测试类证明一下ThreadLocal存储的数据是线程程安全的 

    package com.lin.springboot01;

    import org.junit.jupiter.api.Test;

    public class testThreadLocal {
        @Test
        public void testThreadLocalSetAndGet(){
            //提供一个ThreadLocal对象
            ThreadLocal t1 = new ThreadLocal();
            new Thread(()->{
                t1.set("张三");
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
            },"绿色").start();

            new Thread(()->{
                t1.set("李四");
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
                System.out.println(Thread.currentThread().getName()+":"+t1.get());
            },"黄色").start();
        }

    }

接上一篇获取用户详细信息，用ThreadLocal进行优化

ThreadLocalUtil：工具类

package com.lin.springboot01.utils;

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 防止内存泄露
    public static void remove(){
        THREAD_LOCAL.remove();
    }
}

 LoginInterceptor：ThreadLocalUtil.set(claims)将数据存储到ThreadLocal中

package com.lin.springboot01.interceptors;

import com.lin.springboot01.pojo.Result;
import com.lin.springboot01.utils.JwtUtil;
import com.lin.springboot01.utils.ThreadLocalUtil;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

import java.util.Map;

@Component
public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String token = request.getHeader("Authorization");
        try {
            //能否解析成功
            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) {
            //解析失败，httpServletResponse响应码设置为401
            response.setStatus(401);
            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();
    }
}

UserController：改用ThreadLocalUtil获取用户name，在把参数传给findByName方法

    @GetMapping("/userInfo")
    public Result<User> userInfo(/*@RequestHeader(name="Authorization") String token*/){
       /* 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.findByName(username);
        return Result.success(user);
    }