Android应用程序在使用相机意图捕获图像后崩溃。

huangapple
go评论103阅读模式
英文:

Android App crashes after capturing image using camera intent

问题

该应用程序尝试使用设备的摄像头捕获图像并将其上传到 Firebase。然而，在捕获图像后，应用程序崩溃。

显示以下错误：java.lang.NullPointerException: 尝试在空对象引用上调用虚拟方法 'android.net.Uri android.content.Intent.getData()'

MainActivity 中的函数：

  1. private File createImageFile() throws IOException {
  2.     String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
  3.     String imageFileName = "JPEG_" + timeStamp + "_";
  4.     File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
  5.     File image = File.createTempFile(
  6.             imageFileName,  /* 前缀 */
  7.             ".jpg",         /* 后缀 */
  8.             storageDir      /* 目录 */
  9.     );
  11.     mCurrentPhotoPath = image.getAbsolutePath();
  12.     return image;
  13. }
  15. private void dispatchTakePictureIntent() {
  16.     Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
  18.     if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
  19.         // 创建照片应保存的文件
  20.         File photoFile = null;
  21.         try {
  22.             photoFile = createImageFile();
  23.         } catch (IOException e) {
  24.             Log.e("MainActivity", "创建文件时出错", e);
  25.         }
  26.         if (photoFile != null) {
  27.             photoURI = FileProvider.getUriForFile(this,
  28.                     "com.example.android.fileprovider",
  29.                     photoFile);
  30.             takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
  31.             startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
  32.         }
  33.     }
  34. }
  36. @Override
  37. protected void onCreate(Bundle savedInstanceState) {
  38.     super.onCreate(savedInstanceState);
  39.     setContentView(R.layout.activity_main);
  41.     storage = FirebaseStorage.getInstance().getReference();
  42.     take_pic = (Button) findViewById(R.id.take_pic);
  43.     imageView = (ImageView) findViewById(R.id.pic_view);
  45.     progressDialog = new ProgressDialog(this);
  47.     take_pic.setOnClickListener(new View.OnClickListener() {
  48.         @Override
  49.         public void onClick(View view) {
  50.             dispatchTakePictureIntent();
  51.         }
  52.     });
  53. }
  55. @Override
  56. protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  57.     super.onActivityResult(requestCode, resultCode, data);
  59.     if (requestCode == CAMERA_REQUEST_CODE && resultCode == RESULT_OK) {
  60.         progressDialog.setMessage("上传中...");
  61.         progressDialog.show();
  62.         StorageReference filepath;
  64.         Uri uri = data.getData();
  66.         filepath = storage.child("Photos").child(uri.getLastPathSegment());
  68.         filepath.putFile(photoURI).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
  69.             @Override
  70.             public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
  71.                 Toast.makeText(MainActivity.this, "上传成功！", Toast.LENGTH_SHORT).show();
  72.                 progressDialog.dismiss();
  73.             }
  74.         }).addOnFailureListener(new OnFailureListener() {
  75.             @Override
  76.             public void onFailure(@NonNull Exception e) {
  77.                 Toast.makeText(MainActivity.this, "上传失败！", Toast.LENGTH_SHORT).show();
  78.             }
  79.         });
  80.     }
  81. }

如果您需要进一步的帮助或解释，请告诉我。

英文:

The application attempts to capture an image using the device's camera and upload it to FireBase. However, after an image is captured, the app crashes.

It shows the error: java.lang.NullPointerException: Attempt to invoke virtual method 'android.net.Uri android.content.Intent.getData()' on a null object reference

Functions in MainActivity:

