[GitHub] [rocketmq] liuxuzxx commented on issue #3389: The json-style of body in the message is illegal, because of the default settings for fastjson

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liuxuzxx commented on issue #3389:
URL: https://github.com/apache/rocketmq/issues/3389#issuecomment-932666738


   > I have tried to implement some functions for [rocketmq-client-go](https://github.com/apache/rocketmq-client-go), and I got a illgal json-style body for the response of broker with type [TopicStatsTable](https://github.com/apache/rocketmq/blob/master/common/src/main/java/org/apache/rocketmq/common/admin/TopicStatsTable.java). The string converted from the body looks like this:
   > ```
   > {"offsetTable":{{"brokerName":"rocketmq-broker-a","queueId":2,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0},{"brokerName":"rocketmq-broker-a","queueId":3,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0},{"brokerName":"rocketmq-broker-a","queueId":0,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0},{"brokerName":"rocketmq-broker-a","queueId":1,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0},{"brokerName":"rocketmq-broker-a","queueId":6,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0},{"brokerName":"rocketmq-broker-a","queueId":7,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0},{"brokerName":"rocketmq-broker-a","queueId":4,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0},{"brokerName":"rocketmq-broker-a","queueId":5,"topic":"test"}:{"lastUpdateTimestamp":0,"maxOffset":0,"minOffset":0}}}
   > ```
   > 
   > And the [json.Unmarshal](https://pkg.go.dev/encoding/json#Unmarshal) method reports an error:
   > ```
   > invalid character '{' looking for beginning of object key string
   > ```
   > 
   > Simply, the problem is the serialized key of the response should be not an object but a string. And I got that the serialization library for the [rocketmq](https://github.com/apache/rocketmq) is [fastjson](https://github.com/alibaba/fastjson), and there is a reference of this problem in the issue [1.2.58，toJSONString(Object)生成了非标准JSON](https://github.com/alibaba/fastjson/issues/2526). Someone reports that the default settings for fastjson has changed after the version 1.2.36 released, and illegal json string can be serialized. However, the [RemotingSerializable.toJson](https://github.com/apache/rocketmq/blob/fb8bc64e2a2551e76da24cb6af0fb3e5f986f8b3/remoting/src/main/java/org/apache/rocketmq/remoting/protocol/RemotingSerializable.java#L33) method is using the default settings.
   > 
   > And I can give a simple bugfix:
   > 
   > Previous:
   > ```java
   > public static String toJson(final Object obj, boolean prettyFormat) {
   >     return JSON.toJSONString(obj, prettyFormat);
   > }
   > ```
   > After:
   > ```java
   > public static String toJson(final Object obj, boolean prettyFormat) {
   >     if (prettyFormat) {
   >         return JSON.toJSONString(obj, SerializerFeature.WriteNonStringKeyAsString, SerializerFeature.PrettyFormat);
   >     } else {
   >         return JSON.toJSONString(obj, SerializerFeature.WriteNonStringKeyAsString);
   >     }
   > }
   > ```
   > 
   > 
   
   这个出现的地方有点多，获取broker信息的时候，会出现json的key是纯数字问题，或者map<复杂对象，xxx>，这种key也会产生不加双引号的情况，目前探查到三种会出现！


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