用于存储文件的Android Open External Storage目录（sdcard）

Question

我想打开外部存储目录路径以编程方式保存文件。我试过但没有获得SD卡路径。 我怎么能这样做？有没有解决方案？

private File path = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES) + "");

或

private File path = new File(Environment.getExternalStorageDirectory() + "");

我尝试从两个方法的上方获取路径，但两者都指向内部存储器。

当我们打开存储内存时，如果sdcard显示，它将显示如下 -

设备存储＆amp; sd存储卡。

我希望通过编码获得sd内存路径。 我已经在清单中给予了权限 -

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Answer 1

我遇到了同样的问题！

要获取内部SD卡，您可以使用

String extStore = System.getenv("EXTERNAL_STORAGE");
File f_exts = new File(extStore);

要获取外部SD卡，您可以使用

String secStore = System.getenv("SECONDARY_STORAGE");
File f_secs = new File(secStore);

运行代码

 extStore = "/storage/emulated/legacy"
 secStore = "/storage/extSdCarcd"

完美无缺！

Answer 2

内部存储在API中称为“外部存储”。

如Environment文档中所述

  

注意：不要在这里混淆“外部”这个词。此目录最好被视为媒体/共享存储。它是一个文件系统，可以容纳相对大量的数据，并在所有应用程序之间共享（不强制执行权限）。传统上这是一张SD卡，但它也可以作为内置存储器实现，该设备不同于受保护的内部存储器，可以作为文件系统安装在计算机上。

要区分“Environment.getExternalStorageDirectory（）”是否实际返回了物理内部或外部存储，请调用Environment.isExternalStorageEmulated（）。如果它是模仿的，那么它就是内部的。在具有内部存储和SD卡插槽的较新设备上，Environment.getExternalStorageDirectory（）将始终返回内部存储。在仅使用SD卡作为媒体存储选项的旧设备上，它将始终返回SD卡。

无法使用当前的Android API检索所有存储空间。

我在下面的答案中根据Vitaliy Polchuk的方法创建了一个助手

How can I get the list of mounted external storage of android device

注意：启动KitKat二级存储只能作为READ-ONLY 访问，您可能需要使用以下方法检查可写性

/**
 * Checks whether the StorageVolume is read-only
 * 
 * @param volume
 *            StorageVolume to check
 * @return true, if volume is mounted read-only
 */
public static boolean isReadOnly(@NonNull final StorageVolume volume) {
    if (volume.mFile.equals(Environment.getExternalStorageDirectory())) {
        // is a primary storage, check mounted state by Environment
        return android.os.Environment.getExternalStorageState().equals(
                android.os.Environment.MEDIA_MOUNTED_READ_ONLY);
    } else {
        if (volume.getType() == Type.USB) {
            return volume.isReadOnly();
        }
        //is not a USB storagem so it's read-only if it's mounted read-only or if it's a KitKat device
        return volume.isReadOnly() || Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
    }
}

StorageHelper类

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.StringTokenizer;

import android.os.Environment;

public final class StorageHelper {

    //private static final String TAG = "StorageHelper";

    private StorageHelper() {
    }

    private static final String STORAGES_ROOT;

    static {
        final String primaryStoragePath = Environment.getExternalStorageDirectory()
                .getAbsolutePath();
        final int index = primaryStoragePath.indexOf(File.separatorChar, 1);
        if (index != -1) {
            STORAGES_ROOT = primaryStoragePath.substring(0, index + 1);
        } else {
            STORAGES_ROOT = File.separator;
        }
    }

    private static final String[] AVOIDED_DEVICES = new String[] {
        "rootfs", "tmpfs", "dvpts", "proc", "sysfs", "none"
    };

    private static final String[] AVOIDED_DIRECTORIES = new String[] {
        "obb", "asec"
    };

    private static final String[] DISALLOWED_FILESYSTEMS = new String[] {
        "tmpfs", "rootfs", "romfs", "devpts", "sysfs", "proc", "cgroup", "debugfs"
    };

    /**
     * Returns a list of mounted {@link StorageVolume}s Returned list always
     * includes a {@link StorageVolume} for
     * {@link Environment#getExternalStorageDirectory()}
     * 
     * @param includeUsb
     *            if true, will include USB storages
     * @return list of mounted {@link StorageVolume}s
     */
    public static List<StorageVolume> getStorages(final boolean includeUsb) {
        final Map<String, List<StorageVolume>> deviceVolumeMap = new HashMap<String, List<StorageVolume>>();

