SpringBoot之ThreadLocal保存请求用户信息

一、ThreadLocal概述

 线程局部变量，创建一个线程变量后，针对这个变量可以让每个线程拥有自己的变量副本，每个线程是访问的自己的副本，与其他线程的相互独立。

二、具体代码demo实现

（1）创建user实例对象

@Data
public class UserDTO {
    private Long userId;
    private String UserName;
}

（2）创建UserThreadLocal对象

public class UserThreadLocal {

    private UserThreadLocal(){};

    private static final ThreadLocal<UserDTO> USER_DTO_THREAD_LOCAL = new ThreadLocal<>();

    /**
     * 清除信息
     */
    public static void clear(){
        USER_DTO_THREAD_LOCAL.remove();
    }

    /**
     * 保存用户信息
     * @param userDTO
     */
    public static void set(UserDTO userDTO){
        USER_DTO_THREAD_LOCAL.set(userDTO);
    }

    public static UserDTO getCurrentUser(){
       return USER_DTO_THREAD_LOCAL.get();
    }
}

（3）创建用户拦截器

@Component
public class UserInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //此处实际应该根据header的token解析出用户本处为了简单，直接虚构一个用户
        UserDTO userDTo = new UserDTO();
        userDTo.setUserId(10001L);
        userDTo.setUserName("张三");
        UserThreadLocal.set(userDTo);
        return true;
    }

    @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 {
        UserThreadLocal.clear();
    }
}

  (4) 注册用户拦截器

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new UserInterceptor());
    }
}

（5）编写测试接口

@RequestMapping("test")
@RestController
public class TestController {

    @GetMapping("get")
    public UserDTO getUser(){
        UserDTO currentUser = UserThreadLocal.getCurrentUser();
        System.out.println(currentUser);
        return currentUser;
    }
}

（6）效果展示

localhost:8080/test/get