android 卷轴视图(ScrollView)

     卷轴视图是指当拥有很多内容，一屏显示不完时，需要通过滚动来显示视图。比如在做一个阅读器的时候，文章很长，一页显示不完，那么就需要使用卷轴视图来滚动显示下一页。我们下面先来看看运行效果



Activity01

package com.yarin.android.Examples_04_20;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ScrollView;
import android.widget.TextView;

public class Activity01 extends Activity
{
    private LinearLayout mLayout;   
    private ScrollView 	mScrollView;   
    private final Handler mHandler = new Handler();  
    
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		
		//创建一个线性布局
        mLayout = (LinearLayout) findViewById(R.id.layout);   
        //创建一个ScrollView对象
        mScrollView = (ScrollView) findViewById(R.id.ScrollView01);   
  
        Button button = (Button) findViewById(R.id.Button01); 
        
        button.setOnClickListener(mClickListener);   
        //改变默认焦点切换   
        button.setOnKeyListener(mAddButtonKeyListener);
	}
	
	//Button事件监听
	//当点击按钮时，增加一个TextView和Button
	private Button.OnClickListener mClickListener = new Button.OnClickListener() 
	{   
        private int mIndex = 1;   
        public void onClick(View arg0) 
        {   
            // TODO Auto-generated method stub        
            TextView textView = new TextView(Activity01.this);   
            textView.setText("Text View " + mIndex);
            //这里请不要困惑这里是设置 这个textView的布局 FILL_PARENT WRAP_CONTENT 和在xml文件里边设置是一样的
            LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(   
                    LinearLayout.LayoutParams.FILL_PARENT,   
                    LinearLayout.LayoutParams.WRAP_CONTENT   
            );   
            //增加一个TextView到线性布局中
            mLayout.addView(textView, p);   
  
            Button buttonView = new Button(Activity01.this);   
            buttonView.setText("Button " + mIndex++);
            
          //增加一个Button到线性布局中
            mLayout.addView(buttonView, p);   
            //改变默认焦点切换  
            buttonView.setOnKeyListener(mNewButtonKeyListener); 
            //投递一个消息进行滚动   
            mHandler.post(mScrollToBottom);   
        }          
    };   
    
    
    private Runnable mScrollToBottom = new Runnable() 
    {   
        public void run()
        {   
            // TODO Auto-generated method stub   
            
            int off = mLayout.getMeasuredHeight() - mScrollView.getHeight();   
            if (off > 0) 
            {   
                mScrollView.scrollTo(0, off);   
            }                          
        }   
    };   
    
    //事件监听
    private View.OnKeyListener mNewButtonKeyListener = new View.OnKeyListener() 
    {   
        public boolean onKey(View v, int keyCode, KeyEvent event) 
        {   
            if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN &&   
                    event.getAction() == KeyEvent.ACTION_DOWN &&   
                    v == mLayout.getChildAt(mLayout.getChildCount() - 1)) 
            {   
                findViewById(R.id.Button01).requestFocus();   
                return true;   
            }   
            return false;   
        }   
    };   
    
  //事件监听
    private View.OnKeyListener mAddButtonKeyListener = new Button.OnKeyListener() 
    {   
       
        public boolean onKey(View v, int keyCode, KeyEvent event) 
        {   
            // TODO Auto-generated method stub                  
            View viewToFoucus = null;   
            if (event.getAction() == KeyEvent.ACTION_DOWN) 
            {   
            	int iCount = mLayout.getChildCount(); 
                switch (keyCode) 
                {   
                case KeyEvent.KEYCODE_DPAD_UP:   
                    if ( iCount > 0) 
                    {   
                        viewToFoucus = mLayout.getChildAt(iCount - 1);   
                    }   
                    break;   
                case KeyEvent.KEYCODE_DPAD_DOWN:   
                    if (iCount < mLayout.getWeightSum()) 
                    {   
                        viewToFoucus = mLayout.getChildAt(iCount + 1);   
                    }   
                    break;   
                default:   
                    break;   
                }   
            }     
            if (viewToFoucus != null) 
            {   
                viewToFoucus.requestFocus();   
                return true;   
            } 
            else 
            {   
                return false;   
            }   
        }   
    }; 
}

布局文件
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/ScrollView01"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:scrollbars="none">
    <LinearLayout
        android:id="@+id/layout"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="TextView0"/>

        <Button
   android:id="@+id/Button01"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Button0"/>
    </LinearLayout>
</ScrollView>
图片效果 源码见附件