/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.print; import android.app.Activity; import android.app.Application.ActivityLifecycleCallbacks; import android.content.Context; import android.content.IntentSender; import android.content.IntentSender.SendIntentException; import android.os.Bundle; import android.os.CancellationSignal; import android.os.Handler; import android.os.Looper; import android.os.Message; import android.os.ParcelFileDescriptor; import android.os.RemoteException; import android.print.PrintDocumentAdapter.LayoutResultCallback; import android.print.PrintDocumentAdapter.WriteResultCallback; import android.printservice.PrintServiceInfo; import android.text.TextUtils; import android.util.ArrayMap; import android.util.Log; import com.android.internal.os.SomeArgs; import libcore.io.IoUtils; import java.lang.ref.WeakReference; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.Map; /** * System level service for accessing the printing capabilities of the platform. *

* To obtain a handle to the print manager do the following: *

* *
 * PrintManager printManager =
 *         (PrintManager) context.getSystemService(Context.PRINT_SERVICE);
 * 
* *

Print mechanics

*

* The key idea behind printing on the platform is that the content to be printed * should be laid out for the currently selected print options resulting in an * optimized output and higher user satisfaction. To achieve this goal the platform * declares a contract that the printing application has to follow which is defined * by the {@link PrintDocumentAdapter} class. At a higher level the contract is that * when the user selects some options from the print UI that may affect the way * content is laid out, for example page size, the application receives a callback * allowing it to layout the content to better fit these new constraints. After a * layout pass the system may ask the application to render one or more pages one * or more times. For example, an application may produce a single column list for * smaller page sizes and a multi-column table for larger page sizes. *

*

Print jobs

*

* Print jobs are started by calling the {@link #print(String, PrintDocumentAdapter, * PrintAttributes)} from an activity which results in bringing up the system print * UI. Once the print UI is up, when the user changes a selected print option that * affects the way content is laid out the system starts to interact with the * application following the mechanics described the section above. *

*

* Print jobs can be in {@link PrintJobInfo#STATE_CREATED created}, {@link * PrintJobInfo#STATE_QUEUED queued}, {@link PrintJobInfo#STATE_STARTED started}, * {@link PrintJobInfo#STATE_BLOCKED blocked}, {@link PrintJobInfo#STATE_COMPLETED * completed}, {@link PrintJobInfo#STATE_FAILED failed}, and {@link * PrintJobInfo#STATE_CANCELED canceled} state. Print jobs are stored in dedicated * system spooler until they are handled which is they are cancelled or completed. * Active print jobs, ones that are not cancelled or completed, are considered failed * if the device reboots as the new boot may be after a very long time. The user may * choose to restart such print jobs. Once a print job is queued all relevant content * is stored in the system spooler and its lifecycle becomes detached from this of * the application that created it. *

*

* An applications can query the print spooler for current print jobs it created * but not print jobs created by other applications. *

* * @see PrintJob * @see PrintJobInfo */ public final class PrintManager { private static final String LOG_TAG = "PrintManager"; private static final boolean DEBUG = false; private static final int MSG_NOTIFY_PRINT_JOB_STATE_CHANGED = 1; /** * The action for launching the print dialog activity. * * @hide */ public static final String ACTION_PRINT_DIALOG = "android.print.PRINT_DIALOG"; /** * Extra with the intent for starting the print dialog. *

* Type: {@link android.content.IntentSender} *

* * @hide */ public static final String EXTRA_PRINT_DIALOG_INTENT = "android.print.intent.extra.EXTRA_PRINT_DIALOG_INTENT"; /** * Extra with a print job. *

* Type: {@link android.print.PrintJobInfo} *

* * @hide */ public static final String EXTRA_PRINT_JOB = "android.print.intent.extra.EXTRA_PRINT_JOB"; /** * Extra with the print document adapter to be printed. *

