Android -- TabHost、Fragment、状态保存、通信

工程结构                                                                                      

TabAFm到TabEFm都是Fragment，并且每个Fragment对应一个布局文件。

TabAFm.java                                                                            

package com.yydcdut.tabhoststudy;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class TabAFm extends Fragment {

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        System.out.println("AAAAAAAAAA____onAttach");
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        System.out.println("AAAAAAAAAA____onCreate");
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        System.out.println("AAAAAAAAAA____onCreateView");
        return inflater.inflate(R.layout.tab_a, container, false);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        System.out.println("AAAAAAAAAA____onActivityCreated");
    }

    @Override
    public void onStart() {
        super.onStart();
        System.out.println("AAAAAAAAAA____onStart");
    }

    @Override
    public void onResume() {
        super.onResume();
        System.out.println("AAAAAAAAAA____onResume");
    }

    @Override
    public void onPause() {
        super.onPause();
        System.out.println("AAAAAAAAAA____onPause");
    }

    @Override
    public void onStop() {
        super.onStop();
        System.out.println("AAAAAAAAAA____onStop");
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        System.out.println("AAAAAAAAAA____onDestroyView");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        System.out.println("AAAAAAAAAA____onDestroy");
    }

    @Override
    public void onDetach() {
        super.onDetach();
        System.out.println("AAAAAAAAAA____onDetach");
    }

}

如上述代码所示，TabAFm是一个Fragment，对应的布局文件是tab_a.xml，并实现了他的所有的生命周期回调函数并打印，便于调试。tab_a.xml布局中有个EditText，其他的Fragment大同小异，这里就不贴出代码了

MainActivity                                                                             

package com.yydcdut.tabhoststudy;

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.widget.RadioGroup;

public class MainActivity extends FragmentActivity {

    private RadioGroup rgs;
    public List<Fragment> fragments = new ArrayList<Fragment>();

    public String hello = "hello ";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        fragments.add(new TabAFm());
        fragments.add(new TabBFm());
        fragments.add(new TabCFm());
        fragments.add(new TabDFm());
        fragments.add(new TabEFm());

        rgs = (RadioGroup) findViewById(R.id.tabs_rg);

        FragmentTabAdapter2 tabAdapter = new FragmentTabAdapter2(this, fragments, R.id.tab_content, rgs);
        tabAdapter.setOnRgsExtraCheckedChangedListener(new FragmentTabAdapter2.OnRgsExtraCheckedChangedListener(){
            @Override
            public void OnRgsExtraCheckedChanged(RadioGroup radioGroup, int checkedId, int index) {
                System.out.println("Extra---- " + index + " checked!!! ");
            }
        });
    }
}

MainActivity上述代码所示

MainActivity是包含Fragment的Activity（也就是这里的5个Fragment）

他继承了FragmentActivity（因为我这里用的是android-support-v4.jar）

用一个List<Fragment>去维护5个Fragment，也就是5个tab

main布局                                                                                    

有一个id为tab_content的FrameLayout，用来存放要显示的Fragment。底部有一个RadioGroup，用于tab的切换

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@android:color/white"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" >

        <FrameLayout
            android:id="@+id/tab_content"
            android:layout_width="fill_parent"
            android:layout_height="0dp"
            android:layout_weight="1.0"
            android:background="#77557799" />

        <RadioGroup
            android:id="@+id/tabs_rg"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="horizontal"
            android:paddingBottom="7dp"
            android:paddingTop="7dp" >

            <RadioButton
                android:id="@+id/tab_rb_a"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1.0"
                android:background="@drawable/selector_tab"
                android:button="@null"
                android:checked="true"
                android:drawableTop="@drawable/tablatestalert"
                android:gravity="center"
                android:singleLine="true"
                android:text="Tab1"
                android:textColor="#000000"
                android:textSize="13sp" />

            <RadioButton
                android:id="@+id/tab_rb_b"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1.0"
                android:background="@drawable/selector_tab"
                android:button="@null"
                android:drawableTop="@drawable/tabsearch"
                android:gravity="center"
                android:singleLine="true"
                android:text="Tab2"
                android:textColor="#000000"
                android:textSize="13sp" />

            <RadioButton
                android:id="@+id/tab_rb_c"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1.0"
                android:background="@drawable/selector_tab"
                android:button="@null"
                android:drawableTop="@drawable/tabrecommd"
                android:gravity="center"
                android:singleLine="true"
                android:text="Tab3"
                android:textColor="#000000"
                android:textSize="13sp" />

            <RadioButton
                android:id="@+id/tab_rb_d"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1.0"
                android:background="@drawable/selector_tab"
                android:button="@null"
                android:drawableTop="@drawable/tabconfigicon"
                android:gravity="center"
                android:singleLine="true"
                android:text="Tab4"
                android:textColor="#000000"
                android:textSize="13sp" />

