最近在学习ViewPager实现界面的滑动，拜读了郭神的博客文章，并抽取归纳了自己对ViewPager的理解。
ViewPager实现界面滑动的步骤如下：
1.在xml布局内加入控件android.support.v4.view.ViewPager
2.初始化ViewPager并通过findViewById加载
3.编写适配器，通过继承FragmentPagerAdapter并重写getCount()和getItem()来完成
4.编写界面，官方推荐使用Fragment来表示用于滑动的界面
5.实例化适配器，构造方法的参数为FragmentManager，可由getSupportFragmentManager()获取.
6.为ViewPager添加适配器
注意：
1.界面显示的是Fragment，创建活动界面应继承FragmentActivity而不是Activity,适配器应继承FragmentPagerAdapter
2.android.support.v4.app.Fragment和android.app.Fragment这两个包是不同的。
ViewPager来源于support.v4包，因此配合使用的Fragment也应该是support.v4里的包。
导入了错误的Fragment包，可能会报错：
Caused by: java.lang.ClassCastException: com.example.Fragment cannot be cast to android.support.v4.app.Fragment
具体代码如下所示：
activity_main.java
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" > <android.support.v4.view.ViewPager
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/page"
/> </RelativeLayout>
MainActivity.java
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu; public class MainActivity extends FragmentActivity {
private ChatFragment chatFragment;
private FoundFragment foundFragment;
private ContactsFragment contactsFragment; private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager=(ViewPager)findViewById(R.id.page);
//为ViewPager设置适配器
mViewPager.setAdapter(new myPagerAdapter(getSupportFragmentManager()));
}
//继承并定义适配器，构造方法
public class myPagerAdapter extends FragmentPagerAdapter{
public myPagerAdapter(FragmentManager fm) {
super(fm);
// TODO Auto-generated constructor stub
} private final String[] titles = { "聊天", "发现", "通讯录" }; @Override
public CharSequence getPageTitle(int position) {
return titles[position];
} @Override
public int getCount() {
return titles.length;
}
//获取并返回对应的Fragment界面
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
if (chatFragment == null) {
chatFragment = new ChatFragment();
}
return chatFragment;
case 1:
if (foundFragment == null) {
foundFragment = new FoundFragment();
}
return foundFragment;
case 2:
if (contactsFragment == null) {
contactsFragment = new ContactsFragment();
}
return contactsFragment;
default:
return null;
}
}
} //加载选项菜单
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
res/values/string.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">ViewPagerDemo</string>
<string name="action_settings">Settings</string> <string name="first">界面一,向右滑得到界面二</string>
<string name="second">界面二，向右滑得到界面三</string>
<string name="third">界面三，向左滑得到界面二</string>
</resources>
fragment_first.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" > <TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/first"
android:text="@string/first"
/> </LinearLayout>
FirstFragment.java
package com.example.viewpagerdemo; import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup; public class FirstFragment extends Fragment{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// 加载视图
View view =inflater.inflate(R.layout.fragment_first, null);
return view;
}
}
接下来的SecondFragment、ThirdFragmentation都和FirstFragment一样。。不再赘述
运行效果如下所示：
向右滑动到界面二，如下示：
参考的文章链接：