Java tutorial
/* * 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.v4.app; import android.content.Context; import android.content.Intent; import android.content.res.Configuration; import android.content.res.TypedArray; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.os.Parcelable; import android.util.AttributeSet; import android.util.Log; import android.view.KeyEvent; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.Window; import java.io.FileDescriptor; import java.io.PrintWriter; import java.util.ArrayList; import java.util.HashMap; import com.google.android.maps.MapActivity; /** * Base class for activities that want to use the support-based * {@link android.support.v4.app.Fragment} and * {@link android.support.v4.content.Loader} APIs. * * <p>When using this class as opposed to new platform's built-in fragment * and loader support, you must use the {@link #getSupportFragmentManager()} * and {@link #getSupportLoaderManager()} methods respectively to access * those features. * * <p>Known limitations:</p> * <ul> * <li> <p>When using the <fragment> tag, this implementation can not * use the parent view's ID as the new fragment's ID. You must explicitly * specify an ID (or tag) in the <fragment>.</p> * <li> <p>Prior to Honeycomb (3.0), an activity's state was saved before pausing. * Fragments are a significant amount of new state, and dynamic enough that one * often wants them to change between pausing and stopping. These classes * throw an exception if you try to change the fragment state after it has been * saved, to avoid accidental loss of UI state. However this is too restrictive * prior to Honeycomb, where the state is saved before pausing. To address this, * when running on platforms prior to Honeycomb an exception will not be thrown * if you change fragments between the state save and the activity being stopped. * This means that in some cases if the activity is restored from its last saved * state, this may be a snapshot slightly before what the user last saw.</p> * </ul> */ public class FragmentActivity extends MapActivity { private static final String TAG = "FragmentActivity"; private static final String FRAGMENTS_TAG = "android:support:fragments"; // This is the SDK API version of Honeycomb (3.0). private static final int HONEYCOMB = 11; static final int MSG_REALLY_STOPPED = 1; static final int MSG_RESUME_PENDING = 2; final Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case MSG_REALLY_STOPPED: if (mStopped) { doReallyStop(false); } break; case MSG_RESUME_PENDING: mFragments.dispatchResume(); mFragments.execPendingActions(); break; default: super.handleMessage(msg); } } }; final FragmentManagerImpl mFragments = new FragmentManagerImpl(); boolean mCreated; boolean mResumed; boolean mStopped; boolean mReallyStopped; boolean mRetaining; boolean mOptionsMenuInvalidated; boolean mCheckedForLoaderManager; boolean mLoadersStarted; HCSparseArray<LoaderManagerImpl> mAllLoaderManagers; LoaderManagerImpl mLoaderManager; static final class NonConfigurationInstances { Object activity; Object custom; HashMap<String, Object> children; ArrayList<Fragment> fragments; HCSparseArray<LoaderManagerImpl> loaders; } static class FragmentTag { public static final int[] Fragment = { 0x01010003, 0x010100d0, 0x010100d1 }; public static final int Fragment_id = 1; public static final int Fragment_name = 0; public static final int Fragment_tag = 2; } // ------------------------------------------------------------------------ // HOOKS INTO ACTIVITY // ------------------------------------------------------------------------ /** * Dispatch incoming result to the correct fragment. */ @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { int index = requestCode >> 16; if (index != 0) { index--; if (mFragments.mActive == null || index < 0 || index >= mFragments.mActive.size()) { Log.w(TAG, "Activity result fragment index out of range: 0x" + Integer.toHexString(requestCode)); return; } Fragment frag = mFragments.mActive.get(index); if (frag == null) { Log.w(TAG, "Activity result no fragment exists for index: 0x" + Integer.toHexString(requestCode)); return; } frag.onActivityResult(requestCode & 0xffff, resultCode, data); return; } super.onActivityResult(requestCode, resultCode, data); } /** * Take care of popping the fragment back stack or finishing the activity * as appropriate. */ public void onBackPressed() { if (!mFragments.popBackStackImmediate()) { finish(); } } /** * Dispatch configuration change to all fragments. */ @Override public void onConfigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); mFragments.dispatchConfigurationChanged(newConfig); } /** * Perform initialization of all fragments and loaders. */ @Override protected void onCreate(Bundle savedInstanceState) { mFragments.attachActivity(this); // Old versions of the platform didn't do this! if (getLayoutInflater().getFactory() == null) { getLayoutInflater().setFactory(this); } super.onCreate(savedInstanceState); NonConfigurationInstances nc = (NonConfigurationInstances) getLastNonConfigurationInstance(); if (nc != null) { mAllLoaderManagers = nc.loaders; } if (savedInstanceState != null) { Parcelable p = savedInstanceState.getParcelable(FRAGMENTS_TAG); mFragments.restoreAllState(p, nc != null ? nc.fragments : null); } mFragments.dispatchCreate(); } /** * Dispatch to Fragment.onCreateOptionsMenu(). */ @Override public boolean onCreatePanelMenu(int featureId, Menu menu) { if (featureId == Window.FEATURE_OPTIONS_PANEL) { boolean show = super.onCreatePanelMenu(featureId, menu); show |= mFragments.dispatchCreateOptionsMenu(menu, getMenuInflater()); if (android.os.Build.VERSION.SDK_INT >= HONEYCOMB) { return show; } // Prior to Honeycomb, the framework can't invalidate the options // menu, so we must always say we have one in case the app later // invalidates it and needs to have it shown. return true; } return super.onCreatePanelMenu(featureId, menu); } /** * Add support for inflating the <fragment> tag. */ @Override public View onCreateView(String name, Context context, AttributeSet attrs) { if (!"fragment".equals(name)) { return super.onCreateView(name, context, attrs); } String fname = attrs.getAttributeValue(null, "class"); TypedArray a = context.obtainStyledAttributes(attrs, FragmentTag.Fragment); if (fname == null) { fname = a.getString(FragmentTag.Fragment_name); } int id = a.getResourceId(FragmentTag.Fragment_id, View.NO_ID); String tag = a.getString(FragmentTag.Fragment_tag); a.recycle(); View parent = null; // NOTE: no way to get parent pre-Honeycomb. int containerId = parent != null ? parent.getId() : 0; if (containerId == View.NO_ID && id == View.NO_ID && tag == null) { throw new IllegalArgumentException(attrs.getPositionDescription() + ": Must specify unique android:id, android:tag, or have a parent with an id for " + fname); } // If we restored from a previous state, we may already have // instantiated this fragment from the state and should use // that instance instead of making a new one. Fragment fragment = id != View.NO_ID ? mFragments.findFragmentById(id) : null; if (fragment == null && tag != null) { fragment = mFragments.findFragmentByTag(tag); } if (fragment == null && containerId != View.NO_ID) { fragment = mFragments.findFragmentById(containerId); } if (FragmentManagerImpl.DEBUG) Log.v(TAG, "onCreateView: id=0x" + Integer.toHexString(id) + " fname=" + fname + " existing=" + fragment); if (fragment == null) { fragment = Fragment.instantiate(this, fname); fragment.mFromLayout = true; fragment.mFragmentId = id != 0 ? id : containerId; fragment.mContainerId = containerId; fragment.mTag = tag; fragment.mInLayout = true; fragment.mFragmentManager = mFragments; fragment.onInflate(this, attrs, fragment.mSavedFragmentState); mFragments.addFragment(fragment, true); } else if (fragment.mInLayout) { // A fragment already exists and it is not one we restored from // previous state. throw new IllegalArgumentException(attrs.getPositionDescription() + ": Duplicate