我有这个应用程序，它会选择图像到画廊并使用 Imageview 将其显示给测试。我的问题是它在 Android M 上不起作用。我可以选择图像但不会在我的测试中显示。他们说我需要请求许可才能在 Android M 上访问图像但不知道如何。请帮忙。

最佳答案

从 Android 6.0(API 级别 23)开始，用户在应用运行时向应用授予权限，而不是在安装应用时。

类型 1- 当您的应用请求权限时，系统会向用户显示一个对话框。当用户响应时，系统会调用您应用的 onRequestPermissionsResult() 方法，将用户响应传递给它。您的应用程序必须重写该方法才能确定是否授予了权限。回调传递给您传递给 requestPermissions() 的相同请求代码。

private static final int PICK_FROM_GALLERY = 1;

ChoosePhoto.setOnClickListener(new View.OnClickListener()
{
    @Override
    public void onClick (View v){
    try {
        if (ActivityCompat.checkSelfPermission(EditProfileActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(EditProfileActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, PICK_FROM_GALLERY);
        } else {
            Intent galleryIntent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            startActivityForResult(galleryIntent, PICK_FROM_GALLERY);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
  }
});


@Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults)
    {
       switch (requestCode) {
            case PICK_FROM_GALLERY:
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                  Intent galleryIntent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                  startActivityForResult(galleryIntent, PICK_FROM_GALLERY);
                } else {
                    //do something like displaying a message that he didn`t allow the app to access gallery and you wont be able to let him select from gallery
                }
                break;
        }
    }

类型 2- 如果您想在一个地方连续授予运行时权限，那么您可以点击以下链接

Android 6.0 multiple permissions

并在 list 中为您的要求添加权限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

注意 - 如果 Manifest.permission.READ_EXTERNAL_STORAGE 产生错误，请将其替换为 android.Manifest.permission.READ_EXTERNAL_STORAGE。

==>如果您想了解更多关于运行时权限的信息，请点击以下链接

https://developer.android.com/training/permissions/requesting.html

----------------------------更新 1------------ ------------------

使用 EasyPermissions 的运行时权限

EasyPermissions 是一个包装器库，用于在面向 Android M 或更高版本时简化基本系统权限逻辑。

安装 在App级gradle中添加依赖

 dependencies {
// For developers using AndroidX in their applications
implementation 'pub.devrel:easypermissions:3.0.0'

// For developers using the Android Support Library
implementation 'pub.devrel:easypermissions:2.0.1'
}

您的 Activity (或 fragment )覆盖 onRequestPermissionsResult 方法:

 @Override
     public void onRequestPermissionsResult(int requestCode, String[] 
    permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions,grantResults);

        // Forward results to EasyPermissions
        EasyPermissions.onRequestPermissionsResult(requestCode, permissions, grantResults, this);
    }

请求权限

private static final int LOCATION_REQUEST = 222;

调用这个方法

@AfterPermissionGranted(LOCATION_REQUEST)
private void checkLocationRequest() {
   String[] perms = {Manifest.permission.ACCESS_FINE_LOCATION};
    if (EasyPermissions.hasPermissions(this, perms)) {
        // Already have permission, do the thing
        // ...
    } else {
        // Do not have permissions, request them now
        EasyPermissions.requestPermissions(this,"Please grant permission",
                LOCATION_REQUEST, perms);
    }
}

可选地，为了更好的控制，您可以让 Activity/Fragment 实现 PermissionCallbacks 接口(interface)。

实现 EasyPermissions.PermissionCallbacks

 @Override
public void onPermissionsGranted(int requestCode, List<String> list) {
    // Some permissions have been granted
    // ...
}

@Override
public void onPermissionsDenied(int requestCode, List<String> list) {
    // Some permissions have been denied
    // ...
}

链接 -> https://github.com/googlesamples/easypermissions

---------------------------- KOTLIN 的更新 2------------ ----------------------

使用 florent37 的运行时权限

安装在App级gradle中添加依赖

依赖性

implementation 'com.github.florent37:runtime-permission-kotlin:1.1.2'

在代码中

        askPermission(
        Manifest.permission.CAMERA,
        Manifest.permission.READ_EXTERNAL_STORAGE,
        Manifest.permission.WRITE_EXTERNAL_STORAGE
    ) {
       // camera or gallery or TODO
    }.onDeclined { e ->
        if (e.hasDenied()) {
            AlertDialog.Builder(this)
                .setMessage(getString(R.string.grant_permission))
                .setPositiveButton(getString(R.string.yes)) { dialog, which ->
                    e.askAgain()
                } //ask again
                .setNegativeButton(getString(R.string.no)) { dialog, which ->
                    dialog.dismiss()
                }
                .show()
        }

        if (e.hasForeverDenied()) {
            e.goToSettings()
        }
    }

链接-> https://github.com/florent37/RuntimePermission

关于java - 如何请求访问 android M. 上的图库的权限？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39866869/