通过 Android Intent 共享位图 [英] Sharing Bitmap via Android Intent

问题描述

在我的 android 应用程序中，我有一个位图(比如 b)和一个按钮.现在，当我单击按钮时，我想共享位图.我在我的 onClick() 中使用以下代码来实现这一点:-

In my android app, I have a bitmap (say b) and a button. Now when I click on the button, I want to share the bitmap. I am making use of the below code inside my onClick() to achieve this :-

Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("image/png");
intent.putExtra(Intent.EXTRA_STREAM, b);
startActivity(Intent.createChooser(intent , "Share"));

我期待能够处理此意图的所有应用程序的列表，但我什么也没得到.android studio 中没有应用程序列表，也没有任何错误.我的应用程序只是挂了一段时间然后退出.

I was expecting a list of all application which are able to handle this intent but I get nothing. There is no list of apps nor is there any error in android studio. My application just get hanged for sometime and then quits.

我检查了位图，它很好(它不为空).

I have checked the bitmap and it is fine (its not null).

我哪里出错了?

推荐答案

我找到了解决方案的 2 个变体.两者都涉及将位图保存到存储中，但图像不会出现在图库中.

I found 2 variants of the solution. Both involve saving Bitmap to storage, but the image will not appear in the gallery.

保存到外部存储

• 但是到应用程序的私人文件夹.
• 对于 API <= 18，它需要许可，对于较新的则不需要.

在标签前添加到AndroidManifest.xml

Add into AndroidManifest.xml before tag

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="18"/>

2.保存方法:

 /**
 * Saves the image as PNG to the app's private external storage folder.
 * @param image Bitmap to save.
 * @return Uri of the saved file or null
 */
private Uri saveImageExternal(Bitmap image) {
    //TODO - Should be processed in another thread
    Uri uri = null;
    try {
        File file = new File(getExternalFilesDir(Environment.DIRECTORY_PICTURES), "to-share.png");
        FileOutputStream stream = new FileOutputStream(file);
        image.compress(Bitmap.CompressFormat.PNG, 90, stream);
        stream.close();
        uri = Uri.fromFile(file);
    } catch (IOException e) {
        Log.d(TAG, "IOException while trying to write file for sharing: " + e.getMessage());
    }
    return uri;
}

3.检查存储可访问性

外部存储可能无法访问，因此您应该在尝试保存之前检查它:https://developer.android.com/training/data-storage/files

/**
 * Checks if the external storage is writable.
 * @return true if storage is writable, false otherwise
 */
public boolean isExternalStorageWritable() {
    String state = Environment.getExternalStorageState();
    if (Environment.MEDIA_MOUNTED.equals(state)) {
        return true;
    }
    return false;
}

第二个变体

使用 FileProvider 保存到 cacheDir.它不需要任何权限.

Second variant

Saving to cacheDir using FileProvider. It does not require any permissions.

<manifest>
    ...
    <application>
        ...
        <provider
            android:name="android.support.v4.content.FileProvider"
            android:authorities="com.mydomain.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
                <meta-data
                    android:name="android.support.FILE_PROVIDER_PATHS"
                    android:resource="@xml/file_paths" />
        </provider>
        ...
    </application>
</manifest>

2.将路径添加到 res/xml/file_paths.xml

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

3.保存方法:

 /**
 * Saves the image as PNG to the app's cache directory.
 * @param image Bitmap to save.
 * @return Uri of the saved file or null
 */
private Uri saveImage(Bitmap image) {
    //TODO - Should be processed in another thread
    File imagesFolder = new File(getCacheDir(), "images");
    Uri uri = null;
    try {
        imagesFolder.mkdirs();
        File file = new File(imagesFolder, "shared_image.png");

        FileOutputStream stream = new FileOutputStream(file);
        image.compress(Bitmap.CompressFormat.PNG, 90, stream);
        stream.flush();
        stream.close();
        uri = FileProvider.getUriForFile(this, "com.mydomain.fileprovider", file);

    } catch (IOException e) {
        Log.d(TAG, "IOException while trying to write file for sharing: " + e.getMessage());
    }
    return uri;
}

有关文件提供程序的更多信息 - https://developer.android.com/reference/android/support/v4/content/FileProvider

More info about file provider - https://developer.android.com/reference/android/support/v4/content/FileProvider

压缩和保存可能很耗时，因此这应该在不同的线程中完成

/**
 * Shares the PNG image from Uri.
 * @param uri Uri of image to share.
 */
private void shareImageUri(Uri uri){
    Intent intent = new Intent(android.content.Intent.ACTION_SEND);
    intent.putExtra(Intent.EXTRA_STREAM, uri);
    intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
    intent.setType("image/png");
    startActivity(intent);
}

这篇关于通过 Android Intent 共享位图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！