* Type: {@link android.print.IPrintDocumentAdapter} *

* * @hide */ public static final String EXTRA_PRINT_DOCUMENT_ADAPTER = "android.print.intent.extra.EXTRA_PRINT_DOCUMENT_ADAPTER"; /** @hide */ public static final int APP_ID_ANY = -2; private final Context mContext; private final IPrintManager mService; private final int mUserId; private final int mAppId; private final Handler mHandler; private Map mPrintJobStateChangeListeners; /** @hide */ public interface PrintJobStateChangeListener { /** * Callback notifying that a print job state changed. * * @param printJobId The print job id. */ public void onPrintJobStateChanged(PrintJobId printJobId); } /** * Creates a new instance. * * @param context The current context in which to operate. * @param service The backing system service. * @hide */ public PrintManager(Context context, IPrintManager service, int userId, int appId) { mContext = context; mService = service; mUserId = userId; mAppId = appId; mHandler = new Handler(context.getMainLooper(), null, false) { @Override public void handleMessage(Message message) { switch (message.what) { case MSG_NOTIFY_PRINT_JOB_STATE_CHANGED: { SomeArgs args = (SomeArgs) message.obj; PrintJobStateChangeListenerWrapper wrapper = (PrintJobStateChangeListenerWrapper) args.arg1; PrintJobStateChangeListener listener = wrapper.getListener(); if (listener != null) { PrintJobId printJobId = (PrintJobId) args.arg2; listener.onPrintJobStateChanged(printJobId); } args.recycle(); } break; } } }; } /** * Creates an instance that can access all print jobs. * * @param userId The user id for which to get all print jobs. * @return An instance if the caller has the permission to access all print * jobs, null otherwise. * @hide */ public PrintManager getGlobalPrintManagerForUser(int userId) { return new PrintManager(mContext, mService, userId, APP_ID_ANY); } PrintJobInfo getPrintJobInfo(PrintJobId printJobId) { try { return mService.getPrintJobInfo(printJobId, mAppId, mUserId); } catch (RemoteException re) { Log.e(LOG_TAG, "Error getting a print job info:" + printJobId, re); } return null; } /** * Adds a listener for observing the state of print jobs. * * @param listener The listener to add. * @hide */ public void addPrintJobStateChangeListener(PrintJobStateChangeListener listener) { if (mPrintJobStateChangeListeners == null) { mPrintJobStateChangeListeners = new ArrayMap(); } PrintJobStateChangeListenerWrapper wrappedListener = new PrintJobStateChangeListenerWrapper(listener, mHandler); try { mService.addPrintJobStateChangeListener(wrappedListener, mAppId, mUserId); mPrintJobStateChangeListeners.put(listener, wrappedListener); } catch (RemoteException re) { Log.e(LOG_TAG, "Error adding print job state change listener", re); } } /** * Removes a listener for observing the state of print jobs. * * @param listener The listener to remove. * @hide */ public void removePrintJobStateChangeListener(PrintJobStateChangeListener listener) { if (mPrintJobStateChangeListeners == null) { return; } PrintJobStateChangeListenerWrapper wrappedListener = mPrintJobStateChangeListeners.remove(listener); if (wrappedListener == null) { return; } if (mPrintJobStateChangeListeners.isEmpty()) { mPrintJobStateChangeListeners = null; } wrappedListener.destroy(); try { mService.removePrintJobStateChangeListener(wrappedListener, mUserId); } catch (RemoteException re) { Log.e(LOG_TAG, "Error removing print job state change listener", re); } } /** * Gets a print job given its id. * * @return The print job list. * @see PrintJob * @hide */ public PrintJob getPrintJob(PrintJobId printJobId) { try { PrintJobInfo printJob = mService.getPrintJobInfo(printJobId, mAppId, mUserId); if (printJob != null) { return new PrintJob(printJob, this); } } catch (RemoteException re) { Log.e(LOG_TAG, "Error getting print job", re); } return null; } /** * Gets the print jobs for this application. * * @return The print job list. * @see PrintJob */ public List getPrintJobs() { try { List printJobInfos = mService.getPrintJobInfos(mAppId, mUserId); if (printJobInfos == null) { return Collections.emptyList(); } final int printJobCount = printJobInfos.size(); List printJobs = new ArrayList(printJobCount); for (int i = 0; i < printJobCount; i++) { printJobs.add(new PrintJob(printJobInfos.get(i), this)); } return printJobs; } catch (RemoteException re) { Log.e(LOG_TAG, "Error getting print jobs", re); } return Collections.emptyList(); } void cancelPrintJob(PrintJobId printJobId) { try { mService.cancelPrintJob(printJobId, mAppId, mUserId); } catch (RemoteException re) { Log.e(LOG_TAG, "Error cancleing a print job: " + printJobId, re); } } void restartPrintJob(PrintJobId printJobId) { try { mService.restartPrintJob(printJobId, mAppId, mUserId); } catch (RemoteException re) { Log.e(LOG_TAG, "Error restarting a print job: " + printJobId, re); } } /** * Creates a print job for printing a {@link PrintDocumentAdapter} with * default print attributes. *

