cocos2d-x学习篇之网络（http）篇

转自：http://blog.csdn.net/duotianshi86/article/details/10216383

这段时间接触到cocos2d-x，拜读了csdn上很多大大的文章，尤其是小满的专栏，感觉获益不少，觉得像他们那样，边学习，边总结经验，并写出来学习过程与大家分享，我觉得是一件很值得学习的事，所以也打算把自己学习的东西和经验与大家分享，有不足之处或者错误的，还希望请大家能海涵并提出来，共同讨论，共同进步。好了，废话到此。

Cocos2dx 为我们封装了在cocos2dx中http的网络框架，其文件在cocos2dx引擎包的cocos2d-2.1rc0-x-2.1.2\extensions\network文件下的 HttpClient、HttpRequest 、HttpResponse。但是真正的底层，用的还是cURL库。。。

进行一次http交互，需要涉及的有三个类，HttpRequest用来描述一个请求。HttpResponse用来描述对应请求的响应。HttpClient是一个单例模式的类，它的职责就是负责将收到的HttpRequest对象push到发送队列中，并发送一个信号量驱动工作线程工作，工作线程再将收到的数据封装成一个HttpResponse对象push接收队列，并启用调度来派送数据。具体的后面有说道。

1.首先创建一个类，继承自cocos2d-x中的任何一个类都可以（有共同父类CCObject），并实现一个SEL_CallFuncND类型成员函数，用来做收到数据后的回调函数，函数原型为void fun(CCNode*, void*)。

2.当我们需要一次http交互的时候，我们需要new 一个CCHttpRequest对象，并设置url和请求方式（get还是post，本文只说一下get的原理，post区别不大，可以自己看），并将上面说函数设置为收到数据后的回调函数。

3.使用CCHttpClient::getInstance()单例对象，将前一步骤的CCHttpRequest对象作为参数,调用send()方法。

4.在回调函数中，将第二个参数转换成CCHttpResponse *类型，就可以通过CCHttpResponse类的方法来获取返回状态和数据等能容了。

我们先来看看具体的该怎么用，以自带的HttpClientTest.cpp为例。HttpClientTest.cpp:

 //get请求
 void HttpClientTest::onMenuGetTestClicked(cocos2d::CCObject *sender)
 {
     // test 1
     {
         CCHttpRequest* request = new CCHttpRequest();//创建request对象,这里new出来的对象不能使用autorelease()，原因后述
         request->setUrl("http://just-make-this-request-failed.com");//设置url
         request->setRequestType(CCHttpRequest::kHttpGet);//设置请求方式
         request->setResponseCallback(this, callfuncND_selector(HttpClientTest::onHttpRequestCompleted));//这是回调对象和回调函数
         request->setTag("GET test1");//设置用户标识，可以通过response获取
         CCHttpClient::getInstance()->send(request);//使用CCHttpClient共享实例来发送request
         request->release();//调用release()
     }

     // waiting
     m_labelStatusCode->setString("waiting...");

 }
 //这里就是我们要处理接收到数据的回调函数了，sender为CCHttpClient实例指针，data为接收到的response指针
 void HttpClientTest::onHttpRequestCompleted(cocos2d::CCNode *sender, void *data)
 {
     CCHttpResponse *response = (CCHttpResponse*)data;

     if (!response)
     {
         return;
     }

     // 获取对应request的字符串标识
     if (0 != strlen(response->getHttpRequest()->getTag()))
     {
         CCLog("%s completed", response->getHttpRequest()->getTag());
     }
     //获取返回代码，比如200、404等
     int statusCode = response->getResponseCode();
     char statusString[64] = {};
     sprintf(statusString, "HTTP Status Code: %d, tag = %s", statusCode, response->getHttpRequest()->getTag());
     m_labelStatusCode->setString(statusString);
     CCLog("response code: %d", statusCode);

     if (!response->isSucceed())
     {
         CCLog("response failed");
         CCLog("error buffer: %s", response->getErrorBuffer());//可以调用getErrorBuffer()来获取错误原因
         return;
     }

