Question

我遵循了教程，并成功地将数据加载到Firebase中，并在RecyclerView中检索回来，还学会了如何删除数据，但现在我不知道如何在Firebase中更新此数据并显示它在RecyclerView.I中使用Picasso作为图像。

这是我的Gallery.java文件

public class Gallery extends AppCompatActivity {

private static final int PICK_IMAGE_REQUEST= 1;

private Button mButtonChooseImage;
private Button mButtonUpload;
private TextView mTextViewShowGallery;
private EditText mEditTextFileName,mEditTextDesc;
private ImageView mImageView;
private ProgressBar mProgressBar;

private Uri mImageUri;

private StorageReference mStorageRef;
private DatabaseReference mDatabaseRef;

private StorageTask mUploadTask;

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

    mButtonChooseImage = (Button)findViewById(R.id.btnChoose);
    mButtonUpload = (Button)findViewById(R.id.btnUpload);
    mTextViewShowGallery = (TextView)findViewById(R.id.tvShow);
    mImageView = (ImageView)findViewById(R.id.imgView);
    mProgressBar = (ProgressBar)findViewById(R.id.progress_bar);
    mEditTextFileName = (EditText)findViewById(R.id.txtName);
    mEditTextDesc = (EditText)findViewById(R.id.txtDesc);

    mStorageRef = FirebaseStorage.getInstance().getReference("uploads");
    mDatabaseRef = FirebaseDatabase.getInstance().getReference("uploads");

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

           openFileChooser();
        }
    });

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

            if (mUploadTask != null && mUploadTask.isInProgress())
            {
                Toast.makeText(Gallery.this, "Upload In Progress", Toast.LENGTH_SHORT).show();
            }
            else
            {
                uploadFile();
            }
        }
    });

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

            openImagesActivity();
        }
    });
}


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

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == PICK_IMAGE_REQUEST && resultCode == RESULT_OK
            && data != null && data.getData() != null)
    {
        mImageUri = data.getData();

        Picasso.with(this).load(mImageUri).into(mImageView);
    }
}

private String getFileExtension(Uri uri)
{
    ContentResolver cR = getContentResolver();
    MimeTypeMap mime = MimeTypeMap.getSingleton();
    return mime.getExtensionFromMimeType(cR.getType(uri));
}


private void uploadFile()
{
    if (mImageUri != null)
    {
        StorageReference fileReference = mStorageRef.child(System.currentTimeMillis()
                + "." + getFileExtension(mImageUri));

        mUploadTask = fileReference.putFile(mImageUri)
                .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

                        Handler handler = new Handler();
                        handler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                mProgressBar.setProgress(0);
                            }
                        },500);

                        Toast.makeText(Gallery.this, "Upload Successful", Toast.LENGTH_LONG).show();
                        UploadImage uploadImage = new UploadImage(mEditTextFileName.getText().toString().trim(),
                                mEditTextDesc.getText().toString().trim(),taskSnapshot.getDownloadUrl().toString());
                        String uploadId = mDatabaseRef.push().getKey();
                        mDatabaseRef.child(uploadId).setValue(uploadImage);
                    }
                })
                .addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {

                        Toast.makeText(Gallery.this,e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                })
                .addOnPausedListener(new OnPausedListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onPaused(UploadTask.TaskSnapshot taskSnapshot) {

                        double progress = (100.0 * taskSnapshot.getBytesTransferred() / taskSnapshot.getTotalByteCount());
                        mProgressBar.setProgress((int)progress);
                    }
                });

    } else {

        Toast.makeText(this, "No File Selected", Toast.LENGTH_SHORT).show();
    }
}

private void openImagesActivity()
{
    Intent intent = new Intent(Gallery.this,ImagesActivity.class);
    startActivity(intent);
}

}

下面的一个是针对recyclerview的ImagesActivity，这里的删除操作正常工作，正如我所提到的，我已经使用AlertDialog打开并更新我试图模仿gallery.java中的一些东西的细节但是不能弄清楚他们应该如何安排。

public class ImagesActivity extends AppCompatActivity implements ImageAdapter.OnItemClickListener {

private RecyclerView mRecyclerView;
private ImageAdapter mAdapter;
private ProgressBar mProgressCircle;
private static final int PICK_IMAGE_REQUEST= 1;
private StorageTask mUploadTask;

private Uri mImageUri;
private StorageReference mStorageRef;

private FirebaseStorage mStorage;
private DatabaseReference mDatabaseRef;
private ValueEventListener mDBListener;

private List<UploadImage> mUploads;

