标签：decorview 触摸事件 tools dispatch can false ble out button
所谓事件分发，就是将一次完整的点击所包含的点击事件传递到某个具体的View或ViewGroup，让该View或该ViewGroup处理它（消费它）。分发是从上往下（父到子）依次传递的，其中可能经过的对象有最上层Activity，中间层ViewGroup，最下层View。
源码查找：
1.自己的Activity的setContentView()方法
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_event_distribution);
}
2.跳转到Activity.java的setContentView()方法，可以看到，调用了getWindow()的方法
public void setContentView(@LayoutRes int layoutResID) {
getWindow().setContentView(layoutResID);
initWindowDecorActionBar();
}
3.Activity.java的mWindow来自PhoneWindow
mWindow = new PhoneWindow(this, window, activityConfigCallback);
4.PhoneWindow.java-->setContentView()-->?installDecor()，在PhoneWindow中调用了installDecor()方法
@Override
public void setContentView(int layoutResID) {
// Note: FEATURE_CONTENT_TRANSITIONS may be set in the process of installing the window
// decor, when theme attributes and the like are crystalized. Do not check the feature
// before this happens.
if (mContentParent == null) {
installDecor(); //继续执行
} else if (!hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
mContentParent.removeAllViews();
}
..................
5.PhoneWindow.java-->setContentView()-->?installDecor()-->?generateLayout(mDecor)，在?installDecor()中又继续执行了generateLayout(mDecor)方法。
mContentParent = generateLayout(mDecor);
6.PhoneWindow.java-->generateLayout()
ViewGroup generateLayout(DecorView decor)
7.PhoneWindow.java-->generateLayout()-->?int layoutResource，layoutResource根据不同情况，返回不同的资源文件，也就是布局文件。
int layoutResource;
8.PhoneWindow.java-->generateLayout()-->R.layout.screen_title; 拿出一个常用的布局文件，screen_title.xml
layoutResource = R.layout.screen_title;
9.screen_title.xml的代码， ViewStub是用来显示ActionBar的，另外两个FrameLayout，一个显示TitleView，一个显示ContentView，平时写的内容，正是ContentView。
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:fitsSystemWindows="true">
<!-- Popout bar for action modes -->
<ViewStub android:id="@+id/action_mode_bar_stub"
android:inflatedId="@+id/action_mode_bar"
android:layout="@layout/action_mode_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="?attr/actionBarTheme" />
<FrameLayout
android:layout_width="match_parent"
android:layout_height="?android:attr/windowTitleSize"
style="?android:attr/windowTitleBackgroundStyle">
<TextView android:id="@android:id/title"
style="?android:attr/windowTitleStyle"
android:background="@null"
android:fadingEdge="horizontal"
android:gravity="center_vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</FrameLayout>
<FrameLayout android:id="@android:id/content"
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:foregroundGravity="fill_horizontal|top"
android:foreground="?android:attr/windowContentOverlay" />
</LinearLayout>
如以下结构图：
涉及到的方法
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
//分发事件
return super.dispatchTouchEvent(ev);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
//拦截事件
return super.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//消费事件
return super.onTouchEvent(event);
}
Activity涉及到的方法：dispatchTouchEvent()、onTouchEvent()
ViewGroup涉及到的方法：dispatchTouchEvent()、onInterceptTouchEvent()
View涉及到的方法：dispatchTouchEvent()、onTouchEvent()
每一次事件分发，都是从dispatchTouchEvent()开始的。
1）查看Activity的源码，调用了getWindow().superDispatchTouchEvent(ev)
public boolean dispatchTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
