SpringBoot 整合 JWT 实现登录和拦截

前言：

用户登录的功能就是需要服务提供者知道调用者是一个合法用户，非法用户不给予服务。SpringBoot + JWT（Json web token）是目前比较成熟的方案，整体逻辑如下：

1. 服务提供者对所有调用（部分接口除外，例如登录接口）都进行拦截认证，只有认证通过才提供服务

2. 用户通过登录获取认证信息

3. 用户携带认证信息调用服务即可通过拦截认证获取服务

一、版本和工具

1. SpringBoot：2.3.2.RELEASE

2. JDK：1.8_251

3. JWT依赖：

        <dependency>
            <groupId>com.auth0</groupId>
            <artifactId>java-jwt</artifactId>
            <version>3.16.0</version>
        </dependency>

二、用户的基本信息

用户结构体一般信息不少，这里为了简化就写两个核心字段：

public class User {
    private String userName;
    private String password;

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

三、认证和登录服务

认证服务使用 java-jwt 包的一些方法：

import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTVerificationException;
import com.auth0.jwt.interfaces.DecodedJWT;

import java.util.Date;
import java.util.HashMap;

public class JwtTokenUtils {

    private static final int EXPIRE_TIME = 5 * 60 * 1000;  // 过期时间5分钟
    private static final String SECRET_KEY = "123"; // 加密的密钥

    public static String sign(User user) {
        Date date = new Date(System.currentTimeMillis() + EXPIRE_TIME);
        HashMap<String, Object> head = new HashMap<String, Object>() {
            {
                put("typ", "JWT");
                put("alg", "HS256");
            }
        }; // 这块是 JWT 认证的一些声明信息
        Algorithm algorithm = Algorithm.HMAC256(SECRET_KEY);
        return JWT.create()
                .withHeader(head)
                .withClaim("username", user.getUserName())  // 把用户名整合到 token 里加密
                .withClaim("password", user.getPassword())  // 把用密码整合到 token 里加密，其实密码没必要
                .withExpiresAt(date).sign(algorithm);
    }

    public static boolean verity(String token) {
        try {
            Algorithm algorithm = Algorithm.HMAC256(SECRET_KEY);
            JWTVerifier verifier = JWT.require(algorithm).build();
            DecodedJWT jwt = verifier.verify(token);
            System.out.println("调用 username:" + jwt.getClaim("username"));  // 整合到 token 里加密的信息都是可以取出来的
            return true;
        } catch (IllegalArgumentException | JWTVerificationException e) {
            return false;
        }
    }

}

登录服务，这里把token直接刷到响应头里面：

import org.springframework.stereotype.Service;

import javax.servlet.http.HttpServletResponse;

@Service
public class LoginService {


    public String login(HttpServletResponse response, User user) {

        // 对账号和密码进行验证，一般是和数据库的数据对比，这里简化
        if (!user.getUserName().equals("admin")) return "账号错误";
        if (!user.getPassword().equals("admin")) return "密码错误";

        String token = JwtTokenUtils.sign(user);
        response.setHeader("token", token);
        return "登录成功";
    }

}

四、拦截器

拦截器的作用就是拦截调用：

import com.test.login.JwtTokenUtils;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

@Component
public class AuthHandlerInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("进入拦截器.......");
        String token = request.getHeader("token");
        if (null == token) {
            System.out.println("缺少认证信息");
            return false;  // 这里一般都是抛出自定义异常给全局异常处理，这里为了简化不做扩展说明
        }
        System.out.println("header token:" + token);
        boolean auth = JwtTokenUtils.verity(token);
        System.out.println("认证结果:" + auth);
        return auth;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

注册拦截器，并配置排除登录接口：

注意：不要继承 WebMvcConfigurationSupport ，springboot 2.x 后会导致配置失效

import com.test.filter.login.AuthHandlerInterceptor;
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.WebMvcConfigurationSupport;

@Configuration
public class WebAppConfig implements WebMvcConfigurer{

    @Autowired
    AuthHandlerInterceptor authHandlerInterceptor;

    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(authHandlerInterceptor)
                .excludePathPatterns("/client/login"); // 排除登录接口
    }
}

五、登录接口和测试调用接口

登录接口和测试调用接口如下：

import com.test.login.LoginService;
import com.test.login.User;
import com.test.result.Data;
import com.test.result.ResultBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletResponse;

@RestController
@RequestMapping("/client")
public class ControllerTest {

    @Autowired
    private LoginService loginService;

    @GetMapping("/login")
    public String login(
            HttpServletResponse response,
            @RequestParam(value = "username") String userName,
            @RequestParam(value = "password") String password
    ) {
        System.out.println("进入登录接口.....");
        User user = new User();
        user.setUserName(userName);
        user.setPassword(password);
        String loginResult = loginService.login(response, user);
        System.out.println("登录服务结果：" + loginResult);
        return loginResult;
    }

    @GetMapping("/test")
    public String name() {
        return "this is from client-1";
    }

}