  1.  private File createImageFile() throws IOException {
  2. String timeStamp = new SimpleDateFormat(&quot;yyyyMMdd_HHmmss&quot;).format(new Date());
  3. String imageFileName = &quot;JPEG_&quot; + timeStamp + &quot;_&quot;;
  4. File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
  5. File image = File.createTempFile(
  6. imageFileName,  /* prefix */
  7. &quot;.jpg&quot;,         /* suffix */
  8. storageDir      /* directory */
  9. );
  10. mCurrentPhotoPath = image.getAbsolutePath();
  11. return image;
  12. }
  13. private void dispatchTakePictureIntent() {
  14. Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
  15. if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
  16. // Create the File where the photo should go
  17. File photoFile = null;
  18. try {
  19. photoFile = createImageFile();
  20. } catch (IOException e) {
  21. Log.e(&quot;MainActivity&quot;, &quot;Error creating file&quot;, e);
  22. }
  23. if (photoFile != null) {
  24. photoURI = FileProvider.getUriForFile(this,
  25. &quot;com.example.android.fileprovider&quot;,
  26. photoFile);
  27. takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
  28. startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
  29. }
  30. }
  31. }
  32. @Override
  33. protected void onCreate(Bundle savedInstanceState) {
  34. super.onCreate(savedInstanceState);
  35. setContentView(R.layout.activity_main);
  36. storage = FirebaseStorage.getInstance().getReference();
  37. take_pic = (Button) findViewById(R.id.take_pic);
  38. imageView = (ImageView) findViewById(R.id.pic_view);
  39. progressDialog = new ProgressDialog(this);
  40. take_pic.setOnClickListener(new View.OnClickListener() {
  41. @Override
  42. public void onClick(View view) {
  43. dispatchTakePictureIntent();
  44. }
  45. });
  46. }
  47. @Override
  48. protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  49. super.onActivityResult(requestCode, resultCode, data);
  50. if (requestCode == CAMERA_REQUEST_CODE &amp;&amp; resultCode == RESULT_OK) {
  51. progressDialog.setMessage(&quot;Uploading...&quot;);
  52. progressDialog.show();
  53. StorageReference filepath;
  54. Uri uri = data.getData();
  55. filepath = storage.child(&quot;Photos&quot;).child(uri.getLastPathSegment());
  56. filepath.putFile(photoURI).addOnSuccessListener(new OnSuccessListener&lt;UploadTask.TaskSnapshot&gt;() {
  57. @Override
  58. public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
  59. Toast.makeText(MainActivity.this, &quot;Upload Successful!&quot;, Toast.LENGTH_SHORT).show();
  60. progressDialog.dismiss();
  61. }
  62. }).addOnFailureListener(new OnFailureListener() {
  63. @Override
  64. public void onFailure(@NonNull Exception e) {
  65. Toast.makeText(MainActivity.this, &quot;Upload Failed!&quot;, Toast.LENGTH_SHORT).show();
  66. }
  67. });
  68. }
  69. }

答案1

得分: 1

由于您的意图数据为null，您会收到该错误。这也曾经发生在我身上，当使用拍照意图（take picture intent）时，您的onActivityResult始终将数据返回为null。作为一种解决方法，我将photoURI设置为活动的全局变量，并在onActivityResult中再次调用它。代码如下：

首先，您声明该变量：

  1. Uri myPhotoUri = null;

然后，在dispatchTakePictureIntent函数中初始化它：

  1. private void dispatchTakePictureIntent() {
  2.     Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
  4.     if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
  5.         // 创建照片应该保存的文件
  6.         File photoFile = null;
  7.         try {
  8.             photoFile = createImageFile();
  9.         } catch (IOException e) {
  10.             Log.e("MainActivity", "Error creating file", e);
  11.         }
  12.         if (photoFile != null) {
  14.             // 在这里初始化uri
  15.             myPhotoUri = FileProvider.getUriForFile(this,
  16.                     "com.example.android.fileprovider",
  17.                     photoFile);
  18.             takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, myPhotoUri);
  19.             startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
  20.         }
  21.     }
  22. }

在您的onActivityResult中，您使用该uri来调用您的Firebase函数。它现在将具有上传所需的信息：

  1. @Override
  2. protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  3.     super.onActivityResult(requestCode, resultCode, data);
  5.     if (requestCode == CAMERA_REQUEST_CODE && resultCode == RESULT_OK) {
  6.         progressDialog.setMessage("Uploading...");
  7.         progressDialog.show();
  8.         StorageReference filepath;
  10.         // 不再需要 Uri uri = data.getData();
  11.         filepath = storage.child("Photos").child(myPhotoUri.getLastPathSegment());
  13.         // 在这里调用它
  14.         filepath.putFile(myPhotoUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
  15.             @Override
  16.             public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
  17.                 Toast.makeText(MainActivity.this, "Upload Successful!", Toast.LENGTH_SHORT).show();
  18.                 progressDialog.dismiss();
  19.             }
  20.         }).addOnFailureListener(new OnFailureListener() {
  21.             @Override
  22.             public void onFailure(@NonNull Exception e) {
  23.                 Toast.makeText(MainActivity.this, "Upload Failed!", Toast.LENGTH_SHORT).show();
  24.             }
  25.         });
  26.     }
  27. }

希望这对您有所帮助！

英文:

