java synchronized实现可见性过程解析

/**
 * synchronized能够实现原子性(同步)、可见性
 * 
 * @author xuwenjin
 */
public class SynchronizedDemo {
  //共享变量
  private boolean ready = false;
  private int result = 0;
  private int number = 1;
  /**
   * 写操作
   */
  public void write() {
    ready = true; //1.1
    number = 2;  //1.2
  }
  /**
   * 读操作
   */
  public void read() {
    if (ready) {       //2.1
      result = number * 3; //2.2
    }
    System.out.println("result:" + result);
  }
  //内部线程类
  private class WriteReadThread extends Thread {
    
    private boolean flag = false;    
    public WriteReadThread(boolean flag){
      this.flag = flag;
    }    
    @Override
    public void run() {
      if (flag) {
        write();
      }else {
        read();
      }
    }
  }
  public static void main(String[] args) {
    SynchronizedDemo demo = new SynchronizedDemo();
    //启动线程执行写操作
    demo.new WriteReadThread(true).start();
    //启动线程执行读操作
    demo.new WriteReadThread(false).start();
  }
}

/**
   * 写操作
   */
  public synchronized void write() {
    ready = true; //1.1
    number = 2;  //1.2
  }
  /**
   * 读操作
   */
  public synchronized void read() {
    if (ready) {       //2.1
      result = number * 3; //2.2
    }
    System.out.println("result:" + result);
  }