Kotlin中如何替换MutableMap内指定KEY对应的VALUE（附场景实例）

原始响应数据类型为 MutableMap<String!, String!>，响应内容如下：

{sendbird_call={"user_id":"91990000000","push_sound":"default","is_voip":true,"push_alert":"","client_id":"xxxxx-xxx-xxxx-xxxx-xxxxxxx","command":{"sequence_number":2,"payload":{"sdp":"sdpppppp","call_id":"xxxx-xxx-xxx-xxxx-xxxxxx","peer_connection_id":null},"delivery_info":{"type":"push"},"message_id":"xxxx-xxxx-xxx-xx-xxxx","cmd":"SGNL","type":"offer","call_type":"direct_call","version":1},"receiver_type":"client"},
message=}

需求为将上述响应中 peer_connection_id 的值从 null 修改为 ""。

原实现代码 #

var msgData = JSONObject(receivedMap["sendbird_call"])
  if (msgData.has("command")) {
     val dataCommand: JSONObject = msgData.getJSONObject("command")
        if (dataCommand.has("payload")) {
           val dataPay: JSONObject = dataCommand.getJSONObject("payload")
              if (dataPay.has("peer_connection_id")) {
                 if(dataPay.getString("peer_connection_id").equals(null)){
                    dataPay.put("peer_connection_id","")
                 }
              }
        }
  }

原代码可优化点 #

• 多层if嵌套结构冗余，可读性差，后续如果JSON层级结构变动，维护成本很高
• 直接调用getString("peer_connection_id")读取null值时，多数JSON解析库会直接抛出类型异常，存在崩溃风险
• 判空写法不严谨，equals(null)的写法本身就有触发空指针的可能

优化后实现方案 #

private fun replacePeerID(receivedMap: Map<String, String>): Map<String, String> {
    val msgData = JSONObject(receivedMap["sendbird_call"])
    msgData.optJSONObject("command")
        ?.optJSONObject("payload")
        ?.let { payload ->
            if (payload.has("peer_connection_id") && payload.opt("peer_connection_id") == null) {
                payload.put("peer_connection_id", "")
            }
        }
    // 补充修改后数据回写逻辑，避免只修改JSONObject未同步到Map的问题
    if (receivedMap is MutableMap) {
        receivedMap["sendbird_call"] = msgData.toString()
    }
    return receivedMap
}

优化说明 #

• 用optJSONObject替代getJSONObject+has()判断逻辑，结合Kotlin空安全调用符?.自动处理节点不存在的场景，完全消除多层嵌套
• 用opt("peer_connection_id")读取字段值，即使字段为null也不会抛出异常，判空逻辑更安全
• 补充了修改后的JSON数据回写Map的逻辑，解决了原有参考实现修改不生效的问题

内容的提问来源于stack exchange，提问作者Arnold Brown