id 0x" + Integer.toHexString(id) + ", tag " + tag + ", or parent id 0x" + Integer.toHexString(containerId) + " with another fragment for " + fname); } else { // This fragment was retained from a previous instance; get it // going now. fragment.mInLayout = true; // If this fragment is newly instantiated (either right now, or // from last saved state), then give it the attributes to // initialize itself. if (!fragment.mRetaining) { fragment.onInflate(this, attrs, fragment.mSavedFragmentState); } mFragments.moveToState(fragment); } if (fragment.mView == null) { throw new IllegalStateException("Fragment " + fname + " did not create a view."); } if (id != 0) { fragment.mView.setId(id); } if (fragment.mView.getTag() == null) { fragment.mView.setTag(tag); } return fragment.mView; } /** * Destroy all fragments and loaders. */ @Override protected void onDestroy() { super.onDestroy(); doReallyStop(false); mFragments.dispatchDestroy(); if (mLoaderManager != null) { mLoaderManager.doDestroy(); } } /** * Take care of calling onBackPressed() for pre-Eclair platforms. */ @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if (android.os.Build.VERSION.SDK_INT < 5 /* ECLAIR */ && keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { // Take care of calling this method on earlier versions of // the platform where it doesn't exist. onBackPressed(); return true; } return super.onKeyDown(keyCode, event); } /** * Dispatch onLowMemory() to all fragments. */ @Override public void onLowMemory() { super.onLowMemory(); mFragments.dispatchLowMemory(); } /** * Dispatch context and options menu to fragments. */ @Override public boolean onMenuItemSelected(int featureId, MenuItem item) { if (super.onMenuItemSelected(featureId, item)) { return true; } switch (featureId) { case Window.FEATURE_OPTIONS_PANEL: return mFragments.dispatchOptionsItemSelected(item); case Window.FEATURE_CONTEXT_MENU: return mFragments.dispatchContextItemSelected(item); default: return false; } } /** * Call onOptionsMenuClosed() on fragments. */ @Override public void onPanelClosed(int featureId, Menu menu) { switch (featureId) { case Window.FEATURE_OPTIONS_PANEL: mFragments.dispatchOptionsMenuClosed(menu); break; } super.onPanelClosed(featureId, menu); } /** * Dispatch onPause() to fragments. */ @Override protected void onPause() { super.onPause(); mResumed = false; if (mHandler.hasMessages(MSG_RESUME_PENDING)) { mHandler.removeMessages(MSG_RESUME_PENDING); mFragments.dispatchResume(); } mFragments.dispatchPause(); } /** * Dispatch onResume() to fragments. */ @Override protected void onResume() { super.onResume(); mHandler.sendEmptyMessage(MSG_RESUME_PENDING); mResumed = true; mFragments.execPendingActions(); } /** * Dispatch onResume() to fragments. */ @Override protected void onPostResume() { super.onPostResume(); mHandler.removeMessages(MSG_RESUME_PENDING); mFragments.dispatchResume(); mFragments.execPendingActions(); } /** * Dispatch onPrepareOptionsMenu() to fragments. */ @Override public boolean onPreparePanel(int featureId, View view, Menu menu) { if (featureId == Window.FEATURE_OPTIONS_PANEL && menu != null) { if (mOptionsMenuInvalidated) { mOptionsMenuInvalidated = false; menu.clear(); onCreatePanelMenu(featureId, menu); } boolean goforit = super.onPreparePanel(featureId, view, menu); goforit |= mFragments.dispatchPrepareOptionsMenu(menu); return goforit && menu.hasVisibleItems(); } return super.onPreparePanel(featureId, view, menu); } /** * Retain all appropriate fragment and loader state. You can NOT * override this yourself! Use {@link #onRetainCustomNonConfigurationInstance()} * if you want to retain your own state. */ @Override public final Object onRetainNonConfigurationInstance() { if (mStopped) { doReallyStop(true); } Object custom = onRetainCustomNonConfigurationInstance(); ArrayList<Fragment> fragments = mFragments.retainNonConfig(); boolean retainLoaders = false; if (mAllLoaderManagers != null) { // prune out any loader