* Calling this method brings the print UI allowing the user to customize * the print job and returns a {@link PrintJob} object without waiting for the * user to customize or confirm the print job. The returned print job instance * is in a {@link PrintJobInfo#STATE_CREATED created} state. *

* This method can be called only from an {@link Activity}. The rationale is that * printing from a service will create an inconsistent user experience as the print * UI would appear without any context. *

*

* Also the passed in {@link PrintDocumentAdapter} will be considered invalid if * your activity is finished. The rationale is that once the activity that * initiated printing is finished, the provided adapter may be in an inconsistent * state as it may depend on the UI presented by the activity. *

*

* The default print attributes are a hint to the system how the data is to * be printed. For example, a photo editor may look at the photo aspect ratio * to determine the default orientation and provide a hint whether the printing * should be in portrait or landscape. The system will do a best effort to * selected the hinted options in the print dialog, given the current printer * supports them. *

* * @param printJobName A name for the new print job which is shown to the user. * @param documentAdapter An adapter that emits the document to print. * @param attributes The default print job attributes or null. * @return The created print job on success or null on failure. * @throws IllegalStateException If not called from an {@link Activity}. * @throws IllegalArgumentException If the print job name is empty or the * document adapter is null. * * @see PrintJob */ public PrintJob print(String printJobName, PrintDocumentAdapter documentAdapter, PrintAttributes attributes) { if (!(mContext instanceof Activity)) { throw new IllegalStateException("Can print only from an activity"); } if (TextUtils.isEmpty(printJobName)) { throw new IllegalArgumentException("printJobName cannot be empty"); } if (documentAdapter == null) { throw new IllegalArgumentException("documentAdapter cannot be null"); } PrintDocumentAdapterDelegate delegate = new PrintDocumentAdapterDelegate( (Activity) mContext, documentAdapter); try { Bundle result = mService.print(printJobName, delegate, attributes, mContext.getPackageName(), mAppId, mUserId); if (result != null) { PrintJobInfo printJob = result.getParcelable(EXTRA_PRINT_JOB); IntentSender intent = result.getParcelable(EXTRA_PRINT_DIALOG_INTENT); if (printJob == null || intent == null) { return null; } try { mContext.startIntentSender(intent, null, 0, 0, 0); return new PrintJob(printJob, this); } catch (SendIntentException sie) { Log.e(LOG_TAG, "Couldn't start print job config activity.", sie); } } } catch (RemoteException re) { Log.e(LOG_TAG, "Error creating a print job", re); } return null; } /** * Gets the list of enabled print services. * * @return The enabled service list or an empty list. * @hide */ public List getEnabledPrintServices() { try { List enabledServices = mService.getEnabledPrintServices(mUserId); if (enabledServices != null) { return enabledServices; } } catch (RemoteException re) { Log.e(LOG_TAG, "Error getting the enabled print services", re); } return Collections.emptyList(); } /** * Gets the list of installed print services. * * @return The installed service list or an empty list. * @hide */ public List getInstalledPrintServices() { try { List installedServices = mService.getInstalledPrintServices(mUserId); if (installedServices != null) { return installedServices; } } catch (RemoteException re) { Log.e(LOG_TAG, "Error getting the installed print services", re); } return Collections.emptyList(); } /** * @hide */ public PrinterDiscoverySession createPrinterDiscoverySession() { return new PrinterDiscoverySession(mService, mContext, mUserId); } private static final class PrintDocumentAdapterDelegate extends IPrintDocumentAdapter.Stub implements ActivityLifecycleCallbacks { private final Object mLock = new Object(); private CancellationSignal