统制android弹出框不消失(用到反射的方法)

Android中的弹出框在被点击时， 无论点击哪个按钮都会关闭窗口。 但是有的情况下我们不需要立即关闭窗口。下面的情况是弹出框中要求用户输入文件名， 并在点击确定时检查文件名的合法性， 不合法则提示用户重新输入， 弹出框要保持在界面上。 点击取消时弹出框消失。 这里通过对控件的反射来实现：?
/**our button handler**/?
??? private ButtonHandler bHandler;?

//pop up dialog with own button handler?
??? private void popUpDialog(AlertDialog dialog) {?
??????? /*?
???????? * alert dialog's default handler will always close dialog whenever user?
???????? * clicks on which button. we have to replace default handler with our?
???????? * own handler for blocking close action.?
???????? * Reflection helps a lot.?
???????? */?
??????? try {?
??????????? Field field = dialog.getClass().getDeclaredField("mAlert");?
??????????? field.setAccessible(true);?
????????????
??????????? //retrieve mAlert value?
??????????? Object obj = field.get(dialog);?
??????????? field = obj.getClass().getDeclaredField("mHandler");?
??????????? field.setAccessible(true);?
??????????? //replace mHandler with our own handler?
??????????? field.set(obj, bHandler);?
??????? } catch (SecurityException e) {?
??????????? Debug.error(e.getMessage());?
??????? } catch (NoSuchFieldException e) {?
??????????? Debug.error(e.getMessage());?
??????? } catch (IllegalArgumentException e) {?
??????????? Debug.error(e.getMessage());?
??????? } catch (IllegalAccessException e) {?
??????????? Debug.error(e.getMessage());?
??????? }?
????????
??????? //we can show this dialog now.?
??????? dialog.show();?
??? }?
??? /*?
???? * define our own button handler, do not deal with dismiss message.?
???? */?
??? class? ButtonHandler? extends? Handler {?

???????? private? WeakReference<DialogInterface> mDialog;?

???????? public ButtonHandler(DialogInterface dialog) {?
??????????? mDialog = new WeakReference<DialogInterface>(dialog);?
???????? }?

???????? public void handleMessage(Message msg) {?
???????????? switch (msg.what) {?
???????????????? case DialogInterface.BUTTON_POSITIVE:?
???????????????? case DialogInterface.BUTTON_NEGATIVE:?
???????????????? case DialogInterface.BUTTON_NEUTRAL:?
??????????????????? ((DialogInterface.OnClickListener) msg.obj).onClick(mDialog?
??????????????????????????? .get(), msg.what);?
???????????????????? break ;?
??????????? }?
??????? }?
??? }?

然后创建一个AlertDialog时如下去调用：?
//create dialog?
??????????? mDialog = new AlertDialog.Builder(mContext)?
??????????? .setView(selectImageView)?
??????????? .setNegativeButton(android.R.string.cancel, mOnDialogClickListener)?
??????????? .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {?
??????????????? public void onClick(DialogInterface dialog, int arg1) {?
??????????????????? //check input file name?
??????????????????? if (isValidFileName(fileNameInput.getText().toString())) {?
??????????????????????? String fileName = fileNameInput.getText().toString().trim();?
??????????????????????? mediaList.get(0).setName(fileName);?
??????????????????????? saveMedia(mediaList);?
??????????????????????? dialog.dismiss();?
??????????????????? } else {?
??????????????????????? Toast.makeText(mContext, R.string.invalid_file_name, 1500).show();?
??????????????????? }?
????????????????????
??????????????? }?
??????????? }).create();?
mOnDialogClickListener用来处理关闭窗口事件：?
/*?
???? * cancel dialog listener?
???? */?
??? OnClickListener mOnDialogClickListener = new DialogInterface.OnClickListener() {?
??????? public void onClick(DialogInterface dialog, int buttonId) {?
??????????? switch (buttonId) {?
??????????????? case DialogInterface.BUTTON_NEGATIVE:?
??????????????????? dialog.dismiss();?
??????????????????? break;?
??????????????? case DialogInterface.BUTTON_POSITIVE:?
????????????????????
??????????????????? break;?
??????????? }?
????????????
??????? }?
??? };