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【移动应用开发技术】andriod开发之Activity渲染机制的示例分析
public
class
MainActivity
extends
Activity
{
@Override
protected
void
onCreate(Bundle
savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}final
void
attach(Context
context,
ActivityThread
aThread,
Instrumentation
instr,
IBinder
token,
int
ident,
Application
application,
Intent
intent,
ActivityInfo
info,
CharSequence
title,
Activity
parent,
String
id,
NonConfigurationInstances
lastNonConfigurationInstances,
Configuration
config,
String
referrer,
IVoiceInteractor
voiceInteractor,
Window
window)
{
...
mWindow
=
new
PhoneWindow(this,
window);
...
}
public
Window
getWindow()
{
return
mWindow;
}
public
void
setContentView(@LayoutRes
int
layoutResID)
{
getWindow().setContentView(layoutResID);
initWindowDecorActionBar();
}public
void
setContentView(int
layoutResID)
{
if
(mContentParent
==
null)
{
installDecor();
}
else
{
mContentParent.removeAllViews();
}
mLayoutInflater.inflate(layoutResID,
mContentParent);
final
Callback
cb
=
getCallback();
if
(cb
!=
null
&&
!isDestroyed())
{
cb.onContentChanged();
}
}
private
void
installDecor()
{
if
(mDecor
==
null)
{
mDecor
=
generateDecor();
...
}
if
(mContentParent
==
null)
{
//mContentParent
实际上是mDecor的一个子view
mContentParent
=
generateLayout(mDecor);
...
}
...
}
protected
DecorView
generateDecor()
{
return
new
DecorView(getContext(),
-1);
}
private
final
class
DecorView
extends
FrameLayout
implements
RootViewSurfaceTaker
{
...
}protected
ViewGroup
generateLayout(DecorView
decor)
{
...
if
((features
&
((1
<<
FEATURE_LEFT_ICON)
|
(1
<<
FEATURE_RIGHT_ICON)))
!=
0)
{
...
layoutResource
=
ernal.R.layout.screen_title_icons;
...
}
else
if
((features
&
((1
<<
FEATURE_PROGRESS)
|
(1
<<
FEATURE_INDETERMINATE_PROGRESS)))
!=
0
&&
(features
&
(1
<<
FEATURE_ACTION_BAR))
==
0)
{
layoutResource
=
ernal.R.layout.screen_progress;
}
else
if
((features
&
(1
<<
FEATURE_CUSTOM_TITLE))
!=
0)
{
...
layoutResource
=
ernal.R.layout.screen_custom_title;
...
}
...
else{
layoutResource
=
ernal.R.layout.screen_simple;
}
...
View
in
=
mLayoutInflater.inflate(layoutResource,
null);
decor.addView(in,
new
ViewGroup.LayoutParams(MATCH_PARENT,
MATCH_PARENT));
ViewGroup
contentParent
=
(ViewGroup)findViewById(ID_ANDROID_CONTENT);
...
return
contentParent;
}<LinearLayout
xmlns:android="/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:orientation="vertical">
<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"
/>
<FrameLayout
android:id="@android:id/content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:foregroundInsidePadding="false"
android:foregroundGravity="fill_horizontal|top"
android:foreground="?android:attr/windowContentOverlay"
/>
</LinearLayout>
/upload/information/20200623/125/124092.pngActivity的布局是怎样被系统渲染的final
void
handleResumeActivity(IBinder
token,
boolean
clearHide,
boolean
isForward,
boolean
reallyResume)
{
...
//performResumeActivity方法会调用Activity.onResume
ActivityClientRecord
r
=
performResumeActivity(token,
clearHide);
...
r.window
=
r.activity.getWindow();
View
decor
=
r.window.getDecorView();
decor.setVisibility(View.INVISIBLE);
ViewManager
wm
=
a.getWindowManager();
WindowManager.LayoutParams
l
=
r.window.getAttributes();
a.mDecor
=
decor;
l.type
=
WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
l.softInputMode
|=
forwardBit;
if
(a.mVisibleFromClient)
{
a.mWindowAdded
=
true;
wm.addView(decor,
l);
}
...
}为什么不能在子线程中操作viewpublic
class
MainActivity
extends
Activity
{
@Override
protected
void
onCreate(Bundle
savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new
Thread(new
Runnable()
{
@Override
public
void
run()
{
((TextView)findViewById(R.id.textView)).setText("子线程中操作view");
}
}).start();
}
}/upload/information/20200623/125/124093.pngpublic
class
MainActivity
extends
Activity
{
@Override
protected
void
onCreate(Bundle
savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new
Thread(new
Runnable()
{
@Override
public
void
run()
{
try
{
Thread.sleep(1000);
}
catch
(InterruptedException
e)
{
e.printStackTrace();
}
((TextView)findViewById(R.id.textView)).setText("子线程中操作view");
}
}).start();
}
}02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
FATAL
EXCEPTION:
Thread-5
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
Process:
com.example.linjw.myapplication,
PID:
3780
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
android.view.ViewRootImpl$CalledFromWrongThreadException:
Only
the
original
thread
that
created
a
view
hierarchy
can
touch
its
views.
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6987)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:1104)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.view.View.requestLayout(View.java:19807)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.view.View.requestLayout(View.java:19807)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.view.View.requestLayout(View.java:19807)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.view.View.requestLayout(View.java:19807)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.support.constraint.ConstraintLayout.requestLayout(ConstraintLayout.java:874)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.view.View.requestLayout(View.java:19807)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.widget.TextView.checkForRelayout(TextView.java:7375)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.widget.TextView.setText(TextView.java:4487)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.widget.TextView.setText(TextView.java:4344)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
android.widget.TextView.setText(TextView.java:4319)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
com.example.linjw.myapplication.MainActivity$1.run(MainActivity.java:20)
02-28
22:36:48.550
3780
3817
E
AndroidRuntime:
at
java.lang.Thread.run(Thread.java:760)public
ViewRootImpl(Context
context,
Display
display)
{
...
mThread
=
Thread.currentThread();
...
}
void
checkThread()
{
if
(mThread
!=
Thread.currentThread())
{
throw
new
CalledFromWrongThreadException(
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