Android部分源码—app

/* * Copyright (C) 2006 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.app; import android.util.ArrayMap; import android.util.SuperNotCalledException; import com.android.internal.app.ActionBarImpl; import com.android.internal.policy.PolicyManager; import android.content.ComponentCallbacks2; import android.content.ComponentName; import android.content.ContentResolver; import android.content.Context; import android.content.CursorLoader; import android.content.IIntentSender; import android.content.Intent; import android.content.IntentSender; import android.content.SharedPreferences; import android.content.pm.ActivityInfo; import android.content.pm.PackageManager; import android.content.pm.PackageManager.NameNotFoundException; import android.content.res.Configuration; import android.content.res.Resources; import android.content.res.TypedArray; import android.database.Cursor; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.drawable.Drawable; import android.media.AudioManager; import android.net.Uri; import android.os.Build; import android.os.Bundle; import android.os.Handler; import android.os.IBinder; import android.os.Looper; import android.os.Parcelable; import android.os.RemoteException; import android.os.StrictMode; import android.os.UserHandle; import android.text.Selection; import android.text.SpannableStringBuilder; import android.text.TextUtils; import android.text.method.TextKeyListener; import android.util.AttributeSet; import android.util.EventLog; import android.util.Log; import android.util.Slog; import android.util.SparseArray; import android.view.ActionMode; import android.view.ContextMenu; import android.view.ContextMenu.ContextMenuInfo; import android.view.ContextThemeWrapper; import android.view.KeyEvent; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.MotionEvent; import android.view.View; import android.view.View.OnCreateContextMenuListener; import android.view.ViewGroup; import android.view.ViewGroup.LayoutParams; import android.view.ViewManager; import android.view.Window; import android.view.WindowManager; import android.view.WindowManagerGlobal; import android.view.accessibility.AccessibilityEvent; import android.widget.AdapterView; import java.io.FileDescriptor; import java.io.PrintWriter; import java.util.ArrayList; import java.util.HashMap; /** * An activity is a single, focused thing that the user can do. Almost all * activities interact with the user, so the Activity class takes care of * creating a window for you in which you can place your UI with * {@link #setContentView}. While activities are often presented to the user * as full-screen windows, they can also be used in other ways: as floating * windows (via a theme with {@link android.R.attr#windowIsFloating} set) * or embedded inside of another activity (using {@link ActivityGroup}). * * There are two methods almost all subclasses of Activity will implement: * * <ul> * <li> {@link #onCreate} is where you initialize your activity. Most * importantly, here you will usually call {@link #setContentView(int)} * with a layout resource defining your UI, and using {@link #findViewById} * to retrieve the widgets in that UI that you need to interact with * programmatically. * * <li> {@link #onPause} is where you deal with the user leaving your * activity. Most importantly, any changes made by the user should at this * point be committed (usually to the * {@link android.content.ContentProvider} holding the data). * </ul> * * <p>To be of use with {@link android.content.Context#startActivity Context.startActivity()}, all * activity classes must have a corresponding * {@link android.R.styleable#AndroidManifestActivity &lt;activity&gt;} * declaration in their package's <code>AndroidManifest.xml</code>.</p> * * <p>Topics covered here: * <ol> * <li><a href="#Fragments">Fragments</a> * <li><a href="#ActivityLifecycle">Activity Lifecycle</a> * <li><a href="#ConfigurationChanges">Configuration Changes</a> * <li><a href="#StartingActivities">Starting Activities and Getting Results</a> * <li><a href="#SavingPersistentState">Saving Persistent State</a> * <li><a href="#Permissions">Permissions</a> * <li><a href="#ProcessLifecycle">Process Lifecycle</a> * </ol> * * <div class="special reference"> * <h3>Developer Guides</h3> * <p>The Activity class is an important part of an application's overall lifecycle, * and the way activities are launched and put together is a fundamental * part of the platform's application model. For a detailed perspective on the structure of an * Android application and how activities behave, please read the * <a href="{@docRoot}guide/topics/fundamentals.html">Application Fundamentals</a> and * <a href="{@docRoot}guide/topics/fundamentals/tasks-and-back-stack.html">Tasks and Back Stack</a> * developer guides.</p> * * <p>You can also find a detailed discussion about how to create activities in the * <a href="{@docRoot}guide/topics/fundamentals/activities.html">Activities</a> * developer guide.</p> * </div> * * <a name="Fragments"></a> * <h3>Fragments</h3> * * <p>Starting with {@link android.os.Build.VERSION_CODES#HONEYCOMB}, Activity * implementations can make use of the {@link Fragment} class to better * modularize their code, build more sophisticated user interfaces for larger * screens, and help scale their application between small and large screens. * * <a name="ActivityLifecycle"></a> * <h3>Activity Lifecycle</h3> * * <p>Activities in the system are managed as an <em>activity stack</em>. * When a new activity is started, it is placed on the top of the stack * and becomes the running activity -- the previous activity always remains * below it in the stack, and will not come to the foreground again until * the new activity exits.</p> * * <p>An activity has essentially four states:</p> * <ul> * <li> If an activity in the foreground of the screen (at the top of * the stack), * it is <em>active</em> or <em>running</em>. </li> * <li>If an activity has lost focus but is still visible (that is, a new non-full-sized * or transparent activity has focus on top of your activity), it * is <em>paused</em>. A paused activity is completely alive (it * maintains all state and member information and remains attached to * the window manager), but can be killed by the system in extreme * low memory situations. * <li>If an activity is completely obscured by another activity, * it is <em>stopped</em>. It still retains all state and member information, * however, it is no longer visible to the user so its window is hidden * and it will often be killed by the system when memory is needed * elsewhere.</li> * <li>If an activity is paused or stopped, the system can drop the activity * from memory by either asking it to finish, or simply killing its * process. When it is displayed again to the user, it must be * completely restarted and restored to its previous state.</li> * </ul> * * <p>The following diagram shows the important state paths of an Activity. * The square rectangles represent callback methods you can implement to * pe