mLayoutOrWriteCancellation; private Activity mActivity; // Strong reference OK - cleared in finish() private PrintDocumentAdapter mDocumentAdapter; // Strong reference OK - cleared in finish private Handler mHandler; // Strong reference OK - cleared in finish() private IPrintDocumentAdapterObserver mObserver; // Strong reference OK - cleared in finish private LayoutSpec mLastLayoutSpec; private WriteSpec mLastWriteSpec; private boolean mStartReqeusted; private boolean mStarted; private boolean mFinishRequested; private boolean mFinished; private boolean mDestroyed; public PrintDocumentAdapterDelegate(Activity activity, PrintDocumentAdapter documentAdapter) { mActivity = activity; mDocumentAdapter = documentAdapter; mHandler = new MyHandler(mActivity.getMainLooper()); mActivity.getApplication().registerActivityLifecycleCallbacks(this); } @Override public void setObserver(IPrintDocumentAdapterObserver observer) { final boolean destroyed; synchronized (mLock) { if (!mDestroyed) { mObserver = observer; } destroyed = mDestroyed; } if (destroyed) { try { observer.onDestroy(); } catch (RemoteException re) { Log.e(LOG_TAG, "Error announcing destroyed state", re); } } } @Override public void start() { synchronized (mLock) { // Started called or finish called or destroyed - nothing to do. if (mStartReqeusted || mFinishRequested || mDestroyed) { return; } mStartReqeusted = true; doPendingWorkLocked(); } } @Override public void layout(PrintAttributes oldAttributes, PrintAttributes newAttributes, ILayoutResultCallback callback, Bundle metadata, int sequence) { final boolean destroyed; synchronized (mLock) { destroyed = mDestroyed; // If start called and not finished called and not destroyed - do some work. if (mStartReqeusted && !mFinishRequested && !mDestroyed) { // Layout cancels write and overrides layout. if (mLastWriteSpec != null) { IoUtils.closeQuietly(mLastWriteSpec.fd); mLastWriteSpec = null; } mLastLayoutSpec = new LayoutSpec(); mLastLayoutSpec.callback = callback; mLastLayoutSpec.oldAttributes = oldAttributes; mLastLayoutSpec.newAttributes = newAttributes; mLastLayoutSpec.metadata = metadata; mLastLayoutSpec.sequence = sequence; // Cancel the previous cancellable operation.When the // cancellation completes we will do the pending work. if (cancelPreviousCancellableOperationLocked()) { return; } doPendingWorkLocked(); } } if (destroyed) { try { callback.onLayoutFailed(null, sequence); } catch (RemoteException re) { Log.i(LOG_TAG, "Error notifying for cancelled layout", re); } } } @Override public void write(PageRange[] pages, ParcelFileDescriptor fd, IWriteResultCallback callback, int sequence) { final boolean destroyed; synchronized (mLock) { destroyed = mDestroyed; // If start called and not finished called and not destroyed - do some work. if (mStartReqeusted && !mFinishRequested && !mDestroyed) { // Write cancels previous writes. if (mLastWriteSpec != null) { IoUtils.closeQuietly(mLastWriteSpec.fd); mLastWriteSpec = null; } mLastWriteSpec = new WriteSpec(); mLastWriteSpec.callback = callback; mLastWriteSpec.pages = pages; mLastWriteSpec.fd = fd; mLastWriteSpec.sequence = sequence; // Cancel the previous cancellable operation.When the // cancellation completes we will do the pending work. if (cancelPreviousCancellableOperationLocked()) { return; } doPendingWorkLocked(); } } if (destroyed) { try { callback.onWriteFailed(null, sequence); } catch (RemoteException re) { Log.i(LOG_TAG, "Error notifying for cancelled write", re); } } } @Override public void finish() { synchronized (mLock) { // Start not called or finish called or destroyed - nothing to do. if (!mStartReqeusted || mFinishRequested || mDestroyed) { return; } mFinishRequested = true; // When the current write or layout complete we // will do the pending work. if (mLastLayoutSpec != null || mLastWriteSpec != null) { if (DEBUG) { Log.i(LOG_TAG, "Waiting for current operation"); } return; } doPendingWorkLocked(); } } @Override public void onActivityPaused(Activity activity) { /* do nothing */ } @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) { /* do