onUserInteraction();
}
if (getWindow().superDispatchTouchEvent(ev)) {
return true;
}
return onTouchEvent(ev);
}
2）在Activity.java中可以看到，所以getWindow().superDispatchTouchEvent(ev)实际上是调用了PhoneWindow.java中的superDispatchTouchEvent(ev)方法。
public Window getWindow() {
return mWindow;
}
mWindow = new PhoneWindow(this, window, activityConfigCallback); //mWindow的定义
3）然后再看PhoneWindow.java中的superDispatchTouchEvent(ev)方法，是调用DecorView.java的mDecor.superDispatchTouchEvent(event)
@Override
public boolean superDispatchTouchEvent(MotionEvent event) {
return mDecor.superDispatchTouchEvent(event);
}
4）而DecorView是继承FrameLayout，再继承ViewGroup的
private DecorView mDecor; //实例对象
class DecorView extends FrameLayout; //继承FrameLayout
FrameLayout extends ViewGroup; //继承ViewGroup
5）从上面四步来分析，Avtivity的getWindow().superDispatchTouchEvent()方法最后调用的是ViewGroup的dispatchTouchEvent()方法，从而实现了事件从Activity的dispatchTouchEvent()向下传递到ViewGroup的dispatchTouchEvent()方法。
6）返回值分析。
getWindow().superDispatchTouchEvent()返回true，则Avtivity的dispatchTouchEvent()，也会返回true，表示点击事件顺利分发给ViewGroup，由ViewGroup继续进行下一层的分发，Avtivity的分发任务结束。onTouchEvent()，无论onTouchEvent()这个方法返回的是true或者false，本次的事件分发都结束了。
ViewGroup.java中的部分代码
ViewGroup-->dispatchTouchEvent()
public boolean dispatchTouchEvent(MotionEvent ev) {
if (!disallowIntercept) {
intercepted = onInterceptTouchEvent(ev);
ev.setAction(action); // restore action in case it was changed
} else {
intercepted = false;
}
}
方法中使用了onInterceptTouchEvent(ev)方法
onInterceptTouchEvent(ev)默认返回不拦截，可以在ViewGroup中重写改方法来拦截事件。这个源码中，使用到了intercepted这个变量，主要作用是来遍历子ViewGroup和View，
// Check for interception.
final boolean intercepted;
if (!canceled && !intercepted) {
// If the event is targeting accessibility focus we give it to the
// view that has accessibility focus and if it does not handle it
// we clear the flag and dispatch the event to all children as usual.
// We are looking up the accessibility focused host to avoid keeping
// state since these events are very rare.
View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()
? findChildWithAccessibilityFocus() : null;
View的dispatchTouchEvent()的源码
public boolean dispatchTouchEvent(MotionEvent event) {
// If the event should be handled by accessibility focus first.
if (event.isTargetAccessibilityFocus()) {
// We don‘t have focus or no virtual descendant has it, do not handle the event.
if (!isAccessibilityFocusedViewOrHost()) {
return false;
}
// We have focus and got the event, then use normal event dispatch.
event.setTargetAccessibilityFocus(false);
}
boolean result = false;
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
}
final int actionMasked = event.getActionMasked();
if (actionMasked == MotionEvent.ACTION_DOWN) {
// Defensive cleanup for new gesture
stopNestedScroll();
}
if (onFilterTouchEventForSecurity(event)) {
if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
result = true;
}
//noinspection SimplifiableIfStatement
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
result = true;
}
if (!result && onTouchEvent(event)) {
result = true;
}
}
if (!result && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
// Clean up after nested scrolls if this is the end of a gesture;
// also cancel it if we tried an ACTION_DOWN but we didn‘t want the rest
// of the gesture.
