package com.zzz.login.utils;

import io.jsonwebtoken.*;

import java.util.Date;
import java.util.UUID;

/**
 * @author lingqu
 * @date 2021/11/12
 * @apiNote
 */
public class JwtUtls {
    //token 过期时间
    private static long time = 1000*60*60*24;
    //token 的密钥
    private static String SING = "adADafnjk21^TJSVFD%$JFGE&^%DGHJDF^&min";

    //创建token方法
    public static String createToken(){
        JwtBuilder jwtBuilder = Jwts.builder();
        String jwtToken = jwtBuilder
                //header 
                .setHeaderParam("typ","JWT")
                .setHeaderParam("alg","HS256")
                //payload
                .claim("username","admin")
                .claim("role","admin")
                .setExpiration(new Date(System.currentTimeMillis()+time))  // 过期时间
                .setId(UUID.randomUUID().toString())
                //signature
                .signWith(SignatureAlgorithm.HS256,SING) //加密算法和签名密钥
                .compact();

        return jwtToken;
    }

    //验证token方法 如果为空或者解析失败都返回false
    public static boolean checkToken(String token){
        if(token==null){
            return false;
        }
        try {
            Jws<Claims> claimsJws = Jwts.parser().setSigningKey(SING).parseClaimsJws(token);
        } catch (Exception e) {
            return false;
        }
        return true;
    }
}

package com.zzz.login.controller;

import com.zzz.login.entity.User;
import com.zzz.login.utils.JwtUtls;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * @author lingqu
 * @date 2021/11/12
 * @apiNote
 */
@RestController
public class UserController {
    private final String USERNAME = "admin";
    private final String PASSWORD = "123456";

    //登录接口
    @PostMapping("/login")
    //接收post参数需要在方法的参数前面加@RequestBody才能获取到
    public User login(@RequestBody User user) {
        
        //验证用户名和密码这里用的写死的数据，之后会链接数据库来查真实的数据
        if(USERNAME.equals(user.getUsername()) && PASSWORD.equals(user.getPassword())){
            //调用JwtUtil类方法添加token
            user.setToken(JwtUtls.createToken());
            return user;
        }
        return null;
    }

    
    //其他访问页面每次都要调用此接口来验证token
    @GetMapping("/checkToken")
    public Boolean checkToken(HttpServletRequest request){
        //由于token保存在header里，所以参数应该是HttpServletRequest
        //HttpServletRequest可以获取header里面的数据
        String token = request.getHeader("token");
        //调用JwtUtil类里面的检测方法
        return JwtUtls.checkToken(token);
    }


}

package com.zzz.login.entity;

import lombok.Data;

/**
 * @author lingqu
 * @date 2021/11/12
 * @apiNote
 */
@Data
public class User {
    private String username;
    private String password;
    private String token;

}

package com.zzz.login.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * @author lingqu
 * @date 2021/11/12
 * @apiNote
 */
@Configuration
public class crosConfiguration implements WebMvcConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOriginPatterns("*")
                .allowedMethods("GET","HEAD","POST","DELETE","PUT","OPTIONS")
                .allowCredentials(true)
                .maxAge(3600)
                .allowedHeaders("*");

    }
}