ViewPager的简单使用

ViewPager用于实现多页面的切换效果，该类继承于ViewGroup，存在于Google的兼容包里：android-support-v4.jar，使用时记得构建路径，ViewPager使用非常简单，下面用一个简单示例来演示：

Activity：

package com.home.activity;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.view.View;import android.view.ViewGroup;import com.home.view.MyView;import com.home.viewpager.R;public class ViewPagerTestActivity extends Activity {// 声明ViewPager对象private ViewPager viewPager;// 声明存放在ViewPager里面的View的集合private List<View> viewList = new ArrayList<View>();// 声明自定义组件private MyView myView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);// 实例化自定义组件myView = new MyView(this);// 得到界面上的ViewPager实例viewPager = (ViewPager) findViewById(R.id.main_viewpager);// 为viewList集合添加ViewviewList.add(getLayoutInflater().inflate(R.layout.firstview, null));viewList.add(getLayoutInflater().inflate(R.layout.secondview, null));viewList.add(myView);PagerAdapter adapter = new PagerAdapter() {// 用来初始化ViewPager中的view组件@Overridepublic Object instantiateItem(View container, int position) {((ViewGroup) container).addView(viewList.get(position));return viewList.get(position);}// 当页面需要销毁时从ViewPager中去掉@Overridepublic void destroyItem(View container, int position, Object object) {((ViewGroup) container).removeView(viewList.get(position));}// ViewPager中存放的页面个数@Overridepublic int getCount() {return viewList.size();}// 判断切换的两个界面是否是同一个@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1;}};// 为viewPager设置适配器viewPager.setAdapter(adapter);}}

自定义组件类（MyView）：

package com.home.view;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.util.AttributeSet;import android.view.View;public class MyView extends View {public MyView(Context context, AttributeSet attrs) {super(context, attrs);}public MyView(Context context) {super(context);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);Paint paint = new Paint();canvas.drawColor(Color.BLUE);paint.setColor(Color.RED);canvas.drawCircle(30, 30, 30, paint);canvas.drawText("第三个页面", 270, 480, paint);}}

Activity的布局XML：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <android.support.v4.view.ViewPager        android:id="@+id/main_viewpager"        android:layout_width="match_parent"        android:layout_height="match_parent" >    </android.support.v4.view.ViewPager></RelativeLayout>

firstview.xml:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="#FF00FF"    android:gravity="center" >    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="第一个页面" /></LinearLayout>

secondview.xml:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="#00FF00"    android:gravity="center" >    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="第二个页面" /></LinearLayout>