Spring Boot整合JWT的实现步骤

springboot整合jwt步骤：

1、登录时，验证账号和密码成功后，生成jwt，返回给前端；
2、前端接收后保存，再做其他操作，比如增删改查时，同时将jwt传给后端进行验证，如果jwt当做参数一起传给后端，那么每个操作都会有jwt，为了方便，把jwt放到请求头中，通过拦截器来验证。

代码

代码结构图如下，除了常规的controller、entity、mapper和service层，还有两个拦截器和注册拦截器，图中用红字进行注释（这篇文章稍微有点长，因为我把代码都放上来了，结合下边的思路和结构图就能理解个大概）。

思路：有请求过来，通过拦截器进行拦截，但放行登录请求，如果登录成功，生成JWT令牌，返回给前端，当前端再有其他请求过来时，拦截器会拦截并解析token，如果通过就允许业务操作，否则就返回相应提示信息。

Spring Boot整合JWT的实现步骤

1、创建jwt数据库，然后创建user表

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) DEFAULT NULL,
  `password` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4;

插入数据

INSERT INTO `user` VALUES (1, "zhangsan", "123");
INSERT INTO `user` VALUES (2, "lisi", "123");

2、创建Spring Boot项目，在pom文件中，添加jwt等一些依赖和properties：

        <!--jwt-->
        <dependency>
            <groupId>com.auth0</groupId>
            <artifactId>java-jwt</artifactId>
            <version>3.4.0</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.4</version>
        </dependency>
        <!--我的mysql是5.6，所以这里是5.1版本-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.3.8</version>
        </dependency>

编写application.properties

server.port=8899
spring.application.name=jwt

spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/jwt?useSSL=true&characterEncoding=utf-8&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=root

mybatis.type-aliases-package=com.jwt.entity
mybatis.mapper-locations=classpath:mapper/*Mapper.xml

#打印sql
logging.level.com.jwt.mapper=debug

3、编写代码

3.1、编写entity包下的User类

public class User {
    private String id;
    private String username;
    private String password;
    //省略了get和set方法
}

3.2、编写util包下的JWTUtils类

public class JWTUtils {

    private static final String SING = "lu123456";

    /**
     * 生成token
     */
    public static String getToken(Map<String,String> map){
        Calendar instance = Calendar.getInstance();
        //默认7天过期
        instance.add(Calendar.DATE,7);
        //创建jwt builder
        JWTCreator.Builder builder = JWT.create();

        map.forEach((k,v)->{
            builder.withClaim(k,v);
        });

        String token = builder.withExpiresAt(instance.getTime())
                .sign(Algorithm.HMAC256(SING));
        return token;
    }

    /**
     * 验证token合法性
     */
    public static DecodedJWT verify(String token){
        return JWT.require(Algorithm.HMAC256(SING)).build().verify(token);
    }
}

3.3、编写controller层下UserController类

@RestController
@Slf4j
public class UserController {
    @Autowired
    private UserService userService;

    @GetMapping("/user/login")
    public Map<String,Object> login(User user){
        log.info("用户名：[{}]",user.getUsername());
        log.info("密码：[{}]",user.getPassword());

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

        try {
            User userDB = userService.login(user);
            Map<String,String> payload = new HashMap<>();
            payload.put("id",userDB.getId());
            payload.put("username",userDB.getUsername());
            //生成JWT令牌
            String token = JWTUtils.getToken(payload);
            map.put("state",true);
            map.put("token",token);
            map.put("msg","认证成功");
        }catch (Exception e){
            map.put("state",false);
            map.put("msg",e.getMessage());
        }
        return map;
    }

    @PostMapping("/user/test")
    public Map<String,Object> test(String token){
        Map<String, Object> map = new HashMap<>();
        map.put("state",true);
        map.put("msg","请求成功");
        return map;
    }
}

3.4、编写service层下UserService类和UserServiceImpl 类

public interface UserService {
    User login (User user);
}

实现类：

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    @Transactional(propagation = Propagation.SUPPORTS)
    public User login(User user) {
        //查询数据库
        User userDB = userMapper.login(user);
        if (userDB != null){
            return userDB;
        }
        throw new RuntimeException("登录失败");
    }
}

3.5、编写mapper层的UserMapper类

@Mapper
public interface UserMapper {
    User login(User user);
}

3.6、编写与UserMapper 对应的UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.jwt.mapper.UserMapper">

    <select id="login" parameterType="com.jwt.entity.User" resultType="com.jwt.entity.User">
        SELECT * FROM user WHERE username = #{username} AND password = #{password}
    </select>

</mapper>

3.7、配置拦截器，这样得到jwt后，再次请求时把jwt放到请求头中，就可以不用当参数传递。
编写JWTInterceptor类：

/**
 * 配置拦截器
 */
public class JWTInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Map<String, Object> map = new HashMap<>();

        //获取请求头中的令牌
        String token = request.getHeader("token");

        try {
            //验证令牌
            DecodedJWT verify = JWTUtils.verify(token);
            return true;
        } catch (SignatureVerificationException e){
            e.printStackTrace();
            map.put("msg","无效签名");
        } catch (TokenExpiredException e){
            e.printStackTrace();
            map.put("msg","token过期");
        } catch (AlgorithmMismatchException e){
            e.printStackTrace();
            map.put("msg","token算法不一致");
        } catch (Exception e){
            e.printStackTrace();
            map.put("msg","token无效");
        }
        map.put("state","flase");

        //将map转为json
        String json = new ObjectMapper().writeValueAsString(map);
        response.setContentType("application/json;charset=UTF-8");
        response.getWriter().println(json);
        return false;
    }
}

编写InterceptorConfig类：

/**
 * 注册拦截器
 */
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new JWTInterceptor())
                //拦截
                .addPathPatterns("/user/test")
                //放行
                .excludePathPatterns("/user/login");
    }
}