     // dump data
     std::vector<char> *buffer = response->getResponseData();//用来获取接收到的数据
     printf("Http Test, dump data: ");
     for (unsigned int i = 0; i < buffer->size(); i++)
     {
         printf("%c", (*buffer)[i]);
     }
     printf("\n");
 }

基本上一个http交互就是这个样子了，下面我们深入的看一下CCHttpClient是怎么工作的，先来看一张图，画的不好或者不足之处，请勿拍砖

其实就是当我们第一次CCHttpClient::getInstance()时，CCHttpClient会将自己的成员函数dispathResponseCallbacks()挂载至CCScheduler(可以理解成一个调度者，它会定时调用所有挂载至上面的函数)，并将它初始设置为停止调度。在当我们第一次调用send()发送数据时，CCHttpClient会创建一个工作线程（之后再调用send()就不会创建线程了），然后再将传递过来的CCHttpRequest对象push到发送队列s_requestQueue，并发送一个信号给工作线程，驱使其工作。工作线程首先从发送队列中取得一个CCHttpRequest对象，并new 一个CCHttpResponse对象，将参数设置给cURL，cURL会在获取到数据的填充response，工作线程将填充后的response再放到接收队列s_responseQueue中去，同时，启用调度。下一次CCScheduler就会CCHttpClient::dispatchResponseCallbacks()了，在该函数中，它会调用我们在第二步中设置给request的回调函数，并将response传递过去。基本过程就是这样。下面来详解相关的源文件。HttpRequest.h，其实这个文件没什么好说的，都有注释

 class CCHttpRequest : public CCObject
 {
 public:
     /** 请求类型枚举，可以通过setReqeustType(param) 设置*/
     typedef enum
     {
         kHttpGet,
         kHttpPost,
         kHttpUnkown,
     } HttpRequestType;

     /** Constructor
         Because HttpRequest object will be used between UI thead and network thread,
         requestObj->autorelease() is forbidden to avoid crashes in CCAutoreleasePool
         new/retain/release still works, which means you need to release it manually
         Please refer to HttpRequestTest.cpp to find its usage
     这里是有注释的，因为要跨线程，所以就不能用autorelease()
     我们在使用HttpRequest的时候，需要自己new，然后再release下就可以了
     当我们把HttpRequest传递给CCHttpClient的时候，CCHttpClient已经帮我们retain了
     工作线程中，需要使用CCHttpRequest对象new一个CCHttpResponse,CCHttprequest会retain一次，所以工作线程也会release一次
     具体的后文有
      */
     CCHttpRequest()
     {
         _requestType = kHttpUnkown;
         _url.clear();
         _requestData.clear();
         _tag.clear();
         _pTarget = NULL;
         _pSelector = NULL;
         _pUserData = NULL;
     };

     virtual ~CCHttpRequest()
     {
         if (_pTarget)
         {
             _pTarget->release();
         }
     };

     /** 重载autorelease函数，禁止调用 */
     CCObject* autorelease(void)
     {
         CCAssert(false, "HttpResponse is used between network thread and ui thread \
                  therefore, autorelease is forbidden here");
         return NULL;
     }

     // setter/getters for properties

     /** 设置请求类型
         目前支持kHttpGet 和 kHttpPost
      */
     inline void setRequestType(HttpRequestType type)
     {
         _requestType = type;
     };
     /** 返回请求类型 */
     inline HttpRequestType getRequestType()
     {
         return _requestType;
     };

     /** 设置请求url
      */
     inline void setUrl(const char* url)
     {
         _url = url;
     };
     /** 获取请求url */
     inline const char* getUrl()
     {
         return _url.c_str();
     };