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

    mRecyclerView = findViewById(R.id.recycler_view);
    mProgressCircle= findViewById(R.id.progress_circle);
    mRecyclerView.setHasFixedSize(true);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(this));

    mUploads = new ArrayList<>();


    mAdapter = new ImageAdapter(ImagesActivity.this,mUploads);

    mRecyclerView.setAdapter(mAdapter);

    mAdapter.setOnItemClickListener(ImagesActivity.this);

    mStorage = FirebaseStorage.getInstance();
    mDatabaseRef = FirebaseDatabase.getInstance().getReference("uploads");

    mDBListener = mDatabaseRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            mUploads.clear();

            for (DataSnapshot postSnapshot : dataSnapshot.getChildren()){

                UploadImage uploadImage = postSnapshot.getValue(UploadImage.class);
                uploadImage.setKey(postSnapshot.getKey());
                mUploads.add(uploadImage);
            }

            mAdapter.notifyDataSetChanged();

            mProgressCircle.setVisibility(View.INVISIBLE);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

            Toast.makeText(ImagesActivity.this, databaseError.getMessage(), Toast.LENGTH_SHORT).show();
            mProgressCircle.setVisibility(View.INVISIBLE);
        }
    });


}

private String getFileExtension(Uri uri)
{
    ContentResolver cR = getContentResolver();
    MimeTypeMap mime = MimeTypeMap.getSingleton();
    return mime.getExtensionFromMimeType(cR.getType(uri));
}


@Override
public void onItemClick(int position) {
    Toast.makeText(this, "Normal Click", Toast.LENGTH_SHORT).show();
}



@Override
public void onUpdateClick(int position) {

    AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);
    LayoutInflater inflater = getLayoutInflater();
    final View dialogView = inflater.inflate(R.layout.update_dialog, null);
    dialogBuilder.setView(dialogView);

    final EditText TextName = (EditText) dialogView.findViewById(R.id.txtName);
    final EditText TextDesc = (EditText) dialogView.findViewById(R.id.txtDesc);
    final ImageView ImageView = (ImageView) dialogView.findViewById(R.id.imgView);
    final Button chooseFile = (Button) dialogView.findViewById(R.id.btnChoose);
    final Button UpdateDetails = (Button) dialogView.findViewById(R.id.btnUpdate);

    dialogBuilder.setTitle("Update Details");
    final AlertDialog b = dialogBuilder.create();
    b.show();


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

            openFileChooser();

        }
    });


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

            if (mUploadTask != null && mUploadTask.isInProgress())
            {
                Toast.makeText(ImagesActivity.this, "Upload In Progress", Toast.LENGTH_SHORT).show();
            }
            else
            {
                if (mImageUri != null)
                {
                    StorageReference fileReference = mStorageRef.child(System.currentTimeMillis()
                            + "." + getFileExtension(mImageUri));

                    mUploadTask = fileReference.putFile(mImageUri)
                            .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                                @Override
                                public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {


                                    Toast.makeText(ImagesActivity.this, "Update Successful", Toast.LENGTH_LONG).show();
                                    UploadImage uploadImage = new UploadImage(TextName.getText().toString().trim(),
                                            TextDesc.getText().toString().trim(),taskSnapshot.getDownloadUrl().toString());
                                    String uploadId = mDatabaseRef.push().getKey();
                                    mDatabaseRef.setValue(uploadImage);
                                    mDatabaseRef.child(uploadId).setValue(uploadImage);
                                }
                            })
                            .addOnFailureListener(new OnFailureListener() {
                                @Override
                                public void onFailure(@NonNull Exception e) {

                                    Toast.makeText(ImagesActivity.this,e.getMessage(), Toast.LENGTH_SHORT).show();
                                }
                            });

                } else {

                    Toast.makeText(ImagesActivity.this, "No File Selected", Toast.LENGTH_SHORT).show();
                }

            }

            b.dismiss();

        }

    });



    UploadImage selectedItem = mUploads.get(position);
    final String selectedKey = selectedItem.getKey();
  //  Toast.makeText(this, "Update Clicked", Toast.LENGTH_SHORT).show();

}

private void openFileChooser() {

    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    startActivityForResult(intent,PICK_IMAGE_REQUEST);
}


@Override
public void onDeleteClick(int position) {

    UploadImage selectedItem = mUploads.get(position);
    final String selectedKey = selectedItem.getKey();

