如何分享Android应用内生成的Bitmap图片？附二维码生成代码

Hey there! Based on your existing QR code generation code, let's walk through how to add sharing functionality for WhatsApp and email. Here's what you need to do:

Step 1: Prepare Permissions & File Provider (For Android 7.0+) #

First, you need to handle file access properly, especially for newer Android versions.

Add this to your AndroidManifest.xml (inside the <application> tag) to set up a File Provider, which lets you safely share files with other apps:

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

Then create a res/xml/file_paths.xml file with this content to define which files your app can share:

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

Note: Using getExternalFilesDir() means you don't need to request WRITE_EXTERNAL_STORAGE permission (since Android 10+), as this directory is private to your app but accessible to other apps via File Provider.

Step 2: Save the Generated Bitmap to a File #

Add this method to your activity to save the QR code Bitmap to a local file:

private Uri saveBitmapToFile(Bitmap bitmap) {
    // Get the app's private Pictures directory
    File picturesDir = new File(getExternalFilesDir(Environment.DIRECTORY_PICTURES), "QR Codes");
    if (!picturesDir.exists()) {
        picturesDir.mkdirs();
    }

    // Create a unique filename (you can adjust this as needed)
    String fileName = "QR_" + System.currentTimeMillis() + ".png";
    File imageFile = new File(picturesDir, fileName);

    try (FileOutputStream fos = new FileOutputStream(imageFile)) {
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
        fos.flush();
        // Get the content URI using File Provider
        return FileProvider.getUriForFile(this, getPackageName() + ".fileprovider", imageFile);
    } catch (IOException e) {
        e.printStackTrace();
        return null;
    }
}

Step 3: Create the Sharing Intent #

Add this method to handle sharing the image via WhatsApp, email, or other apps:

private void shareImage(Uri imageUri) {
    if (imageUri == null) {
        Toast.makeText(this, "Failed to save image for sharing", Toast.LENGTH_SHORT).show();
        return;
    }

    // Create base share intent
    Intent shareIntent = new Intent(Intent.ACTION_SEND);
    shareIntent.setType("image/png");
    shareIntent.putExtra(Intent.EXTRA_STREAM, imageUri);
    shareIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION); // Grant access to the file

    // Option 1: Let the user choose which app to share with
    startActivity(Intent.createChooser(shareIntent, "Share QR Code via"));

    // Option 2: Directly share to WhatsApp (if installed)
    /*
    PackageManager pm = getPackageManager();
    try {
        Intent whatsAppIntent = new Intent(Intent.ACTION_SEND);
        whatsAppIntent.setPackage("com.whatsapp");
        whatsAppIntent.setType("image/png");
        whatsAppIntent.putExtra(Intent.EXTRA_STREAM, imageUri);
        whatsAppIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        startActivity(whatsAppIntent);
    } catch (ActivityNotFoundException e) {
        Toast.makeText(this, "WhatsApp not installed", Toast.LENGTH_SHORT).show();
    }
    */

    // Option 3: Directly share via email
    /*
    Intent emailIntent = new Intent(Intent.ACTION_SEND);
    emailIntent.setType("image/png");
    emailIntent.putExtra(Intent.EXTRA_EMAIL, new String[]{"recipient@example.com"});
    emailIntent.putExtra(Intent.EXTRA_SUBJECT, "My QR Code");
    emailIntent.putExtra(Intent.EXTRA_TEXT, "Here's the QR code I generated!");
    emailIntent.putExtra(Intent.EXTRA_STREAM, imageUri);
    emailIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
    startActivity(Intent.createChooser(emailIntent, "Send QR Code via Email"));
    */
}

Step 4: Integrate with Your Existing QR Code Generation #

Update your gerarQRCode() method to save the bitmap and trigger sharing (or link this to a button click event if you don't want to share immediately):

private void gerarQRCode() {
    String texto = edtTexto.getText().toString();
    MultiFormatWriter multiFormatWriter = new MultiFormatWriter();
    try {
        BitMatrix bitmatrix = multiFormatWriter.encode(texto, BarcodeFormat.QR_CODE, 2000, 2000);
        BarcodeEncoder barcodeEncoder = new BarcodeEncoder();
        Bitmap bitmap = barcodeEncoder.createBitmap(bitmatrix);
        ivQRCode.setImageBitmap(bitmap);

        // Save and share the QR code (call this here, or link to a button click)
        Uri imageUri = saveBitmapToFile(bitmap);
        shareImage(imageUri);
    } catch (WriterException e) {
        e.printStackTrace();
    }
}

Key Notes: #

• Permissions: For Android 9 and below, you may need to request WRITE_EXTERNAL_STORAGE permission at runtime. For Android 10+, using getExternalFilesDir() avoids this requirement.
• Error Handling: Make sure to handle cases where the bitmap fails to save, or the target app (like WhatsApp) isn't installed.
• File Cleanup: You might want to add logic to delete old QR code files periodically to save storage space.

内容的提问来源于stack exchange，提问作者Almir Kubo