android.widget.ViewAnimator类继承至FrameLayout，ViewAnimator类的作用是为FrameLayout里面的View切换提供动画效果。该类有如下几个和动画相关的函数：
l setInAnimation：设置View进入屏幕时候使用的动画，该函数有两个版本，一个接受单个参数，类型为android.view.animation.Animation；一个接受两个参数，类型为Context和int，分别为Context对象和定义Animation的resourceID。
- setOutAnimation: 设置View退出屏幕时候使用的动画，参数setInAnimation函数一样。
- showNext： 调用该函数来显示FrameLayout里面的下一个View。
- showPrevious： 调用该函数来显示FrameLayout里面的上一个View。
一般不直接使用ViewAnimator而是使用它的两个子类ViewFlipper和ViewSwitcher。ViewFlipper可以用来指定FrameLayout内多个View之间的切换效果，可以一次指定也可以每次切换的时候都指定单独的效果。该类额外提供了如下几个函数：
- isFlipping： 用来判断View切换是否正在进行
- setFilpInterval：设置View之间切换的时间间隔
- startFlipping：使用上面设置的时间间隔来开始切换所有的View，切换会循环进行
- stopFlipping: 停止View切换
ViewSwitcher 顾名思义Switcher特指在两个View之间切换。可以通过该类指定一个ViewSwitcher.ViewFactory 工程类来创建这两个View。该类也具有两个子类ImageSwitcher、TextSwitcher分别用于图片和文本切换。
开始写个例子：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content" android:text="@string/hello" />
<ViewFlipper android:id="@+id/viewflipper"
android:layout_width="fill_parent" android:layout_height="wrap_content">
</ViewFlipper>
<ViewSwitcher android:layout_height="wrap_content"
android:layout_width="fill_parent" android:id="@+id/ButtonViewSwitcher">
<LinearLayout android:layout_width="fill_parent"
android:layout_height="wrap_content" android:gravity="center"
android:padding="2dp" android:background="@android:color/darker_gray"
android:id="@+id/ButtonLayout">
<Button android:id="@+id/button1" android:layout_height="wrap_content"
android:layout_weight="1" android:text="上一个"
android:layout_width="fill_parent" />
<Button android:id="@+id/button2" android:layout_height="wrap_content"
android:layout_weight="1" android:text="btn2"
android:layout_width="fill_parent" />
<Button android:id="@+id/button3" android:layout_height="wrap_content"
android:layout_weight="1" android:text="下一个"
android:layout_width="fill_parent" />
</LinearLayout>
</ViewSwitcher>
</LinearLayout>
public class ViewFipperTest extends Activity implements OnClickListener {
private Button btn1, btn2, btn3;
private ViewFlipper flipper;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
_initUICtrls();
}
private void _initUICtrls() {
btn1 = (Button) findViewById(R.id.button1);
btn1.setOnClickListener(this);
btn2 = (Button) findViewById(R.id.button2);
btn2.setOnClickListener(this);
btn3 = (Button) findViewById(R.id.button3);
btn3.setOnClickListener(this);
flipper = (ViewFlipper) findViewById(R.id.viewflipper);
flipper.addView(addButtonByText("Start"), new LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
flipper.addView(addTextByText("gangwangchina"));
flipper.addView(addImageById(R.drawable.icon));
flipper.addView(addTextByText("Fushan Liaoli"));
flipper.addView(addImageById(R.drawable.icon));
flipper.addView(addButtonByText("End"), new LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
// flipper.setInAnimation(AnimationUtils.loadAnimation(this,
// android.R.anim.fade_in));
// flipper.setOutAnimation(AnimationUtils.loadAnimation(this,
// android.R.anim.fade_out));
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch(v.getId()){
case R.id.button1:
flipper.setInAnimation(AnimationHelper.inFromLeftAnimation());
flipper.setOutAnimation(AnimationHelper.outToRightAnimation());
flipper.showPrevious();
break;
case R.id.button3:
flipper.setInAnimation(AnimationHelper.inFromRightAnimation());
flipper.setOutAnimation(AnimationHelper.outToLeftAnimation());
flipper.showNext();
break;
}
}
public View addTextByText(String text) {
TextView tv = new TextView(this);
tv.setText(text);
tv.setGravity(1);
return tv;
}
public View addImageById(int id) {
ImageView iv = new ImageView(this);
iv.setImageResource(id);
return iv;
}
public View addButtonByText(String text) {
Button btn = new Button(this);
btn.setText(text);
return btn;
}
private static class AnimationHelper {
public static Animation inFromRightAnimation() {
Animation inFromRight = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, +1.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
inFromRight.setDuration(350);
inFromRight.setInterpolator(new AccelerateInterpolator());
return inFromRight;
}
public static Animation outToLeftAnimation() {
Animation outtoLeft = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, -1.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
outtoLeft.setDuration(350);
outtoLeft.setInterpolator(new AccelerateInterpolator());
return outtoLeft;
}
public static Animation inFromLeftAnimation() {
Animation inFromLeft = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, -1.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
inFromLeft.setDuration(350);
inFromLeft.setInterpolator(new AccelerateInterpolator());
return inFromLeft;
}
public static Animation outToRightAnimation() {
Animation outtoRight = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, +1.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
outtoRight.setDuration(350);
outtoRight.setInterpolator(new AccelerateInterpolator());
return outtoRight;
}
}
}
里面的AnimationHelper 类是用来处理切换效果的。
实际效果如下：
