onInterceptTouchEvent与OnTouchEvent

onInterceptTouchEvent用于拦截touch事件

OnTouchEvent 处理touch事件

onInterceptTouchEvent主要用于拦截touch事件，当返回值为true时，该事件不向下层view传递，而是本层onTouchEvent中处理touch事件。返回值为false时，事件传递到下层View的onInterceptTouchEvent

onTouchEvent，返回值为true时，touch事件被消耗不会向上层传递，返回false时，touch事件继续向上层view中的OntouchEvent传递，同时下次touch事件不会再传递到本层view处理

 Demo实例

容器父View

public class MyLayout extends ViewGroup {

	private int lastX;
	private int lastY;
	private int thresholdX=100;
	private boolean isDrag=false;
	
	
	public MyLayout(Context context, AttributeSet attrs) {
		// TODO Auto-generated constructor stub
		super(context, attrs);
	}

	public MyLayout(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		// TODO Auto-generated constructor stub

	}
	
	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		// TODO Auto-generated method stub
           for (int i = 0; i < getChildCount(); i++) {
        	   View child=getChildAt(i);
   
        		   child.layout(0, 0, child.getMeasuredWidth(), child.getMeasuredHeight());  			
		  }
	}
	  @Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		// TODO Auto-generated method stub
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		for (int i = 0; i <getChildCount(); i++) {
			View child=getChildAt(i);
			//child.measure(widthMeasureSpec,heightMeasureSpec);
			LayoutParams lp=(LayoutParams)child.getLayoutParams();
			
			child.measure(getChildMeasureSpec(widthMeasureSpec, 0, lp.width), getChildMeasureSpec(heightMeasureSpec,0,lp.height));
			
		}
	}
	@Override
	 public boolean dispatchTouchEvent(MotionEvent ev) {
			// TODO Auto-generated method stub
			return super.dispatchTouchEvent(ev);
		}
	 @Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		// TODO Auto-generated method stub
		 switch (ev.getAction()) {
			case MotionEvent.ACTION_DOWN:
				Log.i("debug", "-----onInterceptTouchEvent-------Aciton_down----------");
				break;
			case MotionEvent.ACTION_MOVE:
				Log.i("debug", "--------onInterceptTouchEvent----Aciton_move----------");
				break;
			case MotionEvent.ACTION_CANCEL:
				Log.i("debug", "---------onInterceptTouchEvent---Aciton_cancel----------");
				break;
			case MotionEvent.ACTION_UP:
				Log.i("debug", "-------onInterceptTouchEvent-----Aciton_up----------");
				break;

			default:
				break;
			}
		return false;
	}
	 @Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		
		 switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
			Log.i("debug", "-----mylayout-------Aciton_down----------");
			break;
		case MotionEvent.ACTION_MOVE:
			Log.i("debug", "------mylayout-----Aciton_move----------");
			break;
		case MotionEvent.ACTION_CANCEL:
			Log.i("debug", "------mylayout-----Aciton_cancel----------");
			break;
		case MotionEvent.ACTION_UP:
			Log.i("debug", "------mylayout-----Aciton_up----------");
			break;

		default:
			break;
		}
		 
		return true;
	}

自定义子view

public class CustomeImageView extends ImageView {
	public CustomeImageView(Context context, AttributeSet attrs) {
		super(context, attrs);
		// TODO Auto-generated constructor stub
	}

	public CustomeImageView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		// TODO Auto-generated constructor stub
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		 switch (event.getAction()) {
			case MotionEvent.ACTION_DOWN:
				Log.i("debug", "-------imageview-----Aciton_down----------");
				break;
			case MotionEvent.ACTION_MOVE:
				Log.i("debug", "-------ImageView-----Aciton_move----------");
				break;
			case MotionEvent.ACTION_CANCEL:
				Log.i("debug", "-------ImageView-----Aciton_cancel----------");
				break;
			case MotionEvent.ACTION_UP:
				Log.i("debug", "--------ImageView----Aciton_up----------");
				break;

			default:
				break;
			}
		return false;
	}

}

步骤一，MyLayout中onInterceptTouchEvent返回true，touch事件不会传递给子View，打印LOG

步骤二，MyLayout中onInterceptTouchEvent返回false,子View中的onTouchEvent能接受到触摸事件，Log

步骤三，在子VIew中测试OnTouchEvent返回值f（前提触摸事件可以传递到子view）若返回false，在一次touch事件中（Action_down开始Action_up结束）子view接受一次down事件，并把事件向上层传递

步骤三，在子VIew中测试OnTouchEvent返回值f（前提触摸事件可以传递到子view）若返回true，子View可以接受touch的所有事件，并且事件不会向上层传递

总结，android触摸事件传递机制，首先是dispatchTouchEvent根据onInterceptTouchEvent的返回值确定事件是分发给自己还是分配给子VIew的dispatchTouchEvent，子View在决定事件是否继续向下传递，事件传递到最后一个view时，调用该view的onTouchEvent函数去处理触摸事件，若函数返回true，则以后就会在此处理，不会向上层的onTouchEvent传递。返回false，就会传递到上一层的onTouchEvent，根据返回值决定是否处理事件，