前言
最近專案中用到了DialogFragment,用起來很方便,但是坑比較多,於是自己研究了下原始碼,理清楚DialogFragment中Dialog和Fragment的關係,以及DialogFragment的原理。
DialogFragment的使用方法
1、重寫onCreateDialog方法建立AlertDialog
1.1 簡單的AlertDialog
public class FireMissilesDialogFragment extends DialogFragment {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
// Use the Builder class for convenient dialog construction
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage(R.string.dialog_fire_missiles)
.setPositiveButton(R.string.fire, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// FIRE ZE MISSILES!
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// User cancelled the dialog
}
});
// Create the AlertDialog object and return it
return builder.create();
}
}
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1.2 自定義佈局的AlertDialog
如果想讓對話方塊具有自定義佈局,請建立一個佈局,然後通過呼叫 AlertDialog.Builder 物件上的 setView() 將其新增到 AlertDialog。
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
// Get the layout inflater
LayoutInflater inflater = getActivity().getLayoutInflater();
// Inflate and set the layout for the dialog
// Pass null as the parent view because its going in the dialog layout
builder.setView(inflater.inflate(R.layout.dialog_signin, null))//R.layout.dialog_sign 自定義佈局
// Add action buttons
.setPositiveButton(R.string.signin, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int id) {
// sign in the user ...
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
LoginDialogFragment.this.getDialog().cancel();
}
});
return builder.create();
}
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1.3 DialogFragment與所在的Acitivty互動
當使用者觸控對話方塊的某個操作按鈕或從列表中選擇某一項時,DialogFragment 可能會執行必要的操作,如果想將事件傳遞給開啟該對話方塊的 Activity 或Fragment。 可以為每種點選事件定義一種方法。
public class NoticeDialogFragment extends DialogFragment {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
// Build the dialog and set up the button click handlers
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage(R.string.dialog_fire_missiles)
.setPositiveButton(R.string.fire, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
//將點選Positive事件傳遞給所在的Activity
mListener.onDialogPositiveClick(NoticeDialogFragment.this);
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
//將點選Negative 事件傳遞給所在的Activity
mListener.onDialogNegativeClick(NoticeDialogFragment.this);
}
});
return builder.create();
}
//定義一個監聽的介面,DialogFragment所在的Activity實現這個介面
public interface NoticeDialogListener {
public void onDialogPositiveClick(DialogFragment dialog);
public void onDialogNegativeClick(DialogFragment dialog);
}
// Use this instance of the interface to deliver action events
NoticeDialogListener mListener;
// Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (NoticeDialogListener) activity;
//獲取DialogFragment所在的Activity,執行mListener方法時會自動呼叫Actvity中相應的方法
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement NoticeDialogListener");
}
}
...
}
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DialgFragment所在的Acitivity如下
public class MainActivity extends FragmentActivity
implements NoticeDialogFragment.NoticeDialogListener{
...
public void showNoticeDialog() {
// 建立DialogFragment的例項來顯示
DialogFragment dialog = new NoticeDialogFragment();
dialog.show(getSupportFragmentManager(), "NoticeDialogFragment");
}
//當DialogFragment中發生相應的點選事件時會自動呼叫到這裡面的兩個方法。
@Override
public void onDialogPositiveClick(DialogFragment dialog) {
// 使用者點選DialogFragment中的positive按鈕
...
}
@Override
public void onDialogNegativeClick(DialogFragment dialog) {
// 使用者點選DialogFragment中的 negative 按鈕
...
}
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2.重寫onCreateView
有時候需要彈出框,但是不需要AlertDialog裡面的功能,就可以重寫onCreateView實現自己的佈局
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.message_share_websit_dialog, container);
initView(view);
return view;
}
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3 以彈出框方式顯示對話方塊和全屏Fragment方式顯示對話方塊
有時候在大尺寸的手機或者pad上可以將DialogFragment作為彈出框形式展示,在小螢幕的手機上作為一個普通Fragment的形式展示。
public class CustomDialogFragment extends DialogFragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout to use as dialog or embedded fragment
return inflater.inflate(R.layout.purchase_items, container, false);
}
/** The system calls this only when creating the layout in a dialog. */
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
// The only reason you might override this method when using onCreateView() is
// to modify any dialog characteristics. For example, the dialog includes a
// title by default, but your custom layout might not need it. So here you can
// remove the dialog title, but you must call the superclass to get the Dialog.
Dialog dialog = super.onCreateDialog(savedInstanceState);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
return dialog;
}
}
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以下程式碼可根據螢幕尺寸決定將片段顯示為對話方塊還是全屏 UI:
public void showDialog() {
FragmentManager fragmentManager = getSupportFragmentManager();
CustomDialogFragment newFragment = new CustomDialogFragment();
if (mIsLargeLayout) {
// 如果時大螢幕的裝置,顯示為彈出框方式
newFragment.show(fragmentManager, "dialog");
} else {
// 如果是小螢幕的手機,顯示為全屏的Fragment
FragmentTransaction transaction = fragmentManager.beginTransaction();
// 設定動畫效果
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
//獲取android.R.id.content佈局,並將newFragment加入到佈局中
transaction.add(android.R.id.content, newFragment)
.addToBackStack(null).commit();
}
}
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DialogFragment中原始碼分析
DialogFragment的繼承結構
public class DialogFragment extends Fragment
implements DialogInterface.OnCancelListener, DialogInterface.OnDismissListener
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可以看出DialogFragment繼承了Fragment是在Fragment基礎之上封裝的,因此DialogFragment既可以作為Dialog來使用也可以作為單獨的Fragment來使用。
問題1:DialogFragment既然繼承了Fragment為什麼會顯示成一個Dialog的形式?
