Android的Fragement基础

天下之事常成于困约，而败于奢靡。这篇文章主要讲述Android的Fragement基础相关的知识，希望能为你提供帮助。
在android3.0的时候，为了适配平板等大屏幕，谷歌引入了碎片(Fragement)的概念。
Fragement可以有自己的布局，同时又可以相当于控件一样显示在Activity里。可以动态添加，也可以静态添加。
Fragement的生命周期和Activity很相似，在Activity的基础上多了五个方法：
onAttach -> onCreate -> oncreateView -> onActivityCreated -> onStart -> onResume -> onPause -> 0nStop -> onDestoryView -> onDestory -> onDetach
onAttach:Fragment和Activity建立关联的时候调用.
onCreateView:为Fragment加载布局时调用。
onActivityCreated:当Activity中的onCreate方法执行完后调用。
onDestoryView:Fragment中的布局被移除时调用。
onDetach:Fragment和Activity解除关联的时候调用。
碎片基础：
http://blog.csdn.net/guolin_blog/article/details/8881711
利用碎片同时兼容手机和平板：
http://blog.csdn.net/guolin_blog/article/details/8744943
随着碎片的广泛应用，Fragement不再只限于解决平板适配的问题了。
【Android的Fragement基础】Fragement + ViewPager + RadioGroup实现仿微信底部滑动菜单栏：
1> 定义主界面

< ?xml version="1.0" encoding="utf-8"?> < LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" xmlns:android="http://schemas.android.com/apk/res/android"> < android.support.v4.view.ViewPager android:id="@+id/main_ViewPager" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1.0" /> < RadioGroup android:id="@+id/main_tab_RadioGroup" android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center" android:orientation="horizontal" > < RadioButton android:id="@+id/radio_message" android:button="@null" android:layout_width="wrap_content" android:layout_height="wrap_content" android:drawableTop="@drawable/icon_message" android:text="Message" android:checked="true" /> < RadioButton android:id="@+id/radio_contacts" android:button="@null" android:layout_width="wrap_content" android:layout_height="wrap_content" android:drawableTop="@drawable/icon_contacts" android:text="Contacts" /> < RadioButton android:id="@+id/radio_setting" android:button="@null" android:layout_width="wrap_content" android:layout_height="wrap_content" android:drawableTop="@drawable/icon_setting" android:text="Settings" /> < /RadioGroup> < /LinearLayout>

2> 图标的点击变色通过xml控制，放于drawable下：

< ?xml version="1.0" encoding="utf-8"?> < selector xmlns:android="http://schemas.android.com/apk/res/android"> < item android:state_checked="true" android:drawable="@drawable/message_selected" /> < item android:state_checked="false" android:drawable="@drawable/message_unselected" /> < /selector>

3> MainActivity类

public class MainActivity extends AppCompatActivity { public ViewPager mViewPager; private RadioGroup mRadioGroup; private RadioButton radioButton_message; private RadioButton radioButton_contacts; private RadioButton radioButton_settings; private ArrayList< Fragment> fragmentArrayList; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // initButton(); initPager(); }public void initButton(){ mRadioGroup = (RadioGroup) findViewById(R.id.main_tab_RadioGroup); radioButton_message = (RadioButton) findViewById(R.id.radio_message); radioButton_contacts = (RadioButton) findViewById(R.id.radio_contacts); radioButton_settings = (RadioButton) findViewById(R.id.radio_setting); //监听button的点击，显示对应的fragement mRadioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() { @Override public void onCheckedChanged(RadioGroup group, int checkedId) { int current = 0; switch (checkedId){ case R.id.radio_message: current = 0; break; case R.id.radio_contacts: current = 1; break; case R.id.radio_setting: current = 2; break; } if (mViewPager.getCurrentItem() != current){ mViewPager.setCurrentItem(current); } } }); } public void initPager(){ mViewPager = (ViewPager) findViewById(R.id.main_ViewPager); fragmentArrayList = new ArrayList< Fragment> (); MessageFragement messageFragement = new MessageFragement(); ContactsFragement contactsFragement = new ContactsFragement(); SettingsFragement settingsFragement = new SettingsFragement(); fragmentArrayList.add(messageFragement); fragmentArrayList.add(contactsFragement); fragmentArrayList.add(settingsFragement); mViewPager.setAdapter(new MyAdapter(getSupportFragmentManager(),fragmentArrayList)); mViewPager.setCurrentItem(0); //监听fragement滑动，显示对应button mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}@Override public void onPageSelected(int position) { switch (position){ case 0: mRadioGroup.check(R.id.radio_message); break; case 1: mRadioGroup.check(R.id.radio_contacts); break; case 2: mRadioGroup.check(R.id.radio_setting); break; } }@Override public void onPageScrollStateChanged(int state) {} }); }public class MyAdapter extends FragmentPagerAdapter { ArrayList< Fragment> list ; public MyAdapter(FragmentManager fm , ArrayList< Fragment> list) { super(fm); this.list = list ; } @Override public android.support.v4.app.Fragment getItem(int arg0) { return list.get(arg0); } @Override public int getCount() { return list.size(); } } }