if (actionMasked == MotionEvent.ACTION_UP ||
actionMasked == MotionEvent.ACTION_CANCEL ||
(actionMasked == MotionEvent.ACTION_DOWN && !result)) {
stopNestedScroll();
}
return result;
}
onTouch()方法，如果onTouch()方法能够消费该事件，就会直接返回True，从而直接结束View的dispatchTouchEvent()方法，不再执行onTouchEvent()方法；onTouchEvent``()方法。ViewGroup的onTouchEvent()方法，直到回调到Activity的onTouchEvent``()方法。
共有三种类型和四个测试代码
Activity：EventDistributionActivity
ViewGroup：EventDistributionLinearLayout1、EventDistributionLinearLayout2
View：EventDistributionButton
分别代码：
EventDistributionActivity.java
public class EventDistributionActivity extends BaseActivity {
Button mBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_event_distribution);
mBtn = findViewById(R.id.btn);
OnClick();
}
public void OnClick() {
mBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.v("showLog", "按钮被点击！");
}
});
mBtn.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
boolean dis = false;
Log.v("showLog", "Button.Touch()=" + dis);
return dis;
}
});
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
//分发事件
boolean dis = super.dispatchTouchEvent(ev);
Log.v("showLog", "Activity.dispatchTouchEvent()=" + dis);
return dis;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//处理事件
boolean dis = super.onTouchEvent(event);
Log.v("showLog", "Activity.onTouchEvent()=" + dis);
return dis;
}
}
EventDistributionLinearLayout1.java
public class EventDistributionLinearLayout1 extends LinearLayout {
public EventDistributionLinearLayout1(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
//分发事件
boolean dis = super.dispatchTouchEvent(ev);
Log.v("showLog", "LinearLayout1.dispatchTouchEvent()=" + dis);
return dis;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
//拦截事件
boolean dis = super.onInterceptTouchEvent(ev);
Log.v("showLog", "LinearLayout1.onInterceptTouchEvent()=" + dis);
return dis;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//消费事件
boolean dis = super.onTouchEvent(event);
Log.v("showLog", "LinearLayout1.onTouchEvent()=" + dis);
return dis;
}
}
EventDistributionLinearLayout2.java
public class EventDistributionLinearLayout2 extends LinearLayout {
public EventDistributionLinearLayout2(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
//分发事件
boolean dis = super.dispatchTouchEvent(ev);
Log.v("showLog", "LinearLayout2.dispatchTouchEvent()=" + dis);
return dis;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
//拦截事件
boolean dis = super.onInterceptTouchEvent(ev);
dis = true;
Log.v("showLog", "LinearLayout2.onInterceptTouchEvent()=" + dis);
return dis;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//消费事件
boolean dis = super.onTouchEvent(event);
Log.v("showLog", "LinearLayout2.onTouchEvent()=" + dis);
return dis;
}
}
EventDistributionButton.java
public class EventDistributionButton extends Button {
public EventDistributionButton(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
//分发事件
boolean dis = super.dispatchTouchEvent(event);
Log.v("showLog", "Button.dispatchTouchEvent()=" + dis);
return dis;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//消费事件
boolean dis = super.onTouchEvent(event);
Log.v("showLog", "Button.onTouchEvent()=" + dis);
return dis;
}
@Override
public boolean performClick() {
boolean dis = super.performClick();
Log.v("showLog", "Button.performClick()="+dis);
return dis;
}
}
activity_event_distribution.xml
<?xml version="1.0" encoding="utf-8"?>
<com.lanjiabin.systemtest.event.EventDistributionLinearLayout1 xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".event.EventDistributionActivity">
