java - 这段代码是线程安全的吗？

我想处理客户请求的流程。每个请求都有其特殊类型。首先，我需要为该类型初始化一些数据，然后，我可以开始处理请求。当客户端类型第一次出现时，我只是初始化相应的数据。之后，将使用该数据处理该类型的所有以下所有请求。

我需要以线程安全的方式执行此操作。

这是我编写的代码。它是线程安全的吗？

public class Test {

    private static Map<Integer, Object> clientTypesInitiated = new ConcurrentHashMap<Integer, Object>();

    /* to process client request we need to
    create corresponding client type data.
    on the first signal we create that data,
    on the second - we process the request*/

    void onClientRequestReceived(int clientTypeIndex) {
        if (clientTypesInitiated.put(clientTypeIndex, "") == null) {
            //new client type index arrived, this type was never processed
            //process data for that client type and put it into the map of types
            Object clientTypeData = createClientTypeData(clientTypeIndex);
            clientTypesInitiated.put(clientTypeIndex, clientTypeData);
        } else {
            //already existing index - we already have results and we can use them
            processClientUsingClientTypeData(clientTypesInitiated.get(clientTypeIndex));
        }
    }

    Object createClientTypeData(int clientIndex) {return new Object();}

    void processClientUsingClientTypeData(Object clientTypeData) {}
}

一方面，对于同一个A，ConcurrentHashMap无法产生map.put(A，B)== null两次。
另一方面，赋值和比较操作不是线程安全的。

那么这段代码可以吗？
如果没有，我该如何解决？

更新:
我接受了Martin Serrano的答案，因为他的代码是线程安全的，并且不容易出现双重初始化问题。但是，我想指出的是，我的版本没有发现任何问题，以下为答案发布，并且我的版本不需要同步。

最佳答案

此代码不是线程安全的，因为

//already existing index - we already have results and we can use them
processClientUsingClientTypeData(clientTypesInitiated.get(clientTypeIndex));

有机会获得您临时插入到放置检查中的“”值。

这样可以使该代码成为线程安全的:

public class Test {

    private static Map<Integer, Object> clientTypesInitiated = new ConcurrentHashMap<Integer, Object>();

    /* to process client request we need to
       create corresponding client type data.
       on the first signal we create that data,
       on the second - we process the request*/

void onClientRequestReceived(int clientTypeIndex) {
    Object clientTypeData = clientTypesInitiated.get(clientTypeIndex);
    if (clientTypeData == null) {
        synchronized (clientTypesInitiated) {
          clientTypeData = clientTypesInitiated.get(clientTypeIndex);
          if (clientTypeData == null) {
              //new client type index arrived, this type was never processed
              //process data for that client type and put it into the map of types
              clientTypeData = createClientTypeData(clientTypeIndex);
              clientTypesInitiated.put(clientTypeIndex, clientTypeData);
          }
        }
    }
    processClientUsingClientTypeData(clientTypeData);
}

Object createClientTypeData(int clientIndex) {return new Object();}

void processClientUsingClientTypeData(Object clientTypeData) {}

}