Android 讓人又愛又恨的觸摸機制（二）

概述： 在上回，從原理上講解了android中觸摸機制的運行模式，那麼這次我們通過代碼來驗證一下這個結論。是驢子是馬拿出來遛一遛吧。另外，所學知識有限，如果有任何問題歡迎拍磚和交流。   補充一下，其實我寫的（一）中，存在一些問題，對於三個與觸摸機制息息相關的方法，並不是上文說的那麼容統，細分而言。只有ViewGroup才完全擁有這三個方法（onTouchEvent，onInterceptTouchEvent，dispatchTouchEvent），而對於View並沒有onInterceptTouchEvent，其實理由很簡單，我已經是最小單位了，我還需要攔截麼？我下面已經木有東東可以接收了~   案例驅動： MainActivity.class 這裡拋出一個問題，有興趣可以回答一下：activity和View是什麼關系呢？是不是感覺兩者好像都是界面？還是另有隱情呢？   public class MainActivity extends Activity{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); }   @Override public boolean dispatchTouchEvent(MotionEvent event) { int action = event.getAction(); switch (action) { case MotionEvent.ACTION_DOWN: System.out.println("MainActivity---dispatchTouchEvent---ACTION_DOWN"); break; case MotionEvent.ACTION_UP: System.out.println("MainActivity---dispatchTouchEvent---ACTION_UP"); break; default: break; } boolean result = super.dispatchTouchEvent(event); System.out.println("MainActivity---dispatchTouchEvent---result:"+result); return result; } } 自定義Button,作為最小View單位，是沒有onInterceptTouchEvent方法可以復寫的。其中只復寫了其他兩個方法。     public class MyButton extends Button {   public MyButton(Context context, AttributeSet attrs) { super(context, attrs); }   @Override public boolean onTouchEvent(MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_DOWN) System.out.println("MyButton---onTouchEvent---ACTION_DOWN"); if (action == MotionEvent.ACTION_MOVE) System.out.println("MyButton---onTouchEvent---ACTION_MOVE"); if (action == MotionEvent.ACTION_UP) System.out.println("MyButton---onTouchEvent---ACTION_UP"); return true; }   @Override public boolean dispatchTouchEvent(MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_DOWN) System.out.println("MyButton---dispatchTouchEvent---ACTION_DOWN"); if (action == MotionEvent.ACTION_MOVE) System.out.println("MyButton---dispatchTouchEvent---ACTION_MOVE"); if (action == MotionEvent.ACTION_UP) System.out.println("MyButton---dispatchTouchEvent---ACTION_UP"); boolean result = super.dispatchTouchEvent(event); System.out.println("MyButton---dispatchTouchEvent---result:"+result); return result; }   } 自定義ViewGroup的子類，MyLinearLayout，可以看到它是存在onInterceptTouchEvent方法，對於其中的子View,它可以進行攔截或者不攔截。     public class MyLinearLayout extends LinearLayout {   public MyLinearLayout(Context context, AttributeSet attrs) { super(context, attrs); }   @Override public boolean onTouchEvent(MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_DOWN) System.out.println("MyLinearLayout---onTouchEvent---ACTION_DOWN"); if (action == MotionEvent.ACTION_MOVE) System.out.println("MyLinearLayout---onTouchEvent---ACTION_MOVE"); if (action == MotionEvent.ACTION_UP) System.out.println("MyLinearLayout---onTouchEvent---ACTION_UP"); boolean result = super.onTouchEvent(event); System.out.println("MyLinearLayout---onTouchEvent---result:"+result); return result; }   @Override public boolean onInterceptTouchEvent(MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_DOWN) System.out.println("MyLinearLayout---onInterceptTouchEvent---ACTION_DOWN"); if (action == MotionEvent.ACTION_MOVE) System.out.println("MyLinearLayout---onInterceptTouchEvent---ACTION_MOVE"); if (action == MotionEvent.ACTION_UP) System.out.println("MyLinearLayout---onInterceptTouchEvent---ACTION_UP"); boolean result = super.onInterceptTouchEvent(event); result = true; System.out.println("MyLinearLayout---onInterceptTouchEvent---result:"+result); return result; }   @Override public boolean dispatchTouchEvent(MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_DOWN) System.out.println("MyLinearLayout---dispatchTouchEvent---ACTION_DOWN"); if (action == MotionEvent.ACTION_MOVE) System.out.println("MyLinearLayout---dispatchTouchEvent---ACTION_MOVE"); if (action == MotionEvent.ACTION_UP) System.out.println("MyLinearLayout---dispatchTouchEvent---ACTION_UP"); boolean result = super.dispatchTouchEvent(event); System.out.println("MyLinearLayout---dispatchTouchEvent---result:"+result); return result; } } 自定義ImageView，和自定義Button相同，作為最小View單位，不存在onInterceptTouchEvent     public class MyImageView extends ImageView {   public MyImageView(Context context, AttributeSet attrs) { super(context, attrs); }   @Override public boolean dispatchTouchEvent(MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_DOWN) System.out.println("MyImageView---dispatchTouchEvent---ACTION_DOWN"); if (action == MotionEvent.ACTION_MOVE) System.out.println("MyImageView---dispatchTouchEvent---ACTION_MOVE"); if (action == MotionEvent.ACTION_UP) System.out.println("MyImageView---dispatchTouchEvent---ACTION_UP"); boolean result = super.dispatchTouchEvent(event); System.out.println("MyImageView---dispatchTouchEvent---result:"+result); return result; }   @Override public boolean onTouchEvent(MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_DOWN) System.out.println("MyImageView---onTouchEvent---ACTION_DOWN"); if (action == MotionEvent.ACTION_MOVE) System.out.println("MyImageView---onTouchEvent---ACTION_MOVE"); if (action == MotionEvent.ACTION_UP) System.out.println("MyImageView---onTouchEvent---ACTION_UP"); return true; } } 最後看一下布局文件，很簡單，這裡不贅述了。     <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" >   <TextView android:id="@+id/title" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_marginTop="10dp" android:textStyle="bold" android:textColor="@color/blue" android:text="@string/touch" />   <com.example.touchevent.MyButton android:id="@+id/button1" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@id/title" android:layout_marginTop="10dp" android:text="@string/mybutton1" />   <com.example.touchevent.MyLinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/button1" android:layout_marginTop="50dp" android:background="@color/blue" android:gravity="center" >   <com.example.touchevent.MyRelativeLayout android:layout_width="200dp" android:layout_height="200dp" android:gravity="center" android:background="@color/dark_gray" > <com.example.touchevent.MyImageView android:layout_width="100dp" android:layout_height="100dp" android:scaleType="fitCenter" android:src="@drawable/jacky" /> </com.example.touchevent.MyRelativeLayout> </com.example.touchevent.MyLinearLayout>   </RelativeLayout>