我正在尝试访问用户设备上的媒体文件(音乐)来播放它们；一个简单的“hello world”——音乐播放器应用。

我遵循了一些教程，它们基本上给出了相同的代码。但这行不通；它一直在崩溃并告诉我:

error.....
Caused by: java.lang.SecurityException: Permission Denial: reading com.android.providers.media.MediaProvider uri content://media/external/audio/media from pid=27696, uid=10059 requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission()
....

现在，这是我的 list 文件:

<?xml version="1.0" encoding="utf-8"?>
<manifest
    xmlns:android="http://schemas.android.com/apk/res/android"
    package="slimsimapps.troff" >

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


<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>
</manifest>

这是我的 Java 方法:

public void initialize() {
    ContentResolver contentResolver = getContentResolver();
    Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
    Cursor cursor = contentResolver.query(uri, null, null, null, null);
    if (cursor == null) {
        // query failed, handle error.
    } else if (!cursor.moveToFirst()) {
        // no media on the device
    } else {
        do {
            addSongToXML(cursor);
        } while (cursor.moveToNext());
    }
}

我试过了:

将其放在 list 文件中的不同位置:

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

在读取外部存储权限时添加 android:maxSdkVersion:

<uses-permission
    android:name="android.permission.READ_EXTERNAL_STORAGE"
    android:maxSdkVersion="21" />

把它放在 list /应用程序/Activity 标签中:

android:exported=“true”

在java方法中将grantUriPremission放在uri和cursro之间:

grantUriPermission(null, uri, Intent.FLAG_GRANT_READ_URI_PERMISSION);

使用它不会崩溃，但是光标变为空:

uri = MediaStore.Audio.Media.getContentUri("EXTERNAL_CONTENT_URI”);

要使用 INTERNAL 内容 uri，这可以按预期工作，但它只提供“操作系统声音”，例如快门声音、低电量声音、按钮点击等:

uri = MediaStore.Audio.Media.INTERNAL_CONTENT_URI;

请帮忙，我知道这应该不是一个难题，但我觉得自己像个初学者!

我已阅读并尝试过(或认为它们不适用于我的问题):

• Android READ_EXTERNAL_STORAGE permission not working
• Require permission only for older android versions: maxSdkVersion does not work?
• Get filename and path from URI from mediastore
• Android KitKat securityException when trying to read from MediaStore
• Android: java.lang.SecurityException: Permission Denial: start Intent

堆栈跟踪:

09-08 06:59:36.619    2009-2009/slimsimapps.troff D/AndroidRuntime﹕ Shutting down VM
    --------- beginning of crash
09-08 06:59:36.619    2009-2009/slimsimapps.troff E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: slimsimapps.troff, PID: 2009
    java.lang.IllegalStateException: Could not execute method for android:onClick
            at android.view.View$DeclaredOnClickListener.onClick(View.java:4452)
            at android.view.View.performClick(View.java:5198)
            at android.view.View$PerformClick.run(View.java:21147)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     Caused by: java.lang.reflect.InvocationTargetException
            at java.lang.reflect.Method.invoke(Native Method)
            at android.view.View$DeclaredOnClickListener.onClick(View.java:4447)
            at android.view.View.performClick(View.java:5198)
            at android.view.View$PerformClick.run(View.java:21147)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     Caused by: java.lang.SecurityException: Permission Denial: reading com.android.providers.media.MediaProvider uri content://media/external/audio/media from pid=2009, uid=10059 requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission()
            at android.os.Parcel.readException(Parcel.java:1599)
            at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:183)
            at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:135)
            at android.content.ContentProviderProxy.query(ContentProviderNative.java:421)
            at android.content.ContentResolver.query(ContentResolver.java:491)
            at android.content.ContentResolver.query(ContentResolver.java:434)
            at slimsimapps.troff.MainActivity.initialize(MainActivity.java:106)
            at slimsimapps.troff.MainActivity.InitializeExternal(MainActivity.java:80)
            at java.lang.reflect.Method.invoke(Native Method)
            at android.view.View$DeclaredOnClickListener.onClick(View.java:4447)
            at android.view.View.performClick(View.java:5198)
            at android.view.View$PerformClick.run(View.java:21147)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
    --------- beginning of system

最佳答案

您的问题有两种解决方案。快速的方法是将 targetApi 降低到 22(build.gradle 文件)。 二是使用新奇的请求许可模型:

if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE)
        != PackageManager.PERMISSION_GRANTED) {

    // Should we show an explanation?
    if (shouldShowRequestPermissionRationale(
            Manifest.permission.READ_EXTERNAL_STORAGE)) {
        // Explain to the user why we need to read the contacts
    }

    requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
            MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);

    // MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE is an
    // app-defined int constant that should be quite unique

    return;
}

在此处找到的 fragment :https://developer.android.com/training/permissions/requesting.html

解决方案 2:如果它不起作用，试试这个:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M
    && ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
        REQUEST_PERMISSION);

return;

}

然后在回调中

@Override
public void onRequestPermissionsResult(final int requestCode, @NonNull final String[] permissions, @NonNull final int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQUEST_PERMISSION) {
    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        // Permission granted.
    } else {
        // User refused to grant permission.
    }
}
}

来自评论。谢谢

关于java - Android 的 READ_EXTERNAL_STORAGE 权限，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32431723/