Android Touch事件总结 一

说明：本博客为原创，转载请注明出处 CSDN-ANDROID 笔记栈
由于作者水平有限，错误在所难免，请见谅，可以留言，本人会及时改正

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索引

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Android Touch事件主要有三个方法：
dispatchTouchEvent（分发）: Touch事件的入口方法
onInterceptTouchEvent（拦截）：ViewGroup拦截事件，不传递给子View
onTouchEvent（处理）：是否消费事件

Activity和View都可以处理TouchEvent事件,Activity是所有事件的入口

TouchEvent 事件是从上而下，从外而内开始传递

Activity(window、DecorView) -> ViewGroup -> View

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Activity View TouchEvent

事件	dispatchTouchEvent	onInterceptTouchEvent	onTouchEvent
Activity	√	×	√
ViewGroup	√	√	√
View	√	×	√

1.分发事件

public boolean dispatchTouchEvent(MotionEvent ev)
{
    return true; // true,MotionEvent已被消费
    // 不调用**super.dispatchTouchEvent()**方法，其他两个方法是不会被调用的！
    // 该方法返回false，代表没有View对该事件进行消费，后续事件将不会被分发给你当前View。
    // super.dispatchTouchEvent()返回结果是根据子View的dispatchTouchEvent方法或者当前View的onTouchEvent方法的返回结果而决定的。
    // 在ViewGroup中，根据特定的排列顺序遍历子Child，调用子View的dispatchTouchEvent的方法来实现事件的分发。
    // （Actvity 永远接收dispatchTouchEvent事件）
}

-如果TouchEvent事件在传递过程中，没有View/ViewGroup对“DOWN”事件进行消费，后续TouchEvent事件(MOVE,UP,CANCEL等)只会被分发到Activity中。

2.拦截事件

public boolean onInterceptTouchEvent(MotionEvent ev)
{
    return true; // true,MotionEvent被当前ViewGroup拦截
    //不会传递给子View的dispatchTouchEvent(),ViewGroup的onTouchEvent（）会被调用。
    //这个方法，SDK文档中有如下说明：（翻译的水平有限，请见谅）
    //1.在这个方法中可以接收“DOWN”事件
    //2....
    //3.这个方法返回false，后续事件将会先传递到该方法，随后传到后onTouch方法中
    //4.这个方法返回true,你将不会接收到如下事件：目标View将会接收到一个CANCEL事件，所有的后续事件将会被传递到onTouchEvnet方法中，该方法将不再接收事件
}

onInterceptTouchEvent不是很好理解，可以参考这篇博文：Android 触摸事件机制(四) ViewGroup中触摸事件详解

3.处理事件

public boolean onTouchEvent(MotionEvent ev)
{
    return true; // true,MotionEvent被消费
}

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传递关系图

ViewGroup中的onInterceptTouchEvent方法，在Action为“DOWN”的时候或者ViewGroup子View有消费TouchEvnet事件的时候（可能有多个子View对TouchEvnet事件进行相应，这些View组成了TouchTarget链表）会被调用

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Demo

GitHub地址: GitHub
环境: Windows7+JAVA8
IDE: AndroidStdio2.2.2
compileSdkVersion:24
测试设备:Nexus5(6.0.1)

Demo中存在多个示例，请在Manifest中更改启动项。

自定义DLFrameLayout继承与FrameLayout,自定义DLView继承与View

分别重载Touch事件的方法，输出日志,代码如下：

 @Override
    public boolean dispatchTouchEvent(MotionEvent ev)
    {
        DLDebug.info(TAG, "dispatchTouchEvent: " + TouchEventHelper.parseAction((ev.getActionMasked())));//输出日志

        boolean dispatchTouchEvent = mDispatchTouchEvent;

        if (mSuperDispatchTouchEvent)//是否调用super方法
        {
            dispatchTouchEvent = super.dispatchTouchEvent(ev) || mDispatchTouchEvent;
        }

        DLDebug.info(TAG, "dispatchTouchEvent: " + dispatchTouchEvent);//输出日志，true/false

        return dispatchTouchEvent;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev)
    {
        DLDebug.info(TAG, "onInterceptTouchEvent: " + TouchEventHelper.parseAction((ev.getActionMasked())));

        boolean onInterceptTouchEvent = mInterceptTouchEvent;

        if (mSuperInterceptTouchEvent)
        {
            onInterceptTouchEvent = super.onInterceptTouchEvent(ev) || mInterceptTouchEvent;
        }

        DLDebug.info(TAG, "onInterceptTouchEvent: " + onInterceptTouchEvent);

        return onInterceptTouchEvent;
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev)
    {
        DLDebug.info(TAG, "onTouchEvent: " + TouchEventHelper.parseAction((ev.getActionMasked())));

        boolean onTouchEvent = mTouchEvent;

        if (mSuperTouchEvent)
        {
            onTouchEvent = super.onTouchEvent(ev) || mTouchEvent;
        }

        DLDebug.info(TAG, "onTouchEvent: " + onTouchEvent);

        return onTouchEvent;
    }

• 验证结果
• 如果自定义View所有方法都返回false，那么后续事件不会被传递到View或者ViewGroup中，只会被传递到Activity中
• 输出日志如下：

