将 DataSnapshot 中的数据编组到 Android studio 中的自定义 class

Question

我似乎无法弄清楚如何将 datasnapshot 中的数据读入我自己的 class。

这是我尝试这样做的函数：

    private void initializeFirebase(){
    my_db = FirebaseDatabase.getInstance();
    DatabaseReference my_ref = my_db.getReference();
    Map<String, ?> values = sharedPreferences.getAll();

    if (!values.isEmpty()){
        final String id = Profile.getCurrentProfile().getId();
        my_ref = my_ref.child("users").child("userid").child(id);
        if (my_ref != null) my_ref.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
                value = dataSnapshot.getValue(UserData.class);
            }

            @Override
            public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

            }

            @Override
            public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
        mergeClassToSharedPreferences();
    }
    else {
        for (Map.Entry<String, ?> entry : values.entrySet()) {
            my_ref.child("userid").child(Profile.getCurrentProfile().
                    getId()).child(entry.getKey()).setValue(entry);
        }
    }
}

这是我写的class：

 public class UserData {

    public String age, customized_message, dreams_response, gender, intro_response,
            rpp_phone_number, substances_response;
    public boolean relapse_prevention_program, firstrun;
    public int distance;

    public UserData(){

    }

    public UserData(String age, String customized_message, String dreams_response, String gender,
                    String intro_response, String rpp_phone_number, String substances_response,
                    boolean relapse_prevention_program, boolean firstrun, int distance){

        this.age = age;
        this.customized_message = customized_message;
        this.dreams_response = dreams_response;
        this.gender = gender;
        this.intro_response = intro_response;
        this.rpp_phone_number = rpp_phone_number;
        this.substances_response = substances_response;
        this.relapse_prevention_program = relapse_prevention_program;
        this.firstrun = firstrun;
        this.distance = distance;
    }

    public String getAge(){
        return age;
    }
    public String getCustomized_message(){
        return customized_message;
    }
    public String getDreams_response(){
        return dreams_response;
    }
    public String getGender(){
        return gender;
    }
    public String getIntro_response(){
        return intro_response;
    }
    public String getRpp_phone_number(){
        return rpp_phone_number;
    }
    public String getSubstances_response(){
        return substances_response;
    }
    public boolean getRelapse_prevention_program(){
        return relapse_prevention_program;
    }
    public boolean getFirstrun(){
        return firstrun;
    }
    public int getDistance(){
        return distance;
    }

    public void setDreams_response(String dreams_response){
        this.dreams_response = dreams_response;
    }
    public void setGender(String gender){
        this.gender = gender;
    }

    public void setIntro_response(String intro_response){
        this.intro_response = intro_response;
    }
    public void setRpp_phone_number(String rpp_phone_number){
        this.rpp_phone_number = rpp_phone_number;
    }
    public void setAge(String age){
        this.age = age;
    }
    public void setCustomized_message(String customized_message){
        this.customized_message = customized_message;
    }
    public void setSubstances_response(String substances_response){
        this.substances_response = substances_response;
    }
    public void setRelapse_prevention_program(boolean relapse_prevention_program){
        this.relapse_prevention_program = relapse_prevention_program;
    }
    public void setFirstrun(boolean firstrun){
        this.firstrun = firstrun;
    }
    public void setDistance(int distance){
        this.distance = distance;
    }
}

我相信我正在正确访问我的树，但每次我尝试运行这段代码时，它只是报告 "W/ClassMapper: No setter/field for key or value found on class"。 enter image description here

Answer 1

您在实时数据库中对数据建模的方式与 SDK 执行自动序列化的方式不兼容。它只接受 key/value 对，其中键映射到对象中的字段，值匹配每个字段可以包含的数据类型。您的数据结构化为每个字段的对象。如果您使用此结构，则需要编写自定义代码以将所有数据从快照中取出并放入您的 POJO 中。

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