nothing */ } @Override public void onActivityStarted(Activity activity) { /* do nothing */ } @Override public void onActivityResumed(Activity activity) { /* do nothing */ } @Override public void onActivityStopped(Activity activity) { /* do nothing */ } @Override public void onActivitySaveInstanceState(Activity activity, Bundle outState) { /* do nothing */ } @Override public void onActivityDestroyed(Activity activity) { // We really care only if the activity is being destroyed to // notify the the print spooler so it can close the print dialog. // Note the the spooler has a death recipient that observes if // this process gets killed so we cover the case of onDestroy not // being called due to this process being killed to reclaim memory. final IPrintDocumentAdapterObserver observer; synchronized (mLock) { if (activity == mActivity) { mDestroyed = true; observer = mObserver; clearLocked(); } else { observer = null; activity = null; } } if (observer != null) { activity.getApplication().unregisterActivityLifecycleCallbacks( PrintDocumentAdapterDelegate.this); try { observer.onDestroy(); } catch (RemoteException re) { Log.e(LOG_TAG, "Error announcing destroyed state", re); } } } private boolean isFinished() { return mDocumentAdapter == null; } private void clearLocked() { mActivity = null; mDocumentAdapter = null; mHandler = null; mLayoutOrWriteCancellation = null; mLastLayoutSpec = null; if (mLastWriteSpec != null) { IoUtils.closeQuietly(mLastWriteSpec.fd); mLastWriteSpec = null; } } private boolean cancelPreviousCancellableOperationLocked() { if (mLayoutOrWriteCancellation != null) { mLayoutOrWriteCancellation.cancel(); if (DEBUG) { Log.i(LOG_TAG, "Cancelling previous operation"); } return true; } return false; } private void doPendingWorkLocked() { if (mStartReqeusted && !mStarted) { mStarted = true; mHandler.sendEmptyMessage(MyHandler.MSG_START); } else if (mLastLayoutSpec != null) { mHandler.sendEmptyMessage(MyHandler.MSG_LAYOUT); } else if (mLastWriteSpec != null) { mHandler.sendEmptyMessage(MyHandler.MSG_WRITE); } else if (mFinishRequested && !mFinished) { mFinished = true; mHandler.sendEmptyMessage(MyHandler.MSG_FINISH); } } private class LayoutSpec { ILayoutResultCallback callback; PrintAttributes oldAttributes; PrintAttributes newAttributes; Bundle metadata; int sequence; } private class WriteSpec { IWriteResultCallback callback; PageRange[] pages; ParcelFileDescriptor fd; int sequence; } private final class MyHandler extends Handler { public static final int MSG_START = 1; public static final int MSG_LAYOUT = 2; public static final int MSG_WRITE = 3; public static final int MSG_FINISH = 4; public MyHandler(Looper looper) { super(looper, null, true); } @Override public void handleMessage(Message message) { if (isFinished()) { return; } switch (message.what) { case MSG_START: { final PrintDocumentAdapter adapter; synchronized (mLock) { adapter = mDocumentAdapter; } if (adapter != null) { adapter.onStart(); } } break; case MSG_LAYOUT: { final PrintDocumentAdapter adapter; final CancellationSignal cancellation; final LayoutSpec layoutSpec; synchronized (mLock) { adapter = mDocumentAdapter; layoutSpec = mLastLayoutSpec; mLastLayoutSpec = null; cancellation = new CancellationSignal(); mLayoutOrWriteCancellation = cancellation; } if (layoutSpec != null && adapter != null) { if (DEBUG) { Log.i(LOG_TAG, "Performing layout"); } adapter.onLayout(layoutSpec.oldAttributes, layoutSpec.newAttributes, cancellation, new MyLayoutResultCallback(layoutSpec.callback, layoutSpec.sequence), layoutSpec.metadata); } } break; case MSG_WRITE: { final PrintDocumentAdapter adapter; final CancellationSignal cancellation; final WriteSpec writeSpec; synchronized (mLock) { adapter = mDocumentAdapter; writeSpec = mLastWriteSpec; mLastWriteSpec = null; cancellation = new CancellationSignal(); mLayoutOrWriteCancellation = cancellation; } if (writeSpec != null && adapter != null) { if (DEBUG) { Log.i(LOG_TAG, "Performing write"); } adapter.onWrite(writeSpec.pages, writeSpec.fd, cancellation, new