            <RadioButton
                android:id="@+id/tab_rb_e"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1.0"
                android:background="@drawable/selector_tab"
                android:button="@null"
                android:drawableTop="@drawable/tababoutus"
                android:gravity="center"
                android:singleLine="true"
                android:text="Tab5"
                android:textColor="#000000"
                android:textSize="13sp" />
        </RadioGroup>
    </LinearLayout>

</LinearLayout>

现在回到MainActivity中，下面这个FragmentTabAdapter类是关键，是我自己编写的用于绑定和处理fragments和RadioGroup之间的逻辑关系

FragmentTabAdapter2 tabAdapter = new FragmentTabAdapter2(this, fragments, R.id.tab_content, rgs);

FragmentTabAdapter2                                                            

package com.yydcdut.tabhoststudy;

import java.util.List;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;

public class FragmentTabAdapter2 {
    private List<Fragment> fragments; // 一个tab页面对应一个Fragment
    private RadioGroup rgs; // 用于切换tab
    private FragmentActivity fragmentActivity; // Fragment所属的Activity
    private int fragmentContentId; // Activity中所要被替换的区域的id

    private int currentTab; // 当前Tab页面索引

    private OnRgsExtraCheckedChangedListener onRgsExtraCheckedChangedListener; // 用于让调用者在切换tab时候增加新的功能

    /**
     * 构造函数
     *
     * @param fragmentActivity
     * @param fragments
     * @param fragmentContentId
     * @param rgs
     */
    public FragmentTabAdapter2(FragmentActivity fragmentActivity,
            List<Fragment> fragments, int fragmentContentId, RadioGroup rgs) {
        this.fragments = fragments;
        this.rgs = rgs;
        this.fragmentActivity = fragmentActivity;
        this.fragmentContentId = fragmentContentId;

        // 默认显示第一页
        FragmentTransaction ft = fragmentActivity.getSupportFragmentManager()
                .beginTransaction();
        ft.add(fragmentContentId, fragments.get(0));
        ft.commit();
        // 设置监听事件
        MyCheckedChangeListener myCheckedChangeListener = new MyCheckedChangeListener();
        rgs.setOnCheckedChangeListener(myCheckedChangeListener);

    }

    /**
     * 监听器内部类
     *
     * @author sansung
     *
     */
    class MyCheckedChangeListener implements OnCheckedChangeListener {

        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            for (int i = 0; i < rgs.getChildCount(); i++) {
                if (rgs.getChildAt(i).getId() == checkedId) {
                    Fragment fragment = fragments.get(i);
                    FragmentTransaction ft = obtainFragmentTransaction(i);

                    getCurrentFragment().onPause(); // 暂停当前tab
                    // getCurrentFragment().onStop(); // 暂停当前tab

                    if (fragment.isAdded()) {
                        // fragment.onStart(); // 启动目标tab的onStart()
                        fragment.onResume(); // 启动目标tab的onResume()
                    } else {
                        ft.add(fragmentContentId, fragment);
                    }
                    showTab(i); // 显示目标tab
                    ft.commit();

                    // 如果设置了切换tab额外功能功能接口
                    if (null != onRgsExtraCheckedChangedListener) {
                        onRgsExtraCheckedChangedListener
                                .OnRgsExtraCheckedChanged(group, checkedId, i);
                    }
                }
            }
        }
    }

    /**
     * 切换tab
     *
     * @param idx
     */
    private void showTab(int idx) {
        for (int i = 0; i < fragments.size(); i++) {
            Fragment fragment = fragments.get(i);
            FragmentTransaction ft = obtainFragmentTransaction(idx);

            if (idx == i) {
                ft.show(fragment);
            } else {
                ft.hide(fragment);
            }
            ft.commit();
        }
        currentTab = idx; // 更新目标tab为当前tab
    }

    /**
     * 获取一个带动画的FragmentTransaction
     *
     * @param index
     * @return
     */
    private FragmentTransaction obtainFragmentTransaction(int index) {
        FragmentTransaction ft = fragmentActivity.getSupportFragmentManager()
                .beginTransaction();
        // 设置切换动画
        if (index > currentTab) {
            ft.setCustomAnimations(R.anim.slide_left_in, R.anim.slide_left_out);
        } else {
            ft.setCustomAnimations(R.anim.slide_right_in,
                    R.anim.slide_right_out);
        }
        return ft;
    }

    public int getCurrentTab() {
        return currentTab;
    }

    public Fragment getCurrentFragment() {
        return fragments.get(currentTab);
    }

    public OnRgsExtraCheckedChangedListener getOnRgsExtraCheckedChangedListener() {
        return onRgsExtraCheckedChangedListener;
    }

    public void setOnRgsExtraCheckedChangedListener(
            OnRgsExtraCheckedChangedListener onRgsExtraCheckedChangedListener) {
        this.onRgsExtraCheckedChangedListener = onRgsExtraCheckedChangedListener;
    }

