependencies>
</project>

SQL 创建表

-- 创建数据库
create database big_event;

-- 使用数据库
use big_event;

-- 用户表
create table user (
	id int unsigned primary key auto_increment comment 'ID',
    username varchar(20) not null unique comment '用户名',
    password varchar(32)  comment '密码',
    nickname varchar(10)  default '' comment '昵称',
    email varchar(128) default '' comment '邮箱',
    user_pic varchar(128) default '' comment '头像',
    create_time datetime not null comment '创建时间',
    update_time datetime not null comment '修改时间'
) comment '用户表';

resources 配置

resources
- application.yml

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/big_event
    username: root
    password: 123456

Java 代码

controller

UserController

package com.zhong.controller;

import com.zhong.pojo.Result;
import com.zhong.pojo.User;
import com.zhong.service.UserService;
import jakarta.validation.constraints.Pattern;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @ClassName : UserController
 * @Description : 用户操作
 * @Author : zhx
 * @Date: 2024-02-27 20:40
 */
@RestController
@RequestMapping("/user")
@Validated
public class UserController {
    @Autowired
    private UserService userService;

    @PostMapping("/register")
    public Result register(@Pattern(regexp = "^\\S{6,16}$") String username, @Pattern(regexp = "^\\S{6,16}$") String password) {
        // 查询用户
        User u = userService.findByUserName(username);
        if (u == null) {
            // 没有被占用
            // 注册
            userService.registerUser(username, password);
            return Result.success();
        } else {
            // 被占用
            return Result.error("用户名已被占用......");
        }
    }
}

exception

GlobalExceptionHandler

package com.zhong.exception;

import com.zhong.pojo.Result;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

/**
 * @ClassName : GlobalExceptionHandler
 * @Description : 全局异常处理
 * @Author : zhx
 * @Date: 2024-02-27 21:37
 */
@RestControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(Exception.class)
    public Result handlerException(Exception e) {
        e.printStackTrace();
        return Result.error(StringUtils.hasLength(e.getMessage()) ? e.getMessage() : "操作失败");
    }
}

mapper

UserMapper

package com.zhong.mapper;

import com.zhong.pojo.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Service;

/**
 * @ClassName : UserMapper
 * @Description : 用户业务逻辑
 * @Author : zhx
 * @Date: 2024-02-27 20:42
 */
@Mapper
public interface UserMapper {
    // 根据用户名查询用户
    @Select("select * from user where username=#{username}")
    User findByUserName(String username);

    // 添加用户
    @Insert("insert into user(username, password, create_time, update_time) values (#{username}, #{password}, now(), now()) ")
    void registerUser(String username, String password);
}

pojo

Result

package com.zhong.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

//统一响应结果
@AllArgsConstructor
@NoArgsConstructor
@Data
public class Result<T> {
    private Integer code;//业务状态码  0-成功  1-失败
    private String message;//提示信息
    private T data;//响应数据

    //快速返回操作成功响应结果(带响应数据)
    public static <E> Result<E> success(E data) {
        return new Result<>(0, "操作成功", data);
    }

    //快速返回操作成功响应结果
    public static Result success() {
        return new Result(0, "操作成功", null);
    }

    public static Result error(String message) {
        return new Result(1, message, null);
    }
}

User

package com.zhong.pojo;

import lombok.Data;

import java.time.LocalDateTime;
@Data
public class User {
    private Integer id;//主键ID
    private String username;//用户名
    private String password;//密码
    private String nickname;//昵称
    private String email;//邮箱
    private String userPic;//用户头像地址
    private LocalDateTime createTime;//创建时间
    private LocalDateTime updateTime;//更新时间
}

service

impl
- UserServiceImpl

package com.zhong.service.impl;

import com.zhong.mapper.UserMapper;
import com.zhong.pojo.User;
import com.zhong.service.UserService;
import com.zhong.utils.Md5Util;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @ClassName : UserServiceImpl
 * @Description : 用户接口实现类
 * @Author : zhx
 * @Date: 2024-02-27 20:41
 */
@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;
    @Override
    public User findByUserName(String username) {
        return userMapper.findByUserName(username);
    }

    @Override
    public void registerUser(String username, String password) {
        // 加密
        String md5String = Md5Util.getMD5String(password);
        // 添加
        userMapper.registerUser(username, md5String);
    }
}

UserService

package com.zhong.service;

import com.zhong.pojo.User;

/**
 * @ClassName : UserService
 * @Description : 用户接口
 * @Author : zhx
 * @Date: 2024-02-27 20:40
 */
public interface UserService {
    // 根据用户名查询用户
    User findByUserName(String username);
    // 注册用户
    void registerUser(String username, String password);
}

utils

Md5Util

package com.zhong.utils;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Md5Util {
    /**
     * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,apache校验下载的文件的正确性用的就是默认的这个组合
     */
    protected static char hexDigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

    protected static MessageDigest messagedigest = null;

    static {
        try {
            messagedigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException nsaex) {
            System.err.println(Md5Util.class.getName() + "初始化失败，MessageDigest不支持MD5Util。");
            nsaex.printStackTrace();
        }
    }

    /**
     * 生成字符串的md5校验值
     *
     * @param s
     * @return
     */
    public static String getMD5String(String s) {
        return getMD5String(s.getBytes());
    }

    /**
     * 判断字符串的md5校验码是否与一个已知的md5码相匹配
     *
     * @param password  要校验的字符串
     * @param md5PwdStr 已知的md5校验码
     * @return
     */
    public static boolean checkPassword(String password, String md5PwdStr) {
        String s = getMD5String(password);
        return s.equals(md5PwdStr);
    }


    public static String getMD5String(byte[] bytes) {
        messagedigest.update(bytes);
        return bufferToHex(messagedigest.digest());
    }

    private static String bufferToHex(byte bytes[]) {
        return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte bytes[], int m, int n) {
        StringBuffer stringbuffer = new StringBuffer(2 * n);
        int k = m + n;
        for (int l = m; l < k; l++) {
            appendHexPair(bytes[l], stringbuffer);
        }
        return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
        char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换, >>>
        // 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同
        char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }
}

BigEventApplication

package com.zhong;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class BigEventApplication {
    public static void main(String[] args) {
        SpringApplication.run(BigEventApplication.class, args);
    }
}