多线程课程002：线程范围内的共享变量

package cn.itcast.heima2;import java.util.HashMap;import java.util.Map;import java.util.Random;//单一条线程，这条线程所产生的数据由在这条线程new出来的对象共享//本题中，线程1产生的数据a，由A对象和B对象使用//线程2产生的数据b，由A对象和B对象使用public class ThreadScopeShareData {//private static int data = 0;private static Map<Thread, Integer> threadData = new HashMap<Thread, Integer>();public static void main(String[] args) {for (int i = 0; i < 2; i++) {new Thread(new Runnable() {@Overridepublic void run() {int data = new Random().nextInt();System.out.println(Thread.currentThread().getName()+ " has put data :" + data);threadData.put(Thread.currentThread(), data);new A().get();new B().get();}}).start();}}static class A {public void get() {int data = threadData.get(Thread.currentThread());System.out.println("A from " + Thread.currentThread().getName()+ " get data :" + data);}}static class B {public void get() {int data = threadData.get(Thread.currentThread());System.out.println("B from " + Thread.currentThread().getName()+ " get data :" + data);}}}

输出结果：

Thread-0 has put data :806274789Thread-1 has put data :1710804129A from Thread-0 get data :806274789A from Thread-1 get data :1710804129B from Thread-0 get data :806274789B from Thread-1 get data :1710804129

下面使用了ThreadLocal类，这个由API提供的类解决了共享变量的思路，其输出结果也如上。

public class ThreadLocalTest {private static ThreadLocal<Integer> x = new ThreadLocal<Integer>();public static void main(String[] args) {for(int i = 0; i < 2; i++){new Thread(new Runnable(){@Overridepublic void run() {int data = new Random().nextInt();System.out.println(Thread.currentThread().getName()+ " has put data: " + data);x.set(data);new A().get();new B().get();}}).start();}}static class A{public void get(){int data = x.get();System.out.println("A from" + Thread.currentThread().getName()+ " get data: " + data );}}static class B{public void get(){int data = x.get();System.out.println("B from" + Thread.currentThread().getName()+ " get data: " + data );}}}

这个需要学习里边的思想

package cn.itcast.heima2;import java.util.HashMap;import java.util.Map;import java.util.Random;//往线程池x里边存入一个整形数据，然后由其他的线程池对象共享使用//新的线程存新的数据吗，由其他线程池对象共享使用//线程池对象的类的设计，单例的设计，拿到实例，set，拿到实例，getpublic 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(){@Overridepublic 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();}}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());}}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{private MyThreadScopeData(){}public static /*synchronized*/ MyThreadScopeData getThreadInstance(){MyThreadScopeData instance = map.get();if(instance == null){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;}}

输出结果如下：

Thread-0 has put data :-1520297586Thread-1 has put data :-1519143339A from Thread-1 get data :-1519143339A from Thread-0 get data :-1520297586A from Thread-1 getMyData: name-1519143339,-1519143339A from Thread-0 getMyData: name-1520297586,-1520297586B from Thread-1 get data :-1519143339B from Thread-0 get data :-1520297586B from Thread-1 getMyData: name-1519143339,-1519143339B from Thread-0 getMyData: name-1520297586,-1520297586