ViewPager(2)FragmentStatePagerAdapter示例

　　FragmentStatePagerAdapter适用于数量比较大的viewPager,只会存在前1个fragment 当前fragment 和下1个fragment，其他销毁，适合加载多数据。本例中有100个pager .

1.代码

1.1 StateViewPagerMain.java

  1 import android.os.Bundle;
  2 import android.support.v4.app.Fragment;
  3 import android.support.v4.view.ViewPager;
  4 import android.view.LayoutInflater;
  5 import android.view.View;
  6 import android.view.ViewGroup;
  7 
  8 import com.txw.e.viewpager.R;
  9 
 10 /**
 11  * A simple {@link Fragment} subclass.
 12  */
 13 public class StateViewPagerMain extends Fragment {
 14 
 15     //1，在layout.xml中添加 ViewPagerFragment,它可以是顶级布局，如下：
 16     /*
 17     <?xml version="1.0" encoding="utf-8"?>
 18     <android.support.v4.view.ViewPagerFragment
 19         android:id="@+id/state_view_pager"
 20         xmlns:android="http://schemas.android.com/apk/res/android"
 21         android:layout_width="match_parent"
 22         android:layout_height="match_parent"/>
 23     */
 24 
 25     //2，准备变量,ViewPager和PagerAdapter（本例中是FragmentStatePagerAdapter）
 26     ViewPager statePager;
 27     StateViewPagerAdapter pagerAdapter;
 28 
 29 
 30     //3，初始化view pager及 adapter
 31     void initViewPager(View v){
 32         //初始化pager
 33         statePager = (ViewPager) v.findViewById(R.id.state_view_pager);
 34 
 35         //构造PageAdapter
 36         pagerAdapter = new StateViewPagerAdapter(getFragmentManager());
 37         statePager.setAdapter(pagerAdapter);
 38 
 39         //设置page 切换的监听器
 40         statePager.addOnPageChangeListener(pageChangeListener);
 41 
 42         //设置pager切换时的动画
 43         statePager.setPageTransformer(true, new ZoomOutPageTransformer());
 44     }
 45 
 46     //4，处理page的切换事件
 47     ViewPager.OnPageChangeListener pageChangeListener = new ViewPager.OnPageChangeListener() {
 48         @Override
 49         public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
 50             System.out.println("onPageScrolled " + position);
 51             System.out.println("positionOffset " + positionOffset);
 52             System.out.println("positionOffsetPixels " + positionOffsetPixels);
 53         }
 54 
 55         @Override
 56         public void onPageSelected(int position) {
 57             System.out.println("onPageSelected " + position);
 58         }
 59 
 60         @Override
 61         public void onPageScrollStateChanged(int state) {
 62             System.out.println("onPageScrollStateChanged " + state);
 63         }
 64     };
 65 
 66     //5，pager之间动画切换类
 67     public class ZoomOutPageTransformer implements ViewPager.PageTransformer {
 68         private static final float MIN_SCALE = 0.85f;
 69         private static final float MIN_ALPHA = 0.5f;
 70 
 71         public void transformPage(View view, float position) {
 72             int pageWidth = view.getWidth();
 73             int pageHeight = view.getHeight();
 74 
 75             if (position < -1) { // [-Infinity,-1)
 76                 // This page is way off-screen to the left.
 77                 view.setAlpha(0);
 78 
 79             } else if (position <= 1) { // [-1,1]
 80                 // Modify the default slide transition to shrink the page as well
 81                 float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
 82                 float vertMargin = pageHeight * (1 - scaleFactor) / 2;
 83                 float horzMargin = pageWidth * (1 - scaleFactor) / 2;
 84                 if (position < 0) {
 85                     view.setTranslationX(horzMargin - vertMargin / 2);
 86                 } else {
 87                     view.setTranslationX(-horzMargin + vertMargin / 2);
 88                 }
 89 
 90                 // Scale the page down (between MIN_SCALE and 1)
 91                 view.setScaleX(scaleFactor);
 92                 view.setScaleY(scaleFactor);
 93 
 94                 // Fade the page relative to its size.
 95                 view.setAlpha(MIN_ALPHA +
 96                         (scaleFactor - MIN_SCALE) /
 97                                 (1 - MIN_SCALE) * (1 - MIN_ALPHA));
 98 
 99             } else { // (1,+Infinity]
100                 // This page is way off-screen to the right.
101                 view.setAlpha(0);
102             }
103         }
104     }
105     @Override
106     public View onCreateView(LayoutInflater inflater, ViewGroup container,
107                              Bundle savedInstanceState) {
108         // Inflate the layout for this fragment
109         View v = inflater.inflate(R.layout.fragment_state_pager_main, container, false);
110 
111         initViewPager(v);
112 
113         return v;
114     }
115 }

