Android得知Scroller(两)——ViewGroup转让scrollTo()

package cc.ac;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.app.Activity;
/**
 * Demo描写叙述:
 * 对ViewGroup调用scrollTo()和scrollBy()方法.
 * 
 * 验证理论:
 * 假如一个ViewGroup(比方此处的XXXLayout)调用了scrollTo(By)()
 * 它的Content(即它全部的子View)都会移动.
 * 
 * 參考资料:
 * 1 http://blog.csdn.net/wangjinyu501/article/details/32339379
 * 2 http://blog.csdn.net/qinjuning/article/details/7247126
 *   Thank you very much
 *   
 * 备注说明:
 * 使用scrollTo(By)()方法移动过程较快并且比較生硬.
 * 为了优化scrollTo(By)()的滑动过程可採用Scroller类.
 * 该类源代码第一句This class encapsulates scrolling.
 * 就指明了该类的目的:封装了滑动过程.
 * 在后面的演示样例中,将学习到Scroller的使用.
 */
public class MainActivity extends Activity {
   private LinearLayout mLinearLayout;
   private Button mButton;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		init();
	}
	
	private void init(){
		mLinearLayout=(LinearLayout) findViewById(R.id.linearLayout);
		mButton=(Button) findViewById(R.id.button);
		mButton.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View view) {
				mLinearLayout.scrollBy(-50, 0);
			}
		});
	}

	
}

main.xml例如以下:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <LinearLayout
        android:id="@+id/linearLayout"
        android:layout_width="fill_parent"
        android:layout_height="300dip"
        android:background="@android:color/darker_gray" >

        <TextView
            android:layout_width="150dip"
            android:layout_height="50dip"
            android:background="@android:color/black"
            android:text="@string/hello_world"
            android:textColor="@android:color/white" />
    </LinearLayout>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="BUTTON" />

</RelativeLayout>