Android View的onTouchEvent和OnTouch區別

還是以自定義的TestButton為例。

我們可以通過重寫onTouchEvent方法來處理諸如down move up的消息：

 

public class TestButton extends Button {

    public TestButton(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    public TestButton(Context context, AttributeSet attributeSet) {
        super(context, attributeSet);
        // TODO Auto-generated constructor stub
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        boolean value = super.onTouchEvent(event);
        System.out.println("super.onTouchEvent: " + value+ " event: " + event.getAction());
        return value;
    }

public class TestButton extends Button {

	public TestButton(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
	}
	
	public TestButton(Context context, AttributeSet attributeSet) {
		super(context, attributeSet);
		// TODO Auto-generated constructor stub
	}
	
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		boolean value = super.onTouchEvent(event);
		System.out.println("super.onTouchEvent: " + value+ " event: " + event.getAction());
		return value;
	}

也可以通過實現OnTouchListener的接口，然后設置TestButton的onTouchListener可以達到同樣的目的

  class OnTouchListenerTest implements View.OnTouchListener{
@Override
public boolean onTouch(View v, MotionEvent event) {
    return false;
}

  }

    class OnTouchListenerTest implements View.OnTouchListener{
		@Override
		public boolean onTouch(View v, MotionEvent event) {
			return false;
		}
    	
    }

TestButton b = (TestButton)findViewById(R.id.button);
OnTouchListenerTest listener = new OnTouchListenerTest();
b.setOnTouchListener(listener);

        TestButton b = (TestButton)findViewById(R.id.button);
        OnTouchListenerTest listener = new OnTouchListenerTest();
        b.setOnTouchListener(listener);

但上述兩種監聽有什么區別呢？

 

先看一下Android源碼中對於View中dispatchTouchEvent的實現：

 

public boolean dispatchTouchEvent(MotionEvent event){
    ... ...
    if(onFilterTouchEventForSecurity(event)){
        ListenerInfo li = mListenerInfo;
        if(li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
            && li.mOnTouchListener.onTouch(this, event)) {
            return true;
        }
        if(onTouchEvent(event)){
            return true;
        }
    }
    ... ...
    return false;
}

//源碼：
	public boolean dispatchTouchEvent(MotionEvent event){
		... ...
		if(onFilterTouchEventForSecurity(event)){
			ListenerInfo li = mListenerInfo;
			if(li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
				&& li.mOnTouchListener.onTouch(this, event)) {
				return true;
			}
			if(onTouchEvent(event)){
				return true;
			}
		}
		... ...
		return false;
	}

可以看到onTouchListener的接口的優先級是要高於onTouchEvent的，假若onTouchListener中的onTouch方法返回true，

 

表示此次事件已經被消費了，那onTouchEvent是接收不到消息的。

因為Button的performClick是利用onTouchEvent實現，假若onTouchEvent沒有被調用到，那么Button的Click事件也無法響應。

綜合來講：

onTouchListener的onTouch方法優先級比onTouchEvent高，會先觸發。

假如onTouch方法返回false會接着觸發onTouchEvent，反之onTouchEvent方法不會被調用。

內置諸如click事件的實現等等都基於onTouchEvent，假如onTouch返回true，這些事件將不會被觸發。

 

 

 

//------------布局文件--------------------

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"

    tools:context="myontouch.bwie.com.myontouch.MainActivity">

    <myontouch.bwie.com.myontouch.TestButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="點擊"
        android:id="@+id/button"/>
</RelativeLayout>

//--------------自定義TextButton--------------------------

public class TestButton extends Button{
    public TestButton(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public TestButton(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        boolean value = super.onTouchEvent(event);
             System.out.println("super.onTouchEvent: " + value+ " event: " + event.getAction());
        Log.i("我是onTouchEvent","onTouchEvent");
             return value;

    }

}


//----------------主Activity-------------

public class MainActivity extends AppCompatActivity {

    private TestButton button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        button = (TestButton) findViewById(R.id.button);

        OnTouchListenerTest listener = new OnTouchListenerTest();
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Log.i("我是OnClickListener","OnClickListener");
            }
        });
       button.setOnTouchListener(listener);

    }



    class OnTouchListenerTest implements View.OnTouchListener {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            Log.i("我是onTouch","onTouch");
            return false;
        }

    }



//---------------下面是我的OnTouch 返回false 時，的打印----------

12-14 13:52:51.550 8752-8752/myontouch.bwie.com.myontouch I/我是onTouch: onTouch
12-14 13:52:51.553 8752-8752/myontouch.bwie.com.myontouch I/System.out: super.onTouchEvent: true event: 0
12-14 13:52:51.554 8752-8752/myontouch.bwie.com.myontouch I/我是onTouchEvent: onTouchEvent
12-14 13:52:51.565 8752-8752/myontouch.bwie.com.myontouch I/我是onTouch: onTouch
12-14 13:52:51.566 8752-8752/myontouch.bwie.com.myontouch I/System.out: super.onTouchEvent: true event: 2
12-14 13:52:51.566 8752-8752/myontouch.bwie.com.myontouch I/我是onTouchEvent: onTouchEvent
12-14 13:52:51.649 8752-8752/myontouch.bwie.com.myontouch I/我是onTouch: onTouch
12-14 13:52:51.649 8752-8752/myontouch.bwie.com.myontouch I/System.out: super.onTouchEvent: true event: 1
12-14 13:52:51.649 8752-8752/myontouch.bwie.com.myontouch I/我是onTouchEvent: onTouchEvent
12-14 13:52:51.656 8752-8752/myontouch.bwie.com.myontouch I/我是OnClickListener: OnClickListener

 

 

//-------------------下面是 onTouch 返回 true時的打印-------------------------

12-14 14:03:33.399 19886-19886/myontouch.bwie.com.myontouch I/我是onTouch: onTouch
12-14 14:03:33.415 19886-19886/myontouch.bwie.com.myontouch I/我是onTouch: onTouch
12-14 14:03:33.429 19886-19886/myontouch.bwie.com.myontouch I/我是onTouch: onTouch