Java生成Token并添加拦截器校验Token，实现判断用户是否登录

添加JWT依赖

<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt</artifactId>
    <version>0.7.0</version>
</dependency>

添加工具类，包含

生成Token方法
从token中获取userId
从token中获取userName
查看Token是否过期

package com.szx.exam.util;

import io.jsonwebtoken.*;
import org.springframework.util.StringUtils;
import java.util.Date;

/**
 * @author songzx
 * @create 2023-06-25 13:55
 */
public class JwtHelper {
    // 随机字符串混淆Token
    private static final String tokenSignKey = "uNvs^pML-E";

    /**
     * 生成Token，并保存userID和userName信息
     * @param userId
     * @param userName
     * @return
     */
    public static String createToken(Long userId, String userName) {
        long tokenExpiration = 1000L * 60 * 60 * 24 * 30; // 过期时间，设置30天
        String token = Jwts.builder()
                .setExpiration(new Date(System.currentTimeMillis() + tokenExpiration))
                .claim("userId", userId)
                .claim("userName", userName)
                .signWith(SignatureAlgorithm.HS512, tokenSignKey)
                .compressWith(CompressionCodecs.GZIP)
                .compact();
        return token;
    }

    /**
     * 从token中获取userID
     * @param token
     * @return
     */
    public static Long getUserId(String token) {
        if (StringUtils.isEmpty(token)) return null;
        Jws<Claims> claimsJws = Jwts.parser().setSigningKey(tokenSignKey).parseClaimsJws(token);
        Claims claims = claimsJws.getBody();
        Integer userId = (Integer) claims.get("userId");
        return userId.longValue();
    }

    /**
     * 从token中获取用户姓名
     * @param token
     * @return
     */
    public static String getUserName(String token) {
        if (StringUtils.isEmpty(token)) return "";
        Jws<Claims> claimsJws = Jwts.parser().setSigningKey(tokenSignKey).parseClaimsJws(token);
        Claims claims = claimsJws.getBody();
        return (String) claims.get("userName");
    }

    /**
     * 查看Token是否过期
     * @param token
     * @return false 未过期，true 已过期
     */
    public static Boolean tokenExpired(String token) {
        try {
            Claims claims = Jwts.parser().setSigningKey(tokenSignKey).parseClaimsJws(token).getBody();
            Date expiration = claims.getExpiration();
            Date currentDate = new Date();
            return expiration.before(currentDate);
        } catch (ExpiredJwtException ex) {
            return true;
        } catch (Exception ex) {
            return true;
        }
    }
}

添加 handle

package com.szx.exam.handle;

import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.szx.exam.exception.SsyxException;
import com.szx.exam.util.JwtHelper;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;

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

/**
 * @author songzx
 * @create 2022-10-12 9:48
 */
public class TokenHandle implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if(!(handler instanceof HandlerMethod)){
            return true;
        }
        // 从请求头中获取token
        String token = request.getHeader("X-Token");
        // 校验token
        if(StringUtils.isEmpty(token) || JwtHelper.tokenExpired(token)){
            throw new SsyxException("登录过期,请重新登录",401);
        }
        return true;
    }
}

添加 TokenConfig，设置需要过滤的接口信息，不在过滤中的接口都将配拦截校验是否存在token

package com.szx.exam.config;

import com.szx.exam.handle.TokenHandle;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * @author songzx
 * @create 2022-10-12 9:51
 */
@Configuration
public class TokenConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new TokenHandle())
                .addPathPatterns("/**")
                .excludePathPatterns("/","/stu/login","/webjars/**","/fonts/**","/images/**","/swagger-ui.html");
    }
}