android中Handler中的obtainMessage()

public final Message obtainMessage (int what, int arg1, int arg2, Object obj)
这里面的4个参数求解释啊。。。

byte[] buffer = new byte[1024];
            int bytes;
bytes = mmInStream.read(buffer);
mHandler.obtainMessage(MainActivity.MESSAGE_READ, bytes, -1, buffer) .sendToTarget();

这个是实例的代码

case MESSAGE_READ:

byte[] readBuf = (byte[]) msg.obj;//这是把缓冲区给了readBuf吗？
           	
 String ss = new String(readBuf, 0,msg.arg1);//这一句什么意思，貌似arg1存的就是读入的值



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-就是你的Message传给Handler的值，

Message msg = handler.obtainMessage();
		msg.arg1 = 1;
		msg.arg2 = 2;
		msg.what = 3;
		msg.obj = Object;

在Handler中接收
Handler handler = new Handler(){

    			@Override
    			public void handleMessage(Message msg) {
        				super.handleMessage(msg);
        //接收Message发送的消息  msg.what   msg.arg1  msg.arg2  msg.obj
        //这里msg.obj需要强转成你传过来的数据类型
}
	
		};

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mHandler.obtainMessage(MainActivity.MESSAGE_READ, bytes, -1, buffer) .sendToTarget();

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new String(readBuf, 0,msg.arg1); String (byte[] data, int offset, int byteCount)
msg.arg1充当了byteCount，也就是字符长度。msg.arg1不是就是在传消息之前的bytes的赋值吗，而bytes = mmInStream.read(buffer)，也就是把单字符给了bytes