Android FirBase RealTimeDb JsonTree设计,基于RealTime聊天的json格式

这一次,我要用 FirBase RealTimeDb实时数据库写个聊天的demo,在存储数据和查询数据时需要规划一下json数据格式,要不然后期就蒙圈了,google的官方文章如下:

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

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": { ... }
  }
}

官方的建议还是要才用的,淡然,我觉得官方给的第二层结构"members"这个对我来说并没有什么用,于是我打算把它去掉,google核心的思想就是避免嵌套,遵循这一原则,我稍微修改了官方的json结构最终是下面的.

存储聊天内容的json

{
  "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": {
     "messages": {
    "青青": {[
      {
        "name": "eclarke",
        "message": "The relay seems to be malfunctioning.",
        "timestamp": 1459361875337
      }]
    }
  }
}

在chats对象中可以查看到聊天的数量,和哪个好友,头像,时间,对方id,拿到id后可以在message信息中获取好友的聊天记录

存储用户信息的json,这个没啥好说的,保存所有用户的信息

{
  users:{userid:
    {
      "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"
    }
    } 
}