ThreadLocal實現線程範圍內的共享變量
阿新 • • 發佈：2019-04-16
run etag dom tar todo tint thread 數據 setname
ThreadLocal變量自動與當前線程相關聯，替代Map，HashMap結構：
package cn.qy.heima2; import java.util.Random; public class ThreadLocalTest { private static ThreadLocal<Integer> xLocal= new ThreadLocal<Integer>(); public static void main(String[] args) { // TODO Auto-generated method stubfor(int i=0;i<2;i++) { new Thread(new Runnable() { @Override public void run() { // TODO Auto-generated method stub int data=new Random().nextInt(); System.out.println(Thread.currentThread().getName()+"has put data:"+data); xLocal.set(data); //xLocal與當前線程相關，進行數據存放 new A().get(); new B().get(); } }).start(); } } staticclass A { public void get() { int data=xLocal.get(); //xLocal與當前線程相關，進行數據取出 System.out.println("A from"+Thread.currentThread().getName()+"get data:"+data); } } static class B { public void get() { int data=xLocal.get(); System.out.println("B from"+Thread.currentThread().getName()+"get data:"+data); } } }
將多個共享變量封裝為一個對象放入ThreadLocal變量裏面：
package cn.qy.heima2; import java.util.Random; public class ThreadLocalTest { private static ThreadLocal<Integer> xLocal= new ThreadLocal<Integer>(); private static ThreadLocal<MyThreadScopeData> mythreadScopedata=new ThreadLocal<MyThreadScopeData>(); public static void main(String[] args) { // TODO Auto-generated method stub for(int i=0;i<2;i++) { new Thread(new Runnable() { @Override public void run() { // TODO Auto-generated method stub int data=new Random().nextInt(); System.out.println(Thread.currentThread().getName() +"has put data:"+data); xLocal.set(data); //xLocal與當前線程相關，進行數據存放 MyThreadScopeData mydata= new MyThreadScopeData(); mydata.setName("qianyong"+data); mydata.setAge(data); mythreadScopedata.set(mydata); new A().get(); new B().get(); } }).start(); } } static class A { public void get() { int data=xLocal.get(); //xLocal與當前線程相關，進行數據取出 System.out.println("A from"+Thread.currentThread().getName()+"get data:"+data); MyThreadScopeData mydata=mythreadScopedata.get(); System.out.println("A from"+Thread.currentThread().getName()+",get myName:"+mydata.getName()+",get myAge:"+mydata.getAge()); } } static class B { public void get() { int data=xLocal.get(); System.out.println("B from"+Thread.currentThread().getName()+"get data:"+data); MyThreadScopeData mydata=mythreadScopedata.get(); System.out.println("B from"+Thread.currentThread().getName()+",get myName:"+mydata.getName()+",get myAge:"+mydata.getAge()); } } } class 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; } }
運行結果：
Thread-0has put data:-2141728227 Thread-1has put data:1848865996 A fromThread-1get data:1848865996 A fromThread-1,get myName:qianyong1848865996,get myAge:1848865996 A fromThread-0get data:-2141728227 A fromThread-0,get myName:qianyong-2141728227,get myAge:-2141728227 B fromThread-1get data:1848865996 B fromThread-1,get myName:qianyong1848865996,get myAge:1848865996 B fromThread-0get data:-2141728227 B fromThread-0,get myName:qianyong-2141728227,get myAge:-2141728227
通過ThreadLocal變量創建與某一線程相關聯的單例對象：
package cn.qy.heima2; import java.util.Random; public class ThreadLocalTest { private static ThreadLocal<Integer> xLocal= new ThreadLocal<Integer>(); private static ThreadLocal<MyThreadScopeData> mythreadScopedata=new ThreadLocal<MyThreadScopeData>(); public static void main(String[] args) { // TODO Auto-generated method stub for(int i=0;i<2;i++) { new Thread(new Runnable() { @Override public void run() { // TODO Auto-generated method stub int data=new Random().nextInt(); System.out.println(Thread.currentThread().getName() +"has put data:"+data); xLocal.set(data); //xLocal與當前線程相關，進行數據存放 /*MyThreadScopeData mydata= new MyThreadScopeData(); mydata.setName("qianyong"+data); mydata.setAge(data); mythreadScopedata.set(mydata);*/ MyThreadScopeData.getThreadInstance().setName("qianyong"+data); MyThreadScopeData.getThreadInstance().setAge(data); new A().get(); new B().get(); } }).start(); } } static class A { public void get() { int data=xLocal.get(); //xLocal與當前線程相關，進行數據取出 System.out.println("A from"+Thread.currentThread().getName()+",get data:"+data); /*MyThreadScopeData mydata=mythreadScopedata.get(); System.out.println("A from"+Thread.currentThread().getName()+",get myName:"+mydata.getName()+",get myAge:"+mydata.getAge());*/ MyThreadScopeData mydata=MyThreadScopeData.getThreadInstance(); System.out.println("A from"+Thread.currentThread().getName()+",get myName:"+mydata.getName()+",get myAge:"+mydata.getAge()); } } static class B { public void get() { int data=xLocal.get(); System.out.println("B from"+Thread.currentThread().getName()+",get data:"+data); /*MyThreadScopeData mydata=mythreadScopedata.get(); System.out.println("B from"+Thread.currentThread().getName()+",get myName:"+mydata.getName()+",get myAge:"+mydata.getAge());*/ MyThreadScopeData mydata=MyThreadScopeData.getThreadInstance(); System.out.println("B from"+Thread.currentThread().getName()+",get myName:"+mydata.getName()+",get myAge:"+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; //創建單例,饑漢模式 //new MyThreadScopeData(); 創建單例，飽漢模式 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; } }
ThreadLocal實現線程範圍內的共享變量