ThreadLocal类及应用技巧

最新推荐文章于 2023-03-02 11:02:32 发布

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#thread #线程范围内数据共享 #ThreadLocal #技巧

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本文详细介绍了ThreadLocal类及其在多线程编程中的应用，包括线程范围内共享数据、多线程同步操作等核心概念。通过实例展示了如何在不同线程间共享变量，并使用ThreadLocal来实现线程隔离的高效数据管理。

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/**
 * ThreadLocalShareData.java
 * cn.com.songjy.test.socket.thread
 * Function： TODO 
 *
 *   version    date      author
 * ──────────────────────────────────
 *   	1.0	 2013-8-16    songjy
 *
 * Copyright (c) 2013, TNT All Rights Reserved.
*/

package cn.com.songjy.test.socket.thread;

import java.util.Random;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * ClassName:ThreadLocalShareData
 * ThreadLocal类及应用技巧
 * @author   songjy
 * @version  1.0
 * @since    v1.0
 * @Date	 2013-8-16	下午4:14:56
 */

public class ThreadLocalShareData {

	private static Log log = LogFactory.getLog(ThreadLocalShareData.class);
	private static ThreadLocal<Integer> thread_data = new ThreadLocal<Integer>();
	//多个变量要求在线程范围内共享可以封装到一个对象中进行存储
	private static ThreadLocal<MyThreadScopeData> my_thread_data = new ThreadLocal<MyThreadScopeData>();
	private static int data;

	public static void main(String[] args) {

		for(int i=0; i<5; i++)
		new Thread(new Runnable() {

			@Override
			public void run() {
				data = new Random().nextInt();
				int data = new Random().nextInt();
				log.info(Thread.currentThread().getName() + " has put data :" + data);
				//thread_data.put(Thread.currentThread(), data);
				thread_data.set(data);
				//my_thread_data.set(new MyThreadScopeData(""+data, 12));
				MyThreadScopeData.getInstance().setName("name-"+data);
				MyThreadScopeData.getInstance().setAge(data);
				new A().get();
				new B().get();
			}
		}).start();
	}

	static class A {
		public void get(){
			//int data = thread_data.get(Thread.currentThread());
			int data = thread_data.get();
			//MyThreadScopeData my = my_thread_data.get();
			MyThreadScopeData my = MyThreadScopeData.getInstance();
			log.info("A from " + Thread.currentThread().getName() + " get data :" + data);
			log.info("A from " + Thread.currentThread().getName() + " get MyThreadScopeData :" + my.getName());
		}
	}

	static class B {
		public void get(){
			//int data = thread_data.get(Thread.currentThread());
			int data = thread_data.get();
			//MyThreadScopeData my = my_thread_data.get();
			MyThreadScopeData my = MyThreadScopeData.getInstance();
			log.info("B from " + Thread.currentThread().getName() + " get data :" + data);
			log.info("B from " + Thread.currentThread().getName() + " get MyThreadScopeData :" + my.getName());
		}
	}
}

//该类被编写成了线程范围内共享的数据类
class MyThreadScopeData {

	private MyThreadScopeData(){}

	/*单例之饱汉模式
	private static MyThreadScopeData instance = new MyThreadScopeData();
	public static synchronized MyThreadScopeData getInstance(){
		return instance;
	}*/

	/*单例之饿汉模式
	private static MyThreadScopeData instance = null;

	public static synchronized MyThreadScopeData getInstance(){

		if(null == instance)
			instance = new MyThreadScopeData();

		return instance;
	}*/

	/*线程范围内共享模式*/
	public static MyThreadScopeData getInstance(){

		MyThreadScopeData instance = map.get();

		if(null == instance) {
			instance = new MyThreadScopeData();
			map.set(instance);
		}

		//return map.get();//也可
		return instance;
	}

	private static ThreadLocal<MyThreadScopeData> map = new ThreadLocal<MyThreadScopeData>();

	private String name;
	private int age;

	/*MyThreadScopeData(String name, int age){
		this.name = name;
		this.age = age;
	}*/

	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}

}