Android ConditionVariable

线程操作经常用到wait和notify，用起来稍显繁琐，而Android给我们封装好了一个ConditionVariable类，用于线程同步。提供了三个方法block()、open()、close()。

void block()//阻塞当前线程，直到条件为openvoid block(long timeout)//阻塞当前线程，直到条件为open或超时void open()//释放所有阻塞的线程void close()//将条件重置为close

ConditionVariable 在创建时还有一种构造方法是 public ConditionVariable (boolean state) ，如果为true，默认时为opened，如果为false则是closed. ，默认public ConditionVariable()为closed.

源码

其实很好理解

private volatile boolean mCondition;

成员内部变量。

//默认构造函数 public ConditionVariable(){        mCondition = false;}

public ConditionVariable(boolean state){        mCondition = state;}

open，释放阻塞，即notifyAll一下，此时成员变量变为true。

public void open(){         synchronized (this) {             boolean old = mCondition;             mCondition = true;             if (!old) {                 this.notifyAll();             }         }}

close，重置成员变量为false

public void close(){         synchronized (this) {             mCondition = false;         }}

block，只有在成员变量为false的时候进行wait等待

public void block(){         synchronized (this) {             while (!mCondition) {                 try {                     this.wait();                 }                 catch (InterruptedException e) {                }            }        }}

public boolean block(long timeout){       // Object.wait(0) means wait forever, to mimic this, we just        // call the other block() method in that case.  It simplifies        // this code for the common case.        if (timeout != 0) {            synchronized (this) {                long now = System.currentTimeMillis();                long end = now + timeout;                while (!mCondition && now < end) {                    try {                        this.wait(end-now);                    }                    catch (InterruptedException e) {                    }                    now = System.currentTimeMillis();                }                return mCondition;            }        } else {            this.block();            return true;        }}

code

简单的延时：

new Thread(new Runnable() {            @Override            public void run() {                // TODO Auto-generated method stub                while(isStart) {                    //延时等待3秒                    mConditionVariable.block(3000);                    //将条件重置，否则block会失效                    mConditionVariable.close();                    //线程唤醒后通知主线程

                    mHandler.sendEmptyMessage(REFRESHTEXT);                }            }        }).start();