     /** 这个设置用于post方式的data数据
      */
     inline void setRequestData(const char* buffer, unsigned int len)
     {
         _requestData.assign(buffer, buffer + len);
     };
     /** Get the request data pointer back */
     inline char* getRequestData()
     {
         return &(_requestData.front());
     }
     /** Get the size of request data back */
     inline int getRequestDataSize()
     {
         return _requestData.size();
     }

     /** 为每个请求设置一个字符串标示，可以通过HttpResponse->getHttpRequest->getTag()获取，因为HttpResponse会将对应的HttpRequest封装在里面
      */
     inline void setTag(const char* tag)
     {
         _tag = tag;
     };
     /** Get the string tag back to identify the request.
         The best practice is to use it in your MyClass::onMyHttpRequestCompleted(sender, HttpResponse*) callback
      */
     inline const char* getTag()
     {
         return _tag.c_str();
     };

     /** Option field. You can attach a customed data in each request, and get it back in response callback.
         But you need to new/delete the data pointer manully
      */
     inline void setUserData(void* pUserData)
     {
         _pUserData = pUserData;
     };
     /** Get the pre-setted custom data pointer back.
         Don't forget to delete it. HttpClient/HttpResponse/HttpRequest will do nothing with this pointer
      */
     inline void* getUserData()
     {
         return _pUserData;
     };

     /** 通过这个函数设置我们的数据处理回调函数
      */
     inline void setResponseCallback(CCObject* pTarget, SEL_CallFuncND pSelector)
     {
         _pTarget = pTarget;
         _pSelector = pSelector;

         if (_pTarget)
         {
             _pTarget->retain();
         }
     }
     /** Get the target of callback selector funtion, mainly used by CCHttpClient */
     inline CCObject* getTarget()
     {
         return _pTarget;
     }
     /** Get the selector function pointer, mainly used by CCHttpClient */
     inline SEL_CallFuncND getSelector()
     {
         return _pSelector;
     }

     /** Set any custom headers **/
     inline void setHeaders(std::vector pHeaders)
     {
         _headers=pHeaders;
     }

     /** Get custom headers **/
     inline std::vector getHeaders()
     {
         return _headers;
     }


 protected:
     // properties
     HttpRequestType             _requestType;    /// 请求方式
     std::string                 _url;            /// 请求url
     std::vector<char>           _requestData;    /// 用于 POST
     std::string                 _tag;            /// 用户自定义标识，可以用来在response回调中区分request
     CCObject*          _pTarget;        /// 回调对象
     SEL_CallFuncND     _pSelector;      /// 回调函数例如 MyLayer::onHttpResponse(CCObject *sender, void *data)
     void*                       _pUserData;      /// 用户自定义数据，和_tag用法一样，只不过是用途不一样
     std::vector    _headers;           /// custom http headers
 };

HttpResponse.h,这个文件和HttpRequest差不多，没什么好说的

 class CCHttpResponse : public CCObject
 {
 public:
     /** Constructor, it's used by CCHttpClient internal, users don't need to create HttpResponse manually
      @param request the corresponding HttpRequest which leads to this response
      */
     CCHttpResponse(CCHttpRequest* request)
     {
         _pHttpRequest = request;
         if (_pHttpRequest)
         {
             _pHttpRequest->retain();
         }

         _succeed = false;
         _responseData.clear();
         _errorBuffer.clear();
     }

     /** Destructor, it will be called in CCHttpClient internal,
      users don't need to desturct HttpResponse object manully
      */
     virtual ~CCHttpResponse()
     {
         if (_pHttpRequest)
         {
             _pHttpRequest->release();
         }
     }

     /** Override autorelease method to prevent developers from calling it */
     CCObject* autorelease(void)
     {
         CCAssert(false, "HttpResponse is used between network thread and ui thread \
                         therefore, autorelease is forbidden here");
         return NULL;
     }

     // getters, will be called by users

     /** Get the corresponding HttpRequest object which leads to this response
         There's no paired setter for it, coz it's already setted in class constructor
      */
     inline CCHttpRequest* getHttpRequest()
     {
         return _pHttpRequest;
     }

