标签：style blog http io ar color os 使用 sp
java synchronized主要用于控制线程同步，中间有很多小的细节，知识，这里我简单的整理一下，做个记录。主要用于方法和代码块的控制
先说说方法控制
模拟银行存款和取款，创建一个Account类，两个属性，一个name和accout。先存1w进去，在用一100个线程取钱1k和存1k。等待所有线程结束后，输出account。没有synchronized控制会造成account不等于1w。使用了synchronized结果正确，性能降低了很多。下面贴一下代码
参考：http://www.cnblogs.com/devinzhang/archive/2011/12/14/2287675.html
Account.java
1 package com.gxf.thread; 2 3 public class Account { 4 public String name; 5 public float amount; 6 7 public Account(String name, float amount){ 8 this.name = name; 9 this.amount = amount; 10 } 11 12 /** 13 * 模拟存钱 14 * @param amt 15 */ 16 public synchronized void deposit(float amt){ 17 float tmp = amount; 18 tmp += amt; 19 try { 20 Thread.sleep(100); 21 } catch (InterruptedException e) { 22 23 e.printStackTrace(); 24 } 25 this.amount = tmp; 26 } 27 28 /** 29 * 模拟取钱 30 * @param amt 31 */ 32 public synchronized void withdraw(float amt){ 33 float tmp = amount; 34 tmp -= amt; 35 try { 36 Thread.sleep(100); 37 } catch (InterruptedException e) { 38 39 e.printStackTrace(); 40 } 41 42 amount = tmp; 43 } 44 }
测试类AccountTest.java
1 package com.gxf.thread; 2 3 public class AccountTest { 4 5 public static void main(String[] args) { 6 final int NUM_THREADS = 5; //线程总数 7 Thread threads[] = new Thread[NUM_THREADS]; 8 final Account zhangsan = new Account("zhangsan", 10000); //张三存1w到银行 9 10 //1000个线程对张三账户进行存钱1k和取1k 11 for(int i = 0; i < NUM_THREADS; i++){ 12 threads[i] = new Thread(new Runnable(){ 13 14 @Override 15 public void run() { 16 zhangsan.deposit(1000); 17 zhangsan.withdraw(1000); 18 } 19 20 }); 21 threads[i].start(); //线程开始 22 } 23 //等待所有线程结束 24 for(int i = 0; i < NUM_THREADS; i++){ 25 try { 26 threads[i].join(); //等待该线程结束 27 } catch (InterruptedException e) { 28 // TODO Auto-generated catch block 29 e.printStackTrace(); 30 } 31 } 32 System.out.println("account = " + zhangsan.amount); 33 } 34 35 }
还有就是修饰一个代码块
参考：http://javacrazyer.iteye.com/blog/759300/
类LockThread向屏幕输出1-9
两个线程同时访问lockThread向屏幕输出的方法，不同步将会输出如：1 1 2 2 3 3...用了同步输出如:1 2 3 ...1 2 3...
LockThread.java
1 package com.gxf.thread; 2 3 public class LockThread implements Runnable { 4 5 @Override 6 public void run() { 7 synchronized(this){ 8 for(int i = 1; i < 10; i++){ 9 System.out.println(i); 10 try { 11 Thread.sleep(1000); 12 } catch (InterruptedException e) { 13 14 e.printStackTrace(); 15 } 16 } 17 } 18 19 } 20 21 }
测试代码
LockThreadTest.java
1 package com.gxf.thread; 2 3 public class LockThreadTest { 4 5 public static void main(String[] args) { 6 LockThread lockThread = new LockThread(); 7 Thread thread1 = new Thread(lockThread); 8 Thread thread2 = new Thread(lockThread); 9 10 thread1.start(); 11 thread2.start(); 12 13 } 14 15 }
ps:我也没检查synchronized拼对没有~
标签：style blog http io ar color os 使用 sp
原文地址：http://www.cnblogs.com/luckygxf/p/4157167.html
