接上一篇：分布式6大核心专题_分布式Session
https://gblfy.blog.csdn.net/article/details/113802195

实现流程
1.引入JWT组件
2.依赖+代码（拦截器+注册拦截器+常量）+配置
3.演示同一程序启动8081端口和8082端口模拟2个服务器分布式
4.调用8081登录接口
5.调用8081获取用户信息接口
6.调用8082获取用户信息接口

1. 引入JWT组件

   <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>com.auth0</groupId><artifactId>java-jwt</artifactId><version>3.10.3</version></dependency>

2. 代码+配置

application.yml

server:port: 8081 #应用web端口

package com.gblfy.distributed.session.controller;import com.auth0.jwt.JWT;
import com.auth0.jwt.algorithms.Algorithm;
import com.gblfy.distributed.session.consts.Const;
import org.springframework.web.bind.annotation.*;import java.util.Date;@RequestMapping("/user")
@RestController
public class UserController {@GetMapping("/loginWithJwt")public String loginWithJwt(@RequestParam String username,@RequestParam String password) {Algorithm algorithm = Algorithm.HMAC256(Const.JWT_KEY);String token = JWT.create().withClaim(Const.LOGIN_USER, username).withClaim(Const.UID, 1).withExpiresAt(new Date(System.currentTimeMillis() + 3600000)).sign(algorithm);return token;}@GetMapping("/infoWithJwt")public String infoWithJwt(@RequestAttribute String login_user) {return login_user;}
}

登录拦截器

package com.gblfy.distributed.session.intercepter;import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTDecodeException;
import com.auth0.jwt.exceptions.TokenExpiredException;
import com.auth0.jwt.interfaces.DecodedJWT;
import com.gblfy.distributed.session.consts.Const;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;@Component
public class LoginIntercepter extends HandlerInterceptorAdapter {/*** 返回true, 表示不拦截，继续往下执行* 返回false/抛出异常，不再往下执行* @param request* @param response* @param handler* @return* @throws Exception*/@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String token = request.getHeader(Const.JWT_TOKEN);if (StringUtils.isEmpty(token)) {throw new RuntimeException("token为空");}Algorithm algorithm = Algorithm.HMAC256(Const.JWT_KEY);JWTVerifier verifier = JWT.require(algorithm).build(); //Reusable verifier instancetry {DecodedJWT jwt = verifier.verify(token);request.setAttribute(Const.UID, jwt.getClaim(Const.UID).asInt());request.setAttribute(Const.LOGIN_USER, jwt.getClaim(Const.LOGIN_USER).asString());}catch (TokenExpiredException e) {//token过期throw new RuntimeException("token过期");}catch (JWTDecodeException e) {//解码失败，token错误throw new RuntimeException("解码失败，token错误");}return true;}
}

注册拦截器

package com.gblfy.distributed.session.config;import com.gblfy.distributed.session.intercepter.LoginIntercepter;
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 WebMvcConfig implements WebMvcConfigurer {@Autowiredprivate LoginIntercepter loginIntercepter;@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(loginIntercepter).addPathPatterns("/user/**")   //未登录的都会被拦截.excludePathPatterns("/user/login");}
}

Const常量

package com.gblfy.distributed.session.consts;public class Const {public static final String JWT_KEY = "gblfy";public static final String JWT_TOKEN = "token";public static final String UID = "uid";public static final String LOGIN_USER = "login_user";
}

3. 分别启动8081端口和8082端口

同上一篇

4. 调用8081登录接口

#登录接口
http://localhost:8081/user/loginWithJwt?username=admin&password=admin

5. 调用8081获取用户信息接口

#获取用户信息接口
http://localhost:8081/user/infoWithJwt?token=登录后的token

注：由于需要在请求header添加token，因此，请使用postman工具测试

6. 调用8082获取用户信息接口

#获取用户信息接口
http://localhost:8082/user/infoWithJwt?token=登录后的token

注：由于需要在请求header添加token，因此，请使用postman工具测试

补充1：
小伙伴发现，只有登陆成功后，携带token才可以访问其他接口，对吧！但是，每次都要手动填写token是不是很麻烦，其实正常的场景，前端会将登录后的token存放到Local Storage中，访问接口时会携带token，后端也会校验此token是否合法。

补充2：
拦截器可以定义多个，比如请求前日志记录拦截器等等，还有就是拦截器异常建议采用自定义异常返回前端比较友好，这里为了方便抛出运行时异常。