Question

这个问题让我发疯。我想念一些关于如何在活动中创建的新线程中处理长操作以及如何在长时间操作完成后修改视图组件（如文本等）的基本但非常重要的知识。

让我先向您展示我的代码中发生此问题的部分：

mProgressDialog = ProgressDialog.show(mContext, "Tripplanner", "please wait...", true, false);
connectAndGetRoute();


private void connectAndGetRoute(){

    new Thread(){
        @Override
        public void run() {
            try {
            if(!connectTo9292ov()) return;// conncetto9292ov() connects to a website, parses the reasult into an arraylist. The arraylist contains route.

            } catch(UnknownHostException e){
                Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();
            }catch (ClientProtocolException e) {
               Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();                   
        } catch (IOException e) {
                Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();
            }

            handler.post(runConnection);
        }

    }.start();

    handler = new Handler();
    runConnection = new Runnable(){
        @Override
        public void run() {
            mProgressDialog.dismiss();
            showOnScreen();
        }   
    };
}

这是我得到的错误：

ERROR/WindowManager(8297): Activity mp.tripplanner.OvPlanner has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@46368a28 that was originally added here
ERROR/WindowManager(8297): android.view.WindowLeaked: Activity mp.tripplanner.OvPlanner has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@46368a28 that was originally added here
ERROR/WindowManager(8297): at android.view.ViewRoot.<init>(ViewRoot.java:251)
ERROR/WindowManager(8297): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
ERROR/WindowManager(8297): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
ERROR/WindowManager(8297): at android.view.Window$LocalWindowManager.addView(Window.java:424)
ERROR/WindowManager(8297): at android.app.Dialog.show(Dialog.java:241)
ERROR/WindowManager(8297): at android.app.ProgressDialog.show(ProgressDialog.java:107)
ERROR/WindowManager(8297): at android.app.ProgressDialog.show(ProgressDialog.java:95)
ERROR/WindowManager(8297): at mp.tripplanner.OvPlanner$3.onClick(OvPlanner.java:351)
ERROR/WindowManager(8297): at android.view.View.performClick(View.java:2408)
ERROR/WindowManager(8297): at android.view.View$PerformClick.run(View.java:8817)
ERROR/WindowManager(8297): at android.os.Handler.handleCallback(Handler.java:587)
ERROR/WindowManager(8297): at android.os.Handler.dispatchMessage(Handler.java:92)
ERROR/WindowManager(8297): at android.os.Looper.loop(Looper.java:144)
ERROR/WindowManager(8297): at android.app.ActivityThread.main(ActivityThread.java:4937)
ERROR/WindowManager(8297): at java.lang.reflect.Method.invokeNative(Native Method)
ERROR/WindowManager(8297): at java.lang.reflect.Method.invoke(Method.java:521)
ERROR/WindowManager(8297): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
ERROR/WindowManager(8297): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
ERROR/WindowManager(8297): at dalvik.system.NativeStart.main(Native Method)

但是在上面的日志之前会将另一条错误消息写入日志，即：

ERROR/AndroidRuntime(8297): FATAL EXCEPTION: Thread-9
ERROR/AndroidRuntime(8297): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
ERROR/AndroidRuntime(8297): at android.os.Handler.<init>(Handler.java:121)
ERROR/AndroidRuntime(8297): at android.widget.Toast.<init>(Toast.java:68)
ERROR/AndroidRuntime(8297): at android.widget.Toast.makeText(Toast.java:231)
ERROR/AndroidRuntime(8297): at mp.tripplanner.OvPlanner$4.run(OvPlanner.java:371)

感谢您的帮助。

Answer 1

您需要在UI线程中创建Handler才能更新UI。然后我会使用处理程序的sendMessage方法，而不是发布runnable：

private static final int HANDLER_MESSAGE_ERROR = 0;
private static final int HANDLER_MESSAGE_COMPLETED = 1;
...
private void connectAndGetRoute(){
    new Thread(){
        @Override
        public void run() {
            try {
                if(!connectTo9292ov()) return;

            } catch(UnknownHostException e){
                sendMessage(HANDLER_MESSAGE_ERROR);
            } catch (ClientProtocolException e) {
                sendMessage(HANDLER_MESSAGE_ERROR);
            } catch (IOException e) {
                sendMessage(HANDLER_MESSAGE_ERROR);
            } finally {
                sendMessage(HANDLER_MESSAGE_COMPLETED);
            }
        }
        private void sendMessage(int what){
            Message msg = Message.obtain();
            msg.what = what;
            mHandler.sendMessage(msg);
        }
    }.start();

}
...
private Handler mHandler = new Handler(){
    @Override
    public void handleMessage(Message msg) {
        switch(msg.what){
        case HANDLER_MESSAGE_ERROR:
            Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();
            break;
        case HANDLER_MESSAGE_COMPLETED:
            mProgressDialog.dismiss();
            showOnScreen();
            break;
        default:
            Log.w("MyTag","Warning: message type \""+msg.what+"\" not supported");
        }
    }
}

Answer 2

只是一个简单的想法。

我认为，这是你在线程中的toast-messages。试着评论它们。

如果您仍想显示消息，请保存线程的状态并在处理程序中处理它。从finally块

中调用你的处理程序

mProgressDialog = ProgressDialog.show(mContext, "Tripplanner", "please wait...", true, false);
connectAndGetRoute();


private void connectAndGetRoute(){

    new Thread(){
        @Override
        public void run() {
            try {
            if(!connectTo9292ov()) return;// conncetto9292ov() connects to a website, parses the reasult into an arraylist. The arraylist contains route.

            } catch(UnknownHostException e){
                // an int member of your activity
                threadStatus = 404;
                // Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();
            }catch (ClientProtocolException e) {
                threadStatus = 404;
               // Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();                   
        } catch (IOException e) {
                threadStatus = 404;
                // Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();
            }
            finally {
            handler.post(runConnection);}
        }

    }.start();

    handler = new Handler();
    runConnection = new Runnable(){
        @Override
        public void run() {
            if (threadStatus == 404) { Toast.makeText(mContext, "failed to connect to server", Toast.LENGTH_LONG).show();}
            else {
            mProgressDialog.dismiss();
            showOnScreen();}
        }   
    };
}

Answer 3

示例代码：

new Thread(new Runnable() {                 
                @Override
                public void run() {
                    doNotUIthings();
                    updateUI.sendEmptyMessage(0);   //Update ui in UI thread
                }
                private Handler updateUI = new Handler(){
                    @Override
                    public void dispatchMessage(Message msg) {
                        super.dispatchMessage(msg);
                        updateUI();
                    }
                };
            }).start();

但我建议使用AsyncTask而不是Java Threads。

活动已泄露窗口com.android.internal.policy.impl.PhoneWindow$DecorView@46368a28，最初在这里添加

3 个答案: