多个Fragment切换时不重新生成实例

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public void switchContent(Fragment fragment) {
if(mContent != fragment) {
mContent = fragment;
mFragmentMan.beginTransaction()
.setCustomAnimations(android.R.anim.fade_in, R.anim.slide_out)
.replace(R.id.content_frame, fragment) // 替换Fragment，实现切换
.commit();
}
}

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public void switchContent(Fragment from, Fragment to) {
if (mContent != to) {
mContent = to;
FragmentTransaction transaction = mFragmentMan.beginTransaction().setCustomAnimations(
android.R.anim.fade_in, R.anim.slide_out);
if (!to.isAdded()) {    // 先判断是否被add过
transaction.hide(from).add(R.id.content_frame, to).commit(); // 隐藏当前的fragment，add下一个到Activity中
} else {
transaction.hide(from).show(to).commit(); // 隐藏当前的fragment，显示下一个
}
}
}

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public class UIFragment extends Fragment{

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment,
container, false);
return view;
}
...
}

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public class HeadlessFragment extends Fragment{

@Override
public void onCreate(Bundle savedInstanceState) {
setRetainInstance(true);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return null;
}
...
}

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if (savedInstanceState == null) {
getFragmentManager().beginTransaction().add(android.R.id.content,
new UIFragment()).commit();
}

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if (savedInstanceState == null) {
// getFragmentManager().beginTransaction()...commit()
}else{
//先通过id或者tag找到“复活”的所有UI-Fragment
UIFragment fragment1 = getFragmentManager().findFragmentById(R.id.fragment1);
UIFragment fragment2 = getFragmentManager().findFragmentByTag("tag");
UIFragment fragment3 = ...
...
//show()一个即可
getFragmentManager().beginTransaction()
.show(fragment1)
.hide(fragment2)
.hide(fragment3)
.hide(...)
.commit();
}