Android上的异常“打开失败：EACCES（权限被拒绝）”

Question

我越来越

open failed: EACCES (Permission denied)

在线OutputStream myOutput = new FileOutputStream(outFileName);

我检查了根目录，并尝试了安卓.permission.WRITE_EXTERNAL_STORAGE

我如何解决这个问题

try {
    InputStream myInput;

    myInput = getAssets().open("XXX.db");

    // Path to the just created empty db
    String outFileName = "/data/data/XX/databases/"
            + "XXX.db";

    // Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);

    // Transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }

    // Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();
    buffer = null;
    outFileName = null;
}
catch (IOException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}

Answer 1

谷歌在安卓Q上有一个新功能：外部存储的过滤视图。一个快速修复方法是将此代码添加到AndroidManifest中。xml文件：

<manifest ... >
    <!-- This attribute is "false" by default on apps targeting Android Q. -->
    <application android:requestLegacyExternalStorage="true" ... >
     ...
    </application>
</manifest>

您可以在此处阅读更多信息：https://developer.android.com/training/data-storage/use-cases

编辑：我开始得到反对票，因为这个答案对于Android 11来说已经过时了。因此，无论谁看到这个答案，请转到上面的链接并阅读说明

Answer 2

我也有同样的问题。。。这个<uses-permission放错地方了。这是正确的：

 <manifest>
        <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
        ...
        <application>
            ...
            <activity> 
                ...
            </activity>
        </application>
    </manifest> 

uses-permission标记需要位于application标记之外

Answer 3

除了所有答案之外，请确保您没有将手机用作USB存储

我在启用USB存储模式的HTC Sensation上也遇到了同样的问题。我仍然可以调试/运行应用程序，但无法保存到外部存储

Answer 4

对于API 23+您需要请求读/写权限，即使它们已经在您的清单中

// Storage Permissions
private static final int REQUEST_EXTERNAL_STORAGE = 1;
private static String[] PERMISSIONS_STORAGE = {
        Manifest.permission.READ_EXTERNAL_STORAGE,
        Manifest.permission.WRITE_EXTERNAL_STORAGE
};

/**
 * Checks if the app has permission to write to device storage
 *
 * If the app does not has permission then the user will be prompted to grant permissions
 *
 * @param activity
 */
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
        );
    }
}

AndroidManifest。xml

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

有关请求API 23+权限的官方文档，请查看https://developer.android.com/training/permissions/requesting.html

Answer 5

在模拟器内运行应用程序时，我曾经观察到过这一点。在emulator设置中，您需要正确指定外部存储器（“SD卡”）的大小。默认情况下，“外部存储”字段为空，这可能意味着没有此类设备，即使在清单中授予了权限，也会抛出EACCES

Answer 6

将android:requestLegacyExternalStorage=“true”添加到android清单 它在SDK 29+上与Android 10（Q）配合使用
或者在迁移Android X之后

 <application
    android:name=".MyApplication"
    android:allowBackup="true"
    android:hardwareAccelerated="true"
    android:icon=""
    android:label=""
    android:largeHeap="true"
    android:supportsRtl=""
    android:theme=""
    android:requestLegacyExternalStorage="true">