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

 

< 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 

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

SectionsPagerAdapter mSectionsPagerAdapter;
ViewPager mViewPager;

 

4.在onCreate中对其进行初始化 

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 

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

@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;

}