    /**
     * 切换tab额外功能功能接口
     */
    static class OnRgsExtraCheckedChangedListener {
        public void OnRgsExtraCheckedChanged(RadioGroup radioGroup,
                int checkedId, int index) {
        }
    }
}

这里解决Fragment切换重新加载布局的办法，用的是把几个Fragment全部Add，然后根据要显示的哪个Fragment设置show或者hide

10-10 11:55:41.168: INFO/System.out(18368): AAAAAAAAAA____onAttach　　　　　　// 第一次进入，显示TabA
10-10 11:55:41.168: INFO/System.out(18368): AAAAAAAAAA____onCreate
10-10 11:55:41.168: INFO/System.out(18368): AAAAAAAAAA____onCreateView
10-10 11:55:41.175: INFO/System.out(18368): AAAAAAAAAA____onActivityCreated
10-10 11:55:41.179: INFO/System.out(18368): AAAAAAAAAA____onStart
10-10 11:55:41.179: INFO/System.out(18368): AAAAAAAAAA____onResume
10-10 11:55:44.980: INFO/System.out(18368): AAAAAAAAAA____onPause　　　　　　// 从TabA切换到TabB（TabA调用onPause）
10-10 11:55:44.980: INFO/System.out(18368): Extra---- 1 checked!!!
10-10 11:55:44.996: INFO/System.out(18368): BBBBBBBBBBB____onAttach
10-10 11:55:44.996: INFO/System.out(18368): BBBBBBBBBBB____onCreate
10-10 11:55:44.996: INFO/System.out(18368): BBBBBBBBBBB____onCreateView
10-10 11:55:45.004: INFO/System.out(18368): BBBBBBBBBBB____onActivityCreated
10-10 11:55:45.004: INFO/System.out(18368): BBBBBBBBBBB____onStart
10-10 11:55:45.004: INFO/System.out(18368): BBBBBBBBBBB____onResume
10-10 11:55:52.062: INFO/System.out(18368): BBBBBBBBBBB____onPause　　　　　　// 从TabB切换到TabC（TabB调用onPause）
10-10 11:55:52.062: INFO/System.out(18368): Extra---- 2 checked!!!
10-10 11:55:52.082: INFO/System.out(18368): CCCCCCCCCC____onAttach
10-10 11:55:52.082: INFO/System.out(18368): CCCCCCCCCC____onCreate
10-10 11:55:52.086: INFO/System.out(18368): CCCCCCCCCC____onCreateView
10-10 11:55:52.090: INFO/System.out(18368): CCCCCCCCCC____onActivityCreated
10-10 11:55:52.090: INFO/System.out(18368): CCCCCCCCCC____onStart
10-10 11:55:52.090: INFO/System.out(18368): CCCCCCCCCC____onResume
10-10 11:56:06.535: INFO/System.out(18368): CCCCCCCCCC____onPause　　　　　　// 从TabC切换到TabB（TabC调用onPause）
10-10 11:56:06.535: INFO/System.out(18368): BBBBBBBBBBB____onResume　　　　// 从TabC切换到TabB（TabB调用onResume）
10-10 11:56:06.535: INFO/System.out(18368): Extra---- 1 checked!!!

好了，到此为止，我们已经用Fragment实现了类似TabHost的功能了，下面来看下各个Fragment之间的通信

现在的情况是TabAFm中有个EditText，TabBFm中有个Button，MainActivity中有个变量“hello”

要做的是，切换到TabA，输入“I'm TabA”，切换到B，点击Button后，Toast显示“hello I'm TabA”

MainActivity中没什么好说的，就一个hello变量：

public String hello = "hello ";

TabAFm在布局文件tab_a.xml中加个EditText，设置个id就可以了

TabBFm中：

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        System.out.println("BBBBBBBBBBB____onActivityCreated");
        this.getView().findViewById(R.id.clickme).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // 获得绑定的FragmentActivity
                MainActivity activity = ((MainActivity)getActivity());
                // 获得TabAFm的控件
                EditText editText = (EditText) activity.fragments.get(0).getView().findViewById(R.id.edit);

                Toast.makeText(activity, activity.hello + editText.getText(), Toast.LENGTH_SHORT).show();
            }
        });
    }

// 获得绑定的FragmentActivity
MainActivity activity = ((MainActivity)getActivity());

通过getActivity()即可得到Fragment所在的FragmentActivity

我是天王盖地虎的分割线                                                                 

源代码：http://pan.baidu.com/s/1dD1Qx01

tabhost学习.zip

参考：http://www.cnblogs.com/tiantianbyconan/p/3360938.html