/*
* Copyright (C) 2012 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.content;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.os.StatFs;
import android.support.v4.os.EnvironmentCompat;
import android.util.Log;
import java.io.File;
/**
* Helper for accessing features in {@link android.content.Context}
* introduced after API level 4 in a backwards compatible fashion.
*/
public class ContextCompat {
private static final String TAG = "ContextCompat";
private static final String DIR_ANDROID = "Android";
private static final String DIR_DATA = "data";
private static final String DIR_OBB = "obb";
private static final String DIR_FILES = "files";
private static final String DIR_CACHE = "cache";
/**
* Start a set of activities as a synthesized task stack, if able.
*
* <p>In API level 11 (Android 3.0/Honeycomb) the recommended conventions for
* app navigation using the back key changed. The back key's behavior is local
* to the current task and does not capture navigation across different tasks.
* Navigating across tasks and easily reaching the previous task is accomplished
* through the "recents" UI, accessible through the software-provided Recents key
* on the navigation or system bar. On devices with the older hardware button configuration
* the recents UI can be accessed with a long press on the Home key.</p>
*
* <p>When crossing from one task stack to another post-Android 3.0,
* the application should synthesize a back stack/history for the new task so that
* the user may navigate out of the new task and back to the Launcher by repeated
* presses of the back key. Back key presses should not navigate across task stacks.</p>
*
* <p>startActivities provides a mechanism for constructing a synthetic task stack of
* multiple activities. If the underlying API is not available on the system this method
* will return false.</p>
*
* @param context Start activities using this activity as the starting context
* @param intents Array of intents defining the activities that will be started. The element
* length-1 will correspond to the top activity on the resulting task stack.
* @return true if the underlying API was available and the call was successful, false otherwise
*/
public static boolean startActivities(Context context, Intent[] intents) {
return startActivities(context, intents, null);
}
/**
* Start a set of activities as a synthesized task stack, if able.
*
* <p>In API level 11 (Android 3.0/Honeycomb) the recommended conventions for
* app navigation using the back key changed. The back key's behavior is local
* to the current task and does not capture navigation across different tasks.
* Navigating across tasks and easily reaching the previous task is accomplished
* through the "recents" UI, accessible through the software-provided Recents key
* on the navigation or system bar. On devices with the older hardware button configuration
* the recents UI can be accessed with a long press on the Home key.</p>
*
* <p>When crossing from one task stack to another post-Android 3.0,
* the application should synthesize a back stack/history for the new task so that
* the user may navigate out of the new task and back to the Launcher by repeated
* presses of the back key. Back key presses should not navigate across task stacks.</p>
*
* <p>startActivities provides a mechanism for constructing a synthetic task stack of
* multiple activities. If the underlying API is not available on the system this method
* will return false.</p>
*
* @param context Start activities using this activity as the starting context
* @param intents Array of intents defining the activities that will be started. The element
* length-1 will correspond to the top activity on the resulting task stack.
* @param options Additional options for how the Activity should be started.
* See {@link android.content.Context#startActivity(Intent, Bundle)
* @return true if the underlying API was available and the call was successful, false otherwise
*/
public static boolean startActivities(Context context, Intent[] intents,
Bundle options) {
final int version = Build.VERSION.SDK_INT;
if (version >= 16) {
ContextCompatJellybean.startActivities(context, intents, options);
return true;
} else if (version >= 11) {
ContextCompatHoneycomb.startActivities(context, intents);
return true;
}
return false;
}
/**
* Returns absolute paths to application-specific directories on all
* external storage devices where the application's OBB files (if there are
* any) can be found. Note if the application does not have any OBB files,
* these directories may not exist.
* <p>
* This is like {@link Context#getFilesDir()} in that these files will be
* deleted when the application is uninstalled, however there are some
* important differences:
* <ul>
* <li>External files are not always available: they will disappear if the
* user mounts the external storage on a computer or removes it.
* <li>There is no security enforced with these files.
* </ul>
* <p>
* External storage devices returned here are considered a permanent part of
* the device, including both emulated external storage and physical media
* slots, such as SD cards in a battery compartment. The returned paths do
* not include transient devices, such as USB flash drives.
* <p>
* An application may store data on any or all of the returned devices. For
* example, an app may choose to store large files on the device with the
* most available space, as measured by {@link StatFs}.