<com.lanjiabin.systemtest.event.EventDistributionLinearLayout2
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.lanjiabin.systemtest.event.EventDistributionButton
android:background="@drawable/button_color_circle_shape1"
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="300dp"
android:text="点击" />
</com.lanjiabin.systemtest.event.EventDistributionLinearLayout2>
</com.lanjiabin.systemtest.event.EventDistributionLinearLayout1>
效果图：一个LinearLayout1包含LinearLayout2再包含一个Button
界面只有一个按钮
测试用例：按钮消费事件，和空白处不消费事件
按住按钮不松开,事件被Button的onTouchEvent()消费
LinearLayout1.onInterceptTouchEvent()=false
LinearLayout2.onInterceptTouchEvent()=false
Button.Touch()=false
Button.onTouchEvent()=true
Button.dispatchTouchEvent()=true
LinearLayout2.dispatchTouchEvent()=true
LinearLayout1.dispatchTouchEvent()=true
Activity.dispatchTouchEvent()=true
按住空白处不松开，没有事件被消费
LinearLayout1.onInterceptTouchEvent()=false
LinearLayout2.onInterceptTouchEvent()=false
LinearLayout2.onTouchEvent()=false
LinearLayout2.dispatchTouchEvent()=false
LinearLayout1.onTouchEvent()=false
LinearLayout1.dispatchTouchEvent()=false
Activity.onTouchEvent()=false
Activity.dispatchTouchEvent()=false
测试用例：在LinearLayout2处截断
修改代码：EventDistributionLinearLayout2.java
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
//拦截事件
boolean dis = super.onInterceptTouchEvent(ev);
dis = true;
Log.v("showLog", "LinearLayout2.onInterceptTouchEvent()=" + dis);
return dis;
}
按住按钮不松开：事件截断生效，将不会继续遍历下层的ViewGroup或者View，所以日志中看不到Button的日志打印。
LinearLayout1.onInterceptTouchEvent()=false
LinearLayout2.onInterceptTouchEvent()=true //截断生效
LinearLayout2.onTouchEvent()=false
LinearLayout2.dispatchTouchEvent()=false
LinearLayout1.onTouchEvent()=false
LinearLayout1.dispatchTouchEvent()=false
Activity.onTouchEvent()=false
Activity.dispatchTouchEvent()=false
测试用例：在View中onTouch()中返回true
也就是在Button中设置onTouch()返回true，则不会产生点击事件，完整的点击事件是被按下和松开的，所以上面没有点击按钮的监听事件的打印日志。
首先，看看完整的点击事件日志，去掉先前测试的改变的代码。
LinearLayout1.onInterceptTouchEvent()=false
LinearLayout2.onInterceptTouchEvent()=false
Button.Touch()=false
Button.onTouchEvent()=true //触摸按下事件被消费
Button.dispatchTouchEvent()=true
LinearLayout2.dispatchTouchEvent()=true
LinearLayout1.dispatchTouchEvent()=true
Activity.dispatchTouchEvent()=true //触摸按下的事件处理结束
LinearLayout1.onInterceptTouchEvent()=false //开始触摸i抬起的事件
LinearLayout2.onInterceptTouchEvent()=false
Button.Touch()=false
Button.onTouchEvent()=true //触摸抬起的事件被消费
Button.dispatchTouchEvent()=true
LinearLayout2.dispatchTouchEvent()=true
LinearLayout1.dispatchTouchEvent()=true
Activity.dispatchTouchEvent()=true
按钮被点击！ //onClick
Button.performClick()=true
开始测试用例：
修改代码：
EventDistributionActivity.java，将boolean dis = false;修改为boolean dis = true;
mBtn.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
boolean dis = true;
Log.v("showLog", "Button.Touch()=" + dis);
return dis;
}
});
按下和松开按钮：可以看到，事件被Button.Touch()消费了，因为在Touch()返回了true，事件没有继续传递下去，所以onClick事件没有被触发，没有生效。
LinearLayout1.onInterceptTouchEvent()=false
LinearLayout2.onInterceptTouchEvent()=false
Button.Touch()=true //触摸事件被消费
Button.dispatchTouchEvent()=true
LinearLayout2.dispatchTouchEvent()=true
LinearLayout1.dispatchTouchEvent()=true
Activity.dispatchTouchEvent()=true //触摸按下事件处理完毕
LinearLayout1.onInterceptTouchEvent()=false
LinearLayout2.onInterceptTouchEvent()=false
Button.Touch()=true
Button.dispatchTouchEvent()=true
LinearLayout2.dispatchTouchEvent()=true
LinearLayout1.dispatchTouchEvent()=true
Activity.dispatchTouchEvent()=true
编程中我们会遇到多少挫折？表放弃，沙漠尽头必是绿洲。
标签：decorview 触摸事件 tools dispatch can false ble out button
原文地址：https://www.cnblogs.com/lanjiabin/p/12853407.html
