以xml的方式实现动画

1、java代码

 package com.example.tweenanim;

 import android.os.Bundle;
 import android.app.Activity;
 import android.view.Menu;
 import android.view.View;
 import android.view.animation.AlphaAnimation;
 import android.view.animation.Animation;
 import android.view.animation.AnimationSet;
 import android.view.animation.AnimationUtils;
 import android.view.animation.RotateAnimation;
 import android.view.animation.ScaleAnimation;
 import android.view.animation.TranslateAnimation;
 import android.widget.ImageView;

 public class MainActivity extends Activity {
     private ImageView iv;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         iv = (ImageView) findViewById(R.id.iv);
     }

     //透明度
     public void click1(View view){
         Animation animation = AnimationUtils.loadAnimation(this,R.anim.alpha_anim);
         iv.startAnimation(animation);
     }
     //缩放
     public void click2(View view){
         Animation animation = AnimationUtils.loadAnimation(this,R.anim.scale_anim);
         iv.startAnimation(animation);
     }
     //旋转
     public void click3(View view){
         Animation animation = AnimationUtils.loadAnimation(this,R.anim.rotate_anim);
         iv.startAnimation(animation);
     }
     //平移
     public void click4(View view){
         Animation animation = AnimationUtils.loadAnimation(this,R.anim.translate_anim);
         iv.startAnimation(animation);
     }
     //组合
     public void click5(View view){
         AnimationSet set = new AnimationSet(false);

         TranslateAnimation ta = new TranslateAnimation(Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 1.0f, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 1.0f);
         ta.setDuration(2000);
         ta.setRepeatCount(2);
         ta.setRepeatMode(Animation.REVERSE);

         RotateAnimation ra = new RotateAnimation(0, 360, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
         ra.setDuration(2000);
         ra.setRepeatCount(2);
         ra.setRepeatMode(Animation.REVERSE);

         ScaleAnimation sa = new ScaleAnimation(0.2f, 2.0f, 0.2f, 2.0f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
         sa.setDuration(2000);
         sa.setRepeatCount(2);
         sa.setRepeatMode(Animation.REVERSE);

         set.addAnimation(ta);
         set.addAnimation(ra);
         set.addAnimation(sa);
         iv.startAnimation(set);
     }

 }

2、动画xml,需要在res目录下新建anim文件夹，然后把以下的xml文件放进去

1)透明度alpha_anim.xml文件

 <?xml version="1.0" encoding="utf-8"?>
 <alpha xmlns:android="http://schemas.android.com/apk/res/android"
     android:fromAlpha="1.0"
     android:toAlpha="0.5"
     android:fillAfter="true"
     android:duration="2000"
     >

 </alpha>

2)缩放scale_anim.xml文件

 <?xml version="1.0" encoding="utf-8"?>
 <scale xmlns:android="http://schemas.android.com/apk/res/android"
     android:fromXScale="0.2"
     android:toXScale="2.0"
     android:fromYScale="0.2"
     android:toYScale="2.0"
     android:pivotX="50%"
     android:pivotY="50%"
     android:duration="2000"
     >

 </scale>

3)旋转rotate_anim.xml文件

 <?xml version="1.0" encoding="utf-8"?>
 <rotate xmlns:android="http://schemas.android.com/apk/res/android"
     android:fromDegrees="0"
     android:toDegrees="360"
     android:pivotX="50%"
     android:pivotY="50%"
     android:duration="2000"
     >

 </rotate>

4)平移translate_anim.xml文件

 <?xml version="1.0" encoding="utf-8"?>
 <translate xmlns:android="http://schemas.android.com/apk/res/android"
     android:fromXDelta="20%p"
     android:toXDelta="100%p"
     android:fromYDelta="20%p"
     android:toYDelta="100%p"
     android:duration="2000"
     >

 </translate>

注意:%后面的p说明是相对于父窗口；如果没有p,则相对于它自己