我已经比较了其他问题，但他们有不同的问题。 我的问题是，如何显示(在用户 Activity 中)卖家在 firebase 数据库中添加的所有产品？ 卖家在添加产品之前有自己的注册和登录 Activity ，这意味着每个卖家都有自己的名字或 ID。 您可以在下面的图片上查看我的数据库示例。
**Sorry guys I have updated the code but now it is crashing the app every time I click the button to go to the add products activity**
public class SellerAddProductActivity extends AppCompatActivity {
private String saveCurrentDate; private String saveCurrentTime; private String CategoryName; private String downloadImageUrl; private String productRandomKey; private String Description; private String Price, Quantity, State; private String Pname, Store; private Button AddProductButton; private EditText InputProductName; private EditText InputProductPrice, InputStoreName; private EditText InputProductDescription, InputProductQauntity, InputProductState; private StorageReference ProductImageRef; private Uri ImageUri; private DatabaseReference ProductsRef, ProductsInfo; private ProgressDialog loadingBar; private static final int GalleryPick = 1; private ImageView InputProductImage; FirebaseUser currentUser; FirebaseUser mAuth; String userID = mAuth.getUid(); //--> Store each seller name with this ID @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_seller_add_product); ProductImageRef = FirebaseStorage.getInstance().getReference().child("Product Images"); CategoryName = getIntent().getExtras().get("category").toString(); ProductsRef = FirebaseDatabase.getInstance().getReference().child("Products"); ProductsInfo = FirebaseDatabase.getInstance().getReference().child("ProductsInfo"); mAuth = FirebaseAuth.getInstance().getCurrentUser(); AddProductButton = (Button) findViewById(R.id.add_product); InputProductName = (EditText) findViewById(R.id.product_name); InputProductImage = (ImageView) findViewById(R.id.product_image_select); InputProductPrice = (EditText) findViewById(R.id.product_price); InputProductQauntity = (EditText) findViewById(R.id.product_quantity); InputProductState = (EditText) findViewById(R.id.product_state); InputStoreName = (EditText) findViewById(R.id.store_name); loadingBar = new ProgressDialog(this); InputProductDescription = (EditText) findViewById(R.id.product_description); InputProductImage.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { OpenGallery(); } }); AddProductButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { validateProductData(); } }); } private void OpenGallery() { Intent galleryIntent = new Intent(); galleryIntent.setAction(Intent.ACTION_GET_CONTENT); galleryIntent.setType("image/*"); startActivityForResult(galleryIntent, GalleryPick); } @Override protected void onActivityResult (int requestCode, int resultCode, @Nullable Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == GalleryPick && resultCode == RESULT_OK && data != null) { ImageUri = data.getData(); InputProductImage.setImageURI(ImageUri); } } private void validateProductData() { Description = InputProductDescription.getText().toString(); Price = InputProductPrice.getText().toString(); Pname = InputProductName.getText().toString(); Quantity = InputProductQauntity.getText().toString(); State = InputProductState.getText().toString(); Store = InputStoreName.getText().toString(); if (ImageUri == null) { Toast.makeText(this, "Please Add Product Image!", Toast.LENGTH_SHORT).show(); } else if (TextUtils.isEmpty(Description)) { Toast.makeText(this, "Please Enter the Product Description!", Toast.LENGTH_SHORT).show(); } else if (TextUtils.isEmpty(Price)) { Toast.makeText(this, "Please Enter the Product Price!", Toast.LENGTH_SHORT).show(); } else if (TextUtils.isEmpty(Pname)) { Toast.makeText(this, "Please Enter the Product Name!", Toast.LENGTH_SHORT).show(); } else if (TextUtils.isEmpty(Quantity)) { Toast.makeText(this, "Enter Quantity in Number!", Toast.LENGTH_SHORT).show(); } else if (TextUtils.isEmpty(State)) { Toast.makeText(this, "Specify the State of your Product!", Toast.LENGTH_SHORT).show(); } else if (TextUtils.isEmpty(Store)) { Toast.makeText(this, "Store Name is Mandatory!", Toast.LENGTH_SHORT).show(); } else { StoreProductInfo(); } } private void StoreProductInfo() { loadingBar.setTitle("Adding Product"); loadingBar.setMessage("Please wait!"); loadingBar.setCanceledOnTouchOutside(false); loadingBar.show(); Calendar calendar = Calendar.getInstance(); SimpleDateFormat currentDate = new SimpleDateFormat("MMM dd, yyyy"); saveCurrentDate = currentDate.format(calendar.getTime()); SimpleDateFormat currentTime = new SimpleDateFormat("HH:mm:ss a"); saveCurrentTime = currentTime.format(calendar.getTime()); // Unique Random Key for the Products added by the admin productRandomKey = saveCurrentDate + saveCurrentTime; // Unique Random Key to store the image added by the admin final StorageReference filePath = ProductImageRef. child(ImageUri.getLastPathSegment() + productRandomKey + ".jpg"); final UploadTask uploadTask = filePath.putFile(ImageUri); //Displaying the Upload Error to the seller uploadTask.addOnFailureListener(new OnFailureListener() { @Override public void onFailure(@NonNull Exception e) { String message = e.toString(); Toast.makeText(SellerAddProductActivity.this, "Error: " + message, Toast.LENGTH_SHORT).show(); loadingBar.dismiss(); } }).