在行车记录仪中，android各个版本对外部存储卡存在着权限上的限制，对获取卡的位置存在不同SDK版本上的差异，car-eye行车记录仪为了保持兼容性。做了最全面的处理：
获取卡的位置：
public String[] initDisk(Context context) {
String sd = null;
Class<?> storageVolumeClazz = null;
ArrayList<String> lineByteList = new ArrayList<String>();
try {
StorageManager storageManager = (StorageManager) context
.getSystemService(Context.STORAGE_SERVICE);
storageVolumeClazz = Class.forName("android.os.storage.StorageVolume");
Method getVolumeList = StorageManager.class.getDeclaredMethod("getVolumeList");
Method isRemovable = storageVolumeClazz.getMethod("isRemovable");
Method getPath = storageVolumeClazz.getMethod("getPath");
Object volumes = getVolumeList.invoke(storageManager);
Method getVolumeState = StorageManager.class.getDeclaredMethod("getVolumeState", String.class);
final int length = Array.getLength(volumes);
for (int i = 0; i < length; i++)
{
Object storageVolumeElement = Array.get(volumes, i);
String path = (String) getPath.invoke(storageVolumeElement);
String state = (String) getVolumeState.invoke(storageManager, path);
boolean removable = (Boolean) isRemovable.invoke(storageVolumeElement);
if(Environment.MEDIA_MOUNTED.equals(state) && removable)
{
lineByteList.add(path);
Log.d(tag, "Disk path : " + path);
}
}
} catch (Exception e)
{
Log.e(tag, e.getMessage());
}
path = new String [lineByteList.size()];
for(int j = 0;j < lineByteList.size(); j++ ){
path[j] = lineByteList.get(j);
}
return path;
}
权限：
public static void verifyStoragePermissions(Activity activity) {
// Check if we have write permission
int permission = ActivityCompat.checkSelfPermission(activity,
Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (permission != PackageManager.PERMISSION_GRANTED) {
// We don't have permission so prompt the user
ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
REQUEST_EXTERNAL_STORAGE);
}
}
对于6.0以上的ANDROID OS:
if(version>=23)
{
verifyStoragePermissions(MainActivity.this);
}
同时在manifest中申明对卡的访问的权限：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
这样就可以动态的获得卡的位置并对外部存储卡进行操作了。需要注意的是，如果还不能对卡进行读写
那么请对android设备进行root处理。
这样就能正常的访问外部存储卡了。
相关代码下载https://github.com/Car-eye-team 欢迎加入技术讨论群：590411159