* <p>
* Starting in {@link android.os.Build.VERSION_CODES#KITKAT}, no permissions
* are required to write to the returned paths; they're always accessible to
* the calling app. Before then,
* {@link android.Manifest.permission#WRITE_EXTERNAL_STORAGE} is required to
* write. Write access outside of these paths on secondary external storage
* devices is not available. To request external storage access in a
* backwards compatible way, consider using {@code android:maxSdkVersion}
* like this:
*
* <pre class="prettyprint"><uses-permission
* android:name="android.permission.WRITE_EXTERNAL_STORAGE"
* android:maxSdkVersion="18" /></pre>
* <p>
* The first path returned is the same as {@link Context#getObbDir()}.
* Returned paths may be {@code null} if a storage device is unavailable.
*
* @see Context#getObbDir()
* @see EnvironmentCompat#getStorageState(File)
*/
public static File[] getObbDirs(Context context) {
final int version = Build.VERSION.SDK_INT;
if (version >= 19) {
return ContextCompatKitKat.getObbDirs(context);
} else {
final File single;
if (version >= 11) {
single = ContextCompatHoneycomb.getObbDir(context);
} else {
single = buildPath(Environment.getExternalStorageDirectory(), DIR_ANDROID, DIR_OBB,
context.getPackageName());
}
return new File[] { single };
}
}
/**
* Returns absolute paths to application-specific directories on all
* external storage devices where the application can place persistent files
* it owns. These files are internal to the application, and not typically
* visible to the user as media.
* <p>
* This is like {@link Context#getFilesDir()} in that these files will be
* deleted when the application is uninstalled, however there are some
* important differences:
* <ul>
* <li>External files are not always available: they will disappear if the
* user mounts the external storage on a computer or removes it.
* <li>There is no security enforced with these files.
* </ul>
* <p>
* External storage devices returned here are considered a permanent part of
* the device, including both emulated external storage and physical media
* slots, such as SD cards in a battery compartment. The returned paths do
* not include transient devices, such as USB flash drives.
* <p>
* An application may store data on any or all of the returned devices. For
* example, an app may choose to store large files on the device with the
* most available space, as measured by {@link StatFs}.
* <p>
* Starting in {@link android.os.Build.VERSION_CODES#KITKAT}, no permissions
* are required to write to the returned paths; they're always accessible to
* the calling app. Before then,
* {@link android.Manifest.permission#WRITE_EXTERNAL_STORAGE} is required to
* write. Write access outside of these paths on secondary external storage
* devices is not available. To request external storage access in a
* backwards compatible way, consider using {@code android:maxSdkVersion}
* like this:
*
* <pre class="prettyprint"><uses-permission
* android:name="android.permission.WRITE_EXTERNAL_STORAGE"
* android:maxSdkVersion="18" /></pre>
* <p>
* The first path returned is the same as
* {@link Context#getExternalFilesDir(String)}. Returned paths may be
* {@code null} if a storage device is unavailable.
*
* @see Context#getExternalFilesDir(String)
* @see EnvironmentCompat#getStorageState(File)
*/
public static File[] getExternalFilesDirs(Context context, String type) {
final int version = Build.VERSION.SDK_INT;
if (version >= 19) {
return ContextCompatKitKat.getExternalFilesDirs(context, type);
} else {
final File single;
if (version >= 8) {
single = ContextCompatFroyo.getExternalFilesDir(context, type);
} else {
single = buildPath(Environment.getExternalStorageDirectory(), DIR_ANDROID, DIR_DATA,
context.getPackageName(), DIR_FILES, type);
}
return new File[] { single };
}
}
/**
* Returns absolute paths to application-specific directories on all
* external storage devices where the application can place cache files it
* owns. These files are internal to the application, and not typically
* visible to the user as media.
* <p>
* This is like {@link Context#getCacheDir()} in that these files will be
* deleted when the application is uninstalled, however there are some
* important differences:
* <ul>
* <li>External files are not always available: they will disappear if the
* user mounts the external storage on a computer or removes it.
* <li>There is no security enforced with these files.
* </ul>
* <p>
* External storage devices returned here are considered a permanent part of
* the device, including both emulated external storage and physical media
* slots, such as SD cards in a battery compartment. The returned paths do
* not include transient devices, such as USB flash drives.
* <p>
* An application may store data on any or all of the returned devices. For
* example, an app may choose to store large files on the device with the
* most available space, as measured by {@link StatFs}.
