/** *  * @描述: 线程范围内共享变量的概念与作用 . * @作者: Wnj . * @创建时间: 2017年5月15日 . * @版本: 1.0 . */public class ThreadLocalTest {    private static ThreadLocal<Integer> x = new ThreadLocal<Integer>();    private static ThreadLocal<MyThreadScopeData> myThreadScopeData = http://www.mamicode.com/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 = http://www.mamicode.com/new Random().nextInt();                    System.out.println(Thread.currentThread().getName()                             + " has put data :" + data);                    x.set(data);/*                    MyThreadScopeData myData = http://www.mamicode.com/new MyThreadScopeData();"name" + data);                    myData.setAge(data);                    myThreadScopeData.set(myData);*/                    MyThreadScopeData.getThreadInstance().setName("name" + data);                    MyThreadScopeData.getThreadInstance().setAge(data);                    new A().get();                    new B().get();                }            }).start();        }    }        static class A{        public void get(){            int data =http://www.mamicode.com/ x.get();            System.out.println("A from " + Thread.currentThread().getName()                     + " get data :" + data);/*            MyThreadScopeData myData = http://www.mamicode.com/myThreadScopeData.get();;"A from " + Thread.currentThread().getName()                     + " getMyData: " + myData.getName() + "," +                    myData.getAge());*/            //获取与本线程有关的实例            MyThreadScopeData myData =http://www.mamicode.com/ MyThreadScopeData.getThreadInstance();            System.out.println("A from " + Thread.currentThread().getName()                     + " getMyData: " + myData.getName() + "," +                    myData.getAge());        }    }        static class B{        public void get(){            int data =http://www.mamicode.com/ 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{    private MyThreadScopeData(){}    public static /*synchronized*/ MyThreadScopeData getThreadInstance(){        //此时的map.get是获取自身的变量，当多个线程同时进来时，获取的是线程本身的变量，所以此种方式不需要加synchronized        MyThreadScopeData instance = map.get();        if(instance == null){ //一个线程进来，判断==null,这时候还没有赋值，刚好这时候被CPU调度到另一个线程，也判断==null            //那么会被new 两次            instance = new MyThreadScopeData();            map.set(instance);        }        return instance;    }    //private static MyThreadScopeData instance = null;//new MyThreadScopeData();    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;    }}