Android - 拍照并通过 Intent 使用自定义名称将它们保存到自定义目的地

Question

我有一个程序可以通过 Intent 打开相机拍照。很多部分已经可以正常工作了。但是，我希望它保存到具有特定文件名的特定文件夹(文件名是可选的，但它真的很有帮助)。

这就是我目前所拥有的。

这是打开相机的代码行:

//TODO camera stuff.
Intent openCam = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

//The two lines of code below were commented out at first.
//They were eventually added when I tried to save it with a custom name and destination
fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE); // create a file to save the image
openCam.putExtra(MediaStore.EXTRA_OUTPUT, fileUri); // set the image file name

startActivityForResult(openCam, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);

结果处理程序在这里:

//TODO handle result
if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
   if (resultCode == RESULT_OK) {
         // Image captured and saved to fileUri specified in the Intent
         Toast.makeText(this, "Image saved to:\n" +
                     data.getData(), Toast.LENGTH_LONG).show();
            System.out.println("I am here");

   } 
   else if (resultCode == RESULT_CANCELED) {
            // User cancelled the image capture
   } 
   else {
            // Image capture failed, advise user
   }
}

在我实现以下两种方法之前，代码运行良好。但是，它以默认文件名(时间戳版本)保存到默认文件夹。 toast 显示“Imaged saved to: null”，因为我还没有设置那部分。

所以这里是应该处理自定义文件名和目的地的方法

/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type){
      return Uri.fromFile(getOutputMediaFile(type));
}

/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
    // To be safe, you should check that the SDCard is mounted
    // using Environment.getExternalStorageState() before doing this.

    Environment.getExternalStorageState();

    File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
              Environment.DIRECTORY_PICTURES), "MyCameraApp");
    // This location works best if you want the created images to be shared
    // between applications and persist after your app has been uninstalled.

    // Create the storage directory if it does not exist
    if (! mediaStorageDir.exists()){
        if (! mediaStorageDir.mkdirs()){
            Log.d("MyCameraApp", "failed to create directory");
            return null;
        }
    }

    // Create a media file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    File mediaFile;
    if (type == MEDIA_TYPE_IMAGE){
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
        "IMG_"+ timeStamp + ".jpg");
    } else {
        return null;
    }

    return mediaFile;
}

*这些代码摘自 developer.android.com 的相机指南。

上面的代码设法打开相机并拍照并保存。但是，当用户决定停止拍照并按下返回键时，就会出现问题。发生的情况是应用程序强制关闭并给出此错误:

10-21 12:44:33.699: E/AndroidRuntime(13016): FATAL EXCEPTION: main
10-21 12:44:33.699: E/AndroidRuntime(13016): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=100, result=-1, data=null} to activity {com.AIC.QRCodeScanner/com.AIC.QRCodeScanner.QRCodeScanner}: java.lang.NullPointerException
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.app.ActivityThread.deliverResults(ActivityThread.java:2536)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.app.ActivityThread.handleSendResult(ActivityThread.java:2578)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.app.ActivityThread.access$2000(ActivityThread.java:117)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:965)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.os.Handler.dispatchMessage(Handler.java:99)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.os.Looper.loop(Looper.java:123)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.app.ActivityThread.main(ActivityThread.java:3691)
10-21 12:44:33.699: E/AndroidRuntime(13016): at java.lang.reflect.Method.invokeNative(Native Method)
10-21 12:44:33.699: E/AndroidRuntime(13016): at java.lang.reflect.Method.invoke(Method.java:507)
10-21 12:44:33.699: E/AndroidRuntime(13016): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847)
10-21 12:44:33.699: E/AndroidRuntime(13016): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
10-21 12:44:33.699: E/AndroidRuntime(13016): at dalvik.system.NativeStart.main(Native Method)
10-21 12:44:33.699: E/AndroidRuntime(13016): Caused by: java.lang.NullPointerException
10-21 12:44:33.699: E/AndroidRuntime(13016): at com.AIC.QRCodeScanner.QRCodeScanner.onActivityResult(QRCodeScanner.java:379)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.app.Activity.dispatchActivityResult(Activity.java:3934)
10-21 12:44:33.699: E/AndroidRuntime(13016): at android.app.ActivityThread.deliverResults(ActivityThread.java:2532)
10-21 12:44:33.699: E/AndroidRuntime(13016):    
... 11 more

它指向的行是这一行(第 379 行):data.getData(), Toast.LENGTH_LONG

但是，文件与拍摄的 Instagram 照片一起保存在文件夹 /Pictures/MyCameraApp 中。

所以问题是: 1、有没有办法让onActivityResult正常工作？我知道我只能求助于使用 startActivity 以免终止该应用程序。 2.有没有办法只用相机拍一张？因此，在用户保存照片后，应用会返回主 Activity 。 3、还有，我可以把它保存到我自己的文件夹里吗？我不确定为什么它会将照片保存在 /Pictures/MyCameraApp 中，我希望它只保存到 /MyCameraApp。

我想我在这里错过了一些简单的东西。

Answer 1

这是使它工作的代码:

//camera stuff
Intent imageIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());

//folder stuff
File imagesFolder = new File(Environment.getExternalStorageDirectory(), "MyImages");
imagesFolder.mkdirs();

File image = new File(imagesFolder, "QR_" + timeStamp + ".png");
Uri uriSavedImage = Uri.fromFile(image);

imageIntent.putExtra(MediaStore.EXTRA_OUTPUT, uriSavedImage);
startActivityForResult(imageIntent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);

它打开相机并精确拍摄一张照片(在用户保存拍摄的图像后返回主 Activity 。它将图像保存到指定的文件夹。