SpringBoot | 使用jwt令牌实现登录认证，使用Md5加密实现注册

对于登录认证中的令牌，其实就是一段字符串，那为什么要那么麻烦去用jwt令牌？其实对于登录这个业务，在平常我们实现这个功能时，可能大部分都是通过比对用户名和密码，只要正确，就登录成功；而并不会考虑到使用jwt令牌。

但是其实使用jwt令牌的好处是：

它可以承载业务数据，减少后续请求查询数据库的次数；
并且可以防篡改，保证信息的合法性和有效性。

前提：

pom.xml文件添加以下依赖：

<!--      java-jwt坐标-->
      <dependency>
          <groupId>com.auth0</groupId>
          <artifactId>java-jwt</artifactId>
          <version>4.4.0</version>
      </dependency>

<!--      单元测试的坐标-->
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-test</artifactId>
      </dependency>
      <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>3.8.1</version>
          <scope>compile</scope>
      </dependency>

测试代码：

package com.xu;

import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.interfaces.Claim;
import com.auth0.jwt.interfaces.DecodedJWT;
import org.junit.jupiter.api.Test;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;

public class JwtTest {
    @Test
    public void testGen(){
        Map<String,Object> claims=new HashMap<>();
        claims.put("id",1);
        claims.put("username","张三");

        //生成jwt的代码
        String token= JWT.create().withClaim("user",claims)//添加载荷
                .withExpiresAt(new Date(System.currentTimeMillis()+1000*60*60*3))
                .sign(Algorithm.HMAC256("xu"));//指定算法，配置密钥
        System.out.println(token);
    }

    @Test
    public void testParse(){
        //定义字符串，模拟用户传递过来的token
        String token="eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjp7ImlkIjoxLCJ1c2VybmFtZSI6IuW8oOS4iSJ9LCJleHAiOjE3MTk0ODgxMjR9.RtU7DxCKObLO2MyVlh0g7GbwxCBI2H23y9kn0kt34Lc";
        JWTVerifier jwtVerifier=JWT.require(Algorithm.HMAC256("xu")).build();

        DecodedJWT decodedJWT= jwtVerifier.verify(token);//验证token，生成一个解析后的jwt对象
        Map<String, Claim> claims=decodedJWT.getClaims();
        System.out.println(claims.get("user"));
    }

}

jwt令牌的生成：

验证jwt令牌：

使用jwt令牌实现登录功能，并且进入需要登录为前提的页面进行判断

项目框架目录：

pojo层：

package com.xu.pojo;
import lombok.Data;

import java.time.LocalDateTime;
//lombok  在编译阶段,为实体类自动生成setter  getter toString
// pom文件中引入依赖   在实体类上添加注解
@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
}

package com.xu.pojo;


import lombok.AllArgsConstructor;
import lombok.Data;
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);
    }
}

service层：

package com.xu.service;

import com.xu.pojo.User;
import org.springframework.stereotype.Service;

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

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

package com.xu.service.impl;

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

@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);

    }
}

mapper层：

package com.xu.mapper;

import com.xu.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);
}

utils层：

实现登录的密码加密功能：

package com.xu.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);
    }

}

实现注册的jwt令牌功能：

package com.xu.utils;

import com.auth0.jwt.JWT;
import com.auth0.jwt.algorithms.Algorithm;

import java.util.Date;
import java.util.Map;

public class JwtUtil {

    private static final String KEY = "xu";
	
	//接收业务数据,生成token并返回
    public static String genToken(Map<String, Object> claims) {
        return JWT.create()
                .withClaim("claims", claims)
                .withExpiresAt(new Date(System.currentTimeMillis() + 1000 * 60 * 60 * 12))
                .sign(Algorithm.HMAC256(KEY));
    }

	//接收token,验证token,并返回业务数据
    public static Map<String, Object> parseToken(String token) {
        return JWT.require(Algorithm.HMAC256(KEY))
                .build()
                .verify(token)
                .getClaim("claims")
                .asMap();
    }

