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。
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');
<!--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
3.1、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");
}
}
运行程序后，使用postman进行测试，登录如下图
请求方式：get
url：http://localhost:8899/user/login?username=zhangsan&password=123
然后点击send，就会看到返回成功和token
请求测试
请求方式：post
url：http://localhost:8899/user/test
点击header，在请求头中添加token，然后点击send
