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. */@Overridepublic 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Buttonprivate 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

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