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1)Activity中的模块化对象。
2)Android3.0中的一个新特性。
1)适配各种屏幕尺寸.
2)对界面中的UI内容进行模块化.
例如：
1)radiogroup+fragment+viewpager 实现底部菜单
2)actionBar(tab)+fragment+viewpager 实现tab导航
3).....
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public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);
DisplayMetrics outMetrics=new DisplayMetrics(); 获取屏幕的长宽的像素 getWindowManager().getDefaultDisplay().getMetrics(outMetrics); int width=outMetrics.widthPixels; int height=outMetrics.heightPixels;
//要借助此对象管理fragment对象 FragmentManager fm=getFragmentManager(); FragmentTransaction ft=fm.beginTransaction(); //使用不同的fragment if(height>width){ ft.replace(R.id.layoutId, new Fragment01(),"tag"); }else{ ft.replace(R.id.layoutId, new Fragment02(),"tag"); } //可选：将fragment添加到回退栈 //ft.addToBackStack(null); ft.commit(); } @Override protected void onResume() { super.onResume(); //根据tag找到对应的fragment Fragment f=getFragmentManager().findFragmentByTag("tag"); Log.i("TAG", "f="+f); } } |
1)类的编写(直接或间接继承fragment,无需在清单配置文件注册)
2)对象的构建(直接执行new的动作)
3)将对象添加到activity(静态方式，动态方式)
4)fragment对象与activity的交互(生命周期方法)
a)fragment: getActivity()
b)activity: findFragmentById,findFragmentByTag
注意：fragment对象的生命周期受activity对象
生命周期的影响。
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public class MainActivity extends Activity implements TabListener { private Fragment frg01,frg02; private String[] tags={"A","B"}; ActionBar bar; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); bar=getActionBar(); bar.setDisplayShowHomeEnabled(false); bar.setDisplayShowTitleEnabled(false); //设置为tab导航 bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); //添加tab bar.addTab(bar.newTab().setText("tab01").setTabListener(this)); bar.addTab(bar.newTab().setText("tab02").setTabListener(this));
if(savedInstanceState!=null){ int pos=savedInstanceState.getInt("posKey"); Fragment frg=getFragmentManager().findFragmentByTag(tags[pos]); if(frg!=null&&!frg.isDetached()){ FragmentTransaction beginTransaction = getFragmentManager().beginTransaction(); beginTransaction.detach(frg); beginTransaction.commit(); } bar.setSelectedNavigationItem(pos); } }
@Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); //获得当前选中的tab的位置 int pos=bar.getSelectedNavigationIndex(); outState.putInt("posKey", pos); } @Override public void onTabSelected(Tab tab, FragmentTransaction ft) { int pos=tab.getPosition(); if(pos==0){ if(frg01==null){ frg01=new Fragment01(); ft.add(R.id.layout,frg01,tags[pos]); }else{ ft.attach(frg01); } }else if(pos==1){ if(frg02==null){ frg02=new Fragment02(); ft.add(R.id.layout,frg02,tags[pos]); }else{ ft.attach(frg02); } } } @Override public void onTabUnselected(Tab tab, FragmentTransaction ft) { int pos=tab.getPosition(); if(pos==0){ ft.detach(frg01); }else if(pos==1){ ft.detach(frg02); } } @Override public void onTabReselected(Tab tab, FragmentTransaction ft) { } } |
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public class MainActivity extends FragmentActivity implements OnCheckedChangeListener, OnPageChangeListener { private ViewPager vPager; private RadioGroup rGroup; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); rGroup=(RadioGroup) findViewById(R.id.radioGroup1); rGroup.setOnCheckedChangeListener(this); setViewPager(); } private void setViewPager(){ vPager = (ViewPager) findViewById(R.id.viewPagerId); vPager.setAdapter(new FrgAdapter(getSupportFragmentManager())); vPager.setOnPageChangeListener(this); } class FrgAdapter extends FragmentPagerAdapter{//android.support.v4
public FrgAdapter(FragmentManager fm) { super(fm); } /**此方法中要返回frgment对象*/ @Override public Fragment getItem(int positon) { if(positon==0){ return new Fragment01(); }else if(positon==1){ return new Fragment02(); }return null; } @Override public int getCount() { return 2; } } /**点击某个RadioButton会执行此方法*/ @Override public void onCheckedChanged(RadioGroup group,int checkedId) { //设置viewPager当前的item(fragment) vPager.setCurrentItem(group.indexOfChild(group.findViewById(checkedId))); } @Override public void onPageScrollStateChanged(int arg0) { } @Override public void onPageScrolled(int arg0, float arg1, int arg2) { } @Override public void onPageSelected(int position) { //选中执行的radioButton rGroup.check(rGroup.getChildAt(position).getId()); } } |
1)ListFragment
2)DialogFragment
3)FragmentTabHost
4)......
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原文地址：http://blog.csdn.net/gsd1602_yingmu/article/details/51336182
