无法将zookeeper对象转换为json，反之亦然

Question

大家好，我有一个简单的问题，我似乎无法将一个zookeeper对象转换为json，反之亦然，使用jons中的GSON库为java web服务。我得到的错误是

Exception in thread "main" java.lang.StackOverflowError
    at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:381)
    at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:376)
    at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:381)
    at com.google.gson.internal.$Gson$Types.resolve($Gson$Types.java:376)

并且它继续发展相当大。从我搜索到的这似乎是太深的嵌套对象和递归的问题。这是我为一个简单的POC尝试的

ZooKeeper zoo;
        try {
            zoo = new ZooKeeper("localhost:2182",5000,null);
            String obj=gson.toJson(zoo, ZooKeeper.class);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

有人可以清楚地解释什么是实际问题，即使它可以转换和使用zookeeper对象作为json（因为与它相关的所有线程）

Answer 1

ZooKeeper是服务器而不是DTO

也许你想用DTO配置做一个json

我的主张

public static void main(String[] args) {
  ZooKeeper zoo;
  try {
    ZooKeeperConfDTO conf = new ZooKeeperConfDTO("localhost:2182", 5000, null);
    zoo = runZoo(conf);
    String json = new Gson().toJson(conf);
    System.out.println(json); //---->{"connectString":"localhost:2182","sessionTimeout":5000}
  } catch (Exception e) {
    e.printStackTrace();
  }
}

private static ZooKeeper runZoo(ZooKeeperConfDTO conf) throws IOException {
  return new ZooKeeper(conf.connectString, conf.sessionTimeout, conf.watcher);
}

并创建了类

import org.apache.zookeeper.Watcher;

public class ZooKeeperConfDTO {
  public String connectString;
  public int sessionTimeout;
  public Watcher watcher;

  public ZooKeeperConfDTO(String connectString, int sessionTimeout, Watcher watcher) {
    this.connectString = connectString;
    this.sessionTimeout = sessionTimeout;
    this.watcher = watcher;
  }
}

版本2：

为ClientCnxn创建TypeAdapter

import java.io.IOException;
import org.apache.zookeeper.ClientCnxn;
import com.google.gson.TypeAdapter;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;

public class ClientCnxnAdapter extends TypeAdapter<ClientCnxn> {
    @Override
    public void write(JsonWriter writer, ClientCnxn cnxn) throws IOException {
        writer.beginObject();
        writer.name("sessionId");
        writer.value(cnxn.getSessionId());
        writer.name("timeOut");
        writer.value(cnxn.getSessionTimeout());
        writer.endObject();
    }

    @Override
    public ClientCnxn read(JsonReader in) throws IOException {
        return null;
    }
}

并使用它

public static void main(String[] args) {
    ZooKeeper zoo;
    try {
        zoo = new ZooKeeper("localhost:2182", 5000, null);
        Gson gson = new GsonBuilder().registerTypeAdapter(ClientCnxn.class, new ClientCnxnAdapter()).create() ;
        String json = gson.toJson(zoo);
        System.out.println(json); //---->{"cnxn":{"sessionId":0,"timeOut":0},"watchManager":{"dataWatches":{},"existWatches":{},"childWatches":{}}}
    } catch (Exception e) {
        e.printStackTrace();
    }
}