在DialogFragment內部定義了一個Dialog mDialog;
當我們重寫了onCreateDialog()方法時,mDialog就是在onCreateDialog()中返回的Dialog,否則就會預設返回一個Dialog。如果我們重寫了onCreateView方法就將該佈局加入到Dialog中。這個方法可以在onActivityCreated中找到
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (!mShowsDialog) {
return;//如果不顯示為Dialog形式的話不做任何處理直接返回。
}
View view = getView();
//獲取dialogFragment的佈局,這個佈局就是我們在onCreateView中找到的佈局。
if (view != null) {
if (view.getParent() != null) {
throw new IllegalStateException(
"DialogFragment can not be attached to a container view");
}
mDialog.setContentView(view);//如果佈局不為null的話,將我們定義的佈局加入到mDialog中。
}
final Activity activity = getActivity();
if (activity != null) {
mDialog.setOwnerActivity(activity);
}
mDialog.setCancelable(mCancelable);
mDialog.setOnCancelListener(this);
mDialog.setOnDismissListener(this);
if (savedInstanceState != null) {
Bundle dialogState = savedInstanceState.getBundle(SAVED_DIALOG_STATE_TAG);
if (dialogState != null) {
mDialog.onRestoreInstanceState(dialogState);
}
}
}
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對應的流程圖:
onGetLayoutInflater重寫了Fragment中獲取顯示佈局的過程,這個過程也決定了最後DialogFragment最後顯示的效果。
@Override
public LayoutInflater onGetLayoutInflater(Bundle savedInstanceState) {
if (!mShowsDialog) {
//如果不顯示Dialog的話直接呼叫Fragment中的onGetLayoutInflater方法
return super.onGetLayoutInflater(savedInstanceState);
}
mDialog = onCreateDialog(savedInstanceState);//否則新建dialog
if (mDialog != null) {
setupDialog(mDialog, mStyle);//設定Dialog的樣式
return (LayoutInflater) mDialog.getContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);//返回dialog的佈局
}
return (LayoutInflater) mHost.getContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
}
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建立Dialog,如果重寫了該方法就返回我們定義的Dialog,否則返回預設的Dialog.
@NonNull
public Dialog onCreateDialog(Bundle savedInstanceState) {
return new Dialog(getActivity(), getTheme());
}
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流程圖如下:
重點:是展示普通的Fragment還是以Dialog形式展示,由mShowsDialog來控制,mShowsDialog也可以由我們來賦值。問題2 DialogFragment展示
DialogFragment的展示也有不同的方式,實際兩種方式本質上是一樣的,都是需要得到FragmentTransaction來對DialogFragment的進行管理。
public void show(FragmentManager manager, String tag) {
mDismissed = false;
mShownByMe = true;
FragmentTransaction ft = manager.beginTransaction();
//獲取FragmentTransaction並將
//當前DialogFragment的例項加入到FragmentTransaction中
ft.add(this, tag);
ft.commit();//提交
}
public int show(FragmentTransaction transaction, String tag) {
mDismissed = false;
mShownByMe = true;
transaction.add(this, tag);
mViewDestroyed = false;
mBackStackId = transaction.commit();
return mBackStackId;
}
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問題3 DialogFragment消失
DialogFragment的消失函式有onDismiss和dismiss兩個,都呼叫了dismissInternal(boolean allowStateLoss)
方法,但是傳入的引數不同;allowStateLoss代表是否允許不儲存DialogFragment的狀態。
傳入自定的Dialog,呼叫 dismissInternal(true);不儲存DialogFragment的狀態。
public void onDismiss(DialogInterface dialog) {
if (!mViewDestroyed) {
dismissInternal(true);
}
}
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dismissInternal(false);儲存DialogFragment的狀態
@Override
public void dismiss() {
dismissInternal(false);
}
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具體的消失邏輯在dismissInternal(boolean allowStateLoss)實現下面具體分析原始碼
void dismissInternal(boolean allowStateLoss) {
if (mDismissed) {
return;//如果當前的DialogFragment的已經消失了,就直接返回
}
mDismissed = true;
mShownByMe = false;
if (mDialog != null) {
mDialog.dismiss();//如果mDialog不為null那麼想將mDialog消失
}
mViewDestroyed = true;
if (mBackStackId >= 0) {//如果mBackStackId >0則將BackStack中所有的mBackStackId之前的DialogFragment都彈出棧
getFragmentManager().popBackStack(mBackStackId,
FragmentManager.POP_BACK_STACK_INCLUSIVE);
mBackStackId = -1;
} else {
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.remove(this);//從FragmentTransaction中移除當前的DialogFragment
if (allowStateLoss) {
ft.commitAllowingStateLoss();//如果允許不儲存狀態執行
} else {
ft.commit();//提交
}
}
}
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由上可知,DialogFragment的消失其實有兩步,首先看自帶的mDialog是不是null如果不是null則先將mDialog消失,然後再移除DialogFragment。 連線:blog.csdn.net/u013309870/…