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

1 2	`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;

}