从非UI线程弹出一个对话框 [英] Popping up a Dialog from a non-UI thread
本文介绍了从非UI线程弹出一个对话框的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在开发一个网络应用程序，这是面向群体。问题是，当我要加入一个组，它首先检查组是安全的，如果是这样，它要求用户名和密码。获取组安全可能需要几秒钟，所以我产卵整个过程中一个新的线程。我想弹出一个对话框，以防组需要的安全性。我想这可能都与后台线程，他们可能无法弹出对话框......但问题是，我需要检查组的安全性在后台线程，因为它需要多一点的时间。
I'm developing a network app, which is group oriented. The thing is that when I'm about to join a group, it first checks if the group is secure, and if so, it asks for user and password. Getting group security may take a couple of seconds so I spawn a new thread for the whole process. I'd like to pop up a Dialog in case the group requires security. I'm thinking it may have to do with background threads, they may not be able to pop up Dialogs... But the thing is that I need to check the group security in the background thread because it takes a bit time.
希望任何人都可以拿出解决方案，或任何方式询问用户名/密码，只有当该组是安全的。这里的后台线程：
Hope anyone can come up with the solution or any way to ask user/pass only when the group is secure. Here's the background thread:
public void run() {
secInf = mGroupId.getSecurityInformation();
if (secInf.getAdmissionLevel() == CreateGroupDialog.PRIVATE_KEY_ACCESS) {
showUserPasswordDialog();
} else {
mService.joinGroup(mGroupId);
// Notifies handler to dismiss ProgresDialog and start activity
mHandler.sendMessage(Message.obtain(mHandler,
GroupsActivity.JOIN_SUCCESSFUL));
}
在哪里showUserPasswordDialog做（mActivity是催生这个线程的活动）：
Where showUserPasswordDialog does (mActivity is the activity that spawned this thread):
private void showUserPasswordDialog() {
AlertDialog dialog;
// add this to your code
// This example shows how to add a custom layout to an AlertDialog
LayoutInflater factory = LayoutInflater.from(mActivity);
final View textEntryView = factory.inflate(
R.layout.alert_dialog_text_entry, null);
AlertDialog.Builder builder = new AlertDialog.Builder(mActivity);
builder.setIcon(R.drawable.alert_dialog_icon);
builder.setTitle(R.string.ask_user_password);
builder.setView(textEntryView);
builder.setPositiveButton(R.string.ok_text,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
String userName = ((EditText) mActivity
.findViewById(R.id.username_edit_alert_dialog))
.getText().toString();
String password = ((EditText) mActivity
.findViewById(R.id.password_edit_alert_dialog))
.getText().toString();
Credentials cred = new CredentialsL1(userName, password);
mSmeppService.joinGroup(mGroupId, cred);
mHandler.sendMessage(Message.obtain(mHandler,
GroupsActivity.JOIN_SUCCESSFUL));
});
builder.setNegativeButton(R.string.cancel_text,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
dialog.cancel();
mHandler.sendMessage(Message.obtain(mHandler,
GroupsActivity.DISMISS_PROGRESS_DIALOG));
}
});
dialog = builder.create();
/* I found this somewhere, but didn't work either */
// Window window = dialog.getWindow();
// WindowManager.LayoutParams lp = window.getAttributes();
// lp.token = textEntryView.getWindowToken();
// lp.type = WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
// window.setAttributes(lp);
// window.addFlags(WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);
dialog.show();
}
我得到这个异常：
I'm getting this exception:
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): FATAL EXCEPTION: Thread-38
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): android.view.InflateException: Binary XML file line #17: Error inflating class android.widget.EditText
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.view.LayoutInflater.createView(LayoutInflater.java:513)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.view.LayoutInflater.rInflate(LayoutInflater.java:618)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.view.LayoutInflater.inflate(LayoutInflater.java:407)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.view.LayoutInflater.inflate(LayoutInflater.java:320)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.view.LayoutInflater.inflate(LayoutInflater.java:276)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at org.pfc.threads.GroupJoinerThread.showUserPasswordDialog(GroupJoinerThread.java:76)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at org.pfc.threads.GroupJoinerThread.run(GroupJoinerThread.java:52)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): Caused by: java.lang.reflect.InvocationTargetException
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.widget.EditText.<init>(EditText.java:51)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at java.lang.reflect.Constructor.constructNative(Native Method)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at java.lang.reflect.Constructor.newInstance(Constructor.java:446)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.view.LayoutInflater.createView(LayoutInflater.java:500)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): ... 8 more
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.os.Handler.<init>(Handler.java:121)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.text.method.MetaKeyKeyListener$MetaKeyDropbackHandler.<init>(MetaKeyKeyListener.java:605)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.text.method.MetaKeyKeyListener.<init>(MetaKeyKeyListener.java:96)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.text.method.BaseKeyListener.<init>(BaseKeyListener.java:25)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.text.method.TextKeyListener.<init>(TextKeyListener.java:66)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.text.method.TextKeyListener.getInstance(TextKeyListener.java:83)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.widget.TextView.<init>(TextView.java:806)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): at android.widget.EditText.<init>(EditText.java:55)
12-13 19:18:31.823: ERROR/AndroidRuntime(1702): ... 12 more
在XML布局文件是：
The XML layout file is:
<EditText
android:id="@+id/username_edit_alert_dialog"
android:enabled="false"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_marginLeft="20dip"
android:layout_marginRight="20dip"
android:scrollHorizontally="true"
android:autoText="false"
android:capitalize="none"
android:gravity="fill_horizontal"
android:textAppearance="?android:attr/textAppearanceMedium" />
<!-- Password -->
<TextView
android:id="@+id/password_view"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_marginLeft="20dip"
android:layout_marginRight="20dip"
android:text="@string/password_view_text"
android:gravity="left"
android:textAppearance="?android:attr/textAppearanceMedium" />
<EditText
android:id="@+id/password_edit_alert_dialog"
android:enabled="false"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_marginLeft="20dip"
android:layout_marginRight="20dip"
android:scrollHorizontally="true"
android:autoText="false"
android:capitalize="none"
android:gravity="fill_horizontal"
android:password="true"
android:textAppearance="?android:attr/textAppearanceMedium" />
推荐答案
您是正确的，你不能从后台线程执行的UI操作。做到这一点的方法是使用处理程序您已经实施，以弹出对话框。所以是这样的：
You are correct that you cannot perform UI operations from a background thread. The way to do it is to use the Handler that you have already implemented to popup the dialog. So something like:
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
switch(msg.what){
case GroupsActivity.DISMISS_PROGRESS_DIALOG:
//your existing dismiss code
break;
case GroupsActivity.CREATE_PROGRESS_DIALOG:
//create the dialog
break;
}
}
};
那么你的run方法是：
Then your run method would be:
public void run() {
secInf = mGroupId.getSecurityInformation();
if (secInf.getAdmissionLevel() == CreateGroupDialog.PRIVATE_KEY_ACCESS) {
// do stuff
mHandler.sendMessage(Message.obtain(mHandler,
GroupsActivity.CREATE_PROGRESS_DIALOG));
// do more stuff
} else {
mService.joinGroup(mGroupId);
// Notifies handler to dismiss ProgresDialog and start activity
mHandler.sendMessage(Message.obtain(mHandler,
GroupsActivity.JOIN_SUCCESSFUL));
}
}
这篇关于从非UI线程弹出一个对话框的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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