* <p>
* Starting in {@link android.os.Build.VERSION_CODES#KITKAT}, no permissions
* are required to write to the returned paths; they're always accessible to
* the calling app. Before then,
* {@link android.Manifest.permission#WRITE_EXTERNAL_STORAGE} is required to
* write. Write access outside of these paths on secondary external storage
* devices is not available. To request external storage access in a
* backwards compatible way, consider using {@code android:maxSdkVersion}
* like this:
*
* <pre class="prettyprint"><uses-permission
* android:name="android.permission.WRITE_EXTERNAL_STORAGE"
* android:maxSdkVersion="18" /></pre>
* <p>
* The first path returned is the same as
* {@link Context#getExternalCacheDir()}. Returned paths may be {@code null}
* if a storage device is unavailable.
*
* @see Context#getExternalCacheDir()
* @see EnvironmentCompat#getStorageState(File)
*/
public static File[] getExternalCacheDirs(Context context) {
final int version = Build.VERSION.SDK_INT;
if (version >= 19) {
return ContextCompatKitKat.getExternalCacheDirs(context);
} else {
final File single;
if (version >= 8) {
single = ContextCompatFroyo.getExternalCacheDir(context);
} else {
single = buildPath(Environment.getExternalStorageDirectory(), DIR_ANDROID, DIR_DATA,
context.getPackageName(), DIR_CACHE);
}
return new File[] { single };
}
}
private static File buildPath(File base, String... segments) {
File cur = base;
for (String segment : segments) {
if (cur == null) {
cur = new File(segment);
} else if (segment != null) {
cur = new File(cur, segment);
}
}
return cur;
}
/**
* Return a drawable object associated with a particular resource ID.
* <p>
* Starting in {@link android.os.Build.VERSION_CODES#LOLLIPOP}, the returned
* drawable will be styled for the specified Context's theme.
*
* @param id The desired resource identifier, as generated by the aapt tool.
* This integer encodes the package, type, and resource entry.
* The value 0 is an invalid identifier.
* @return Drawable An object that can be used to draw this resource.
*/
public static final Drawable getDrawable(Context context, int id) {
final int version = Build.VERSION.SDK_INT;
if (version >= 21) {
return ContextCompatApi21.getDrawable(context, id);
} else {
return context.getResources().getDrawable(id);
}
}
/**
* Returns the absolute path to the directory on the filesystem similar to
* {@link Context#getFilesDir()}. The difference is that files placed under this
* directory will be excluded from automatic backup to remote storage on
* devices running {@link android.os.Build.VERSION_CODES#LOLLIPOP} or later. See
* {@link android.app.backup.BackupAgent BackupAgent} for a full discussion
* of the automatic backup mechanism in Android.
*
* <p>No permissions are required to read or write to the returned path, since this
* path is internal storage.
*
* @return The path of the directory holding application files that will not be
* automatically backed up to remote storage.
*
* @see android.content.Context.getFilesDir
*/
public final File getNoBackupFilesDir(Context context) {
final int version = Build.VERSION.SDK_INT;
if (version >= 21) {
return ContextCompatApi21.getNoBackupFilesDir(context);
} else {
ApplicationInfo appInfo = context.getApplicationInfo();
return createFilesDir(new File(appInfo.dataDir, "no_backup"));
}
}
/**
* Returns the absolute path to the application specific cache directory on
* the filesystem designed for storing cached code. On devices running
* {@link android.os.Build.VERSION_CODES#LOLLIPOP} or later, the system will delete
* any files stored in this location both when your specific application is
* upgraded, and when the entire platform is upgraded.
* <p>
* This location is optimal for storing compiled or optimized code generated
* by your application at runtime.
* <p>
* Apps require no extra permissions to read or write to the returned path,
* since this path lives in their private storage.
*
* @return The path of the directory holding application code cache files.
*/
public final File getCodeCacheDir(Context context) {
final int version = Build.VERSION.SDK_INT;
if (version >= 21) {
return ContextCompatApi21.getCodeCacheDir(context);
} else {
ApplicationInfo appInfo = context.getApplicationInfo();
return createFilesDir(new File(appInfo.dataDir, "code_cache"));
}
}
private synchronized static File createFilesDir(File file) {
if (!file.exists()) {
if (!file.mkdirs()) {
if (file.exists()) {
// spurious failure; probably racing with another process for this app
return file;
}
Log.w(TAG, "Unable to create files subdir " + file.getPath());
return null;
}
}
return file;
}
}
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