bind 一个存在的service的流程

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以bind systemUI中截屏操作的service为例：

首先：

final Object mScreenshotLock = new Object();

//保存一些连接中的状态

ServiceConnection mScreenshotConnection = null;

加入一个bind的timeout机制

final Runnable mScreenshotTimeout = new Runnable() {

@Override public void run() {

synchronized (mScreenshotLock) {

if (mScreenshotConnection != null) {

if(DEBUG) Log.d(TAG, "---grabFlag set false timeout.");

grabFlag = false;

unbindService(mScreenshotConnection);

mScreenshotConnection = null;

}

};

//bindService 和发送截屏请求一气呵成

// Assume this is called from the Handler thread.

private void takeScreenshot() {

synchronized (mScreenshotLock) {

if (mScreenshotConnection != null) {

return;

}

if(DEBUG) Log.d(TAG, "---takeScreenshot-----");

moveFlag = false;

ComponentName cn = new ComponentName("com.android.systemui",

"com.android.systemui.screenshot.TakeScreenshotService");

Intent intent = new Intent();

intent.setComponent(cn);

ServiceConnection conn = new ServiceConnection() {

@Override

public void onServiceConnected(ComponentName name, IBinder service) {

synchronized (mScreenshotLock) {

if (mScreenshotConnection != this) {

return;

}

Messenger messenger = new Messenger(service);

Message msg = Message.obtain(null, 1);

final ServiceConnection myConn = this;

Handler h = new Handler(mHandler.getLooper()) {

@Override

public void handleMessage(Message msg) {

//收到请求处理成功的返回。

synchronized (mScreenshotLock) {

if (mScreenshotConnection == myConn) {

if(DEBUG) Log.d(TAG, "---grabFlag set false ok");

grabFlag = false;

unbindService(mScreenshotConnection);

mScreenshotConnection = null;

mHandler.removeCallbacks(mScreenshotTimeout);

}

};

msg.replyTo = new Messenger(h);

msg.arg1 = msg.arg2 = 0;

msg.arg1 = 1;

msg.arg2 = 1;

try {

if(DEBUG) Log.d(TAG, "---LogControlerService---send--message---");

//发送载屏请求

messenger.send(msg);

} catch (RemoteException e) {

}

@Override

public void onServiceDisconnected(ComponentName name) {}

};

if (bindService(

intent, conn, Context.BIND_AUTO_CREATE, UserHandle.USER_CURRENT)) {

mScreenshotConnection = conn;

//加入一个10s的超时确定在没有bind上时做现场清理。

mHandler.postDelayed(mScreenshotTimeout, 10000);

}

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