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:
private File createImageFile() throws IOException {
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String imageFileName = "JPEG_" + timeStamp + "_";
File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
File image = File.createTempFile(
imageFileName, /* 前缀 */
".jpg", /* 后缀 */
storageDir /* 目录 */
);
mCurrentPhotoPath = image.getAbsolutePath();
return image;
}
private void dispatchTakePictureIntent() {
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
// 创建照片应保存的文件
File photoFile = null;
try {
photoFile = createImageFile();
} catch (IOException e) {
Log.e("MainActivity", "创建文件时出错", e);
}
if (photoFile != null) {
photoURI = FileProvider.getUriForFile(this,
"com.example.android.fileprovider",
photoFile);
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
}
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
storage = FirebaseStorage.getInstance().getReference();
take_pic = (Button) findViewById(R.id.take_pic);
imageView = (ImageView) findViewById(R.id.pic_view);
progressDialog = new ProgressDialog(this);
take_pic.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
dispatchTakePictureIntent();
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQUEST_CODE && resultCode == RESULT_OK) {
progressDialog.setMessage("上传中...");
progressDialog.show();
StorageReference filepath;
Uri uri = data.getData();
filepath = storage.child("Photos").child(uri.getLastPathSegment());
filepath.putFile(photoURI).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
Toast.makeText(MainActivity.this, "上传成功!", Toast.LENGTH_SHORT).show();
progressDialog.dismiss();
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(MainActivity.this, "上传失败!", Toast.LENGTH_SHORT).show();
}
});
}
}
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:
private File createImageFile() throws IOException {
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 */
);
mCurrentPhotoPath = image.getAbsolutePath();
return image;
}
private void dispatchTakePictureIntent() {
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
// Create the File where the photo should go
File photoFile = null;
try {
photoFile = createImageFile();
} catch (IOException e) {
Log.e("MainActivity", "Error creating file", e);
}
if (photoFile != null) {
photoURI = FileProvider.getUriForFile(this,
"com.example.android.fileprovider",
photoFile);
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
}
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
storage = FirebaseStorage.getInstance().getReference();
take_pic = (Button) findViewById(R.id.take_pic);
imageView = (ImageView) findViewById(R.id.pic_view);
progressDialog = new ProgressDialog(this);
take_pic.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
dispatchTakePictureIntent();
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQUEST_CODE && resultCode == RESULT_OK) {
progressDialog.setMessage("Uploading...");
progressDialog.show();
StorageReference filepath;
Uri uri = data.getData();
filepath = storage.child("Photos").child(uri.getLastPathSegment());
filepath.putFile(photoURI).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
Toast.makeText(MainActivity.this, "Upload Successful!", Toast.LENGTH_SHORT).show();
progressDialog.dismiss();
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(MainActivity.this, "Upload Failed!", Toast.LENGTH_SHORT).show();
}
});
}
}
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:
Uri myPhotoUri = null;
然后,在dispatchTakePictureIntent函数中初始化它:
private void dispatchTakePictureIntent() {
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
// 创建照片应该保存的文件
File photoFile = null;
try {
photoFile = createImageFile();
} catch (IOException e) {
Log.e("MainActivity", "Error creating file", e);
}
if (photoFile != null) {
// 在这里初始化uri
myPhotoUri = FileProvider.getUriForFile(this,
"com.example.android.fileprovider",
photoFile);
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, myPhotoUri);
startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
}
}
}
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:
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQUEST_CODE && resultCode == RESULT_OK) {
progressDialog.setMessage("Uploading...");
progressDialog.show();
StorageReference filepath;
// 不再需要 Uri uri = data.getData();
filepath = storage.child("Photos").child(myPhotoUri.getLastPathSegment());
// 在这里调用它
filepath.putFile(myPhotoUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
Toast.makeText(MainActivity.this, "Upload Successful!", Toast.LENGTH_SHORT).show();
progressDialog.dismiss();
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(MainActivity.this, "Upload Failed!", Toast.LENGTH_SHORT).show();
}
});
}
}
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
Uri myPhotoUri = null;
Then, you initiate it in your dispatchTakePictureIntent function:
private void dispatchTakePictureIntent() {
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
// Create the File where the photo should go
File photoFile = null;
try {
photoFile = createImageFile();
} catch (IOException e) {
Log.e("MainActivity", "Error creating file", e);
}
if (photoFile != null) {
//you are adding initializing the uri
myPhotoUri = FileProvider.getUriForFile(this,
"com.example.android.fileprovider",
photoFile);
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
startActivityForResult(takePictureIntent, CAMERA_REQUEST_CODE);
}
}
}
And on your onActivityResult, you use that uri to call to your firebase function. It will now have the information necessary to upload it:
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQUEST_CODE && resultCode == RESULT_OK) {
progressDialog.setMessage("Uploading...");
progressDialog.show();
StorageReference filepath;
//you delete the Uri uri = data.getData();
filepath = storage.child("Photos").child(uri.getLastPathSegment());
//here you call it
filepath.putFile(myPhotoUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
Toast.makeText(MainActivity.this, "Upload Successful!", Toast.LENGTH_SHORT).show();
progressDialog.dismiss();
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(MainActivity.this, "Upload Failed!", Toast.LENGTH_SHORT).show();
}
});
}
}
答案2
得分: 0
首先检查是否具有使用相机的权限,然后
Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQ);
然后在onActivityResult中
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQ && resultCode == Activity.RESULT_OK) {
bitmap = (Bitmap) data.getExtras().get("data");
Bitmap.createScaledBitmap(bitmap, 150, 150, true);
}
}
然后从位图转换为字节数组
public static byte[] getByteArrayFromBitmap(Bitmap bitmap) {
if(bitmap == null) return null;
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 50, byteArrayOutputStream);
return byteArrayOutputStream.toByteArray();
}
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
Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQ);
Then onActivityResult
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQ && resultCode == Activity.RESULT_OK) {
bitmap = (Bitmap) data.getExtras().get("data");
Bitmap.createScaledBitmap(bitmap, 150, 150, true);
}
}
then from bitmap to byte[]
public static byte[] getByteArrayFromBitmap(Bitmap bitmap) {
if(bitmap == null) return null;
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 50, byteArrayOutputStream);
return byteArrayOutputStream.toByteArray();
}
You can now do whatever you want with the bitmap or byte[]
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