ViewPager的使用（实现微信左右切换页卡功能）
ViewPager可以使视图左右滑动，类似于微信的那种左右滑动的页卡选择界面
一、ViewPager创建步骤
① 在XML布局中加入android.support.v4.view.ViewPager
② 加载显示的页卡将Layout布局转换为View对象
(1) LayoutInflater lf getLayoutInflater().from(this);
lf.inflate(resource,root);
(2)View.inflate(context,resource,root);
③ 配置Adapter（三种Adapter）
（1）PagerAdapter 数据源：List<View>
(2)FragmentPagerAdapter 数据源：List<Fragment>
(3)FragmentStatePagerAdapter 数据源：List<Fragment>
二、代码示例
新建四个Fragment和他们的布局下面是MainActivity的xml布局：
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center" >
<android.support.v4.view.PagerTabStrip
android:id="@+id/tab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="top" >
</android.support.v4.view.PagerTabStrip>
<!-- 底部显示标题与上面的顶部显示不能同时出现
<android.support.v4.view.PagerTitleStrip
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom" >
</android.support.v4.view.PagerTitleStrip>
-->
</android.support.v4.view.ViewPager>
第一种PagerAdapter
public class MyPagerAdapter extends PagerAdapter {
private List<View> viewList;
private List<String> titleList;
public MyPagerAdapter(List<View> viewList,List<String> titleList){
this.viewList = viewList;
this.titleList = titleList;
}
/**
* 返回页卡的数量
*/
@Override
public int getCount() {
return viewList.size();
}
/**
* view是否来自对象
*/
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0==arg1;
}
/**
* 实例化一个页卡
*/
@Override
public Object instantiateItem(ViewGroup container, int position) {
container.addView(viewList.get(position));
return viewList.get(position);
}
/**
* 销毁一个页卡
*/
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView(viewList.get(position));
}
/**
* 设置ViewPager的标题
*/
@Override
public CharSequence getPageTitle(int position) {
return titleList.get(position);
}
}
第二种FragmentPagerAdapter
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
private List<Fragment> fragList;
private List<String> titleList;
public MyFragmentPagerAdapter(FragmentManager fm,List<Fragment> fragList,List<String> titleList) {
super(fm);
this.fragList = fragList;
this.titleList = titleList;
}
@Override
public Fragment getItem(int arg0) {
return fragList.get(arg0);
}
@Override
public CharSequence getPageTitle(int position) {
return titleList.get(position);
}
@Override
public int getCount() {
return fragList.size();
}
}
第三种FragmentStatePagerAdapter（该适配器可以动态销毁Fragment）
public class MyFragmentPagerAdapter2 extends FragmentStatePagerAdapter {//该适配器可以动态销毁
private List<Fragment> fragList;
private List<String> titleList;
public MyFragmentPagerAdapter2(FragmentManager fm,List<Fragment> fragList,List<String> titleList) {
super(fm);
this.fragList = fragList;
this.titleList = titleList;
}
@Override
public Fragment getItem(int arg0) {
return fragList.get(arg0);
}
@Override
public CharSequence getPageTitle(int position) {
return titleList.get(position);
}
@Override
public int getCount() {
return fragList.size();
}
@Override
public Object instantiateItem(ViewGroup arg0, int arg1) {
return super.instantiateItem(arg0, arg1);
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
}
}
MainActivity里使用getSupportFragmentManager()该Activity必须继承FragmentActivity：
public class MainActivity extends FragmentActivity implements OnPageChangeListener{
private List<View> viewList;
private List<String> titleList;
private ViewPager pager;
private PagerTabStrip tab;//顶部标题
private List<Fragment> fragList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewList = new ArrayList<View>();
titleList = new ArrayList<String>();
tab = (PagerTabStrip) findViewById(R.id.tab);
View view1 = View.inflate(this,R.layout.view1,null);
View view2 = View.inflate(this,R.layout.view2,null);
View view3 = View.inflate(this,R.layout.view3,null);
View view4 = View.inflate(this,R.layout.view4,null);
viewList.add(view1);
viewList.add(view2);
viewList.add(view3);
viewList.add(view4);
fragList = new ArrayList<Fragment>();
fragList.add(new Fragment1());
fragList.add(new Fragment2());
fragList.add(new Fragment3());
fragList.add(new Fragment4());
//为ViewPager页卡设置标题
titleList.add("第一页");
titleList.add("第二页");
titleList.add("第三页");
titleList.add("第四页");
//为PagerTabStrip设置一些属性
tab.setBackgroundColor(Color.WHITE);
tab.setDrawFullUnderline(false);
tab.setTabIndicatorColor(Color.BLUE);
pager = (ViewPager) findViewById(R.id.pager);
//MyPagerAdapter adapter = new MyPagerAdapter(viewList,titleList);
//MyFragmentPagerAdapter adapter = new MyFragmentPagerAdapter(getSupportFragmentManager(), fragList, titleList);
/**
* 使用getSupportFragmentManager()该Activity必须继承FragmentActivity
*/
MyFragmentPagerAdapter2 adapter = new MyFragmentPagerAdapter2(getSupportFragmentManager(), fragList, titleList);
pager.setAdapter(adapter);
pager.setOnPageChangeListener(this);
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageSelected(int arg0) {
Toast.makeText(this,"当前是第"+(arg0+1)+"个界面", 0).show();
}
}
