Android -- TabHost、Fragment、状态保存、通信-白红宇

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
      
        fragments = new ArrayList
       
        ();    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

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
      
        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
       
         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TabA10-10 11:55:41.168: INFO/System.out(18368): AAAAAAAAAA____onCreate10-10 11:55:41.168: INFO/System.out(18368): AAAAAAAAAA____onCreateView10-10 11:55:41.175: INFO/System.out(18368): AAAAAAAAAA____onActivityCreated10-10 11:55:41.179: INFO/System.out(18368): AAAAAAAAAA____onStart10-10 11:55:41.179: INFO/System.out(18368): AAAAAAAAAA____onResume10-10 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____onAttach10-10 11:55:44.996: INFO/System.out(18368): BBBBBBBBBBB____onCreate10-10 11:55:44.996: INFO/System.out(18368): BBBBBBBBBBB____onCreateView10-10 11:55:45.004: INFO/System.out(18368): BBBBBBBBBBB____onActivityCreated10-10 11:55:45.004: INFO/System.out(18368): BBBBBBBBBBB____onStart10-10 11:55:45.004: INFO/System.out(18368): BBBBBBBBBBB____onResume10-10 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____onAttach10-10 11:55:52.082: INFO/System.out(18368): CCCCCCCCCC____onCreate10-10 11:55:52.086: INFO/System.out(18368): CCCCCCCCCC____onCreateView10-10 11:55:52.090: INFO/System.out(18368): CCCCCCCCCC____onActivityCreated10-10 11:55:52.090: INFO/System.out(18368): CCCCCCCCCC____onStart10-10 11:55:52.090: INFO/System.out(18368): CCCCCCCCCC____onResume10-10 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FragmentActivityMainActivity activity = ((MainActivity)getActivity());

通过getActivity()即可得到Fragment所在的FragmentActivity

本文转自我爱物联网博客园博客，原文链接：http://www.cnblogs.com/yydcdut/p/3889902.html，如需转载请自行联系原作者