使用ViewPager和Fragment实现滑动导航

ViewPage是android-support-v4.jar包提供的用于页面滑动的库,android-support-v4.jar是google推荐使用的一个类库,在项目中使用之前,你必须其添加到项目中(项目点右键Build path->configure build path,然后找到jar进行添加)

1.在xml布局文件中添加android.support.v4.view.ViewPager容器及显示导航所用标签android.support.v4.view.PagerTitleStrip,如我添加的xml内容如下

 

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<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:id="@+id/pager"     android:layout_width="match_parent"     android:layout_height="match_parent"     tools:context=".MainActivity" >       <!--     This title strip will display the currently visible page title, as well as the page     titles for adjacent pages.     -->       <android.support.v4.view.PagerTitleStrip         android:id="@+id/pager_title_strip"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_gravity="top"         android:background="#33b5e5"         android:paddingBottom="4dp"         android:paddingTop="4dp"         android:textColor="#fff" />   </android.support.v4.view.ViewPager>

 

2.在activity中导入以下包 

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import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager;

3.声明变量

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1 2	SectionsPagerAdapter mSectionsPagerAdapter; ViewPager mViewPager;

 

4.在onCreate中对其进行初始化 

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mSectionsPagerAdapter = new SectionsPagerAdapter(                 getSupportFragmentManager());   // Set up the ViewPager with the sections adapter. mViewPager = (ViewPager) findViewById(R.id.pager); mViewPager.setAdapter(mSectionsPagerAdapter);

5.添加类SectionsPagerAdapter,我这里使用了3个标签 

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public class SectionsPagerAdapter extends FragmentPagerAdapter {           public SectionsPagerAdapter(FragmentManager fm) {             super(fm);         }           @Override         public Fragment getItem(int position) {             // getItem is called to instantiate the fragment for the given page.             // Return a DummySectionFragment (defined as a static inner class             // below) with the page number as its lone argument.             Fragment fragment = new HjFragment();             Bundle args = new Bundle();             args.putInt("no", position + 1);             fragment.setArguments(args);               return fragment;         }           @Override         public int getCount() {             // Show 3 total pages.             return 3;         }           @Override         public CharSequence getPageTitle(int position) {             switch (position) {             case 0:                 return "标签1";             case 1:                 return "标签2";             case 2:                 return "标签3";             }             return null;         }     }

可以看到在getItem中返回了一个Fragment,这个就是当滑动到不同标签时显示在ViewPager中的内容,Fragment相当于一个Activity,在可以其中的onCreateView函数中构造需要显示的内容并返回

比如,以下代码将显示一个文本信息

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@Override public View onCreateView(LayoutInflater inflater, ViewGroup container,         Bundle savedInstanceState) {     TextView textView = new TextView(getActivity());     textView.setGravity(Gravity.CENTER);     textView.setText("你选择了标签:"+Integer.toString(getArguments().getInt(             "no")));     return textView;   }