You are getting that errror because your intent.getData is null. It happened to me too, your onActivityResult when using the take picture intent always brings the data as null. As a workaround I made the photoURI a global variable in the activity and onActivityResult called it again. It would be something like this:

First you declare the variable

  1. Uri myPhotoUri = null;

Then, you initiate it in your dispatchTakePictureIntent function:

  1. private void dispatchTakePictureIntent() {
  2. Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
  3. if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
  4. // Create the File where the photo should go
  5. File photoFile = null;
  6. try {
  7. photoFile = createImageFile();
  8. } catch (IOException e) {
  9. Log.e(&quot;MainActivity&quot;, &quot;Error creating file&quot;, e);
  10. }
  11. if (photoFile != null) {
  12. //you are adding initializing the uri
  13. myPhotoUri = FileProvider.getUriForFile(this,
  14. &quot;com.example.android.fileprovider&quot;,
  15. photoFile);
  16. takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
  17. startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
  18. }
  19. }
  20. }

And on your onActivityResult, you use that uri to call to your firebase function. It will now have the information necessary to upload it:

  1. @Override
  2. protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  3. super.onActivityResult(requestCode, resultCode, data);
  4. if (requestCode == CAMERA_REQUEST_CODE &amp;&amp; resultCode == RESULT_OK) {
  5. progressDialog.setMessage(&quot;Uploading...&quot;);
  6. progressDialog.show();
  7. StorageReference filepath;
  8. //you delete the Uri uri = data.getData();
  9. filepath = storage.child(&quot;Photos&quot;).child(uri.getLastPathSegment());
  10. //here you call it
  11. filepath.putFile(myPhotoUri).addOnSuccessListener(new OnSuccessListener&lt;UploadTask.TaskSnapshot&gt;() {
  12. @Override
  13. public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
  14. Toast.makeText(MainActivity.this, &quot;Upload Successful!&quot;, Toast.LENGTH_SHORT).show();
  15. progressDialog.dismiss();
  16. }
  17. }).addOnFailureListener(new OnFailureListener() {
  18. @Override
  19. public void onFailure(@NonNull Exception e) {
  20. Toast.makeText(MainActivity.this, &quot;Upload Failed!&quot;, Toast.LENGTH_SHORT).show();
  21. }
  22. });
  23. }
  24. }

答案2

得分: 0

首先检查是否具有使用相机的权限，然后

  1. Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
  2. startActivityForResult(cameraIntent, CAMERA_REQ);

然后在onActivityResult中

  1. @Override
  2. public void onActivityResult(int requestCode, int resultCode, Intent data) {
  3.     super.onActivityResult(requestCode, resultCode, data);
  4.     if (requestCode == CAMERA_REQ && resultCode == Activity.RESULT_OK) {
  5.         bitmap = (Bitmap) data.getExtras().get("data");
  6.         Bitmap.createScaledBitmap(bitmap, 150, 150, true);
  7.     }
  8. }

然后从位图转换为字节数组

  1. public static byte[] getByteArrayFromBitmap(Bitmap bitmap) {
  2.     if(bitmap == null) return null;
  4.     ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
  5.     bitmap.compress(Bitmap.CompressFormat.JPEG, 50, byteArrayOutputStream);
  7.     return byteArrayOutputStream.toByteArray();
  8. }

现在你可以使用位图或字节数组做任何你想做的事情。

英文:

First check that you have permission for using the camera, then

  1. Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
  2. startActivityForResult(cameraIntent, CAMERA_REQ);

Then onActivityResult

  1. @Override
  2. public void onActivityResult(int requestCode, int resultCode, Intent data) {
  3. super.onActivityResult(requestCode, resultCode, data);
  4. if (requestCode == CAMERA_REQ &amp;&amp; resultCode == Activity.RESULT_OK) {
  5. bitmap = (Bitmap) data.getExtras().get(&quot;data&quot;);
  6. Bitmap.createScaledBitmap(bitmap, 150, 150, true);
  7. }
  8. }

then from bitmap to byte[]

  1. public static byte[] getByteArrayFromBitmap(Bitmap bitmap) {
  2. if(bitmap == null) return null;
  3. ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
  4. bitmap.compress(Bitmap.CompressFormat.JPEG, 50, byteArrayOutputStream);
  5. return byteArrayOutputStream.toByteArray();
  6. }

You can now do whatever you want with the bitmap or byte[]

huangapple
  • 本文由 发表于 2020年8月5日 21:39:17
  • 转载请务必保留本文链接：https://go.coder-hub.com/63266464.html
  • android
  • firebase-storage
  • java
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定