MyWriteResultCallback(writeSpec.callback, writeSpec.fd, writeSpec.sequence)); } } break; case MSG_FINISH: { if (DEBUG) { Log.i(LOG_TAG, "Performing finish"); } final PrintDocumentAdapter adapter; final Activity activity; synchronized (mLock) { adapter = mDocumentAdapter; activity = mActivity; clearLocked(); } if (adapter != null) { adapter.onFinish(); } if (activity != null) { activity.getApplication().unregisterActivityLifecycleCallbacks( PrintDocumentAdapterDelegate.this); } } break; default: { throw new IllegalArgumentException("Unknown message: " + message.what); } } } } private final class MyLayoutResultCallback extends LayoutResultCallback { private ILayoutResultCallback mCallback; private final int mSequence; public MyLayoutResultCallback(ILayoutResultCallback callback, int sequence) { mCallback = callback; mSequence = sequence; } @Override public void onLayoutFinished(PrintDocumentInfo info, boolean changed) { if (info == null) { throw new NullPointerException("document info cannot be null"); } final ILayoutResultCallback callback; synchronized (mLock) { callback = mCallback; clearLocked(); } if (callback != null) { try { callback.onLayoutFinished(info, changed, mSequence); } catch (RemoteException re) { Log.e(LOG_TAG, "Error calling onLayoutFinished", re); } } } @Override public void onLayoutFailed(CharSequence error) { final ILayoutResultCallback callback; synchronized (mLock) { callback = mCallback; clearLocked(); } if (callback != null) { try { callback.onLayoutFailed(error, mSequence); } catch (RemoteException re) { Log.e(LOG_TAG, "Error calling onLayoutFailed", re); } } } @Override public void onLayoutCancelled() { synchronized (mLock) { clearLocked(); } } private void clearLocked() { mLayoutOrWriteCancellation = null; mCallback = null; doPendingWorkLocked(); } } private final class MyWriteResultCallback extends WriteResultCallback { private ParcelFileDescriptor mFd; private int mSequence; private IWriteResultCallback mCallback; public MyWriteResultCallback(IWriteResultCallback callback, ParcelFileDescriptor fd, int sequence) { mFd = fd; mSequence = sequence; mCallback = callback; } @Override public void onWriteFinished(PageRange[] pages) { final IWriteResultCallback callback; synchronized (mLock) { callback = mCallback; clearLocked(); } if (pages == null) { throw new IllegalArgumentException("pages cannot be null"); } if (pages.length == 0) { throw new IllegalArgumentException("pages cannot be empty"); } if (callback != null) { try { callback.onWriteFinished(pages, mSequence); } catch (RemoteException re) { Log.e(LOG_TAG, "Error calling onWriteFinished", re); } } } @Override public void onWriteFailed(CharSequence error) { final IWriteResultCallback callback; synchronized (mLock) { callback = mCallback; clearLocked(); } if (callback != null) { try { callback.onWriteFailed(error, mSequence); } catch (RemoteException re) { Log.e(LOG_TAG, "Error calling onWriteFailed", re); } } } @Override public void onWriteCancelled() { synchronized (mLock) { clearLocked(); } } private void clearLocked() { mLayoutOrWriteCancellation = null; IoUtils.closeQuietly(mFd); mCallback = null; mFd = null; doPendingWorkLocked(); } } } private static final class PrintJobStateChangeListenerWrapper extends IPrintJobStateChangeListener.Stub { private final WeakReference mWeakListener; private final WeakReference mWeakHandler; public PrintJobStateChangeListenerWrapper(PrintJobStateChangeListener listener, Handler handler) { mWeakListener = new WeakReference(listener); mWeakHandler = new WeakReference(handler); } @Override public void onPrintJobStateChanged(PrintJobId printJobId) { Handler handler = mWeakHandler.get(); PrintJobStateChangeListener listener = mWeakListener.get(); if (handler != null && listener != null) { SomeArgs args = SomeArgs.obtain(); args.arg1 = this; args.arg2 = printJobId; handler.obtainMessage(MSG_NOTIFY_PRINT_JOB_STATE_CHANGED, args).sendToTarget(); } } public void destroy() { mWeakListener.clear(); } public PrintJobStateChangeListener getListener() { return mWeakListener.get(); } } }