1.2 StateViewPagerAdapter.java

 1 import android.os.Bundle;
 2 import android.support.v4.app.Fragment;
 3 import android.support.v4.app.FragmentManager;
 4 import android.support.v4.app.FragmentStatePagerAdapter;
 5 
 6 public class StateViewPagerAdapter extends FragmentStatePagerAdapter {
 7 
 8 
 9     /*
10     FragmentStatePagerAdapter适用于数量比较大的viewPager,
11     只会存在 前1个fragment 当前fragment 和下1个fragment，其他销毁，适合加载多数据。
12     */
13     public StateViewPagerAdapter(FragmentManager fm) {
14         super(fm);
15     }
16 
17     @Override
18     public Fragment getItem(int position) {
19         System.out.println("Fragment " + position + " created");
20         StateViewPagerFragment fragment = new StateViewPagerFragment();
21         Bundle args = new Bundle();
22         args.putInt("ID",position);
23 
24         fragment.setArguments(args);
25         return fragment;
26     }
27 
28     @Override
29     public int getCount() {
30         return 100;
31     }
32 }

1.3 StateViewPagerFragment.java

 1 import android.graphics.Color;
 2 import android.os.Bundle;
 3 import android.support.v4.app.Fragment;
 4 import android.view.LayoutInflater;
 5 import android.view.View;
 6 import android.view.ViewGroup;
 7 import android.widget.TextView;
 8 
 9 import com.txw.e.viewpager.R;
10 
11 public class StateViewPagerFragment extends Fragment {
12 
13 
14     @Override
15     public View onCreateView(LayoutInflater inflater, ViewGroup container,
16                              Bundle savedInstanceState) {
17         // Inflate the layout for this fragment
18         View v = inflater.inflate(R.layout.fragment_state_pager, container, false);
19         v.setBackgroundColor(Color.parseColor("#FFFFFF"));
20         Bundle args = getArguments();
21         TextView tv = (TextView) v.findViewById(R.id.state_view_pager_content);
22         tv.setText("Fragment : " + args.getInt("ID"));
23         return v;
24     }
25 
26     @Override
27     public void onCreate(Bundle savedInstanceState) {
28         super.onCreate(savedInstanceState);
29         System.out.println("StateViewPagerFragment" + getArguments().getInt("ID") + "::onCreate()");
30     }
31     @Override
32     public void onDestroy() {
33         super.onDestroy();
34         System.out.println("StateViewPagerFragment" + getArguments().getInt("ID") + "::onDestroy()");
35     }
36 }

2.xml

2.1 fragment_state_pager_main.xml

1 <?xml version="1.0" encoding="utf-8"?>
2 <android.support.v4.view.ViewPager
3     android:id="@+id/state_view_pager"
4     xmlns:android="http://schemas.android.com/apk/res/android"
5     android:background="#FFFFFF"
6     android:layout_width="match_parent"
7     android:layout_height="match_parent"/>

2.2 fragment_state_pager.xml

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2               xmlns:tools="http://schemas.android.com/tools"
 3               android:layout_width="match_parent"
 4               android:layout_height="match_parent"
 5               android:orientation="vertical"
 6               tools:context=".StateViewPager.StateViewPagerFragment">
 7 
 8     <TextView
 9         android:id="@+id/state_view_pager_txt"
10         android:layout_width="match_parent"
11         android:layout_height="wrap_content"
12         android:text="  FragmentStatePagerAdapter适用于数量比较大的viewPager,\n  只会存在 前1个fragment 当前fragment 和下1个fragment，其他销毁，适合加载多数据。本例中有100个pager。\n可以在LogCat中查看page对应的Fragment\n的onCreate,onDestory"/>
13 
14     <TextView
15         android:id="@+id/state_view_pager_content"
16         android:layout_width="match_parent"
17         android:layout_height="match_parent"
18         android:gravity="center_horizontal|center_vertical"
19         android:layout_gravity="center_horizontal|center_vertical"
20         android:text="@string/hello_blank_fragment"/>
21 
22 </LinearLayout>

posted @ 2016-05-20 16:40 f9q 阅读(664) 评论(0) 编辑收藏举报

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