1.1 由于返回数据都是以下这种格式，那么久再编写一个result实体类

报错了，原因是没有构造方法

可以使用lombok的注解自动生成，添加无参的构造器和全参的构造器

package com.geji.pojo;import lombok.AllArgsConstructor;
import lombok.NoArgsConstructor;//统一响应结果
@NoArgsConstructor
@AllArgsConstructor
@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);}
}

接口开发的流程：

Controller接收路由-->Service执行和数据库的逻辑操作-->Mapper映射到真实的数据库操作

1.1 注册

1.1.1 创建相应的类和接口，impl实体类实现impl接口

1.1.2 编写UserControl

package com.geji.controller;import com.geji.pojo.Result;
import com.geji.pojo.User;
import com.geji.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/user")
public class UserController {@Autowiredprivate UserService userService;@PostMapping("/register")public Result register(String username, String password) {//查询用户User u = userService.findByUserName(username);if (u == null) {//没有占用//注册userService.register(username, password);return Result.success();} else {//占用return Result.error("用户名已被占用");}}
}

1.1.3 编写UserService

package com.geji.service;import com.geji.pojo.User;public interface UserService {//根据用户名查找用户User findByUserName(String username);//根据用户名和密码注册void register(String username, String password);
}

1.1.4 编写UserServiceImpl

package com.geji.service.impl;import com.geji.mapper.UserMapper;
import com.geji.pojo.User;
import com.geji.service.UserService;
import com.geji.utils.Md5Util;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class UserServiceImpl implements UserService {@Autowiredprivate UserMapper userMapper;@Overridepublic User findByUserName(String username) {User u = userMapper.findByUserName(username);return u;}@Overridepublic void register(String username, String password) {//加密String md5String = Md5Util.getMD5String(password);//添加userMapper.add(username,md5String);}
}

1.1.4 MD5加密算法

package com.geji.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);}}

1.1.5 编写UserMapper

package com.geji.mapper;import com.geji.pojo.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;@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@Insert("insert into user(username,password,create_time,update_time)" +" values(#{username},#{password},now(),now())")void add(String username, String password);
}

1.1.6 postman接口测试

1.1.6.1 下载安装postman

Download Postman | Get Started for Free

1.1.6.2 创建workspaces

1.1.6.3 创建collections测试用例

1.1.6.3.1 注册接口，post，body，urlencoded

成功

1.1.7 以上Controller类中没有对username和password做参数校验，Spring中提供了注解

1.1.7.1 引入spring validation起步依赖

1.1.7.2 在参数前加上@Pattern注解

1.1.7.3 在Controller类上添加@Validated注解

package com.geji.controller;import com.geji.pojo.Result;
import com.geji.pojo.User;
import com.geji.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;@RestController
@RequestMapping("/user")
@Validated
public class UserController {@Autowiredprivate UserService userService;@PostMapping("/register")public Result register(@Pattern(regexp = "^\\S{5,16}$") String username, @Pattern(regexp = "^\\S{5,16}$") String password) {//查询用户User u = userService.findByUserName(username);if (u == null) {//没有占用//注册userService.register(username, password);return Result.success();} else {//占用return Result.error("用户名已被占用");}}
}

1.1.7.4 编写全局异常处理器，添加exception包，添加注释@RestControllerAdvice

package com.geji.exception;import com.geji.pojo.Result;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;@RestControllerAdvice
public class GlobalExceptionHandler {@ExceptionHandler(Exception.class)public Result handleException(Exception e){e.printStackTrace();return Result.error(StringUtils.hasLength(e.getMessage())? e.getMessage() : "操作失败");}
}