        // this approach considers that all storages are mounted in the same non-root directory
        if (!STORAGES_ROOT.equals(File.separator)) {
            BufferedReader reader = null;
            try {
                reader = new BufferedReader(new FileReader("/proc/mounts"));
                String line;
                while ((line = reader.readLine()) != null) {
                    // Log.d(TAG, line);
                    final StringTokenizer tokens = new StringTokenizer(line, " ");

                    final String device = tokens.nextToken();
                    // skipped devices that are not sdcard for sure
                    if (arrayContains(AVOIDED_DEVICES, device)) {
                        continue;
                    }

                    // should be mounted in the same directory to which
                    // the primary external storage was mounted
                    final String path = tokens.nextToken();
                    if (!path.startsWith(STORAGES_ROOT)) {
                        continue;
                    }

                    // skip directories that indicate tha volume is not a storage volume
                    if (pathContainsDir(path, AVOIDED_DIRECTORIES)) {
                        continue;
                    }

                    final String fileSystem = tokens.nextToken();
                    // don't add ones with non-supported filesystems
                    if (arrayContains(DISALLOWED_FILESYSTEMS, fileSystem)) {
                        continue;
                    }

                    final File file = new File(path);
                    // skip volumes that are not accessible
                    if (!file.canRead() || !file.canExecute()) {
                        continue;
                    }

                    List<StorageVolume> volumes = deviceVolumeMap.get(device);
                    if (volumes == null) {
                        volumes = new ArrayList<StorageVolume>(3);
                        deviceVolumeMap.put(device, volumes);
                    }

                    final StorageVolume volume = new StorageVolume(device, file, fileSystem);
                    final StringTokenizer flags = new StringTokenizer(tokens.nextToken(), ",");
                    while (flags.hasMoreTokens()) {
                        final String token = flags.nextToken();
                        if (token.equals("rw")) {
                            volume.mReadOnly = false;
                            break;
                        } else if (token.equals("ro")) {
                            volume.mReadOnly = true;
                            break;
                        }
                    }
                    volumes.add(volume);
                }

            } catch (IOException ex) {
                ex.printStackTrace();
            } finally {
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (IOException ex) {
                        // ignored
                    }
                }
            }
        }

        // remove volumes that are the same devices
        boolean primaryStorageIncluded = false;
        final File externalStorage = Environment.getExternalStorageDirectory();
        final List<StorageVolume> volumeList = new ArrayList<StorageVolume>();
        for (final Entry<String, List<StorageVolume>> entry : deviceVolumeMap.entrySet()) {
            final List<StorageVolume> volumes = entry.getValue();
            if (volumes.size() == 1) {
                // go ahead and add
                final StorageVolume v = volumes.get(0);
                final boolean isPrimaryStorage = v.file.equals(externalStorage);
                primaryStorageIncluded |= isPrimaryStorage;
                setTypeAndAdd(volumeList, v, includeUsb, isPrimaryStorage);
                continue;
            }
            final int volumesLength = volumes.size();
            for (int i = 0; i < volumesLength; i++) {
                final StorageVolume v = volumes.get(i);
                if (v.file.equals(externalStorage)) {
                    primaryStorageIncluded = true;
                    // add as external storage and continue
                    setTypeAndAdd(volumeList, v, includeUsb, true);
                    break;
                }
                // if that was the last one and it's not the default external
                // storage then add it as is
                if (i == volumesLength - 1) {
                    setTypeAndAdd(volumeList, v, includeUsb, false);
                }
            }
        }
        // add primary storage if it was not found
        if (!primaryStorageIncluded) {
            final StorageVolume defaultExternalStorage = new StorageVolume("", externalStorage, "UNKNOWN");
            defaultExternalStorage.mEmulated = Environment.isExternalStorageEmulated();
            defaultExternalStorage.mType =
                    defaultExternalStorage.mEmulated ? StorageVolume.Type.INTERNAL
                            : StorageVolume.Type.EXTERNAL;
            defaultExternalStorage.mRemovable = Environment.isExternalStorageRemovable();
            defaultExternalStorage.mReadOnly =
                    Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED_READ_ONLY);
            volumeList.add(0, defaultExternalStorage);
        }
        return volumeList;
    }

