android - 如何使用模型类从 Firebase 数据库中获取数据

Question

如何使用模型类从 firbase 数据库中获取数据？

Answer 1

您的模型，根据您要检索的数据应该是这样的（假设您只想要关键字和单词）

 public class Model {

    private String key;
    private String word;
    private String baseText;
    private String mainText;
    private String type;
    private String url;

    public Model() {
    }

    public String getKey() {
        return key;
    }

    public void setKey(String key) {
        this.key = key;
    }

    public String getWord() {
        return word;
    }

    public void setWord(String word) {
        this.word = word;
    }

    public String getBaseText() {
        return baseText;
    }

    public void setBaseText(String baseText) {
        this.baseText = baseText;
    }

    public String getMainText() {
        return mainText;
    }

    public void setMainText(String mainText) {
        this.mainText = mainText;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }
}

然后，您可以通过此操作获取该数据

ref.addValueEventListener(new ValueEventListener() {
  @Override
  public void onDataChange(DataSnapshot dataSnapshot) {
    Model model = dataSnapshot.getValue(Model.class);
    log.d("Key: "+model.getKey() + " word: " + model.getWord());
  }

  @Override
  public void onCancelled(DatabaseError databaseError) {
    System.out.println("The read failed: " + databaseError.getCode());
  }
});

ref您DatabaseReference要提取数据的节点在哪里

参考这个链接

https://firebase.google.com/docs/database/admin/retrieve-data?hl=en#section-start

Answer 2

Let ref be your DatabaseReference then addValueEventListener

Example:

ref.addValueEventListener(new ValueEventListener() {
    public void onDataChange(DataSnapshot dataSnapshot){
       DataModel model = dataSnapshot.getValue(DataModel.class);
    }
}

The same thing can be done with any class, like if you want to get an output of

String -> getValue(String.class)
Integer -> getValue(Integer.class)