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() { @Override public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) { Toast.makeText(SellerAddProductActivity.this, "Image Uploaded!", Toast.LENGTH_SHORT).show(); Task<Uri> uriTask = uploadTask.continueWithTask(new Continuation<UploadTask.TaskSnapshot, Task<Uri>>() { @Override public Task<Uri> then(@NonNull Task<UploadTask.TaskSnapshot> task) throws Exception { if (!task.isSuccessful()) { throw task.getException(); } downloadImageUrl = filePath.getDownloadUrl().toString(); return filePath.getDownloadUrl(); } }).addOnCompleteListener(new OnCompleteListener<Uri>() { @Override public void onComplete(@NonNull Task<Uri> task) { if (task.isSuccessful()) { downloadImageUrl = task.getResult().toString(); Toast.makeText(SellerAddProductActivity.this, "Product Image Added",Toast.LENGTH_SHORT).show();
SaveProductInfoToDatabase(); } } }); } }); } private void SaveProductInfoToDatabase() { HashMap<String, Object> productMap = new HashMap<>(); productMap.put("pid", productRandomKey); productMap.put("storename", Store); productMap.put("date", saveCurrentDate); productMap.put("time", saveCurrentTime); productMap.put("description", Description); productMap.put("image", downloadImageUrl); productMap.put("Category", CategoryName); productMap.put("state", State); productMap.put("quantity", Quantity); productMap.put("price", Price); productMap.put("pname", Pname); ProductsRef.child("Products").child(userID).child(productRandomKey); ProductsInfo.child(productRandomKey).updateChildren(productMap) .addOnCompleteListener(new OnCompleteListener<Void>() { @Override public void onComplete(@NonNull Task<Void> task) { if (task.isSuccessful()) { Intent intent = new Intent(SellerAddProductActivity.this, SellerAddProductActivity.class); startActivity(intent); loadingBar.dismiss(); Toast.makeText(SellerAddProductActivity.this, "ProductAdded",Toast.LENGTH_SHORT).show(); } else { loadingBar.dismiss(); String message = task.getException().toString(); Toast.makeText(SellerAddProductActivity.this, "Error:"+message,Toast.LENGTH_SHORT).show(); } } }); } }
这是我在买家/用户 Activity 中展示产品的方式
public class HomeActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{
private DatabaseReference productsRef; private RecyclerView recyclerView; RecyclerView.LayoutManager layoutManager; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_home); productsRef = FirebaseDatabase.getInstance().getReference().child("Products"); recyclerView = findViewById(R.id.recycler_menu); recyclerView.setHasFixedSize(true); layoutManager = new LinearLayoutManager(this); recyclerView.setLayoutManager(layoutManager); } @Override protected void onStart() { super.onStart(); FirebaseRecyclerOptions<Products> options = new FirebaseRecyclerOptions.Builder<Products>() .setQuery(productsRef, Products.class).build(); FirebaseRecyclerAdapter<Products, ProductsViewHolder> adapter = new FirebaseRecyclerAdapter<Products, ProductsViewHolder>(options) { @Override protected void onBindViewHolder(@NonNull ProductsViewHolder holder,int position,@NonNull final Products model){ holder.txtProductName.setText(model.getPname()); holder.txtProductPrice.setText("Price " + model.getPrice() + "$"); Picasso.get().load(model.getImage()).into(holder.imageView); //sending the product ID to the ProductDetailsActivity holder.itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent intent = new Intent(HomeActivity.this, ProductDetailsActivity.class); intent.putExtra("pid", model.getPid()); startActivity(intent); } }); } @NonNull @Override public ProductsViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_products,parent,false); ProductsViewHolder holder = new ProductsViewHolder(view); return holder; } }; GridLayoutManager gridLayoutManager = new GridLayoutManager(getApplicationContext(), 2); recyclerView.setLayoutManager(gridLayoutManager); adapter.startListening(); recyclerView.setAdapter(adapter); }
最佳答案
据我了解，您想将所有卖家信息显示到您应用中登录的信息。
为此，您可以在产品内部执行 for 循环以获取每个卖家 ID，然后查询每个用户以获取产品。
但是您需要更改数据库结构以使其更容易。
我建议您在嵌套的子产品中存储该产品的 ID，以便在另一个表中查询。例如
Products
|
--- userID
|
--- Products
|
--- product_key1: true
|
--- product_key2: true
然后在另一个节点中有该产品的信息
ProductsInfo
|
--- product_key1
| |
| --- productName: "Orange"
| |
| --- productPrice: 1
|
--- product_key2
|
--- productName: "Pineapple"
|
--- productPrice: 3
所以现在，我们将只获取每个用户 ID 并获取每个用户的产品
首先，您应该使用 getUid() 来获取每个卖家唯一的 UID，而不是硬编码卖家名称。
FirebaseAuth mAuth;
mAuth = FirebaseAuth.getInstance().getCurrentUser();
String userID = mAuth.getUid(); //--> Store each seller name with this ID
现在我们只是在 Products 中循环以获取每个用户 ID
mRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String userKey = ds.getKey();
Log.d("SellersID", userKey);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
现在您已经拥有所有卖家 key ，您可以在 products 中循环并获取每个卖家的每个产品 key ，然后您现在可以从 ProductsInfo 获取数据节点
关于java - 怎样才能拿到卖家的产品，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55142938/