     /** To see if the http reqeust is returned successfully,
         Althrough users can judge if (http return code = 200), we want an easier way
         If this getter returns false, you can call getResponseCode and getErrorBuffer to find more details
      */
     inline bool isSucceed()
     {
         return _succeed;
     };

     /** Get the http response raw data */
     inline std::vector<char>* getResponseData()
     {
         return &_responseData;
     }

     /** Get the http response errorCode
      *  I know that you want to see http 200 :)
      */
     inline int getResponseCode()
     {
         return _responseCode;
     }

     /** Get the rror buffer which will tell you more about the reason why http request failed
      */
     inline const char* getErrorBuffer()
     {
         return _errorBuffer.c_str();
     }

     // setters, will be called by CCHttpClient
     // users should avoid invoking these methods


     /** Set if the http request is returned successfully,
      Althrough users can judge if (http code == 200), we want a easier way
      This setter is mainly used in CCHttpClient, users mustn't set it directly
      */
     inline void setSucceed(bool value)
     {
         _succeed = value;
     };


     /** Set the http response raw buffer, is used by CCHttpClient
      */
     inline void setResponseData(std::vector<char>* data)
     {
         _responseData = *data;
     }


     /** Set the http response errorCode
      */
     inline void setResponseCode(int value)
     {
         _responseCode = value;
     }


     /** Set the error buffer which will tell you more the reason why http request failed
      */
     inline void setErrorBuffer(const char* value)
     {
         _errorBuffer.clear();
         _errorBuffer.assign(value);
     };

 protected:
     bool initWithRequest(CCHttpRequest* request);

     // properties
     //这里要留意下，每个response中都会包含对应的request，所以能在数据处理回调函数中，获取我们在设置request的所有参数，比如像tag,userdata
     CCHttpRequest*        _pHttpRequest;  /// the corresponding HttpRequest pointer who leads to this response
     bool                _succeed;       /// to indecate if the http reqeust is successful simply
     std::vector<char>   _responseData;  /// the returned raw data. You can also dump it as a string
     int                 _responseCode;    /// the status code returned from libcurl, e.g. 200, 404
     std::string         _errorBuffer;   /// if _responseCode != 200, please read _errorBuffer to find the reason

 };

说白了，CCHttpRequest和CCHttpResponse只不过是发送队列中的数据类型，和接收队列中的数据类型，是线程之间传递的参数，下面来说说CCHttpClient

HttpClient.h

 //CCHttpClient是一个单例模式的类，整个程序共享一个实例对象
 class CCHttpClient : public CCObject
 {
 public:
     /** 获取共享的单例对象 **/
     static CCHttpClient *getInstance();

     /** Relase the shared instance **/
     static void destroyInstance();

     /**
      * Add a get request to task queue
      * @param request a CCHttpRequest object, which includes url, response callback etc.
                       please make sure request->_requestData is clear before calling "send" here.
      * @return NULL
      */
     void send(CCHttpRequest* request);


     /**
      * Change the connect timeout
      * @param timeout
      * @return NULL
      */
     inline void setTimeoutForConnect(int value) {_timeoutForConnect = value;};

     /**
      * Get connect timeout
      * @return int
      *
      */
     inline int getTimeoutForConnect() {return _timeoutForConnect;}


     /**
      * Change the download timeout
      * @param value
      * @return NULL
      */
     inline void setTimeoutForRead(int value) {_timeoutForRead = value;};


     /**
      * Get download timeout
      * @return int
      */
     inline int getTimeoutForRead() {return _timeoutForRead;};

 private:
     CCHttpClient();
     virtual ~CCHttpClient();
     bool init(void);

