安卓getExternalFilesDirs方法在模拟器上不返回SD卡

Question

我需要确定SD卡是否可用。我目前正在使用getExternalFilesDirs方法，然后使用Environment.isExternalStorageRemovable来验证路径是否为可移动SD卡。这在操作系统高于棒棒糖的实际设备上工作得很好，但是当我尝试使用模拟的SD卡设置仿真器时，我可以在仿真器上看到SD卡，但方法getExternalFilesDirs无法返回SD卡存储路径，因此我只能看到本地存储。

Answer 1

请尝试使用以下代码：

import android.content.Context;
import android.os.Build;
import android.os.IBinder;

import java.io.File;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

public class RemovableStorageFinder {

    public static File getRemovabeStorageDir(Context context) {
        try {
            List<File> storages = getRemovabeStorages(context);
            if (!storages.isEmpty()) {
                return storages.get(0);
            }
        } catch (Exception ignored) {
        }
        final String SECONDARY_STORAGE = System.getenv("SECONDARY_STORAGE");
        if (SECONDARY_STORAGE != null) {
            return new File(SECONDARY_STORAGE.split(":")[0]);
        }
        return null;
    }

    public static List<File> getRemovabeStorages(Context context) throws Exception {
        List<File> storages = new ArrayList<>();

        Method getService = Class.forName("android.os.ServiceManager")
                .getDeclaredMethod("getService", String.class);
        if (!getService.isAccessible()) getService.setAccessible(true);
        IBinder service = (IBinder) getService.invoke(null, "mount");

        Method asInterface = Class.forName("android.os.storage.IMountService$Stub")
                .getDeclaredMethod("asInterface", IBinder.class);
        if (!asInterface.isAccessible()) asInterface.setAccessible(true);
        Object mountService = asInterface.invoke(null, service);

        Object[] storageVolumes;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            String packageName = context.getPackageName();
            int uid = context.getPackageManager().getPackageInfo(packageName, 0).applicationInfo.uid;
            Method getVolumeList = mountService.getClass().getDeclaredMethod(
                    "getVolumeList", int.class, String.class, int.class);
            if (!getVolumeList.isAccessible()) getVolumeList.setAccessible(true);
            storageVolumes = (Object[]) getVolumeList.invoke(mountService, uid, packageName, 0);
        } else {

            Method getVolumeList = mountService.getClass().getDeclaredMethod("getVolumeList");
            if (!getVolumeList.isAccessible()) getVolumeList.setAccessible(true);
            storageVolumes = (Object[]) getVolumeList.invoke(mountService, (Object[]) null);
        }

        for (Object storageVolume : storageVolumes) {
            Class<?> cls = storageVolume.getClass();
            Method isRemovable = cls.getDeclaredMethod("isRemovable");
            if (!isRemovable.isAccessible()) isRemovable.setAccessible(true);
            if ((boolean) isRemovable.invoke(storageVolume, (Object[]) null)) {
                Method getState = cls.getDeclaredMethod("getState");
                if (!getState.isAccessible()) getState.setAccessible(true);
                String state = (String) getState.invoke(storageVolume, (Object[]) null);
                if (state.equals("mounted")) {
                    Method getPath = cls.getDeclaredMethod("getPath");
                    if (!getPath.isAccessible()) getPath.setAccessible(true);
                    String path = (String) getPath.invoke(storageVolume, (Object[]) null);
                    storages.add(new File(path));
                }
            }
        }

        return storages;
    }

}

要检查SD是否存在，请使用活动中的以下代码行：

            RemovableStorageFinder removableStorageFinder = new RemovableStorageFinder();

            File thisFile = removableStorageFinder.getRemovabeStorageDir(this);


            if(thisFile != null){

             //  There is an SD card, perform your logic here.
            }

PS:我不确定这是否解决了您所面临的仿真器问题，但这通常是确定SD卡是否存在的更好方法。祝你好运！