在springboot里实现jwt

package com.example.demo_mysql.Utils;  

import com.auth0.jwt.JWT;  

import com.auth0.jwt.JWTCreator;  

import com.auth0.jwt.algorithms.Algorithm;  

import com.auth0.jwt.interfaces.Claim;  

import com.auth0.jwt.interfaces.DecodedJWT;  

import java.util.Calendar;  

import java.util.Map;  

public class JwtUtils {  

    /**  

     * 密钥要自己保管好  

     */  

    private static String SECRET = "!Q@W#E$R";  

    /**  

     * 传入 payload 信息获取 token  

     *     * @param map payload  

     * @return token     

     * */    

     public static String getToken(Map<String, String> map) {  

        JWTCreator.Builder builder = JWT.create();  

        //payload  

        map.forEach((k, v) -> {  

            builder.withClaim(k, v);  

        });  

        Calendar instance = Calendar.getInstance();  

        instance.add(Calendar.DATE, 3); // 默认 3 天过期  

        builder.withExpiresAt(instance.getTime());// 指定令牌的过期时间  

        return builder.sign(Algorithm.HMAC256(SECRET));  

    }  

    /**  

     * 验证 token 合法性  

     */  

    public static DecodedJWT verify(String token) {  

        // 如果有任何验证异常，此处都会抛出异常  

        return JWT.require(Algorithm.HMAC256(SECRET)).build().verify(token);  

    }  

    /**  

     * 获取 token 信息方法  

     */  

    public static Map<String, Claim> getTokenInfo(String token) {  

        return JWT.require(Algorithm.HMAC256(SECRET)).build().verify(token).getClaims();  

    }  

}

@GetMapping("/login")  

public Map<String, Object> login(User user){  

    log.info(user.getUsername());  

    log.info(user.getPassword());  

    Map<String, Object> map = new HashMap<>();  

    try{  

        User login = userService.login(user);  

        Map<String, String> payload = new HashMap<>();  

        payload.put("id", String.valueOf(login.getId()));  

        payload.put("password", login.getPassword());  

        // 生成 token  

        String token = JwtUtils.getToken(payload);  

        map.put("status", true);  

        map.put("msg", "登录成功");  

        map.put("token", token); // 响应 token，存储在客户端  

    }catch (Exception e) {  

        log.info("登录失败...");  

        map.put("status", false);  

        map.put("msg", "登录失败");  

    }  

    return map;  

}

package com.example.demo_mysql.Interceptor;  

import com.auth0.jwt.interfaces.DecodedJWT;  

import com.example.demo_mysql.Utils.JwtUtils;  

import com.fasterxml.jackson.databind.ObjectMapper;  

import jakarta.servlet.http.HttpServletRequest;  

import jakarta.servlet.http.HttpServletResponse;  

import org.springframework.web.servlet.HandlerInterceptor;  

import java.util.HashMap;  

public class JwtInterceptor implements HandlerInterceptor {  

    @Override  

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {  

        HashMap<String, String> map = new HashMap<>();  

        // 从请求头中提取 Authorization 值  

        String authHeader = request.getHeader("Authorization");  

        // 检查 Authorization 头是否存在且格式合法  

        if (authHeader == null || !authHeader.startsWith("Bearer ")) {  

			// 失败返回 401 错误码

            System.out.println("验证失败，头不存在");  

            map.put("msg", "验证失败，头不存在");  

            response.setStatus(HttpServletResponse.SC_UNAUTHORIZED); // 401  

            sendJsonResponse(response, map);  

            return false;  

        }  

        // 提取 token（去除 "Bearer" 前缀）  

        String token = authHeader.substring(7);  

        try {  

            // 如果验证成功放行请求  

            DecodedJWT verify = JwtUtils.verify(token);  

            return true;  

        } catch (Exception exception) {  

	        // 失败返回 401 错误码

            System.out.println("验证失败：" + exception);  

            map.put("msg", "验证失败：" + exception);  

            response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);  

            sendJsonResponse(response, map);  

            return false;  

        }  

    }  

	// 封装发送 JSON 响应的逻辑

    private void sendJsonResponse(  

        HttpServletResponse response,  

        HashMap<String, String> map  

    ) throws Exception {  

        response.setContentType("application/json;charset=UTF-8"); // 修正 Content-Type        

        String json = new ObjectMapper().writeValueAsString(map);  

        response.getWriter().write(json);    // 写入 JSON 数据  

        response.getWriter().flush();        // 确保数据发送到客户端  

    }  

}

package com.example.demo_mysql.Config;  

import com.example.demo_mysql.Interceptor.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 InterceptConfig implements WebMvcConfigurer {  

    @Override  

    public void addInterceptors(InterceptorRegistry registry) {  

        // 添加拦截器  

        registry.addInterceptor(new JwtInterceptor())  

                // 拦截的路径即需要进行 token 验证的路径。这里配置全部拦截

                .addPathPatterns("/**")  

                // 放行的路径  

                .excludePathPatterns("/login", "/user_create");  

    }  

}