     /**
      * Init pthread mutex, semaphore, and create new thread for http requests
      * @return bool
      */
     bool lazyInitThreadSemphore();
     /** Poll function called from main thread to dispatch callbacks when http requests finished **/
     void dispatchResponseCallbacks(float delta);

 private:
     int _timeoutForConnect;//连接超时时间
     int _timeoutForRead;//接收数据超时时间

     // std::string reqId;
 };

HttpClient.cpp

 static pthread_t        s_networkThread;//工作线程句柄
 static pthread_mutex_t  s_requestQueueMutex;//请求队列互斥变量
 static pthread_mutex_t  s_responseQueueMutex;//接收队列互斥变量
 static sem_t *          s_pSem = NULL;//用来驱动线程工作的信号量
 static unsigned long    s_asyncRequestCount = 0;//当前需要处理的request个数

 #if CC_TARGET_PLATFORM == CC_PLATFORM_IOS
 #define CC_ASYNC_HTTPREQUEST_USE_NAMED_SEMAPHORE 1
 #else
 #define CC_ASYNC_HTTPREQUEST_USE_NAMED_SEMAPHORE 0
 #endif

 #if CC_ASYNC_HTTPREQUEST_USE_NAMED_SEMAPHORE
 #define CC_ASYNC_HTTPREQUEST_SEMAPHORE "ccHttpAsync"
 #else
 static sem_t s_sem;
 #endif

 #if (CC_TARGET_PLATFORM == CC_PLATFORM_WIN32)
 typedef int int32_t;
 #endif

 static bool need_quit = false;      //退出标识

 static CCArray* s_requestQueue = NULL;  //请求队列（下面都说request队列）
 static CCArray* s_responseQueue = NULL; //接收队列（下面都说response队列）

 static CCHttpClient *s_pHttpClient = NULL; // 全局单例CCHttpClient对象

 static char s_errorBuffer[CURL_ERROR_SIZE];//错误提示buffer

 typedef size_t (*write_callback)(void *ptr, size_t size, size_t nmemb, void *stream);//这个是用于cURL收到数据的回调函数


 // 这个便是当cURL接收到数据回调的函数，也就是在这里对response进行填充，这里的声明方式和fwrite()函数一样
 size_t writeData(void *ptr, size_t size, size_t nmemb, void *stream)
 {
     //ptr指向接受到的数据，sizes为字节数
     //这里传过来的stream中保存了CCHttpResponse::_responseData
     std::vector<char> *recvBuffer = (std::vector<char>*)stream;
     size_t sizes = size * nmemb;

     // add data to the end of recvBuffer
     // 将接受到的数据写到response中去
     recvBuffer->insert(recvBuffer->end(), (char*)ptr, (char*)ptr+sizes);

     return sizes;
 }

 // Prototypes
 bool configureCURL(CURL *handle);
 int processGetTask(CCHttpRequest *request, write_callback callback, void *stream, int32_t *errorCode);
 int processPostTask(CCHttpRequest *request, write_callback callback, void *stream, int32_t *errorCode);
 // int processDownloadTask(HttpRequest *task, write_callback callback, void *stream, int32_t *errorCode);


 // 工作线程
 static void* networkThread(void *data)
 {
     CCHttpRequest *request = NULL;

     while (true)
     {
         // 等待主线程发送信号，就是调用send()函数
         int semWaitRet = sem_wait(s_pSem);
         if (semWaitRet < 0) {
             CCLog("HttpRequest async thread semaphore error: %s\n", strerror(errno));
             break;
         }
         //退出
         if (need_quit)
         {
             break;
         }

         // step 1: send http request if the requestQueue isn't empty
         request = NULL;

         pthread_mutex_lock(&s_requestQueueMutex); //给request队列上锁
         if (0 != s_requestQueue->count())
         {
             request = dynamic_cast(s_requestQueue->objectAtIndex(0));//取得第一个request
             s_requestQueue->removeObjectAtIndex(0);  //将其移除队列
             // 这里的request的引用次数为1，因为只有在send()函数中retain了一次
         }
         pthread_mutex_unlock(&s_requestQueueMutex);//request队列解锁

         if (NULL == request)
         {
             continue;
         }

         // 同步调用cURL库

         // 使用request来创建一个response
         CCHttpResponse *response = new CCHttpResponse(request);