managers that were already stopped and so // have nothing useful to retain. for (int i = mAllLoaderManagers.size() - 1; i >= 0; i--) { LoaderManagerImpl lm = mAllLoaderManagers.valueAt(i); if (lm.mRetaining) { retainLoaders = true; } else { lm.doDestroy(); mAllLoaderManagers.removeAt(i); } } } if (fragments == null && !retainLoaders && custom == null) { return null; } NonConfigurationInstances nci = new NonConfigurationInstances(); nci.activity = null; nci.custom = custom; nci.children = null; nci.fragments = fragments; nci.loaders = mAllLoaderManagers; return nci; } /** * Save all appropriate fragment state. */ @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); Parcelable p = mFragments.saveAllState(); if (p != null) { outState.putParcelable(FRAGMENTS_TAG, p); } } /** * Dispatch onStart() to all fragments. Ensure any created loaders are * now started. */ @Override protected void onStart() { super.onStart(); mStopped = false; mReallyStopped = false; mHandler.removeMessages(MSG_REALLY_STOPPED); if (!mCreated) { mCreated = true; mFragments.dispatchActivityCreated(); } mFragments.noteStateNotSaved(); mFragments.execPendingActions(); if (!mLoadersStarted) { mLoadersStarted = true; if (mLoaderManager != null) { mLoaderManager.doStart(); } else if (!mCheckedForLoaderManager) { mLoaderManager = getLoaderManager(-1, mLoadersStarted, false); } mCheckedForLoaderManager = true; } // NOTE: HC onStart goes here. mFragments.dispatchStart(); if (mAllLoaderManagers != null) { for (int i = mAllLoaderManagers.size() - 1; i >= 0; i--) { LoaderManagerImpl lm = mAllLoaderManagers.valueAt(i); lm.finishRetain(); lm.doReportStart(); } } } /** * Dispatch onStop() to all fragments. Ensure all loaders are stopped. */ @Override protected void onStop() { super.onStop(); mStopped = true; mHandler.sendEmptyMessage(MSG_REALLY_STOPPED); mFragments.dispatchStop(); } // ------------------------------------------------------------------------ // NEW METHODS // ------------------------------------------------------------------------ /** * Use this instead of {@link #onRetainNonConfigurationInstance()}. * Retrieve later with {@link #getLastCustomNonConfigurationInstance()}. */ public Object onRetainCustomNonConfigurationInstance() { return null; } /** * Return the value previously returned from * {@link #onRetainCustomNonConfigurationInstance()}. */ public Object getLastCustomNonConfigurationInstance() { NonConfigurationInstances nc = (NonConfigurationInstances) getLastNonConfigurationInstance(); return nc != null ? nc.custom : null; } /** * Invalidate the activity's options menu. This will cause relevant presentations * of the menu to fully update via calls to onCreateOptionsMenu and * onPrepareOptionsMenu the next time the menu is requested. */ public void supportInvalidateOptionsMenu() { if (android.os.Build.VERSION.SDK_INT >= HONEYCOMB) { // If we are running on HC or greater, we can use the framework // API to invalidate the options menu. ActivityCompatHoneycomb.invalidateOptionsMenu(this); return; } // Whoops, older platform... we'll use a hack, to manually rebuild // the options menu the next time it is prepared. mOptionsMenuInvalidated = true; } /** * Print the Activity's state into the given stream. This gets invoked if * you run "adb shell dumpsys activity <activity_component_name>". * * @param prefix Desired prefix to prepend at each line of output. * @param fd The raw file descriptor that the dump is being sent to. * @param writer The PrintWriter to which you should dump your state. This will be * closed for you after you return. * @param args additional arguments to the dump request. */ public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) { if (android.os.Build.VERSION.SDK_INT >= HONEYCOMB) { // XXX This can only work if we can call the super-class impl. :/ //ActivityCompatHoneycomb.dump(this, prefix, fd, writer, args); } writer.print(prefix); writer.print("Local FragmentActivity "); writer.print(Integer.toHexString(System.identityHashCode(this))); writer.println(" State:"); String innerPrefix = prefix + " "; writer.print(innerPrefix); writer.print("mCreated="); writer.print(mCreated); writer.print("mResumed="); writer.print(mResumed); writer.print(" mStopped="); writer.print(mStopped); writer.print(" mReallyStopped="); writer.println(mReallyStopped); writer.print(innerPrefix); writer.print("mLoadersStarted="); writer.println(mLoadersStarted); if (mLoaderManager != null) { writer.print(prefix); writer.print("Loader Manager "); writer.print(Integer.toHexString(System.identityHashCode(mLoaderManager))); writer.println(":"); mLoaderManager.dump(prefix + " ", fd, writer, args); } mFragments.dump(prefix, fd, writer, args); } void doReallyStop(boolean retaining) { if (!mReallyStopped) { mReallyStopped = true; mRetaining = retaining; mHandler.removeMessages(MSG_REALLY_STOPPED); onReallyStop(); } } /** * Pre-HC, we didn't have a way to determine whether an activity was * being stopped for a config change or not until we saw * onRetainNonConfigurationInstance() called after onStop(). However * we need to know this, to know whether to retain fragments. This will * tell us what we need to know. */ void onReallyStop() { if (mLoadersStarted) { mLoadersStarted = false; if (mLoaderManager != null) { if (!mRetaining) { mLoaderManager.doStop(); } else { mLoaderManager.doRetain(); } } } mFragments.dispatchReallyStop(); } // ------------------------------------------------------------------------ // FRAGMENT SUPPORT // ------------------------------------------------------------------------ /** * Called when a fragment is attached to the activity. */ public void onAttachFragment(Fragment fragment) { } /** * Return the FragmentManager for interacting with fragments associated * with this activity. */ public FragmentManager getSupportFragmentManager() { return mFragments; } /** * Modifies the standard behavior to allow results to be delivered to fragments. * This imposes a restriction that requestCode be <= 0xffff. */ @Override public void startActivityForResult(Intent intent, int requestCode) { if (requestCode != -1 && (requestCode & 0xffff0000) != 0) { throw new IllegalArgumentException("Can only use lower 16 bits for requestCode"); } super.startActivityForResult(intent, requestCode); } /** * Called by Fragment.startActivityForResult() to implement its behavior. */ public void startActivityFromFragment(Fragment fragment, Intent intent, int requestCode) { if (requestCode == -1) { super.startActivityForResult(intent, -1); return; } if ((requestCode & 0xffff0000) != 0) { throw new IllegalArgumentException("Can only use lower 16 bits for requestCode"); } super.startActivityForResult(intent, ((fragment.mIndex + 1) << 16) + (requestCode & 0xffff)); } void invalidateSupportFragmentIndex(int index) { //Log.v(TAG, "invalidateFragmentIndex: index=" + index); if (mAllLoaderManagers != null) { LoaderManagerImpl lm = mAllLoaderManagers.get(index); if (lm != null && !lm.mRetaining) { lm.doDestroy(); mAllLoaderManagers.remove(index); } } } // ------------------------------------------------------------------------ // LOADER SUPPORT // ------------------------------------------------------------------------ /** * Return the LoaderManager for this fragment, creating it if needed. */ public LoaderManager getSupportLoaderManager() { if (mLoaderManager != null) { return mLoaderManager; } mCheckedForLoaderManager = true; mLoaderManager = getLoaderManager(-1, mLoadersStarted, true); return mLoaderManager; } LoaderManagerImpl getLoaderManager(int index, boolean started, boolean create) { if (mAllLoaderManagers == null) { mAllLoaderManagers = new HCSparseArray<LoaderManagerImpl>(); } LoaderManagerImpl lm = mAllLoaderManagers.get(index); if (lm == null) { if (create) { lm = new LoaderManagerImpl(this, started); mAllLoaderManagers.put(index, lm); } } else { lm.updateActivity(this); } return lm; } @Override protected boolean isRouteDisplayed() { return false; } }