Json_tree.txt

{users:[
	{
	  "id": "00000000-0000-0000-0000-000000000000",
	  "createTime": "0001-01-01 00:00:00",
	  "level": 0,
	  "nick": "string",
	  "gender": false,
	  "birthday": "0001-01-01 00:00:00",
	  "cellphoneNumber": "string",
	  "emailAddress": "string",
	  "name": "string",
	  "picture": "string""address": "string"
	},
	{...},
	{...},
	]
}


{
  // Chats contains only meta info about each conversation
  // stored under the chats's unique ID
  "chats": {

  chatlist:[
  { {
      "title": "Historical Tech Pioneers",
      "lastMessage": "ghopper: Relay malfunction found. Cause: moth.",
      "timestamp": 1459361875666,
      "member":"天涯恋",
	"fridlogo":"pic"
	"messageid":"青青"
    }},
    { ... },
    { ... }]
   
  },


  // Messages are separate from data we may want to iterate quickly
  // but still easily paginated and queried, and organized by chat
  // converation ID
  "messages": {
    "青青": {
      "m1": {
        "name": "eclarke",
        "message": "The relay seems to be malfunctioning.",
        "timestamp": 1459361875337
      },
      "m2": { ... },
      "m3": { ... }
    },
    "明明": { ... },
    "亮亮": { ... }
  }
}


{
  // Chats contains only meta info about each conversation
  // stored under the chats's unique ID
  "chats": {
    chatlist: [
      {
        {
          "title": "Historical Tech Pioneers",
          "lastMessage": "ghopper: Relay malfunction found. Cause: moth.",
          "timestamp": 1459361875666,
          "member": "天涯恋",
          "fridlogo": "pic""messageid": "青青"
        }
      }
      ,
    { ... },
    { ... }
    ]
  },

   // Messages are separate from data we may want to iterate quickly
  // but still easily paginated and queried, and organized by chat
  // converation ID

  "messages": {
    "青青": {
      "m1": {
        "name": "eclarke",
        "message": "The relay seems to be malfunctioning.",
        "timestamp": 1459361875337
      }
      ,
      "m2": { ... },
      "m3": { ... }
    }
  ,
    "明明": { ... },
    "亮亮": { ... }
  }
}







完成对象:

{
  users:{userid:
    {
      "id": "00000000-0000-0000-0000-000000000000",
      "createTime": "0001-01-01 00:00:00",
      "level": "1",
      "nick": "dingding",
      "isOnline": false,
      "birthday": "0001-01-01 00:00:00",
      "cellphoneNumber": "15617771050",
      "emailAddress": "ake@gmail.com",
      "name": "ake",
      "picture": "string",
      "address": "科学大道"
    }
    }
  
}


{
  "chats": {
    chatlist: [
      {
        {
          "title": "Historical Tech Pioneers",
          "lastMessage": "ghopper: Relay malfunction found. Cause: moth.",
          "timestamp": 1459361875666,
          "member": "天涯恋",
          "fridlogo": "pic",
	  "messageid": "青青"
        }
      }
    ]
  },
  "messages": {
    "青青": {[
      {
        "name": "eclarke",
        "message": "The relay seems to be malfunctioning.",
        "timestamp": 1459361875337
      }]
    }
  }
}


https://firebase.google.com/docs/database/android/structure-data



避免嵌套数据

因为 Firebase Realtime Database 允许嵌套数据的深度多达 32 层，您可能不禁认为嵌套应是默认结构。然而，当您提取数据库中某个位置的数据时，也会检索所有子节点。另外，当您向某用户授予数据库中某个节点的读写访问权时，也会将该节点下所有数据的访问权授予该用户。因此，在实践中建议最好将您的数据结构平面化。

为举例说明为什么嵌套数据不正确，现假设一个如下所示的多层嵌套结构：

{
  // This is a poorly nested data architecture, because iterating the children
  // of the "chats" node to get a list of conversation titles requires
  // potentially downloading hundreds of megabytes of messages
  "chats": {
    "one": {
      "title": "Historical Tech Pioneers",
      "messages": {
        "m1": { "sender": "ghopper", "message": "Relay malfunction found. Cause: moth." },
        "m2": { ... },
        // a very long list of messages
      }
    },
    "two": { ... }
  }
}
若采用这种嵌套设计，循环访问数据就会出现问题。例如，要列出聊天对话标题，就需要将整个 chats 树（包括所有成员和消息）都下载到客户端。

平展数据结构

如果数据被拆分到不同路径（又称反规范化），则可根据需要通过不同调用有效地下载。 请考虑此平面化结构：

{
  // Chats contains only meta info about each conversation
  // stored under the chats's unique ID
  "chats": {
    "one": {
      "title": "Historical Tech Pioneers",
      "lastMessage": "ghopper: Relay malfunction found. Cause: moth.",
      "timestamp": 1459361875666
    },
    "two": { ... },
    "three": { ... }
  },

  // Conversation members are easily accessible
  // and stored by chat conversation ID
  "members": {
    // we'll talk about indices like this below
    "one": {
      "ghopper": true,
      "alovelace": true,
      "eclarke": true
    },
    "two": { ... },
    "three": { ... }
  },

  // Messages are separate from data we may want to iterate quickly
  // but still easily paginated and queried, and organized by chat
  // converation ID
  "messages": {
    "one": {
      "m1": {
        "name": "eclarke",
        "message": "The relay seems to be malfunctioning.",
        "timestamp": 1459361875337
      },
      "m2": { ... },
      "m3": { ... }
    },
    "two": { ... },
    "three": { ... }
  }
}
现在，每个对话只需下载几个字节即可循环访问房间列表，同时可以快速提取元数据，在 UI 中列出或显示房间。

在消息到达时，可单独提取和显示，从而确保 UI 的及时响应和速度。