【发布时间】：2021-07-16 15:55:32
【问题描述】：
我正在为我的学校项目创建一个应用程序，我的编码不是那么先进，所以我提前为我糟糕的编码道歉。所以我正在尝试获取下载的 Uri，所以一旦用户用图片完成表单，我就可以将详细信息上传到实时数据库，以便在我的应用程序的其他部分中使用。
//I use this code below, I got it from the Firebase documents//
ref.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
@Override
public void onSuccess(Uri uri) {
// picUri is a globally declared string and I use it to set my database values,
picUri=(uri.toString());
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception) {
// Handle any errors
}
});
我相信这与 Firebase 方法是异步的事实有关吗？所以 uri.toString() 没有被解析成全局字符串变量？因为我一直在玩，我意识到当我执行 .setValue(object) 将我的对象写入实时数据库时，uri 确实被捕获了，但这太乱了，然后我就无法捕获另一个价值观。我读过我需要写一个回调，那里有很多指南，我真的很困惑。
有人可以指导我参考指南或 youtube 教程，了解如何理解回调并实现回调以获取此值，或者我做错了什么，请指教，谢谢。
照片和其他参数正在成功记录，它只是我无法捕获的图片的uri。 （我暂时将 categoryinput 替换为 picUri 以更轻松地运行测试）
我是新用户，所以我无法上传图片，但数据库和布局的图片是： https://i.ibb.co/YbdSzwB/databasestack.png
https://i.ibb.co/SVG2zxL/stackoverflow.png
我将输入我的整个代码仅供参考
package com.example.giventake;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.widget.*;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.OnProgressListener;
import com.google.firebase.storage.StorageReference;
import com.google.firebase.storage.UploadTask;
import java.io.IOException;
public class ListPage extends AppCompatActivity {
/*Declare all variables I'll be using*/
private EditText title, category, description;
private ImageView image, image2, image3;
private FirebaseAuth mAuth;
private FirebaseStorage storage;
private StorageReference storageReference;
private FirebaseDatabase rootNode;
private DatabaseReference referenceItems;
private Uri filePath;
private Uri filePath2;
private Uri filePath3;
private final int PICK_IMAGE_REQUEST = 1;
private final int PICK_IMAGE2_REQUEST = 2;
private final int PICK_IMAGE3_REQUEST = 3;
String picUri;
/*Declare all variables I'll be using*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
/*Initialise all instances of variables*/
title = (EditText) findViewById(R.id.editTextItemTitle);
category = (EditText) findViewById(R.id.editTextItemCategory);
description = (EditText) findViewById(R.id.editTextItemDescription);
image = (ImageView) findViewById(R.id.imgViewPic);
image2 = (ImageView) findViewById(R.id.imgViewPic2);
image3 = (ImageView) findViewById(R.id.imgViewPic3);
image.setImageResource(R.drawable.ic_baseline_list_24);
image2.setImageResource(R.drawable.ic_baseline_list_24);
image3.setImageResource(R.drawable.ic_baseline_list_24);
storage = FirebaseStorage.getInstance();
storageReference = storage.getReference();
mAuth = FirebaseAuth.getInstance();
rootNode = FirebaseDatabase.getInstance();
referenceItems = rootNode.getReference("Items");
/*Initialise all instances of variables*/
}
/*This is to upload images from your phones direction*/
public void onFirstPicClick(View view) {
Intent i = new Intent();
i.setType("image/*");
i.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(i, "Select Picture"), PICK_IMAGE_REQUEST);
}
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) {
filePath = data.getData();
try {
Bitmap bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), filePath);
image.setImageBitmap(bitmap);
} catch (IOException e) {
e.printStackTrace();
}
}
}
/*This is to upload images from your phones direction*/
public void onSubmitClicked(View view) {
//Fetching data
String titleInput = title.getText().toString().trim();
//String categoryInput = category.getText().toString().trim();
String descriptionInput = description.getText().toString().trim();
String itemId = referenceItems.child(mAuth.getCurrentUser().getUid()).push().getKey();
referenceItems = referenceItems.child(mAuth.getCurrentUser().getUid()).child(itemId);
if (filePath != null) {
StorageReference ref = storageReference.child("Images").child(mAuth.getCurrentUser().getUid()).child(itemId).child("Pic1");
ref.putFile(filePath)
.addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
// Toast.makeText(ListPage.this, "Uploaded", Toast.LENGTH_SHORT).show();
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(ListPage.this, "Picture upload failed" + e.getMessage(), Toast.LENGTH_SHORT).show();
}
})
.addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
@Override
public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
double progress = (100.0 * taskSnapshot.getBytesTransferred() / taskSnapshot
.getTotalByteCount());
}
});
ref.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
@Override
public void onSuccess(Uri uri) {
// Got the download URL for 'users/me/profile.png'
picUri=(uri.toString());
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception) {
// Handle any errors
}
});
}
//ItemsHelperClass item = new ItemsHelperClass(titleInput, categoryInput, descriptionInput, itemId);
ItemsHelperClass item = new ItemsHelperClass(titleInput,picUri,descriptionInput,itemId);
referenceItems.setValue(item).addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if (task.isSuccessful()) {
Intent i = new Intent(ListPage.this, MainActivity.class);
startActivity(i);
finish();
// getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new HomeFragment()).commit();
} else {
//If it fails to add
Toast.makeText(ListPage.this, "Something went wrong, please try again", Toast.LENGTH_LONG).show();
}
}
}
);
}
}
【问题讨论】：
-
picUri=(uri.toString())可能在您的代码使用picUri之前运行。如果您在调试器中运行代码并在这些行上设置断点，则可以轻松验证这一点。修复总是相同的：任何需要下载 URL 的代码都需要在onSuccess内或从那里调用。例如：stackoverflow.com/questions/54563258/…
标签： java android firebase firebase-storage