12-05 15:10:35.440  V/DL_MainActivity: dispatchTouchEvent: DOWN
12-05 15:10:35.440  I/DL_DLFrameLayout: dispatchTouchEvent: DOWN
12-05 15:10:35.440  I/DL_DLFrameLayout: onInterceptTouchEvent: DOWN
12-05 15:10:35.440  I/DL_DLFrameLayout: onInterceptTouchEvent: false
12-05 15:10:35.440  D/DL_DLView: dispatchTouchEvent: DOWN
12-05 15:10:35.441  D/DL_DLView: onTouchEvent: DOWN
12-05 15:10:35.441  D/DL_DLView: onTouchEvent: false
12-05 15:10:35.441  D/DL_DLView: dispatchTouchEvent: false
12-05 15:10:35.441  I/DL_DLFrameLayout: onTouchEvent: DOWN
12-05 15:10:35.441  I/DL_DLFrameLayout: onTouchEvent: false
12-05 15:10:35.441  I/DL_DLFrameLayout: dispatchTouchEvent: false
12-05 15:10:35.441  V/DL_MainActivity: onTouchEvent: DOWN
12-05 15:10:35.441  V/DL_MainActivity: onTouchEvent: false
12-05 15:10:35.441  V/DL_MainActivity: dispatchTouchEvent: false
12-05 15:10:35.634  V/DL_MainActivity: dispatchTouchEvent: MOVE
12-05 15:10:35.634  V/DL_MainActivity: onTouchEvent: MOVE
12-05 15:10:35.634  V/DL_MainActivity: onTouchEvent: false
12-05 15:10:35.634  V/DL_MainActivity: dispatchTouchEvent: false
....
12-05 15:10:36.021  V/DL_MainActivity: dispatchTouchEvent: UP
12-05 15:10:36.021  V/DL_MainActivity: onTouchEvent: UP
12-05 15:10:36.021  V/DL_MainActivity: onTouchEvent: false
12-05 15:10:36.021  V/DL_MainActivity: dispatchTouchEvent: false
// 根据日志可以看出，后续的MOVE/UP事件没有传递到自定义View中。

• 验证结果
• 如果ViewGroup onInterceptTouchEvent()中返回true，并且onTouchEvent()中也返回true，那么事件不会被传递到子View中，并且能接收后续事件。

• 输入日志如下：

  
  12-05 15:38:03.241  V/DL_MainActivity: dispatchTouchEvent: DOWN
  12-05 15:38:03.241  I/DL_DLFrameLayout: dispatchTouchEvent: DOWN
  12-05 15:38:03.241  I/DL_DLFrameLayout: onInterceptTouchEvent: DOWN
  12-05 15:38:03.241  I/DL_DLFrameLayout: onInterceptTouchEvent: true
  12-05 15:38:03.241  I/DL_DLFrameLayout: onTouchEvent: DOWN
  12-05 15:38:03.241  I/DL_DLFrameLayout: onTouchEvent: true
  12-05 15:38:03.241  I/DL_DLFrameLayout: dispatchTouchEvent: true
  12-05 15:38:03.242  V/DL_MainActivity: dispatchTouchEvent: true
  12-05 15:38:03.268  V/DL_MainActivity: dispatchTouchEvent: MOVE
  12-05 15:38:03.268  I/DL_DLFrameLayout: dispatchTouchEvent: MOVE
  12-05 15:38:03.268  I/DL_DLFrameLayout: onTouchEvent: MOVE
  12-05 15:38:03.269  I/DL_DLFrameLayout: onTouchEvent: true
  12-05 15:38:03.269  I/DL_DLFrameLayout: dispatchTouchEvent: true
  12-05 15:38:03.269  V/DL_MainActivity: dispatchTouchEvent: true
  12-05 15:38:03.285  V/DL_MainActivity: dispatchTouchEvent: MOVE
  12-05 15:38:03.285  I/DL_DLFrameLayout: dispatchTouchEvent: MOVE
  12-05 15:38:03.285  I/DL_DLFrameLayout: onTouchEvent: MOVE
  12-05 15:38:03.285  I/DL_DLFrameLayout: onTouchEvent: true
  12-05 15:38:03.285  I/DL_DLFrameLayout: dispatchTouchEvent: true
  12-05 15:38:03.285  V/DL_MainActivity: dispatchTouchEvent: true
  12-05 15:38:03.302  V/DL_MainActivity: dispatchTouchEvent: MOVE
  12-05 15:38:03.302  I/DL_DLFrameLayout: dispatchTouchEvent: MOVE
  12-05 15:38:03.302  I/DL_DLFrameLayout: onTouchEvent: MOVE
  12-05 15:38:03.302  I/DL_DLFrameLayout: onTouchEvent: true
  12-05 15:38:03.302  I/DL_DLFrameLayout: dispatchTouchEvent: true
  12-05 15:38:03.302  V/DL_MainActivity: dispatchTouchEvent: true
  12-05 15:38:03.318  V/DL_MainActivity: dispatchTouchEvent: MOVE
  12-05 15:38:03.318  I/DL_DLFrameLayout: dispatchTouchEvent: MOVE
  12-05 15:38:03.318  I/DL_DLFrameLayout: onTouchEvent: MOVE
  12-05 15:38:03.318  I/DL_DLFrameLayout: onTouchEvent: true
  12-05 15:38:03.318  I/DL_DLFrameLayout: dispatchTouchEvent: true
  12-05 15:38:03.318  V/DL_MainActivity: dispatchTouchEvent: true
  12-05 15:38:03.323  V/DL_MainActivity: dispatchTouchEvent: UP
  12-05 15:38:03.323  I/DL_DLFrameLayout: dispatchTouchEvent: UP
  12-05 15:38:03.323  I/DL_DLFrameLayout: onTouchEvent: UP
  12-05 15:38:03.323  I/DL_DLFrameLayout: onTouchEvent: true
  12-05 15:38:03.323  I/DL_DLFrameLayout: dispatchTouchEvent: true
  12-05 15:38:03.323  V/DL_MainActivity: dispatchTouchEvent: true
  //事件确实没有传递到子View中，ViewGroup接收了MOVE/UP事件

大家可以下载源码，察看其他情况下的输出结果

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