    /**
     * Sets {@link StorageVolume.Type}, removable and emulated flags and adds to
     * volumeList
     * 
     * @param volumeList
     *            List to add volume to
     * @param v
     *            volume to add to list
     * @param includeUsb
     *            if false, volume with type {@link StorageVolume.Type#USB} will
     *            not be added
     * @param asFirstItem
     *            if true, adds the volume at the beginning of the volumeList
     */
    private static void setTypeAndAdd(final List<StorageVolume> volumeList,
            final StorageVolume v,
            final boolean includeUsb,
            final boolean asFirstItem) {
        final StorageVolume.Type type = resolveType(v);
        if (includeUsb || type != StorageVolume.Type.USB) {
            v.mType = type;
            if (v.file.equals(Environment.getExternalStorageDirectory())) {
                v.mRemovable = Environment.isExternalStorageRemovable();
            } else {
                v.mRemovable = type != StorageVolume.Type.INTERNAL;
            }
            v.mEmulated = type == StorageVolume.Type.INTERNAL;
            if (asFirstItem) {
                volumeList.add(0, v);
            } else {
                volumeList.add(v);
            }
        }
    }

    /**
     * Resolved {@link StorageVolume} type
     * 
     * @param v
     *            {@link StorageVolume} to resolve type for
     * @return {@link StorageVolume} type
     */
    private static StorageVolume.Type resolveType(final StorageVolume v) {
        if (v.file.equals(Environment.getExternalStorageDirectory())
                && Environment.isExternalStorageEmulated()) {
            return StorageVolume.Type.INTERNAL;
        } else if (containsIgnoreCase(v.file.getAbsolutePath(), "usb")) {
            return StorageVolume.Type.USB;
        } else {
            return StorageVolume.Type.EXTERNAL;
        }
    }

    /**
     * Checks whether the array contains object
     * 
     * @param array
     *            Array to check
     * @param object
     *            Object to find
     * @return true, if the given array contains the object
     */
    private static <T> boolean arrayContains(T[] array, T object) {
        for (final T item : array) {
            if (item.equals(object)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks whether the path contains one of the directories
     * 
     * For example, if path is /one/two, it returns true input is "one" or
     * "two". Will return false if the input is one of "one/two", "/one" or
     * "/two"
     * 
     * @param path
     *            path to check for a directory
     * @param dirs
     *            directories to find
     * @return true, if the path contains one of the directories
     */
    private static boolean pathContainsDir(final String path, final String[] dirs) {
        final StringTokenizer tokens = new StringTokenizer(path, File.separator);
        while (tokens.hasMoreElements()) {
            final String next = tokens.nextToken();
            for (final String dir : dirs) {
                if (next.equals(dir)) {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Checks ifString contains a search String irrespective of case, handling.
     * Case-insensitivity is defined as by
     * {@link String#equalsIgnoreCase(String)}.
     * 
     * @param str
     *            the String to check, may be null
     * @param searchStr
     *            the String to find, may be null
     * @return true if the String contains the search String irrespective of
     *         case or false if not or {@code null} string input
     */
    public static boolean containsIgnoreCase(final String str, final String searchStr) {
        if (str == null || searchStr == null) {
            return false;
        }
        final int len = searchStr.length();
        final int max = str.length() - len;
        for (int i = 0; i <= max; i++) {
            if (str.regionMatches(true, i, searchStr, 0, len)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Represents storage volume information
     */
    public static final class StorageVolume {

        /**
         * Represents {@link StorageVolume} type
         */
        public enum Type {
            /**
             * Device built-in internal storage. Probably points to
             * {@link Environment#getExternalStorageDirectory()}
             */
            INTERNAL,

            /**
             * External storage. Probably removable, if no other
             * {@link StorageVolume} of type {@link #INTERNAL} is returned by
             * {@link StorageHelper#getStorages(boolean)}, this might be
             * pointing to {@link Environment#getExternalStorageDirectory()}
             */
            EXTERNAL,

            /**
             * Removable usb storage
             */
            USB
        }

        /**
         * Device name
         */
        public final String device;

        /**
         * Points to mount point of this device
         */
        public final File file;

        /**
         * File system of this device
         */
        public final String fileSystem;

        /**
         * if true, the storage is mounted as read-only
         */
        private boolean mReadOnly;

        /**
         * If true, the storage is removable
         */
        private boolean mRemovable;

        /**
         * If true, the storage is emulated
         */
        private boolean mEmulated;

        /**
         * Type of this storage
         */
        private Type mType;

        StorageVolume(String device, File file, String fileSystem) {
            this.device = device;
            this.file = file;
            this.fileSystem = fileSystem;
        }

        /**
         * Returns type of this storage
         * 
         * @return Type of this storage
         */
        public Type getType() {
            return mType;
        }

        /**
         * Returns true if this storage is removable
         * 
         * @return true if this storage is removable
         */
        public boolean isRemovable() {
            return mRemovable;
        }

        /**
         * Returns true if this storage is emulated
         * 
         * @return true if this storage is emulated
         */
        public boolean isEmulated() {
            return mEmulated;
        }

