如何从 onSucces class 更改字符串的值

Question

这里我读了一些我想用来创建“Produs”对象的输入，我将它上传到 firebase 存储，然后我想检索它以显示对象列表，当我想要的时候我遇到了问题更新图像存储的路径，以便稍后检索。

public class Add extends AppCompatActivity {
    DatabaseReference mDatabase;
    EditText etNume, etCantitate, etPret;
    Button btnSubmit, btnImage;
    Uri mImage;
    ImageView ivTest;
    public static String path="";
    StorageReference mStorageRef;
    final int GALLERY_INTENT = 2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add);
        mDatabase = FirebaseDatabase.getInstance().getReference();
        etNume = findViewById(R.id.etNume);
        etCantitate = findViewById(R.id.etCantitate);
        etPret = findViewById(R.id.etPret);
        btnSubmit = findViewById(R.id.btnSubmit);
        btnImage = findViewById(R.id.btnImage);
        ivTest =findViewById(R.id.ivTest);
        mStorageRef = FirebaseStorage.getInstance().getReference();

        btnImage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.setType("image/*");
                startActivityForResult(i, GALLERY_INTENT);
            }
        });



        btnSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String nume, pret,cantitate;
                nume = etNume.getText().toString().trim();
                pret = etPret.getText().toString().trim();
                cantitate = etCantitate.getText().toString().trim();

                if(TextUtils.isEmpty(nume)){
                    etNume.setError("Email is required.");
                    return;
                }
                if(TextUtils.isEmpty(pret)){
                    etPret.setError("Email is required.");
                    return;
                }
                if(TextUtils.isEmpty(cantitate)){
                    etCantitate.setError("Email is required.");
                    return;
                }
                StorageReference file = mStorageRef.child("Produs").child(nume + ".jpg");
                file.putFile(mImage).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                        path += taskSnapshot.getMetadata().toString(); /// good path
                        Toast.makeText(Add.this, path, Toast.LENGTH_SHORT).show();

                    }
                });
                Toast.makeText(Add.this, path, Toast.LENGTH_SHORT).show();/// null path
                Produs p=new Produs(nume,cantitate,pret,path);
                Task task =mDatabase.child("Produs").child(nume).setValue(p);


                task.addOnSuccessListener(new OnSuccessListener() {
                    @Override
                    public void onSuccess(Object o) {
                        Toast.makeText(Add.this, "Produsul a fost adaugat cu succes", Toast.LENGTH_SHORT).show();
                        startActivity(new Intent(getApplicationContext(),MainActivity.class));
                    }
                });

                task.addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Toast.makeText(Add.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                });

            }
        });
    }

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

        if(requestCode == GALLERY_INTENT && resultCode == RESULT_OK && data != null && data.getData() != null){
            mImage = data.getData();
            ivTest.setImageURI(mImage);


        }
    }

}

如何从 onSuccess 方法更改路径？基本上我想在上传图像以构建“Produs”对象后更改路径另外，这是图像存储的好路径吗？因为 taskSnapshot.getdownloadURL() 对我不起作用。

Answer 1

问题不在于您设置和读取 path 变量的位置，问题在于您何时执行此操作。由于 getDownloadURL() 方法调用服务器，它的 onSuccess 可能运行比您想象的要晚得多。

如果您看到 path 的错误值，很可能是设置它的 onSuccess 还没有运行。验证这一点的最简单方法是在调试器中设置读写断点和运行ning，或者添加一些日志记录并检查 logcat.[=23= 中的顺序]

此类问题的解决方案总是相同的：任何需要下载 URL 的代码都需要在 onSuccess 中，从那里调用，或者在某些地方同步其他方式。

因此，在您的情况下，将 `` 移动到 onSuccess:

StorageReference file = mStorageRef.child("Produs").child(nume + ".jpg");
file.putFile(mImage).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
        path += taskSnapshot.getMetadata().toString(); /// good path
        Toast.makeText(Add.this, path, Toast.LENGTH_SHORT).show();

        Toast.makeText(Add.this, path, Toast.LENGTH_SHORT).show();
        Produs p=new Produs(nume,cantitate,pret,path);
        Task task =mDatabase.child("Produs").child(nume).setValue(p);

        task.addOnSuccessListener(new OnSuccessListener() {
            ...
        });

        task.addOnFailureListener(new OnFailureListener() {
            ...
        });
    }
});

有关这方面的更多信息，请参阅：

Can someone help me with logic of the firebase on success listener

并非所有这些都与 Cloud Storage for Firebase 直接相关，但解释也适用于此。

如何从 onSucces class 更改字符串的值

How to change value of string from onSucces class

java

android

firebase

firebase-storage