--- /dev/null
+/*
+ * Copyright (C) 2011 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.support.v2.content;
+
+import android.content.Context;
+import android.database.ContentObserver;
+import android.os.Handler;
+import android.support.v2.util.DebugUtils;
+
+import java.io.FileDescriptor;
+import java.io.PrintWriter;
+
+/**
+ * Static library support version of the framework's {@link android.content.Loader}.
+ * Used to write apps that run on platforms prior to Android 3.0. When running
+ * on Android 3.0 or above, this implementation is still used; it does not try
+ * to switch to the framework's implementation. See the framework SDK
+ * documentation for a class overview.
+ */
+public class Loader<D> {
+ int mId;
+ OnLoadCompleteListener<D> mListener;
+ Context mContext;
+ boolean mStarted = false;
+ boolean mAbandoned = false;
+ boolean mReset = true;
+ boolean mContentChanged = false;
+
+ public final class ForceLoadContentObserver extends ContentObserver {
+ public ForceLoadContentObserver() {
+ super(new Handler());
+ }
+
+ @Override
+ public boolean deliverSelfNotifications() {
+ return true;
+ }
+
+ @Override
+ public void onChange(boolean selfChange) {
+ onContentChanged();
+ }
+ }
+
+ public interface OnLoadCompleteListener<D> {
+ /**
+ * Called on the thread that created the Loader when the load is complete.
+ *
+ * @param loader the loader that completed the load
+ * @param data the result of the load
+ */
+ public void onLoadComplete(Loader<D> loader, D data);
+ }
+
+ /**
+ * Stores away the application context associated with context. Since Loaders can be used
+ * across multiple activities it's dangerous to store the context directly.
+ *
+ * @param context used to retrieve the application context.
+ */
+ public Loader(Context context) {
+ mContext = context.getApplicationContext();
+ }
+
+ /**
+ * Sends the result of the load to the registered listener. Should only be called by subclasses.
+ *
+ * Must be called from the process's main thread.
+ *
+ * @param data the result of the load
+ */
+ public void deliverResult(D data) {
+ if (mListener != null) {
+ mListener.onLoadComplete(this, data);
+ }
+ }
+
+ /**
+ * @return an application context retrieved from the Context passed to the constructor.
+ */
+ public Context getContext() {
+ return mContext;
+ }
+
+ /**
+ * @return the ID of this loader
+ */
+ public int getId() {
+ return mId;
+ }
+
+ /**
+ * Registers a class that will receive callbacks when a load is complete.
+ * The callback will be called on the process's main thread so it's safe to
+ * pass the results to widgets.
+ *
+ * <p>Must be called from the process's main thread.
+ */
+ public void registerListener(int id, OnLoadCompleteListener<D> listener) {
+ if (mListener != null) {
+ throw new IllegalStateException("There is already a listener registered");
+ }
+ mListener = listener;
+ mId = id;
+ }
+
+ /**
+ * Remove a listener that was previously added with {@link #registerListener}.
+ *
+ * Must be called from the process's main thread.
+ */
+ public void unregisterListener(OnLoadCompleteListener<D> listener) {
+ if (mListener == null) {
+ throw new IllegalStateException("No listener register");
+ }
+ if (mListener != listener) {
+ throw new IllegalArgumentException("Attempting to unregister the wrong listener");
+ }
+ mListener = null;
+ }
+
+ /**
+ * Return whether this load has been started. That is, its {@link #startLoading()}
+ * has been called and no calls to {@link #stopLoading()} or
+ * {@link #reset()} have yet been made.
+ */
+ public boolean isStarted() {
+ return mStarted;
+ }
+
+ /**
+ * Return whether this loader has been abandoned. In this state, the
+ * loader <em>must not</em> report any new data, and <em>must</em> keep
+ * its last reported data valid until it is finally reset.
+ */
+ public boolean isAbandoned() {
+ return mAbandoned;
+ }
+
+ /**
+ * Return whether this load has been reset. That is, either the loader
+ * has not yet been started for the first time, or its {@link #reset()}
+ * has been called.
+ */
+ public boolean isReset() {
+ return mReset;
+ }
+
+ /**
+ * Starts an asynchronous load of the Loader's data. When the result
+ * is ready the callbacks will be called on the process's main thread.
+ * If a previous load has been completed and is still valid
+ * the result may be passed to the callbacks immediately.
+ * The loader will monitor the source of
+ * the data set and may deliver future callbacks if the source changes.
+ * Calling {@link #stopLoading} will stop the delivery of callbacks.
+ *
+ * <p>This updates the Loader's internal state so that
+ * {@link #isStarted()} and {@link #isReset()} will return the correct
+ * values, and then calls the implementation's {@link #onStartLoading()}.
+ *
+ * <p>Must be called from the process's main thread.
+ */
+ public final void startLoading() {
+ mStarted = true;
+ mReset = false;
+ mAbandoned = false;
+ onStartLoading();
+ }
+
+ /**
+ * Subclasses must implement this to take care of loading their data,
+ * as per {@link #startLoading()}. This is not called by clients directly,
+ * but as a result of a call to {@link #startLoading()}.
+ */
+ protected void onStartLoading() {
+ }
+
+ /**
+ * Force an asynchronous load. Unlike {@link #startLoading()} this will ignore a previously
+ * loaded data set and load a new one. This simply calls through to the
+ * implementation's {@link #onForceLoad()}. You generally should only call this
+ * when the loader is started -- that is, {@link #isStarted()} returns true.
