Java多线程编程之ThreadLocal线程范围内的共享变量

package com.ljq.test.thread;
 
import java.util.Random;
 
/**
 * ThreadLocal类及应用技巧
 *
 * 将线程范围内共享数据进行封装，封装到一个单独的数据类中，提供设置获取方法
 * 将该类单例化，提供获取实例对象的方法，获取到的实例对象是已经封装好的当前线程范围内的对象
 */
public class ThreadLocalTest {
 
  private static ThreadLocal<Integer> x = new ThreadLocal<Integer>();
  //private static ThreadLocal<MyThreadScopeData> myThreadScopeData = new ThreadLocal<MyThreadScopeData>();
  public static void main(String[] args) {
    for(int i=0;i<2;i++){
      new Thread(new Runnable(){
        @Override
        public void run() {
          int data = new Random().nextInt();
          System.out.println(Thread.currentThread().getName() + " has put data :" + data);
          x.set(data);
           
          /*         
          MyThreadScopeData myData = new MyThreadScopeData();
          myData.setName("name" + data);
          myData.setAge(data);
          myThreadScopeData.set(myData);
          */
          MyThreadScopeData.getThreadInstance().setName("name" + data);
          MyThreadScopeData.getThreadInstance().setAge(data);
          new A().get();
          new B().get();
        }
      }).start();
    }
  }
   
  //使用获取到的线程范围内的对象实例调用相应方法
  static class A{
    public void get(){
      int data = x.get();
      System.out.println("A from " + Thread.currentThread().getName() + " get data :" + data);
       
      /*     
      MyThreadScopeData myData = myThreadScopeData.get();
      System.out.println("A from " + Thread.currentThread().getName()
          + " getMyData: " + myData.getName() + "," + myData.getAge());
      */
      MyThreadScopeData myData = MyThreadScopeData.getThreadInstance();
      System.out.println("A from " + Thread.currentThread().getName()
          + " getMyData: " + myData.getName() + "," + myData.getAge());
    }
  }
   
  //使用获取到的线程范围内的对象实例调用相应方法
  static class B{
    public void get(){
      int data = x.get();    
      System.out.println("B from " + Thread.currentThread().getName() + " get data :" + data);
       
      MyThreadScopeData myData = MyThreadScopeData.getThreadInstance();
      System.out.println("B from " + Thread.currentThread().getName()
          + " getMyData: " + myData.getName() + "," + myData.getAge());     
    }   
  }
}
 
 
class MyThreadScopeData {
 
  // 单例
  private MyThreadScopeData() {
  }
 
  // 提供获取实例方法，不加synchronized关键字表示线程各拿各自的数据，互不干扰
  public static/* synchronized */MyThreadScopeData getThreadInstance() {
    // 从当前线程范围内数据集中获取实例对象
    MyThreadScopeData instance = map.get();
    if (instance == null) {
      instance = new MyThreadScopeData();
      map.set(instance);
    }
    return instance;
  }
 
  // 将实例对象存入当前线程范围内数据集中
  private static ThreadLocal<MyThreadScopeData> map = new ThreadLocal<MyThreadScopeData>();
 
  private String name;
  private int 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;
  }
}