有没有一种通用的方法来找到外置SD卡的位置?
请不要与外部存储混淆。
Environment.getExternalStorageState()返回内部SD挂载点的路径，例如/mnt/sdcard。但问题是关于外部SD的。我如何获得类似/mnt/sdcard/external_sd的路径(它可能因设备而异)?
我想我将以根据文件系统名称过滤mount命令的输出作为结束。但我不确定这种方式是否足够稳健。
当前回答
根据这里找到的一些答案，我想出了以下解决方案。
代码:
public class ExternalStorage {
public static final String SD_CARD = "sdCard";
public static final String EXTERNAL_SD_CARD = "externalSdCard";
/**
* @return True if the external storage is available. False otherwise.
*/
public static boolean isAvailable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state) || Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
return true;
}
return false;
}
public static String getSdCardPath() {
return Environment.getExternalStorageDirectory().getPath() + "/";
}
/**
* @return True if the external storage is writable. False otherwise.
*/
public static boolean isWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
/**
* @return A map of all storage locations available
*/
public static Map<String, File> getAllStorageLocations() {
Map<String, File> map = new HashMap<String, File>(10);
List<String> mMounts = new ArrayList<String>(10);
List<String> mVold = new ArrayList<String>(10);
mMounts.add("/mnt/sdcard");
mVold.add("/mnt/sdcard");
try {
File mountFile = new File("/proc/mounts");
if(mountFile.exists()){
Scanner scanner = new Scanner(mountFile);
while (scanner.hasNext()) {
String line = scanner.nextLine();
if (line.startsWith("/dev/block/vold/")) {
String[] lineElements = line.split(" ");
String element = lineElements[1];
// don't add the default mount path
// it's already in the list.
if (!element.equals("/mnt/sdcard"))
mMounts.add(element);
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
try {
File voldFile = new File("/system/etc/vold.fstab");
if(voldFile.exists()){
Scanner scanner = new Scanner(voldFile);
while (scanner.hasNext()) {
String line = scanner.nextLine();
if (line.startsWith("dev_mount")) {
String[] lineElements = line.split(" ");
String element = lineElements[2];
if (element.contains(":"))
element = element.substring(0, element.indexOf(":"));
if (!element.equals("/mnt/sdcard"))
mVold.add(element);
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
for (int i = 0; i < mMounts.size(); i++) {
String mount = mMounts.get(i);
if (!mVold.contains(mount))
mMounts.remove(i--);
}
mVold.clear();
List<String> mountHash = new ArrayList<String>(10);
for(String mount : mMounts){
File root = new File(mount);
if (root.exists() && root.isDirectory() && root.canWrite()) {
File[] list = root.listFiles();
String hash = "[";
if(list!=null){
for(File f : list){
hash += f.getName().hashCode()+":"+f.length()+", ";
}
}
hash += "]";
if(!mountHash.contains(hash)){
String key = SD_CARD + "_" + map.size();
if (map.size() == 0) {
key = SD_CARD;
} else if (map.size() == 1) {
key = EXTERNAL_SD_CARD;
}
mountHash.add(hash);
map.put(key, root);
}
}
}
mMounts.clear();
if(map.isEmpty()){
map.put(SD_CARD, Environment.getExternalStorageDirectory());
}
return map;
}
}
用法:
Map<String, File> externalLocations = ExternalStorage.getAllStorageLocations();
File sdCard = externalLocations.get(ExternalStorage.SD_CARD);
File externalSdCard = externalLocations.get(ExternalStorage.EXTERNAL_SD_CARD);
其他回答
根据这里找到的一些答案，我想出了以下解决方案。
代码:
public class ExternalStorage {
public static final String SD_CARD = "sdCard";
public static final String EXTERNAL_SD_CARD = "externalSdCard";
/**
* @return True if the external storage is available. False otherwise.
*/
public static boolean isAvailable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state) || Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
return true;
}
return false;
}
public static String getSdCardPath() {
return Environment.getExternalStorageDirectory().getPath() + "/";
}
/**
* @return True if the external storage is writable. False otherwise.
*/
public static boolean isWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
/**
* @return A map of all storage locations available
*/
public static Map<String, File> getAllStorageLocations() {
Map<String, File> map = new HashMap<String, File>(10);
List<String> mMounts = new ArrayList<String>(10);
List<String> mVold = new ArrayList<String>(10);
mMounts.add("/mnt/sdcard");
mVold.add("/mnt/sdcard");
try {
File mountFile = new File("/proc/mounts");
if(mountFile.exists()){
Scanner scanner = new Scanner(mountFile);
while (scanner.hasNext()) {
String line = scanner.nextLine();
if (line.startsWith("/dev/block/vold/")) {
String[] lineElements = line.split(" ");
String element = lineElements[1];
// don't add the default mount path
// it's already in the list.