+ *
+ * <p>Must be called from the process's main thread.
+ */
+ public void forceLoad() {
+ onForceLoad();
+ }
+
+ /**
+ * Subclasses must implement this to take care of requests to {@link #forceLoad()}.
+ * This will always be called from the process's main thread.
+ */
+ protected void onForceLoad() {
+ }
+
+ /**
+ * Stops delivery of updates until the next time {@link #startLoading()} is called.
+ * Implementations should <em>not</em> invalidate their data at this point --
+ * clients are still free to use the last data the loader reported. They will,
+ * however, typically stop reporting new data if the data changes; they can
+ * still monitor for changes, but must not report them to the client until and
+ * if {@link #startLoading()} is later called.
+ *
+ * <p>This updates the Loader's internal state so that
+ * {@link #isStarted()} will return the correct
+ * value, and then calls the implementation's {@link #onStopLoading()}.
+ *
+ * <p>Must be called from the process's main thread.
+ */
+ public void stopLoading() {
+ mStarted = false;
+ onStopLoading();
+ }
+
+ /**
+ * Subclasses must implement this to take care of stopping their loader,
+ * as per {@link #stopLoading()}. This is not called by clients directly,
+ * but as a result of a call to {@link #stopLoading()}.
+ * This will always be called from the process's main thread.
+ */
+ protected void onStopLoading() {
+ }
+
+ /**
+ * Tell the Loader that it is being abandoned. This is called prior
+ * to {@link #reset} to have it retain its current data but not report
+ * any new data.
+ */
+ public void abandon() {
+ mAbandoned = true;
+ onAbandon();
+ }
+
+ /**
+ * Subclasses implement this to take care of being abandoned. This is
+ * an optional intermediate state prior to {@link #onReset()} -- it means that
+ * the client is no longer interested in any new data from the loader,
+ * so the loader must not report any further updates. However, the
+ * loader <em>must</em> keep its last reported data valid until the final
+ * {@link #onReset()} happens. You can retrieve the current abandoned
+ * state with {@link #isAbandoned}.
+ */
+ protected void onAbandon() {
+ }
+
+ /**
+ * Resets the state of the Loader. The Loader should at this point free
+ * all of its resources, since it may never be called again; however, its
+ * {@link #startLoading()} may later be called at which point it must be
+ * able to start running again.
+ *
+ * <p>This updates the Loader's internal state so that
+ * {@link #isStarted()} and {@link #isReset()} will return the correct
+ * values, and then calls the implementation's {@link #onReset()}.
+ *
+ * <p>Must be called from the process's main thread.
+ */
+ public void reset() {
+ onReset();
+ mReset = true;
+ mStarted = false;
+ mAbandoned = false;
+ mContentChanged = false;
+ }
+
+ /**
+ * Subclasses must implement this to take care of resetting their loader,
+ * as per {@link #reset()}. This is not called by clients directly,
+ * but as a result of a call to {@link #reset()}.
+ * This will always be called from the process's main thread.
+ */
+ protected void onReset() {
+ }
+
+ /**
+ * Take the current flag indicating whether the loader's content had
+ * changed while it was stopped. If it had, true is returned and the
+ * flag is cleared.
+ */
+ public boolean takeContentChanged() {
+ boolean res = mContentChanged;
+ mContentChanged = false;
+ return res;
+ }
+
+ /**
+ * Called when {@link ForceLoadContentObserver} detects a change. The
+ * default implementation checks to see if the loader is currently started;
+ * if so, it simply calls {@link #forceLoad()}; otherwise, it sets a flag
+ * so that {@link #takeContentChanged()} returns true.
+ *
+ * <p>Must be called from the process's main thread.
+ */
+ public void onContentChanged() {
+ if (mStarted) {
+ forceLoad();
+ } else {
+ // This loader has been stopped, so we don't want to load
+ // new data right now... but keep track of it changing to
+ // refresh later if we start again.
+ mContentChanged = true;
+ }
+ }
+
+ /**
+ * For debugging, converts an instance of the Loader's data class to
+ * a string that can be printed. Must handle a null data.
+ */
+ public String dataToString(D data) {
+ StringBuilder sb = new StringBuilder(64);
+ DebugUtils.buildShortClassTag(data, sb);
+ sb.append("}");
+ return sb.toString();
+ }
+
+ @Override
+ public String toString() {
+ StringBuilder sb = new StringBuilder(64);
+ DebugUtils.buildShortClassTag(this, sb);
+ sb.append(" id=");
+ sb.append(mId);
+ sb.append("}");
+ return sb.toString();
+ }
+
+ /**
+ * Print the Loader's state into the given stream.
+ *
+ * @param prefix Text to print at the front of each line.
+ * @param fd The raw file descriptor that the dump is being sent to.
+ * @param writer A PrintWriter to which the dump is to be set.
+ * @param args Additional arguments to the dump request.
+ */
+ public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
+ writer.print(prefix); writer.print("mId="); writer.print(mId);
+ writer.print(" mListener="); writer.println(mListener);
+ writer.print(prefix); writer.print("mStarted="); writer.print(mStarted);
+ writer.print(" mContentChanged="); writer.print(mContentChanged);
+ writer.print(" mAbandoned="); writer.print(mAbandoned);
+ writer.print(" mReset="); writer.println(mReset);
+ }
+}
\ No newline at end of file
notaz.gp2x.de / android_pandora.git / blobdiff