java - Android - 将具有 Firebase 功能的监听器保留在类之外

Question

我想在 MVC 中编写我的应用程序。问题是我是 Android 新手，如果函数不在主类中，我不知道如何拥有监听器/回调。

public void addNewUser(String firstname, String lastname, String email, Integer gender, String uid, String profileImageUrl){

        Map<String, Object> data = new HashMap<>();
        data.put("firstname", firstname);
        data.put("lastname", lastname);
        data.put("email", email);
        data.put("gender", gender);
        data.put("boxId", "independent");
        data.put("notificationsEnabled", true);
        data.put("profileImageUrl", profileImageUrl);

        mFirebaseFirestore.collection("usersP").add(data)
                .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                    @Override
                    public void onSuccess(DocumentReference documentReference) {
                        mProgressBar.setVisibility(View.GONE);

                        mIRegisterActivity.inflateFragment("Register Box", mHashMap);
                        Log.d(TAG, "DocumentSnapshot written with ID: " + documentReference.getId());
                    }
                })
                .addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Log.d(TAG, "Error adding document", e);
                    }
                });

    }

我想在不同的 Java 类中使用此函数。但如果我这样做，我不知道如何仅在函数完成执行时才能启动操作 -> 换句话说，当它是 addOnSuccessListener 时。

你知道我该怎么做吗？

我习惯用 swift 编码，它会是这样的:

func addUser(id: String, completion: @escaping (User) -> Void) {
      // Code and then
      completion(user)
   }

Answer 1

您应该为 MyFirebaseListener 创建您的自己的自定义监听器，并通过实现此接口(interface)来更新 Activity 中的内容

public interface MyFirebaseListener {
    void onSuccess(DocumentReference documentReference)
    void onFailure(Exception e)
}

现在将Activity作为参数传递给MyFirebaseListener到addNewUser()方法，如下所示

public class UserApi{

    public void addNewUser(String firstname, 
                String lastname, 
                String email, 
                Integer gender, 
                String uid, 
                String profileImageUrl,
                MyFirebaseListener myFirebaseListener){

        Map<String, Object> data = new HashMap<>();
        data.put("firstname", firstname);
        data.put("lastname", lastname);
        data.put("email", email);
        data.put("gender", gender);
        data.put("boxId", "independent");
        data.put("notificationsEnabled", true);
        data.put("profileImageUrl", profileImageUrl);

        mFirebaseFirestore.collection("usersP").add(data)
                .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                    @Override
                    public void onSuccess(DocumentReference documentReference) {
                        myFirebaseListener.onSuccess(documentReference)
                    }
                })
                .addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        myFirebaseListener.onFailure(e)
                    }
                });

    }
}

在您的 Activity 中实现 MyFirebaseListener 接口(interface)，因此您需要重写以下方法，并在这些实现的方法中执行UI修改，如下所示

public class MyActivity extends AppCompatActivity implements MyFirebaseListener {

    void someMethod(){
        addNewUser(firstname, 
                lastname, 
                email, 
                gender,
                uid,
                profileImageUrl,
                this) // <- This will be reference to Activity with Type of MyFirebaseListener
    }

    void onSuccess(DocumentReference documentReference){
        mProgressBar.setVisibility(View.GONE);
        mIRegisterActivity.inflateFragment("Register Box", mHashMap);
        Log.d(TAG, "DocumentSnapshot written with ID: " + documentReference.getId());
    }
    void onFailure(Exception e){
        Log.d(TAG, "Error adding document", e);
    }
}

这就是您如何使用自定义界面分离UI 逻辑和服务逻辑