保存图像并将其显示在图库中

Question

我正在尝试从 https://developer.android.com/training/camera/photobasics 实现 google 的代码，但是我有点卡住了。

这是我的 MainActivity：

package com.example.storage_thingy;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.FileProvider;
import android.Manifest;

import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    ImageView imageView;
    Button saveimage;
    Button takephoto;

    static final int REQUEST_IMAGE_CAPTURE = 1;
    String currentPhotoPath;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = findViewById(R.id.imageview);
        saveimage = findViewById(R.id.savegallery);
        takephoto = findViewById(R.id.takephoto);

        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},1);


        saveimage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                saveToGallery();
            }
        });

        takephoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                dispatchTakePictureIntent();
            }
        });

    }

    private File createImageFile() throws IOException {
        // Create an image file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
        File image = File.createTempFile(
                imageFileName,  /* prefix */
                ".jpg",         /* suffix */
                storageDir      /* directory */
        );

        // Save a file: path for use with ACTION_VIEW intents
        currentPhotoPath = image.getAbsolutePath();
        return image;
    }



    private void dispatchTakePictureIntent() {
        Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        // Ensure that there's a camera activity to handle the intent
        if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
            // Create the File where the photo should go
            File photoFile = null;
            try {
                photoFile = createImageFile();
            } catch (IOException ex) {
                // Error occurred while creating the File
                Context context = getApplicationContext();
                CharSequence text = "IOException!";
                int duration = Toast.LENGTH_SHORT;

                Toast toast = Toast.makeText(context, text, duration);
                toast.show();
            }
            // Continue only if the File was successfully created
            if (photoFile != null) {
                Uri photoURI = FileProvider.getUriForFile(this,
                        "com.example.android.fileprovider",
                        photoFile);
                takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
                startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
            }
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
            Bundle extras = data.getExtras();
            Bitmap imageBitmap = (Bitmap) extras.get("data");
            imageView.setImageBitmap(imageBitmap);
        }
    }


    private void saveToGallery(){
        Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        File f = new File(currentPhotoPath);
        Uri contentUri = Uri.fromFile(f);
        mediaScanIntent.setData(contentUri);
        this.sendBroadcast(mediaScanIntent);

    }

}

然后是清单文件：

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.storage_thingy">


    <uses-feature android:name="android.hardware.camera" android:required="true" />

    <application
        
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Storage_thingy">
        <activity

            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="com.example.android.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths"></meta-data>
        </provider>

    </application>
</manifest>

然后 file_paths.xml

<?xml version="1.0" encoding="utf-8"?>
<paths> xmlns:android="http://schemas.android.com/apk/res/android">
    <external-files-path name="files" path="." />
</paths>

我一直收到运行时异常，说 onActivityResult 方法中的数据为空，但我不明白为什么？有什么想法吗？

Answer 1

只需更换：

  Bundle extras = data.getExtras();
  Bitmap imageBitmap = (Bitmap) extras.get("data");
  imageView.setImageBitmap(imageBitmap);

有：

imageView.setImageURI(Uri.fromFile(photoFile));

改变saveToGallery方法以及createImageFile:

  private File createImageFile() throws IOException {
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = Build.VERSION.SDK_INT < Build.VERSION_CODES.Q ? Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES) : getExternalFilesDir(Environment.DIRECTORY_PICTURES);
        File image = File.createTempFile(
                imageFileName,  /* prefix */
                ".jpg",         /* suffix */
                storageDir      /* directory */
        );
        currentPhotoPath = image.getAbsolutePath();
        return image;
    }


private void saveToGallery() {
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
        Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        intent.setData(Uri.parse("file://" + photoFile.getAbsolutePath()));
        sendBroadcast(intent);
    } else {
        ContentValues contentValues = new ContentValues();
        contentValues.put(MediaStore.Images.Media.DISPLAY_NAME, photoFile.getName());
        contentValues.put(MediaStore.Images.Media.MIME_TYPE, "image/*");
        Uri contentUri;
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
        } else {
            contentUri = MediaStore.Images.Media.INTERNAL_CONTENT_URI;
        }
        contentValues.put(MediaStore.Images.Media.RELATIVE_PATH, Environment.DIRECTORY_PICTURES);
        contentValues.put(MediaStore.MediaColumns.IS_PENDING, 1);
        Uri uri = getContentResolver().insert(contentUri, contentValues);
        OutputStream os = null;
        try {
            Bitmap bitmap = BitmapFactory.decodeFile(photoFile.getAbsolutePath());
            os = getContentResolver().openOutputStream(uri);
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, os);
            contentValues.clear();
            contentValues.put(MediaStore.MediaColumns.IS_PENDING, 0);
            getContentResolver().update(uri, contentValues, null, null);
        } catch (Exception e) {
            getContentResolver().delete(uri, null, null);
            e.printStackTrace();
        } finally {
            try {
                if (os != null) {
                    os.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        mediaScanIntent.setData(contentUri);
        this.sendBroadcast(mediaScanIntent);
    }

}

并且 file_path.xml 到 :

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path name="external" path="." />
    <external-files-path name="external_files" path="." />
    <cache-path name="cache" path="." />
    <external-cache-path name="external_cache" path="." />
    <files-path name="files" path="." />
</paths>

我已经在 Android 11 和 Android 5.1.1 上测试过了，我能够在我的图库中看到捕获的图像。

保存图像并将其显示在图库中

Saving an image and displaying it in gallery

java

android

android-external-storage

saving-data