if (!element.equals("/mnt/sdcard"))
mMounts.add(element);
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
try {
File voldFile = new File("/system/etc/vold.fstab");
if(voldFile.exists()){
Scanner scanner = new Scanner(voldFile);
while (scanner.hasNext()) {
String line = scanner.nextLine();
if (line.startsWith("dev_mount")) {
String[] lineElements = line.split(" ");
String element = lineElements[2];
if (element.contains(":"))
element = element.substring(0, element.indexOf(":"));
if (!element.equals("/mnt/sdcard"))
mVold.add(element);
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
for (int i = 0; i < mMounts.size(); i++) {
String mount = mMounts.get(i);
if (!mVold.contains(mount))
mMounts.remove(i--);
}
mVold.clear();
List<String> mountHash = new ArrayList<String>(10);
for(String mount : mMounts){
File root = new File(mount);
if (root.exists() && root.isDirectory() && root.canWrite()) {
File[] list = root.listFiles();
String hash = "[";
if(list!=null){
for(File f : list){
hash += f.getName().hashCode()+":"+f.length()+", ";
}
}
hash += "]";
if(!mountHash.contains(hash)){
String key = SD_CARD + "_" + map.size();
if (map.size() == 0) {
key = SD_CARD;
} else if (map.size() == 1) {
key = EXTERNAL_SD_CARD;
}
mountHash.add(hash);
map.put(key, root);
}
}
}
mMounts.clear();
if(map.isEmpty()){
map.put(SD_CARD, Environment.getExternalStorageDirectory());
}
return map;
}
}
用法:
Map<String, File> externalLocations = ExternalStorage.getAllStorageLocations();
File sdCard = externalLocations.get(ExternalStorage.SD_CARD);
File externalSdCard = externalLocations.get(ExternalStorage.EXTERNAL_SD_CARD);
这是我用来找到外部卡的方法。使用mount cmd返回然后解析vfat部分。
String s = "";
try {
Process process = new ProcessBuilder().command("mount")
.redirectErrorStream(true).start();
process.waitFor();
InputStream is = process.getInputStream();
byte[] buffer = new byte[1024];
while (is.read(buffer) != -1) {
s = s + new String(buffer);
}
is.close();
} catch (Exception e) {
e.printStackTrace();
}
//用行分隔mount列表
String[] lines = s.split("\n");
for(int i=0; i<lines.length; i++) {
//如果行内有挂载路径且为vfat类型，说明可能是内置或者外置sd的挂载点
if(-1 != lines[i].indexOf(path[0]) && -1 != lines[i].indexOf("vfat")) {
//再用空格分隔
String[] blocks = lines[i].split("\\s");
for(int j=0; j<blocks.length; j++) {
//判断是否是挂载为vfat类型
if(-1 != blocks[j].indexOf(path[0])) {
//Test if it is the external sd card.
}
}
}
}
它适用于所有外部设备，但确保只获得外部设备文件夹名，然后你需要从给定的位置使用文件类获取文件。
public static List<String> getExternalMounts() {
final List<String> out = new ArrayList<>();
String reg = "(?i).*vold.*(vfat|ntfs|exfat|fat32|ext3|ext4).*rw.*";
String s = "";
try {
final Process process = new ProcessBuilder().command("mount")
.redirectErrorStream(true).start();
process.waitFor();
final InputStream is = process.getInputStream();
final byte[] buffer = new byte[1024];
while (is.read(buffer) != -1) {
s = s + new String(buffer);
}
is.close();
} catch (final Exception e) {
e.printStackTrace();
}
// parse output
final String[] lines = s.split("\n");
for (String line : lines) {
if (!line.toLowerCase(Locale.US).contains("asec")) {
if (line.matches(reg)) {
String[] parts = line.split(" ");
for (String part : parts) {
if (part.startsWith("/"))
if (!part.toLowerCase(Locale.US).contains("vold"))
out.add(part);
}
}
}
}
return out;
}
调用:
List<String> list=getExternalMounts();
if(list.size()>0)
{
String[] arr=list.get(0).split("/");
int size=0;
if(arr!=null && arr.length>0) {
size= arr.length - 1;
}
File parentDir=new File("/storage/"+arr[size]);
if(parentDir.listFiles()!=null){
File parent[] = parentDir.listFiles();
for (int i = 0; i < parent.length; i++) {
// get file path as parent[i].getAbsolutePath());
}
}
}
访问外部存储
为了读写外部存储上的文件，你的应用程序必须获得READ_EXTERNAL_STORAGE或WRITE_EXTERNAL_STORAGE系统权限。例如:
<manifest ...>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
...
</manifest>
这就是我如何找到外部存储路径。
public static String getExternalStoragePath(Context context){
File[] f = ContextCompat.getExternalFilesDirs(context, null);
String internalPath = Environment.getExternalStorageDirectory().getAbsolutePath();
String excessive = "";
String externalPath = "";
for (File file : f) {
if (file.getAbsolutePath().startsWith(internalPath)) {
excessive = file.getAbsolutePath().replaceAll(internalPath, "");
}
}
for (File file : f) {
if (!file.getAbsolutePath().startsWith(excessive)) {
externalPath = file.getAbsolutePath().replaceAll(excessive, "");
}
}
return externalPath;
}
只要简单地使用这个:
String primary_sd = System.getenv("EXTERNAL_STORAGE");
if(primary_sd != null)
Log.i("EXTERNAL_STORAGE", primary_sd);
String secondary_sd = System.getenv("SECONDARY_STORAGE");
if(secondary_sd != null)
Log.i("SECONDARY_STORAGE", secondary_sd)
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