用户--注册

查询用户，判断用户名是否被占用。

1.没有被占用，则注册

2.被占用，则显示用户名已被占用！

3.添加注解：用户名和密码的长度为5-16。

@Pattern(regexp = "^\\S{5,16}$") String username, @Pattern(regexp = "^\\S(5,16)$") String password

controller : UserController

import com.example.pojo.Result;
import com.example.pojo.User;
import com.example.service.UserService;
import jakarta.validation.constraints.Pattern;
import org.springframework.beans.factory.annotation.Autowired;

@RestController
@RequestMapping("/user")
@Validated
public class UserController {
    @Autowired
    private 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 user = userService.findByUserName(username);
        if(user == 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！");
        }
    }
}

 

service : UserService

public interface UserService {
    //根据用户名查询用户
    User findByUserName(String username);

    //注册
    void register(String username, String password);
}

 

service：impl：UserServiceImpl

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
    @Override
    public User findByUserName(String username) {
        User u = userMapper.findByUserName(username);
        return u;
    }

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

util：Md5Util

package com.example.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);
    }

}

 

mapper : UserMapper

@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);
}