【SpringBoot实战篇】获取用户详细信息-ThreadLocal优化

1 分析问题

对token的解析当初在拦截器中已经写过。期待的是在拦截器里写了，在其他地方就不写了，应该去复用拦截器里面得到的结果

2 解决方式-ThreadLocal

2.1提供线程局部变量

• 用来存取数据: set()/get()
• 使用ThreadLocal存储的数据, 线程安全

2.2过程图解

2.3代码实现

工具类

package com.aaa.utils;

import java.util.HashMap;
import java.util.Map;

/**
 * ThreadLocal 工具类
 */
@SuppressWarnings("all")
public class ThreadLocalUtil {
    //提供ThreadLocal对象,
    private static final ThreadLocal THREAD_LOCAL = new ThreadLocal();

    //根据键获取值
    public static <T> T get(){
        return (T) THREAD_LOCAL.get();
    }
	
    //存储键值对
    public static void set(Object value){
        THREAD_LOCAL.set(value);
    }


    //清除ThreadLocal 防止内存泄漏
    public static void remove(){
        THREAD_LOCAL.remove();
    }
}

拦截器

package com.aaa.interceptors;

import com.aaa.pojo.Result; //统一返回结果
import com.aaa.utils.JwtUtil;//token令牌
import com.aaa.utils.ThreadLocalUtil;//线程
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

import java.util.Map;

@Component
public class LoginInterceptor implements HandlerInterceptor {
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //令牌验证
        String token = request.getHeader("Authorization");
        //验证token
        try {
           
            Map<String, Object> claims = JwtUtil.parseToken(token);

            //把业务数据存储到ThreadLocal中
            ThreadLocalUtil.set(claims);
            //放行
            return true;
        } catch (Exception e) {
            //http响应状态码为401
            response.setStatus(401);
            //不放行
            return false;
        }
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        //清空ThreadLocal中的数据
        ThreadLocalUtil.remove();
    }
}

控制器

    @GetMapping("/userInfo")
    public Result<User> userInfo(/*@RequestHeader(name = "Authorization") String token*/) {
        //根据用户名查询用户
       /* Map<String, Object> map = JwtUtil.parseToken(token);
        String username = (String) map.get("username");*/
        Map<String, Object> map = ThreadLocalUtil.get();
        String username = (String) map.get("username");
        User user = userService.findByUserName(username);
        return Result.success(user);
    }

 3 小结

• 用来存取数据: set()/get()
• 使用ThreadLocal存储的数据, 线程安全
• 用完记得调用remove方法释放