如何在android中访问外部存储(可移动SD卡)

Question

我一直在尝试访问android中的内部和外部SD卡。我已经尝试了StackOverFlow中的许多可用代码，但在大多数或所有Android版本上都不起作用。然后，我找到了两个解决方案。一个在Kitkat&上面，另一个工作在低于Kitkat。我试着把它们合并在一起，结果成功了！

如果有人有比这更好的解决方案，请分享。

Answer 1

这两个答案是我为了让它发挥作用而合并的。

1. 如何在android6.0中以编程方式获取SD_Card路径

2. 查找外部SD卡位置

这是解决方案，

在AndroidManifest.xml中添加这行代码可以从Android获得读取外部存储的权限。

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

现在，将此类添加到您的项目中。

public class StoragePath {
File[] getExternalFilesDirs;
/**
* Constructor for KitKat & above
* @param getExternalFilesDirs
*/
public StoragePath(File[] getExternalFilesDirs) {
this.getExternalFilesDirs = getExternalFilesDirs;
}
/**
* Constructor for lower than Kitkat
*
*/
public StoragePath() {
}
public String[] getDeviceStorages() {
List<String> results = new ArrayList<>();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { //Method 1 for KitKat & above
File[] externalDirs = getExternalFilesDirs;
for (File file : externalDirs) {
String path = file.getPath().split("/Android")[0];
boolean addPath = false;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
addPath = Environment.isExternalStorageRemovable(file);
} else {
addPath = Environment.MEDIA_MOUNTED.equals(EnvironmentCompat.getStorageState(file));
}
if (addPath) {
results.add(path);
}
}
}
if (results.isEmpty()) { //Method 2 for all versions
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);
}
}
}
}
results.addAll(out);
}
//Below few lines is to remove paths which may not be external memory card, like OTG (feel free to comment them out)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
for (int i = 0; i < results.size(); i++) {
if (!results.get(i).toLowerCase().matches(".*[0-9a-f]{4}[-][0-9a-f]{4}")) {
Log.d("Tag", results.get(i) + " might not be extSDcard");
results.remove(i--);
}
}
} else {
for (int i = 0; i < results.size(); i++) {
if (!results.get(i).toLowerCase().contains("ext") && !results.get(i).toLowerCase().contains("sdcard")) {
Log.d("Tag", results.get(i) + " might not be extSDcard");
results.remove(i--);
}
}
}
//Get path to the Internal Storage aka ExternalStorageDirectory
final String internalStoragePath = Environment.getExternalStorageDirectory().getAbsolutePath();
results.add(0, internalStoragePath);
String[] storageDirectories = new String[results.size()];
for (int i = 0; i < results.size(); ++i) storageDirectories[i] = results.get(i);
return storageDirectories;
}
}

现在使用这个类，

StoragePath storagePath;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
storagePath = new StoragePath(getExternalFilesDirs(null));
}else {
storagePath = new StoragePath();
}
String[] storages;
storages = storagePath.getDeviceStorages();

字符串数组storages现在包含存储的路径。