    StorageReference imageRef = mStorage.getReferenceFromUrl(selectedItem.getImageUrl());
    imageRef.delete().addOnSuccessListener(new OnSuccessListener<Void>() {
        @Override
        public void onSuccess(Void aVoid) {

            mDatabaseRef.child(selectedKey).removeValue();
            Toast.makeText(ImagesActivity.this, "Item Deleted", Toast.LENGTH_SHORT).show();
        }
    });
}

@Override
protected void onDestroy() {
    super.onDestroy();
    mDatabaseRef.removeEventListener(mDBListener);
}

}

下面是一个名为UploadImage.java的set和get方法

public class UploadImage {

private String mName;
private String mDesc;
private String mImageUrl;
private String mKey;


public UploadImage()
{
    //Empty Constructor Needed
}

public UploadImage(String name, String desc, String imageUrl)
{
    if (name.trim().equals(""))
    {
        name = "No Name";
        desc = "No Description";
    }
    mName = name;
    mDesc = desc;
    mImageUrl = imageUrl;
}

public String getName() {
    return mName;
}

public void setName(String name) {
    mName = name;
}

public String getDesc() {
    return mDesc;
}

public void setDesc(String desc) {
    mDesc=desc;
}

public String getImageUrl() {
    return mImageUrl;
}

public void setImageUrl(String imageUrl) {
    mImageUrl=imageUrl;
}

@Exclude
public String getKey(){
    return mKey;
}

@Exclude
public void setKey(String key){
    mKey = key;
}

}

以下适配器

public class ImageAdapter extends RecyclerView.Adapter<ImageAdapter.ImageViewHolder> {

    private Context mContext;
    private List<UploadImage> mUploads;
    private OnItemClickListener mListener;

    public ImageAdapter(Context context, List<UploadImage> uploads){

        mContext = context;
        mUploads = uploads;
    }

    @Override
    public ImageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View v = LayoutInflater.from(mContext).inflate(R.layout.image_item,parent,false);
        return new ImageViewHolder(v);
    }

    @Override
    public void onBindViewHolder(ImageViewHolder holder, int position) {

        UploadImage uploadImageCurrent = mUploads.get(position);
        holder.textViewName.setText(uploadImageCurrent.getName());
        Picasso.with(mContext)
                .load(uploadImageCurrent.getImageUrl())
                .placeholder(R.drawable.ic_image_black_24dp)
                .fit()
                .centerCrop()
                .into(holder.imageView);
    }

    @Override
    public int getItemCount() {
        return mUploads.size();
    }

    public class ImageViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener,
            View.OnCreateContextMenuListener, MenuItem.OnMenuItemClickListener{

        public TextView textViewName;
        public ImageView imageView;

        public ImageViewHolder(View itemView) {
            super(itemView);

            textViewName = itemView.findViewById(R.id.text_view_name);
            imageView = itemView.findViewById(R.id.image_view_upload);

            itemView.setOnClickListener(this);
            itemView.setOnCreateContextMenuListener(this);
        }

        @Override
        public void onClick(View v) {

            if (mListener != null)
            {
                int position = getAdapterPosition();
                if (position != RecyclerView.NO_POSITION){

                    //To Handle Normal Item Clicks
                    mListener.onItemClick(position);
                }
            }
        }

        @Override
        public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {

            menu.setHeaderTitle("Select Action");
            MenuItem Update = menu.add(Menu.NONE, 1, 1, "Update");
            MenuItem Delete = menu.add(Menu.NONE, 2, 2, "Delete");

            Update.setOnMenuItemClickListener(this);
            Delete.setOnMenuItemClickListener(this);
        }

        @Override
        public boolean onMenuItemClick(MenuItem item) {

            if (mListener != null)
            {
                int position = getAdapterPosition();
                if (position != RecyclerView.NO_POSITION){

                    //To Check Which Menu Item Was Clicked
                    switch (item.getItemId())
                    {
                        case 1:
                            mListener.onUpdateClick(position);
                            return true;
                        case 2:
                            mListener.onDeleteClick(position);
                            return true;
                    }
                }
            }
            return false;
        }
    }

    public interface OnItemClickListener{

        void onItemClick(int position);
        void onUpdateClick(int position);
        void onDeleteClick(int position);
    }

    public void setOnItemClickListener(OnItemClickListener listener){

        mListener = listener;
    }
}

此解决方案如何更新。

Answer 1

firebase存储中没有更新方法，因此需要解决方法：

获取您要删除的文件的名称
删除要更新的文件
上传新文件
使用以前的文件名重命名文件

如何更新Firebase中的图像和文本并在RecyclerView中检索它们

1 个答案: