问题
A short tutorial for people like me who had some trouble finding a way to implement TabHost and ViewPager, including page swiping with fingers and tab click to change pages. The shown solution is compatible with Android versions 2.2+.
It includes Tabs initialization, ViewPager connected with Tabs and Page Scrolling management.
Its main peculiarity is the optimization for earlier versions of Android (Android 2.2 (Froyo), API version 8) and the simple implementation for different purposes.
回答1:
The tutorial includes 4 classes and 2 layouts. It has been tested with an Android phone 2.2, and you can just copy & paste to try it.
MainActivity.java (the main activity):
package samples.tabhost.andreaoid.net;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
public class MainActivity extends FragmentActivity implements OnTabChangeListener, OnPageChangeListener {
MyPageAdapter pageAdapter;
private ViewPager mViewPager;
private TabHost mTabHost;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager = (ViewPager) findViewById(R.id.viewpager);
// Tab Initialization
initialiseTabHost();
// Fragments and ViewPager Initialization
List<Fragment> fragments = getFragments();
pageAdapter = new MyPageAdapter(getSupportFragmentManager(), fragments);
mViewPager.setAdapter(pageAdapter);
mViewPager.setOnPageChangeListener(MainActivity.this);
}
// Method to add a TabHost
private static void AddTab(MainActivity activity, TabHost tabHost, TabHost.TabSpec tabSpec) {
tabSpec.setContent(new MyTabFactory(activity));
tabHost.addTab(tabSpec);
}
// Manages the Tab changes, synchronizing it with Pages
public void onTabChanged(String tag) {
int pos = this.mTabHost.getCurrentTab();
this.mViewPager.setCurrentItem(pos);
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
// Manages the Page changes, synchronizing it with Tabs
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
int pos = this.mViewPager.getCurrentItem();
this.mTabHost.setCurrentTab(pos);
}
@Override
public void onPageSelected(int arg0) {
}
private List<Fragment> getFragments(){
List<Fragment> fList = new ArrayList<Fragment>();
// TODO Put here your Fragments
MySampleFragment f1 = MySampleFragment.newInstance("Sample Fragment 1");
MySampleFragment f2 = MySampleFragment.newInstance("Sample Fragment 2");
MySampleFragment f3 = MySampleFragment.newInstance("Sample Fragment 3");
fList.add(f1);
fList.add(f2);
fList.add(f3);
return fList;
}
// Tabs Creation
private void initialiseTabHost() {
mTabHost = (TabHost) findViewById(android.R.id.tabhost);
mTabHost.setup();
// TODO Put here your Tabs
MainActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("Tab1").setIndicator("Tab1"));
MainActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("Tab2").setIndicator("Tab2"));
MainActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("Tab3").setIndicator("Tab3"));
mTabHost.setOnTabChangedListener(this);
}
}
MyPageAdapter.java (fragment manager):
package samples.tabhost.andreaoid.net;
import java.util.List;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class MyPageAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public MyPageAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
}
@Override
public Fragment getItem(int position) {
return this.fragments.get(position);
}
@Override
public int getCount() {
return this.fragments.size();
}
}
MyTabFactory (tab manager):
package samples.tabhost.andreaoid.net;
import android.content.Context;
import android.view.View;
import android.widget.TabHost.TabContentFactory;
public class MyTabFactory implements TabContentFactory {
private final Context mContext;
public MyTabFactory(Context context) {
mContext = context;
}
public View createTabContent(String tag) {
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}
MySampleFragment.java (the single fragment - included for demonstration purposes):
package samples.tabhost.andreaoid.net;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class MySampleFragment extends Fragment {
private static View mView;
public static final MySampleFragment newInstance(String sampleText) {
MySampleFragment f = new MySampleFragment();
Bundle b = new Bundle();
b.putString("bString", sampleText);
f.setArguments(b);
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
mView = inflater.inflate(R.layout.sample_fragment, container, false);
String sampleText = getArguments().getString("bString");
TextView txtSampleText = (TextView) mView.findViewById(R.id.txtViewSample);
txtSampleText.setText(sampleText);
return mView;
}
}
activity_main.xml:
<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" >
<TabHost
android:id="@android:id/tabhost"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TabWidget
android:id="@android:id/tabs"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="0" />
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="0" />
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom" />
</LinearLayout>
</TabHost>
</RelativeLayout>
sample_fragment.xml (you can put here your fragment layout):
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/txtViewSample"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:text="" />
</RelativeLayout>
来源：https://stackoverflow.com/questions/17687717/tutorial-to-implement-the-use-of-tabhost-in-android-2-2-viewpager-and-fragment