Firebase 数据库没有显示图片

Question

因此，当我上传图片时，我将图片保存到应用程序的数据库中。它将它正确地上传到存储和数据库，但是当我重新启动应用程序时它没有显示它。 我使用方法filechooser() 选择文件并使用fileuploader() 上传。它工作得很好。

enter code herepublic class ProfilBearbeiten extends AppCompatActivity  {




Button bestätigen;
private SharedPreferences speicher;
private SharedPreferences.Editor editor;
TextView fullName,email;
EditText ort,beschreibung, telefonummer, interessen;
FirebaseAuth fAuth;
FirebaseFirestore fStore;
String userId;
ImageView user;
Uri imageurl;
StorageReference mStorageRef;

private StorageTask uploadtask;
private Bitmap compressor;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.profilbearbeiten);

    fAuth = FirebaseAuth.getInstance();
    fStore = FirebaseFirestore.getInstance();
    FirebaseDatabase database = FirebaseDatabase.getInstance();
    mStorageRef= FirebaseStorage.getInstance().getReference().child("Images");
    DatabaseReference reference = database.getReference();

    userId = fAuth.getCurrentUser().getUid();
    fullName = findViewById(R.id.tv_name);
    email    = findViewById(R.id.tvEmail);
    bestätigen = findViewById(R.id.btbestätigen);
    ort = findViewById(R.id.tv_address);
    telefonummer = findViewById(R.id.tvTel);
    interessen = findViewById(R.id.tvInt);
    beschreibung = findViewById(R.id.tvBesc);
    user = findViewById(R.id.User);


    user.setOnClickListener(new View.OnClickListener() {
                                @Override
                                public void onClick(View view) {
                                    filechooser();
                              //      fileuploader();

                                    Picasso.get().load(imageurl).into(user);


                                }
                            });


            bestätigen.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

                    // get Information from Edit Text or fileuploader()
                    final String eemail = email.getText().toString().trim();
                    final String efullname = fullName.getText().toString();
                    final String eort = ort.getText().toString();
                    final String einteresssen = interessen.getText().toString();
                    final String ebeschreibung = beschreibung.getText().toString();
                    final String etelefonnummer = telefonummer.getText().toString();
                    final String bild = "";
                    final String image = imageurl != null ? imageurl.toString() : null;


                    userId = fAuth.getCurrentUser().getUid();
                    DocumentReference documentReference = fStore.collection("users").document(userId);

                    //save edited Information in Database

                        Map<String, Object> user = new HashMap<>();
                        user.put("Benutername", efullname);
                        user.put("EMail", eemail);
                        user.put("Ort", eort);
                        user.put("Interessen", einteresssen);
                        user.put("Beschreibung", ebeschreibung);
                        user.put("Telefonnummer", etelefonnummer);
                        user.put("Image", image);
                        documentReference.set(user);


                    Intent intent = new Intent(ProfilBearbeiten.this, Profile.class);
                    startActivity(intent);
                    fileuploader();
                }
            });
    DocumentReference documentReference = fStore.collection("users").document(userId);
    documentReference.addSnapshotListener(this, new EventListener<DocumentSnapshot>() {
        @Override
        public void onEvent(@Nullable DocumentSnapshot documentSnapshot, @Nullable FirebaseFirestoreException e) {

            fullName.setText(documentSnapshot.getString("Benutername"));
            email.setText(documentSnapshot.getString("EMail"));
            ort.setText(documentSnapshot.getString("Ort"));
            telefonummer.setText(documentSnapshot.getString("Telefonnummer"));
            interessen.setText(documentSnapshot.getString("Interessen"));
            beschreibung.setText(documentSnapshot.getString("Beschreibung"));
            Picasso.get().load(documentSnapshot.getString("Image")).into(user);


        }
    });





}
// uploads and open gallery on device
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode== 1 && resultCode==RESULT_OK && data != null && data.getData() != null){
        imageurl=data.getData();
        user.setImageURI(imageurl);

    }
}

private void filechooser(){
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(intent, 1);


}

private String getExtension(Uri uri) {
    ContentResolver cr = getContentResolver();
    MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
    return mimeTypeMap.getExtensionFromMimeType(cr.getType(uri));
}


private void fileuploader () {
        StorageReference Ref = mStorageRef.child(System.currentTimeMillis()+","+getExtension(imageurl));
        uploadtask = Ref.putFile(imageurl)
            .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                @Override
                public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

                    // Get a URL to the uploaded content
                    Toast.makeText(ProfilBearbeiten.this, "Image Uploaded", Toast.LENGTH_LONG).show();

                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception exception) {
                    // Handle unsuccessful uploads
                    // ...
                }
            });
}

}

如您所见。 URL 保存在数据库中的图像下。当我上传图片并切换到其他页面时，当我回到这张幻灯片时，将显示图片。但是每当我关闭应用程序并重新启动它时，即使 URL 仍然以相同的方式在数据库中，图片也会消失。也许我的错误是如何加载它？ Picasso.get().load(documentSnapshot.getString("Image")).into(user);

Answer 1

您在数据库中存储的 URL 是将其上传到 Cloud Storage 的设备上的图像的本地 URL。它是特定 Android 设备上的本地路径，相机在其中写入文件。

虽然此 URL 最初可以在该特定设备上运行，但以后可能无法运行（因为文件可能会被 Android 清理），并且它肯定不会在其他设备上运行（因为图像不存在那里） )。

要拥有一个可以随时随地使用的 URL，您需要生成一个所谓的下载 URL，并将 那个 值存储在数据库中。您通常在上传图片后立即执行此操作，并调用 getDownloadURL：

StorageReference Ref = mStorageRef.child(System.currentTimeMillis()+","+getExtension(imageurl));
uploadtask = Ref.putFile(imageurl)
    .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
            Toast.makeText(ProfilBearbeiten.this, "Image Uploaded", Toast.LENGTH_LONG).show();
            // Get a URL to the uploaded content
            Ref.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                @Override
                public void onSuccess(Uri uri) {
                    // Got the download URL, so write it to the database
                    userId = fAuth.getCurrentUser().getUid();
                    DocumentReference documentReference = fStore.collection("users").document(userId);

                    documentReference.update("Image", uri.toString());
                }
            }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception exception) {
                    // Handle any errors
                }
        }
    })
    .addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception exception) {
            // Handle unsuccessful uploads
            // ...
        }
    });

另请参阅uploading files 上的文档，其中还显示了如何防止嵌套任务失败处理程序。