JWT整理

1.标头(header)
2.有效载荷(Payload)
3.签名(signature)

header
标头通常是由两部分组成:令牌的类型(jwt)和所使用的签名算法，例如 HMAC SHA256或RSA
它会使用BASE64 编码组成jwt结构的第一部分
// base64是一种编码，可以被翻译回成原来的样子。并不是一种加密过程
{
“alg” : “HS256”,
“typ”:“JWT”
}
base64对json数据进行的编码

payload
–令牌的第二部分是有效负载，其中包含声明，声明是有关实体（通常是用户）和其他数据的声明，同样的，它会使用base64编码组成jwt结构的第二部分
{
“name”:“zhangdan”
“admin”:true
}

signatrue
前面的都在使用base64进行编码，即前端可以解开知道里面的信息.singature需要使用header和payload以及我们提供的一个秘钥，然后使用header中指定的算法(hs256)进行签名，签名作用是保证jwt秘钥被篡改过

构建一个令牌

    @Test
    void contextLoads() {
        HashMap map = new HashMap<>();
        Calendar instance = Calendar.getInstance();
        instance.add(Calendar.DAY_OF_MONTH,20);

        String token = JWT.create()
                .withHeader(map) //header
                //payload
                .withClaim("userId", 323)
                .withClaim("username", "xiaohao")
                //过期时间
                .withExpiresAt(instance.getTime())
                //签名
                .sign(Algorithm.HMAC256("Life is too short for me to learn Python"));

        System.out.println(token);
    }

运行结果

eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJleHAiOjE2NTc4MDg0
NzgsInVzZXJJZCI6MzIzLCJ1c2VybmFtZSI6InhpYW9oYW8ifQ.u0nQRy
cV2ovv8jb4NFPsWRibPAr9n5hYJVzIZcVwx98

解析秘钥

   @Test
    public void test(){
        JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256("Life is too short for me to learn Python")).build();
        DecodedJWT verify = jwtVerifier.verify("eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJleHAiOjE2NTc4MDgzOTAsInVzZXJJZCI6MzIzLCJ1c2VybmFtZSI6InhpYW9oYW8ifQ.m9bX3sKZetWrqRR10DePuTgEocqKVKTR6JqfcYnYOQ4");
        System.out.println(verify.getClaim("userId").asInt());
        System.out.println(verify.getClaim("username").asString());
    }

运行结果

323
xiaohao

package com.wh.utils;
import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTCreator;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.interfaces.DecodedJWT;

import java.util.Calendar;
import java.util.Map;

public class jwtUtils {
    
    private static final String sing="Life is too short for me to learn Python";
    public static String getToken(Map map){
        Calendar instance = Calendar.getInstance();
        instance.add(Calendar.DAY_OF_MONTH,20);

        JWTCreator.Builder builder = JWT.create();
        //payload
        map.forEach((k,v)->{
            builder.withClaim(k,v);
        });
        String token = builder.withExpiresAt(instance.getTime())
                .sign(Algorithm.HMAC256(sing));
    
        return token;

    }
    
    public static  DecodedJWT verify(String token){
      return  JWT.require(Algorithm.HMAC256(sing)).build().verify(token);
    }
   
}

在maven里面加入一下

		
            org.projectlombok
            lombok
            1.18.16
        

        
            com.alibaba
            druid
            1.1.19
        

        
            mysql
            mysql-connector-java
            8.0.25
        

        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.2.1
        

配置application.properties

# 应用名称
spring.application.name=jwt
# 应用服务 WEB 访问端口
server.port=9999
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/jwt?characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=123456
mybatis.type.aliases-package=com.wh.entity
mybatis.mapper-locations=classpath:com/wh/mapper
    private static final String sing="Life is too short for me to learn Python";
    public Object getToken;

    public static String getToken(HashMap map){
        Calendar instance = Calendar.getInstance();
        instance.add(Calendar.DAY_OF_MONTH,20);

        JWTCreator.Builder builder = JWT.create();
        //payload
        map.forEach((k,v)->{
            builder.withClaim(k,v);
        });
        String token = builder.withExpiresAt(instance.getTime())
                .sign(Algorithm.HMAC256(sing));

        return token;

    }
    
    public static  DecodedJWT verify(String token){
      return  JWT.require(Algorithm.HMAC256(sing)).build().verify(token);
    }

}

测试

localhost:9999/user/login?name=zs&password=123

结果

{
    "msg": "认证成功",
    "state": true,
    "token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJuYW1lIjoienMiLCJpZCI6IjEiLCJleHAiOjE2NTc4ODQzNTl9.mpsj60Nf9f04s5uKPE-raL7ygfU9sV7GyccwSIWjoRM"
}

token解析

 public Map test(String token) {
        HashMap map = new HashMap<>();
        log.info("当前token为:[{}]", token);
        try {
            DecodedJWT verify = jwtUtils.verify(token);
            map.put("state", true);
            map.put("msg", "请求成功");
            return map;
        } catch (SignatureVerificationException e) {
            e.printStackTrace();
            map.put("msg", "无效签名");
        } catch (TokenExpiredException e) {
            e.printStackTrace();
            map.put("msg", "token过期");
        } catch (AlgorithmMismatchException e) {
            e.printStackTrace();
            map.put("msg", "token算法不一致");
        } catch (Exception e) {
            e.printStackTrace();
            map.put("msg", "无效签名");
        }
        map.put("state", false);
        return map;
    }

解析代码比较冗余，使用拦截器
新建一个interceptor的包

package com.wh.interceptors;

import com.auth0.jwt.exceptions.AlgorithmMismatchException;
import com.auth0.jwt.exceptions.SignatureVerificationException;
import com.auth0.jwt.exceptions.TokenExpiredException;
import com.auth0.jwt.interfaces.DecodedJWT;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.wh.utils.jwtUtils;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;

public class JwtInterceptor implements HandlerInterceptor {
    @Resource
    com.wh.utils.jwtUtils jwtUtils;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HashMap map = new HashMap<>();
        //       获取请求头的令牌
        String token = request.getHeader("token");
        try {
            DecodedJWT verify = jwtUtils.verify(token);
            map.put("state", true);
            map.put("msg", "请求成功");
            return true;
        } catch (SignatureVerificationException e) {
            e.printStackTrace();
            map.put("msg", "无效签名");
        } catch (TokenExpiredException e) {
            e.printStackTrace();
            map.put("msg", "token过期");
        } catch (AlgorithmMismatchException e) {
            e.printStackTrace();
            map.put("msg", "token算法不一致");
        } catch (Exception e) {
            e.printStackTrace();
            map.put("msg", "无效签名");
        }
        map.put("state",false);
//        将map转为json jackjson
        String json = new ObjectMapper().writeValueAsString(map);
        response.setContentType("application/json; charset=UTF-8");
        response.getWriter().println(json);
        return  false;
    }
}

最后建一个拦截器

package com.wh.config;

import com.wh.interceptors.JwtInterceptor;
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 InterceptorConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new JwtInterceptor())
                .addPathPatterns("/user/test")
                .excludePathPatterns("/user/login");
        //所有用户都放行，其他接口都验证
    }
}