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