如何在图像上显示图像从内部存储中选择的视图

Question

我是安卓处理图像的新手。我想从内部存储加载图像，但它给了我权限被拒绝错误，然后我已将权限添加到 android 清单文件。但我仍然无法完成我的任务。

这是我的代码：

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ImageView image = (ImageView)findViewById(R.id.imageView);
        Bitmap bm = BitmapFactory.decodeFile("/storage/emulated/0/DCIM/Camera/IMG_20151102_193132.jpg");
        image.setImageBitmap(bm);
    }
}

日志猫：

01-16 15:16:11.345 6533-6533/com.example.jaytanna.imagemap E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: /storage/emulated/0/DCIM/Camera/IMG_20151102_193132.jpg: open failed: EACCES (Permission denied)

它不显示任何图像。请帮我解决这个问题。谢谢。

Answer 1

检查这个

     File imgFile = new  File("/storage/emulated/0/DCIM/Camera/IMG_20151102_193132.jpg");
      if(imgFile.exists()){
        Bitmap myBitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath());
        ImageView myImage = (ImageView) findViewById(R.id.imageviewTest);
        myImage.setImageBitmap(myBitmap);
      };

并在清单文件中包含此权限：

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

对于 API 23+，您需要请求读/写权限，即使它们已在清单中。

// 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
        );
    }
}

为了处理响应，您可以使用我从 http://web.archive.org/web/20160111030837/http://developer.android.com/training/permissions/requesting.html 复制的这段代码 —

@Override
public void onRequestPermissionsResult(int requestCode,
        String permissions[], int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST_READ_CONTACTS: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                // permission was granted, yay! Do the
                // contacts-related task you need to do.
            } else {
                // permission denied, boo! Disable the
                // functionality that depends on this permission.
            }
            return;
        }
        // other 'case' lines to check for other
        // permissions this app might request
    }
}

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 2

您需要

像这样添加运行时允许检查：

    public  boolean isStoragePermissionGranted() {
    if (Build.VERSION.SDK_INT >= 23) {
        if (checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE)
                == PackageManager.PERMISSION_GRANTED) {
            Log.v(TAG,"Permission is granted");
            return true;
        } else {
            Log.v(TAG,"Permission is revoked");
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
            return false;
        }
    }
    else { //permission is automatically granted on sdk<23 upon installation
        Log.v(TAG,"Permission is granted");
        return true;
    }
}

像这样使用它：

if(isStoragePermissionGranted()){
 Bitmap bm = BitmapFactory.decodeFile("/storage/emulated/0/DCIM/Camera/IMG_20151102_193132.jpg");
 image.setImageBitmap(bm);
 }

在 中捕获结果

    @Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if(grantResults[0]== PackageManager.PERMISSION_GRANTED){
        Log.v(TAG,"Permission: "+permissions[0]+ "was "+grantResults[0]);
        //resume tasks needing this permission
        Bitmap bm = BitmapFactory.decodeFile("/storage/emulated/0/DCIM/Camera/IMG_20151102_193132.jpg");
       image.setImageBitmap(bm);
    }
}

Answer 3

Intent gallery = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.INTERNAL_CONTENT_URI);
        startActivityForResult(gallery,PICK_IMAGE);

@Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode == RESULT_OK && requestCode == PICK_IMAGE){
         imageUri = data.getData();
         imageView.setImageURI(imageUri);
        }
    }

这将起作用。 简单易行

Answer 4

您是否在应用设置中启用了该权限？（READ_EXTERNAL_STORAGE或WRITE_EXTERNAL_STORAGE都将显示为"storage"）