在进行android开发时难免同时会用到onClick和onTouch事件,比如要实现view有click事件,并且通过onTouch实现了跟随手指而移动,在移动完成后不进行人和事情。如果直接使用,在移动完成松手以后也会出现click事件,主要在于android的事件分发机制原因。本文将通过反射机制来实现

View事件的分发机制

本文只对会用到的事件的响应顺序做一些简单的介绍,更多的分析请查找其他资料
为了便于理解,直接通过代码来进行分析,创建一个activity,摆放一个button,button实现三个listener事件(setOnClickListener,setOnLongClickListener,setOnTouchListener),代码如下:

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    Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Log.i("mandroid.cn", "button被点击");
}
});
button.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View view) {
Log.i("mandroid.cn", "button被长按");
return false;
}
});
button.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
switch (motionEvent.getAction()) {
case MotionEvent.ACTION_DOWN: {
Log.i("mandroid.cn", "button按下");
break;
}
case MotionEvent.ACTION_MOVE: {
Log.i("mandroid.cn", "button移动");
break;
}
case MotionEvent.ACTION_UP: {
Log.i("mandroid.cn", "button松开");
break;
}
}
//返回true不响应click事件
return true;
}
});

运行后按下button,查看打印的log如下

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11-20 00:28:11.005 27548-27548/com.wrbug.myapplication I/mandroid.cn: button按下
11-20 00:28:11.017 27548-27548/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:28:11.034 27548-27548/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:28:11.042 27548-27548/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:28:11.051 27548-27548/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:28:11.059 27548-27548/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:28:11.066 27548-27548/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:28:11.067 27548-27548/com.wrbug.myapplication I/mandroid.cn: button松开

可以发现并未响应onClick和onLongClick事件,是由于在onTouch里面返回为true时,就不会往其他地方分发,将返回改为false再次运行:

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11-20 00:47:27.020 21781-21781/com.wrbug.myapplication I/mandroid.cn: button按下
11-20 00:47:27.052 21781-21781/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:47:27.069 21781-21781/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 00:47:27.070 21781-21781/com.wrbug.myapplication I/mandroid.cn: button松开
11-20 00:47:27.070 21781-21781/com.wrbug.myapplication V/AudioManager: playSoundEffect effectType: 0
11-20 00:47:27.070 21781-21781/com.wrbug.myapplication V/AudioManager: querySoundEffectsEnabled...
11-20 00:47:27.070 21781-21781/com.wrbug.myapplication I/mandroid.cn: button被点击

改为false的时候。在移动完成时都会响应click事件,目前我们就是要实现检测到view在移动后,不执行click和longclick操作,没有移动则执行。

实现

为了方便,只以onClick的方式来讲解。通过查看View的源码,View的listener都存在一个静态内部类里面
view源码查看地址:http://android.mandroid.cn/java/android/view/View.java

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static class ListenerInfo {
/**
* Listener used to dispatch focus change events.
* This field should be made private, so it is hidden from the SDK.
* {@hide}
*/
protected OnFocusChangeListener mOnFocusChangeListener;

/**
* Listeners for layout change events.
*/
private ArrayList<OnLayoutChangeListener> mOnLayoutChangeListeners;

protected OnScrollChangeListener mOnScrollChangeListener;

/**
* Listeners for attach events.
*/
private CopyOnWriteArrayList<OnAttachStateChangeListener> mOnAttachStateChangeListeners;

/**
* Listener used to dispatch click events.
* This field should be made private, so it is hidden from the SDK.
* {@hide}
*/
public OnClickListener mOnClickListener;

/**
* Listener used to dispatch long click events.
* This field should be made private, so it is hidden from the SDK.
* {@hide}
*/
protected OnLongClickListener mOnLongClickListener;

/**
* Listener used to dispatch context click events. This field should be made private, so it
* is hidden from the SDK.
* {@hide}
*/
protected OnContextClickListener mOnContextClickListener;

/**
* Listener used to build the context menu.
* This field should be made private, so it is hidden from the SDK.
* {@hide}
*/
protected OnCreateContextMenuListener mOnCreateContextMenuListener;

private OnKeyListener mOnKeyListener;

private OnTouchListener mOnTouchListener;

private OnHoverListener mOnHoverListener;

private OnGenericMotionListener mOnGenericMotionListener;

private OnDragListener mOnDragListener;

private OnSystemUiVisibilityChangeListener mOnSystemUiVisibilityChangeListener;

OnApplyWindowInsetsListener mOnApplyWindowInsetsListener;
}

ListenerInfo mListenerInfo;

通过反射获取mListenerInfo实例,再获取mListenerInfo里面的mOnClickListener,最后调用mOnClickListener.onClick()方法即可,修改后的onTouch代码如下

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button.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
switch (motionEvent.getAction()) {
case MotionEvent.ACTION_DOWN: {
Log.i("mandroid.cn", "button按下");
//记录按下时的位置
x = motionEvent.getRawX();
y = motionEvent.getRawY();
break;
}
case MotionEvent.ACTION_MOVE: {
Log.i("mandroid.cn", "button移动");
break;
}
case MotionEvent.ACTION_UP: {
//检测移动的距离,如果很微小可以认为是点击事件
if (Math.abs(motionEvent.getRawX() - x) < 10 && Math.abs(motionEvent.getRawY() - y) < 10) {
try {
Field field = View.class.getDeclaredField("mListenerInfo");
field.setAccessible(true);
Object object = field.get(view);
field = object.getClass().getDeclaredField("mOnClickListener");
field.setAccessible(true);
object = field.get(object);
if (object != null && object instanceof View.OnClickListener) {
((View.OnClickListener) object).onClick(view);
}
} catch (Exception e) {

}
} else {
Log.i("mandroid.cn", "button已移动");
}
break;
}
}
return true;
}
});

log如下,也达到我们要求

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//第一次点击
11-20 01:28:51.189 32174-32174/com.wrbug.myapplication I/mandroid.cn: button按下
11-20 01:28:52.057 32174-32174/com.wrbug.myapplication I/mandroid.cn: button被点击
//第二次点击
11-20 01:28:53.335 32174-32174/com.wrbug.myapplication I/mandroid.cn: button按下
11-20 01:28:54.055 32174-32174/com.wrbug.myapplication I/mandroid.cn: button被点击
//移动
11-20 01:28:55.238 32174-32174/com.wrbug.myapplication I/mandroid.cn: button按下
11-20 01:28:55.269 32174-32174/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 01:28:55.278 32174-32174/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 01:28:55.285 32174-32174/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 01:28:55.294 32174-32174/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 01:28:55.301 32174-32174/com.wrbug.myapplication I/mandroid.cn: button移动
11-20 01:28:55.302 32174-32174/com.wrbug.myapplication I/mandroid.cn: button已移动

应用到的项目 MoveableLayout

正在开发一款开源的控件,功能是一个layout里面的控件开源自由移动,互不影响,不交叉重叠,使用到了上述的方法,也欢迎大家star和提出建议,目前只实现了移动,近期会实现其他功能,参考地址:https://github.com/WrBug/MoveableLayout