1、在pom.xml添加依赖

        <dependency>
            <groupId>com.auth0</groupId>
            <artifactId>java-jwt</artifactId>
            <version>3.4.0</version>
        </dependency>

2、自定义两个注解PassToken、UserLoginToken

package com.cn.commodity.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface UserLoginToken {
    boolean required() default true;
}

package com.cn.commodity.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface PassToken {
    boolean required() default true;
}

3、定义一个获取token的服务TokenService

package com.cn.commodity.service;

import com.auth0.jwt.JWT;
import com.auth0.jwt.algorithms.Algorithm;
import com.cn.commodity.entity.User;
import org.springframework.stereotype.Service;

@Service("tokenService")
public class TokenService {

    public String getToken(User user) { //生成token
        String token="";
        token= JWT.create().withAudience(String.valueOf(user.getId()))
                .sign(Algorithm.HMAC256(user.getPassword()));
        return token;
    }
}

4、定义一个拦截器

package com.cn.commodity.interceptor;

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.JWTVerificationException;
import com.cn.commodity.annotations.PassToken;
import com.cn.commodity.annotations.UserLoginToken;
import com.cn.commodity.entity.User;
import com.cn.commodity.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;

public class AuthenticationInterceptor implements HandlerInterceptor {
    @Autowired
    UserService userService;

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object object) throws Exception {
        String token = httpServletRequest.getHeader("token");// 从 http 请求头中取出 token
        // 如果不是映射到方法直接通过
        if (!(object instanceof HandlerMethod)) {
            return true;
        }
        HandlerMethod handlerMethod = (HandlerMethod) object;
        Method method = handlerMethod.getMethod();
        //检查是否有passtoken注释，有则跳过认证
        if (method.isAnnotationPresent(PassToken.class)) {
            PassToken passToken = method.getAnnotation(PassToken.class);
            if (passToken.required()) {
                return true;
            }
        }
        //检查有没有需要用户权限的注解
        if (method.isAnnotationPresent(UserLoginToken.class)) {
            UserLoginToken userLoginToken = method.getAnnotation(UserLoginToken.class);
            if (userLoginToken.required()) {
                // 执行认证
                if (token == null) {
                    throw new RuntimeException("无token，请重新登录");
                }
                // 获取 token 中的 user id
                String userId;
                try {
                    userId = JWT.decode(token).getAudience().get(0);
                } catch (JWTDecodeException j) {
                    throw new RuntimeException("401");
                }
                User user = userService.getUserById(Integer.parseInt(userId));
                if (user == null) {
                    throw new RuntimeException("用户不存在，请重新登录");
                }
                // 验证 token
                JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(user.getPassword())).build();
                try {
                    jwtVerifier.verify(token);
                } catch (JWTVerificationException e) {
                    throw new RuntimeException("401");
                }
                return true;
            }
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest,
                           HttpServletResponse httpServletResponse,
                           Object o, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest,
                                HttpServletResponse httpServletResponse,
                                Object o, Exception e) throws Exception {
    }
}

View Code

5、在项目中应用该拦截器

package com.cn.commodity.interceptor;

import org.springframework.context.annotation.Bean;
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(authenticationInterceptor())
                .addPathPatterns("/**");    // 拦截所有请求，通过判断是否有 @LoginRequired 注解 决定是否需要登录
    }
    @Bean
    public AuthenticationInterceptor authenticationInterceptor() {
        return new AuthenticationInterceptor();
    }
}

6、在controller层应用注解进行验证

package com.cn.commodity.controller;

import com.alibaba.fastjson.JSONObject;
import com.cn.commodity.annotations.UserLoginToken;
import com.cn.commodity.dao.UserDao;
import com.cn.commodity.entity.User;
import com.cn.commodity.service.TokenService;
import com.cn.commodity.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import javax.annotation.Resource;

@RestController
@RequestMapping("api")
public class UserApi {
    @Autowired
    UserService userService;
    @Autowired
    TokenService tokenService;

    @Resource
    private UserDao userDao;
    //登录
    @PostMapping("/login")
    public Object login(@RequestBody User user){
        JSONObject jsonObject=new JSONObject();
        //User userForBase=userService.getUserById(user.getId());
        User userForBase=userDao.selectOne(user);
        if(userForBase==null){
            jsonObject.put("message","登录失败,用户不存在");
            return jsonObject;
        }else {
            if (!userForBase.getPassword().equals(user.getPassword())){
                jsonObject.put("message","登录失败,密码错误");
                return jsonObject;
            }else {
                String token = tokenService.getToken(userForBase);
                jsonObject.put("token", token);
                jsonObject.put("user", userForBase);
                return jsonObject;
            }
        }
    }
    @UserLoginToken
    @GetMapping("/getMessage")
    public String getMessage(){
        return "你已通过验证";
    }
}

7、运行测试

a) 登陆获取token

#获取token,在项目中可以将token和user组合存在redis中。
post请求参数：
    {
    "userName":"yangwj1",
    "password":"wj1"
     }
    
请求url:http://localhost:8080/api/login

返回参数:
    {
    "user": {
        "id": 2,
        "userName": "yangwj1",
        "password": "wj1",
        "age": 1
    },
        "token":         "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOiIyIn0.z2EzbIbYLCmw5PM5Yx9arE5QGUH9ET_AC0BEy9SyE8A"
    }

b)对api进行token验证

请求参数header中：
   token=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOiIyIn0.z2EzbIbYLCmw5PM5Yx9arE5QGUH9ET_AC0BEy9SyE8A

请求url:http://localhost:8080/api/getMessage

返回参数：你已通过验证