Android实现仿慕课网下拉加载动画

package com.example.loading_drawable;

import android.content.Context;
import android.graphics.drawable.AnimationDrawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.animation.Animation;
import android.widget.ImageView;

public class MyImgView extends ImageView {
// 动画图层类
private AnimationDrawable bg_anim;

public MyImgView(Context context) {
super(context, null);
initView();
}

public MyImgView(Context context, AttributeSet attrs) {
super(context, attrs, 0);
}

public MyImgView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);

}
　　//初始化
private void initView() {
setBackgroundResource(R.drawable.flash_anim);
bg_anim = (AnimationDrawable) getBackground();
Log.i("AAA", "iniView");
}

/**
* 开启动画效果
*/
public void startAnim() {
if (bg_anim != null) {
 bg_anim.start();
}
}

/**
* 停止动画效果
*/
public void stopAnim() {
if (bg_anim != null && bg_anim.isRunning()) {
 bg_anim.stop();
}
}

/*
* (non-Javadoc)
* 
* @see android.widget.ImageView#setVisibility(int) 当控件被显示时就调用 开启动画效果，反之
*/
@Override
public void setVisibility(int visibility) {
super.setVisibility(visibility);
if (visibility == View.VISIBLE) {
 startAnim();
} else {
 stopAnim();
}
}

}

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false">
<item android:drawable="@drawable/a01_02" android:duration="50"/>
<item android:drawable="@drawable/a01_04" android:duration="50"/>
<item android:drawable="@drawable/a01_06" android:duration="50"/>
<item android:drawable="@drawable/a01_08" android:duration="50"/>
<item android:drawable="@drawable/a01_10" android:duration="50"/>
<item android:drawable="@drawable/a01_12" android:duration="50"/>
<item android:drawable="@drawable/a01_14" android:duration="50"/>
<item android:drawable="@drawable/a01_16" android:duration="50"/>
<item android:drawable="@drawable/a01_25" android:duration="50"/>
<item android:drawable="@drawable/a01_26" android:duration="50"/>
<item android:drawable="@drawable/a01_27" android:duration="50"/>
<item android:drawable="@drawable/a01_28" android:duration="50"/>
<item android:drawable="@drawable/a01_30" android:duration="50"/>
<item android:drawable="@drawable/a01_31" android:duration="50"/>
<item android:drawable="@drawable/a01_32" android:duration="50"/>
<item android:drawable="@drawable/a01_41" android:duration="50"/>
<item android:drawable="@drawable/a01_42" android:duration="50"/>
<item android:drawable="@drawable/a01_43" android:duration="50"/>
<item android:drawable="@drawable/a01_44" android:duration="50"/>
<item android:drawable="@drawable/a01_45" android:duration="50"/>
<item android:drawable="@drawable/a01_46" android:duration="50"/>
<item android:drawable="@drawable/a01_47" android:duration="50"/>
<item android:drawable="@drawable/a01_48" android:duration="50"/>
<item android:drawable="@drawable/a01_57" android:duration="50"/>
<item android:drawable="@drawable/a01_58" android:duration="50"/>
<item android:drawable="@drawable/a01_59" android:duration="50"/>
<item android:drawable="@drawable/a01_60" android:duration="50"/>
<item android:drawable="@drawable/a01_61" android:duration="50"/>
<item android:drawable="@drawable/a01_62" android:duration="50"/>
<item android:drawable="@drawable/a01_63" android:duration="50"/>
<item android:drawable="@drawable/a01_64" android:duration="50"/>
</animation-list>

package com.example.loading_drawable;

import android.app.Activity;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;

/**
* @author Administrator 慕课网下拉刷新进度显示控件
* 
*/
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 LinearLayout rootLayout = new LinearLayout(this);
 rootLayout.setOrientation(LinearLayout.VERTICAL);
 rootLayout.setLayoutParams(new LinearLayout.LayoutParams(
   LinearLayout.LayoutParams.MATCH_PARENT,
   LinearLayout.LayoutParams.MATCH_PARENT));
 rootLayout.setGravity(Gravity.CENTER);

 Button btn = new Button(this);
 btn.setText("展现动画");

 final MyImgView imgView = new MyImgView(MainActivity.this);
 imgView.setLayoutParams(new LinearLayout.LayoutParams(
   LinearLayout.LayoutParams.WRAP_CONTENT,
   LinearLayout.LayoutParams.WRAP_CONTENT));
 imgView.setVisibility(View.GONE);

 rootLayout.addView(btn);
 rootLayout.addView(imgView);

 setContentView(rootLayout);

 btn.setOnClickListener(new OnClickListener() {

  @Override
  public void onClick(View arg0) {
   imgView.setVisibility(View.VISIBLE);
  }
 });
}
}