        /**
         * Returns true if this storage is mounted as read-only
         * 
         * @return true if this storage is mounted as read-only
         */
        public boolean isReadOnly() {
            return mReadOnly;
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + ((file == null) ? 0 : file.hashCode());
            return result;
        }

        /**
         * Returns true if the other object is StorageHelper and it's
         * {@link #file} matches this one's
         * 
         * @see Object#equals(Object)
         */
        @Override
        public boolean equals(Object obj) {
            if (obj == this) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final StorageVolume other = (StorageVolume) obj;
            if (file == null) {
                return other.file == null;
            }
            return file.equals(other.file);
        }

        @Override
        public String toString() {
            return file.getAbsolutePath() + (mReadOnly ? " ro " : " rw ") + mType + (mRemovable ? " R " : "")
                    + (mEmulated ? " E " : "") + fileSystem;
        }
    }
}

Answer 3

希望它对你有用：

File yourFile = new File(Environment.getExternalStorageDirectory(), "textarabics.txt");

这将给你sdcard路径：

File path = Environment.getExternalStorageDirectory();

试试这个：

String pathName = "/mnt/";

或试试这个：

String pathName = "/storage/";

Answer 4

补充 rijul gupta 回答：

String strSDCardPath = System.getenv("SECONDARY_STORAGE");

    if ((strSDCardPath == null) || (strSDCardPath.length() == 0)) {
        strSDCardPath = System.getenv("EXTERNAL_SDCARD_STORAGE");
    }

    //If may get a full path that is not the right one, even if we don't have the SD Card there. 
    //We just need the "/mnt/extSdCard/" i.e and check if it's writable
    if(strSDCardPath != null) {
        if (strSDCardPath.contains(":")) {
            strSDCardPath = strSDCardPath.substring(0, strSDCardPath.indexOf(":"));
        }
        File externalFilePath = new File(strSDCardPath);

        if (externalFilePath.exists() && externalFilePath.canWrite()){
            //do what you need here
        }
    }

Answer 5

将@ rijul的答案向前推进，它在棉花糖及以上版本中无效：

       //for pre-marshmallow versions
       String path = System.getenv("SECONDARY_STORAGE");

       // For Marshmallow, use getExternalCacheDirs() instead of System.getenv("SECONDARY_STORAGE")
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
           File[] externalCacheDirs = mContext.getExternalCacheDirs();
           for (File file : externalCacheDirs) {
               if (Environment.isExternalStorageRemovable(file)) {
                   // Path is in format /storage.../Android....
                   // Get everything before /Android
                   path = file.getPath().split("/Android")[0];
                   break;
               }
           }
       }


        // Android avd emulator doesn't support this variable name so using other one
        if ((null == path) || (path.length() == 0))
            path = Environment.getExternalStorageDirectory().getAbsolutePath();

Answer 6

  

我想打开外部存储目录路径来保存文件   以编程方式。我试过但没有获得SD卡路径。我能怎么做   这有什么解决方案？

要将您的应用文件存储在SD卡中，应在File[] getExternalFilesDirs (String type)课程中使用Context方法。通常，第二个返回路径将是microSD卡的存储路径（如果有）。

在我的手机上，在将/storage/sdcard1/Android/data/your.application.package.appname/files作为参数传递给null后，返回的第二条路径为getExternalFilesDirs (String type)。但路径可能因手机不同而不同，不同的Android版本。

File getExternalStorageDirectory ()类中的File getExternalStoragePublicDirectory (String type)和Environment可能会返回SD卡目录或内部存储目录，具体取决于您的手机型号和Android操作系统版本。

因为根据Official Android Guide外部存储可以

  

可移动存储介质（如SD卡）或内部存储介质   （不可拆卸）存储。

根据Google /官方Android文档，内部和外部存储术语与我们的想法相差甚远。

Answer 7

是的，它可能会在KITKAT中工作。

在KITKAT +之上，它将进入内部存储：路径如（storage / emulated / 0）。

请考虑一下，“ Xender应用程序”如何授予写入外部SD卡的权限。

因此，幸运的是，在Android 5.0和更高版本中，有一种新的官方方式可供应用程序写入外部SD卡。应用程序必须要求用户授予对SD卡上文件夹的写访问权限。他们打开系统文件夹选择器对话框。用户需要导航到该特定文件夹并选择它。

有关更多详细信息，请参阅https://metactrl.com/docs/sdcard-on-lollipop/

Answer 8

尝试使用

new File(Environment.getExternalStorageDirectory(),"somefilename");

不要忘记添加WRITE_EXTERNAL STORAGE和READ_EXTERNAL STORAGE权限