android 实用工具类-手机存储

import android.content.Context;
import android.content.pm.PackageManager;
import android.os.Environment;

import java.io.File;
import java.io.IOException;

import static android.os.Environment.MEDIA_MOUNTED;

/**
* Provides application storage paths
*
* @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
* @since 1.0.0
*/
public final class StorageUtils {

private static final String EXTERNAL_STORAGE_PERMISSION = "android.permission.WRITE_EXTERNAL_STORAGE";
private static final String INDIVIDUAL_DIR_NAME = "uil-images";

private StorageUtils() {
}

/**
* Returns application cache directory. Cache directory will be created on SD card
* <i>("/Android/data/[app_package_name]/cache")</i> if card is mounted and app has appropriate permission. Else -
* Android defines cache directory on device's file system.
*
* @param context Application context
* @return Cache {@link File directory}.<br />
* <b>NOTE:</b> Can be null in some unpredictable cases (if SD card is unmounted and
* {@link android.content.Context#getCacheDir() Context.getCacheDir()} returns null).
*/
public static File getCacheDirectory(Context context) {
return getCacheDirectory(context, true);
}

/**
* Returns application cache directory. Cache directory will be created on SD card
* <i>("/Android/data/[app_package_name]/cache")</i> (if card is mounted and app has appropriate permission) or
* on device's file system depending incoming parameters.
*
* @param context        Application context
* @param preferExternal Whether prefer external location for cache
* @return Cache {@link File directory}.<br />
* <b>NOTE:</b> Can be null in some unpredictable cases (if SD card is unmounted and
* {@link android.content.Context#getCacheDir() Context.getCacheDir()} returns null).
*/
public static File getCacheDirectory(Context context, boolean preferExternal) {
File appCacheDir = null;
String externalStorageState;
try {
externalStorageState = Environment.getExternalStorageState();
} catch (NullPointerException e) { // (sh)it happens (Issue #660)
externalStorageState = "";
}
if (preferExternal && MEDIA_MOUNTED.equals(externalStorageState) && hasExternalStoragePermission(context)) {
appCacheDir = getExternalCacheDir(context);
}
if (appCacheDir == null) {
appCacheDir = context.getCacheDir();
}
if (appCacheDir == null) {
String cacheDirPath = "/data/data/" + context.getPackageName() + "/cache/";
L.w("Can't define system cache directory! '%s' will be used.", cacheDirPath);
appCacheDir = new File(cacheDirPath);
}
return appCacheDir;
}

/**
* Returns individual application cache directory (for only image caching from ImageLoader). Cache directory will be
* created on SD card <i>("/Android/data/[app_package_name]/cache/uil-images")</i> if card is mounted and app has
* appropriate permission. Else - Android defines cache directory on device's file system.
*
* @param context Application context
* @return Cache {@link File directory}
*/
public static File getIndividualCacheDirectory(Context context) {
File cacheDir = getCacheDirectory(context);
File individualCacheDir = new File(cacheDir, INDIVIDUAL_DIR_NAME);
if (!individualCacheDir.exists()) {
if (!individualCacheDir.mkdir()) {
individualCacheDir = cacheDir;
}
}
return individualCacheDir;
}

/**
* Returns specified application cache directory. Cache directory will be created on SD card by defined path if card
* is mounted and app has appropriate permission. Else - Android defines cache directory on device's file system.
*
* @param context  Application context
* @param cacheDir Cache directory path (e.g.: "AppCacheDir", "AppDir/cache/images")
* @return Cache {@link File directory}
*/
public static File getOwnCacheDirectory(Context context, String cacheDir) {
File appCacheDir = null;
if (MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) && hasExternalStoragePermission(context)) {
appCacheDir = new File(Environment.getExternalStorageDirectory(), cacheDir);
}
if (appCacheDir == null || (!appCacheDir.exists() && !appCacheDir.mkdirs())) {
appCacheDir = context.getCacheDir();
}
return appCacheDir;
}

private static File getExternalCacheDir(Context context) {
File dataDir = new File(new File(Environment.getExternalStorageDirectory(), "Android"), "data");
File appCacheDir = new File(new File(dataDir, context.getPackageName()), "cache");
if (!appCacheDir.exists()) {
if (!appCacheDir.mkdirs()) {
L.w("Unable to create external cache directory");
return null;
}
try {
new File(appCacheDir, ".nomedia").createNewFile();
} catch (IOException e) {
L.i("Can't create \".nomedia\" file in application external cache directory");
}
}
return appCacheDir;
}

private static boolean hasExternalStoragePermission(Context context) {
int perm = context.checkCallingOrSelfPermission(EXTERNAL_STORAGE_PERMISSION);
return perm == PackageManager.PERMISSION_GRANTED;
}
}