Android进度条(星级评分)使用详解(二)

public class MainActivity extends ActionBarActivity {
 private ImageView image = null;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  image = (ImageView)findViewById(R.id.image);
  SeekBar seekBar = (SeekBar) findViewById(R.id.seekBar);
  seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
   //当拖动条发生改变时触发该方法
   public void onProgressChanged(SeekBar seekBar, int progress,
     boolean fromUser) {	 //Notification that the progress level has changed
    image.setImageAlpha(progress);//动态改变图片的透明度
   }
   public void onStopTrackingTouch(SeekBar seekBar) {	//Notification that the user has finished a touch gesture     
   }
   public void onStartTrackingTouch(SeekBar seekBar) {	//Notification that the user has started a touch gesture      
   }    
  });
 }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ImageView
        android:id="@+id/image"
        android:layout_width="fill_parent"
        android:layout_height="250dp"
        android:src="@drawable/hehe"/>
    <!--定义一个拖动条，并改变它的滑块外观  -->
 <SeekBar
     android:id="@+id/seekBar"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:max="255"                    //设置拖动条的最大值
     android:progress="255"             //设置拖动条当前默认值
     android:thumb="@drawable/android" /> 
</LinearLayout>

protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  image = (ImageView) findViewById(R.id.image);
  RatingBar ratingBar = (RatingBar) findViewById(R.id.ratingBar);
  ratingBar.setOnRatingBarChangeListener(new OnRatingBarChangeListener() {
   public void onRatingChanged(RatingBar ratingBar, float rating,
     boolean fromUser) {
    image.setImageAlpha((int)(rating*255)/5);// 动态改变图片的透明度
   }
  });

<RatingBar
      android:id="@+id/ratingBar"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
     android:max="255"
     android:numStars="5"
     android:stepSize="0.5"
     android:progress="255"/>