}

controller层：

package com.xu.controller;

import com.xu.pojo.Result;
import com.xu.pojo.User;
import com.xu.service.UserService;
import com.xu.utils.JwtUtil;
import com.xu.utils.Md5Util;
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;

import java.util.HashMap;
import java.util.Map;

@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 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");
        }
    }
    @PostMapping("login")
    public Result<String> login(@Pattern(regexp = "^\\S{5,16}$")String username, @Pattern(regexp = "^\\S{5,16}$")String password){
        //根据用户名查询用户
        User loginUser=userService.findByUserName(username);

        //判断用户是否存在
        if(loginUser==null){
            return Result.error("用户名错误");
        }

        //判断密码是否正确
        if(Md5Util.getMD5String(password).equals(loginUser.getPassword())){
            //登录成功
            Map<String,Object> claims=new HashMap<>();
            claims.put("id",loginUser.getId());
            claims.put("username",loginUser.getUsername());
            String token= JwtUtil.genToken(claims);

            return Result.success(token);
        }
        return Result.error("密码错误");

    }
}

使用localhost:8080/article/list测试登录中jwt令牌的功能：

package com.xu.controller;

import com.xu.pojo.Result;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
@RequestMapping("/article")
public class ArticleController {
    @GetMapping("/list")
    public Result<String> list(){
        return Result.success("所有文章数据");
    }
}

interceptors层（令牌验证）：

package com.xu.interceptors;

import com.xu.pojo.Result;
import com.xu.utils.JwtUtil;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

import java.util.Map;

@Component
public class LoginInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //令牌验证
        String token=request.getHeader("Authorization");
        //验证token
        try {
            Map<String,Object> claims= JwtUtil.parseToken(token);
            //放行
            return true;
        }catch (Exception e){
            response.setStatus(401);
            //不放行
            return false;
        }
    }
}

exception层：

package com.xu.exception;

import com.xu.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");

    }
}

config层（没有header的“令牌”，不拦截登录，注册页面）：

package com.xu.config;

import com.xu.interceptors.LoginInterceptor;
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.WebMvcConfigurer;
@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private LoginInterceptor loginInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        //登录接口和注册接口不拦截
        registry.addInterceptor(loginInterceptor).excludePathPatterns("/user/login","/user/register");
    }
}

pom.xml文件：

<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>

  <parent>
    <artifactId>spring-boot-starter-parent</artifactId>
    <groupId>org.springframework.boot</groupId>
    <version>3.1.3</version>
  </parent>
  <groupId>com.xu</groupId>
  <artifactId>big-news</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>big-news</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>
<!--      <version>3.3.0</version>-->
    </dependency>

<!--    mybatis依赖-->
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>3.0.0</version>
    </dependency>
<!--    mysql驱动依赖-->
    <dependency>
      <groupId>com.mysql</groupId>
      <artifactId>mysql-connector-j</artifactId>
<!--      <version></version>-->
    </dependency>

<!--      lombok依赖-->
      <dependency>
          <groupId>org.projectlombok</groupId>
          <artifactId>lombok</artifactId>
      </dependency>

<!--      validation依赖-->
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-validation</artifactId>
      </dependency>

<!--      java-jwt坐标-->
      <dependency>
          <groupId>com.auth0</groupId>
          <artifactId>java-jwt</artifactId>
          <version>4.4.0</version>
      </dependency>

<!--      单元测试的坐标-->
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-test</artifactId>
      </dependency>
      <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>3.8.1</version>
          <scope>compile</scope>
      </dependency>

  </dependencies>
</project>

分析：

用户登录：

用户登录成功后，系统会自动下发JWT令牌，然后在后续的每次请求中，浏览器都需要在请求头header中携带到服务端，请求头的名称为 Authorization，值为true 登录时下发的JWT令牌。

用户注册：

用户注册使用Md5加密，防止数据库的密码被泄露，并且在用户注册时使用validation校验参数。