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ViewSwitcher 的作用简单来说就是：在两个视图间转换时显示动画
它的两个子类应该很熟悉，ImageSwitcher：转换图片时增加动画效果;TextSwitcher：转换文字时增加动画效果;其实例见apidemos中ImageSwitcher实例和TextSwitcher实例
但不要忽略ViewSwicher,在一些场合还是很有用的
在android里视图切换是一个很常见的需求，比如说加载view和后台背景，当后台加载数据时，loding view显示，数据View隐藏，加载完成，反向此过程。使用ViewSwicher提供了简单的逻辑，产生更可读的代码。
举个最常见的例子，模拟点击LoadMoreItems按钮或得更多数据。
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<?xml
version="1.0"
encoding="utf-8"?>
<Button
xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/btn_loadmorecontacts" android:text="Load
More Items" android:layout_width="fill_parent" android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceLarge" android:minHeight="?android:attr/listPreferredItemHeight" android:textColor="#FFFFFF" android:background="@android:drawable/list_selector_background" android:clickable="true" android:onClick="onClick"
/> |
大致是这样子
加载中视图：
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<?xml
version="1.0"
encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center_horizontal" android:minHeight="?android:attr/listPreferredItemHeight">
<ProgressBar
android:id="@+id/progressbar" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true"
/> <TextView
android:text="Loading…" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_toRightOf="@+id/progressbar" android:layout_centerVertical="true" android:gravity="center" android:padding="10dip" android:textColor="#FFFFFF"
/> </RelativeLayout> |
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public
class ViewSwitcherExample extends ListActivity implements
OnClickListener { //sample
list items static
final String[] ITEMS = new
String[] {
"List
Item 1",
"List
Item 2",
"List
Item 3",
"List
Item 4",
"List
Item 5",
"List
Item 6",
"List
Item 7",
"List
Item 8",
"List
Item 9",
"List
Item 10"
}; //the
ViewSwitcher private
ViewSwitcher switcher; /**
Called when the activity is first created. */ @Override
public
void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
//no
window title requestWindowFeature(Window.FEATURE_NO_TITLE);
//create
the ViewSwitcher in the current context switcher
= new
ViewSwitcher(this);
//footer
Button: see XML1 Button
footer = (Button)View.inflate(this,
R.layout.btn_loadmore, null);
//progress
View: see XML2 View
progress = View.inflate(this,
R.layout.loading_footer, null);
//add
the views (first added will show first) switcher.addView(footer);
switcher.addView(progress);
//add
the ViewSwitcher to the footer getListView().addFooterView(switcher);
//add
items to the ListView setListAdapter(new
ArrayAdapter(this,
android.R.layout.simple_list_item_1,
ITEMS)); }
@Override
/*
Load More Button Was Clicked */ public
void onClick(View arg0) { //first
view is showing, show the second progress view switcher.showNext();
//and
start background work new
getMoreItems().execute(); }
/**
Background Task To Get More Items**/ private
class getMoreItems extends AsyncTask { @Override
protected
Object doInBackground(Void… params) { //code
to add more items //...
try
{ Thread.sleep(3000);
//only
to demonstrate }
catch
(InterruptedException e) { e.printStackTrace();
}
return
null;
}
@Override
/*
Background Task is Done */ protected
void onPostExecute(Object result) { //go
back to the first view switcher.showPrevious();
//update
the ListView }
}
} |
当然你也可以使用xml形式构造ViewSwicher,这里加上了系统自带的切换效果@android:anim/slide_in_left和@android:anim/slide_out_right
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<?xmlversion="1.0"encoding="utf-8"?>
<ViewSwitcherxmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/profileSwitcher"android:layout_width="fill_parent" android:layout_height="fill_parent"android:inAnimation="@android:anim/slide_in_left" android:outAnimation="@android:anim/slide_out_right">
<RelativeLayout
android:layout_width="wrap_content"android:layout_height="wrap_content">
<ProgressBar
android:id="@+id/progressbar" android:layout_width="wrap_content"android:layout_height="wrap_content" android:layout_centerVertical="true"/>
<TextView
android:text="Loading…"android:layout_height="wrap_content" android:layout_width="wrap_content"android:layout_toRightOf="@+id/progressbar" android:gravity="center"/>
</RelativeLayout>
<RelativeLayout
android:layout_width="wrap_content"android:layout_height="wrap_content" android:gravity="center_horizontal">
<TextView
android:text="Finished!"android:layout_height="wrap_content" android:layout_width="wrap_content"android:layout_centerVertical="true"/>
</RelativeLayout>
</ViewSwitcher> |
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原文地址：http://blog.csdn.net/love_xsq/article/details/44922407
