Firebase自定义Java对象 [英] Firebase to custom Java object

问题描述

  {
users：{
mchen：{
friends：{brinchen：true}，
name：Mary Chen，
widgets：{one：true，three：true} 
}，
brinchen：{...} ，
hmadi：{...} 
} 
} 
  

如何为上面的例子编写自定义对象类？ Firebase中的指南只显示一个简单的例子。和往常一样，您需要一个将JSON中的每个属性映射到Java类的Java类一个字段+ getter：

  static class User {
 String name; 
 Map< String，Boolean>朋友; 
 Map< String，Boolean>小部件; 
 
 public User（）{} 
 
 public String getName（）{return name; } 
 public Map< String，Boolean> getFriends（）{return friends; } 
 public Map< String，Boolean> getWidgets（）{返回小部件; } 
 $ b $ @覆盖
 public String toString（）{
 returnUser {+ 
name ='+ name +'\''+ 
，friends =+ friends + 
，widgets =+ widgets + 
'}'; 
 
 
 
 
 
 
 $ b我真的只是按照这些指令从关于Android数据阅读的Firebase指南：
 
 
我们将创建一个代表博客文章的Java类。与上次一样，我们必须确保我们的字段名称与Firebase数据库中的属性名称相匹配，并为该类提供默认的无参数构造函数。
 
 
然后你可以像这样加载信息： 
 
 
  Firebase ref = new Firebase（https：// stackoverflow.firebaseio.com/34882779/users）; （DataSnapshot userSnapshot：dataSnapshot.getChildren（））的
公共无效onDataChange（DataSnapshot dataSnapshot）{
 $ ref $ addDistenerForSingleValueEvent（new ValueEventListenerBase（）{
 @Override 
 $ b System.out.println（userSnapshot.getKey（）+：+ userSnapshot.getValue（User.class））; 
} 
} 
}）; 
  
有了这个输出：
 
 $ blockquote 
 
 brinchen：用户{name ='Brin Chen'，friends = {mchen = true，hmadi = true}，widgets = {one = true，three = true，two = true}} 
 $ b $ hmadi：User {name ='Horace Madi'，friends = {brinchen = true}，widgets = {one = true，two = true}}  
 
 
 mchen：用户{name ='Mary Chen'，friends = {brinchen = true}，widgets = {one = true，three = true}} 
 
 
{
  "users": {
    "mchen": {
      "friends": { "brinchen": true },
      "name": "Mary Chen",
      "widgets": { "one": true, "three": true }
    },
    "brinchen": { ... },
    "hmadi": { ... }
  }
}
How to write custom object class for the above example? The guides in Firebase only show simple example.
解决方案
As usual, you need a Java class that maps each property from the JSON to a field+getter:
static class User {
    String name;
    Map<String, Boolean> friends;
    Map<String, Boolean> widgets;

    public User() { }

    public String getName() { return name; }
    public Map<String, Boolean> getFriends() { return friends; }
    public Map<String, Boolean> getWidgets() { return widgets; }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", friends=" + friends +
                ", widgets=" + widgets +
                '}';
    }
}
I really just follow these instructions from the Firebase guide on reading data on Android:

  
We'll create a Java class that represents a Blog Post. Like last time, we have to make sure that our field names match the names of the properties in the Firebase database and give the class a default, parameterless constructor.
Then you can load the information like this:
Firebase ref = new Firebase("https://stackoverflow.firebaseio.com/34882779/users");
ref.addListenerForSingleValueEvent(new ValueEventListenerBase() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot userSnapshot: dataSnapshot.getChildren()) {
            System.out.println(userSnapshot.getKey()+": "+userSnapshot.getValue(User.class));
        }
    }
});
With this output:

  
brinchen: User{name='Brin Chen', friends={mchen=true, hmadi=true}, widgets={one=true, three=true, two=true}}
  
  
hmadi: User{name='Horace Madi', friends={brinchen=true}, widgets={one=true, two=true}}
  
  
mchen: User{name='Mary Chen', friends={brinchen=true}, widgets={one=true, three=true}}


                        
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