         // 在CCHttpTtpResponse构造中，会将request再retain一次
         request->release();
         // 这里，只有response中有request的一次引用计数

         int responseCode = -1;
         int retValue = 0;

         // 根据请求类型设置cURL参数
         switch (request->getRequestType())
         {
             case CCHttpRequest::kHttpGet: // HTTP GET
                 retValue = processGetTask(request,
                                           writeData,
                                           response->getResponseData(),
                                           &responseCode);
                 break;

             case CCHttpRequest::kHttpPost: // HTTP POST
                 retValue = processPostTask(request,
                                            writeData,
                                            response->getResponseData(),
                                            &responseCode);
                 break;

             default:
                 CCAssert(true, "CCHttpClient: unkown request type, only GET and POSt are supported");
                 break;
         }

         // 设置返回代码
         response->setResponseCode(responseCode);

         if (retValue != 0)
         {
             response->setSucceed(false);
             response->setErrorBuffer(s_errorBuffer);
         }
         else
         {
             response->setSucceed(true);
         }


         // 将response加入队列
         pthread_mutex_lock(&s_responseQueueMutex);//给response加锁
         s_responseQueue->addObject(response);
         pthread_mutex_unlock(&s_responseQueueMutex);//解锁

         // 启动CCScheduler调度
         CCDirector::sharedDirector()->getScheduler()->resumeTarget(CCHttpClient::getInstance());
     }

     // 线程退出，清理request队列
     pthread_mutex_lock(&s_requestQueueMutex);
     s_requestQueue->removeAllObjects();
     pthread_mutex_unlock(&s_requestQueueMutex);
     s_asyncRequestCount -= s_requestQueue->count();

     if (s_pSem != NULL) {
 #if CC_ASYNC_HTTPREQUEST_USE_NAMED_SEMAPHORE
         sem_unlink(CC_ASYNC_HTTPREQUEST_SEMAPHORE);
         sem_close(s_pSem);
 #else
         sem_destroy(s_pSem);
 #endif

         s_pSem = NULL;
         //释放互斥变量
         pthread_mutex_destroy(&s_requestQueueMutex);
         pthread_mutex_destroy(&s_responseQueueMutex);

         s_requestQueue->release();
         s_responseQueue->release();
     }

     pthread_exit(NULL);

     return 0;
 }

 //设置cURL超时属性
 bool configureCURL(CURL *handle)
 {
     if (!handle) {
         return false;
     }

     int32_t code;
     //设置错误信息缓冲
     code = curl_easy_setopt(handle, CURLOPT_ERRORBUFFER, s_errorBuffer);
     if (code != CURLE_OK) {
         return false;
     }
     //设置超时时间
     code = curl_easy_setopt(handle, CURLOPT_TIMEOUT, CCHttpClient::getInstance()->getTimeoutForRead());
     if (code != CURLE_OK) {
         return false;
     }
     code = curl_easy_setopt(handle, CURLOPT_CONNECTTIMEOUT, CCHttpClient::getInstance()->getTimeoutForConnect());
     if (code != CURLE_OK) {
         return false;
     }

     return true;
 }

 //处理get方式请求
 //stream传递过来的是response->getResponseData()
 //关于cURL的东西这里就不多说了
 int processGetTask(CCHttpRequest *request, write_callback callback, void *stream, int *responseCode)
 {
     CURLcode code = CURL_LAST;
     //初始化cURL
     CURL *curl = curl_easy_init();

     do {
         if (!configureCURL(curl)) //配置cURL
         {
             break;
         }

         /* handle custom header data */
         /* create curl linked list */
         struct curl_slist *cHeaders=NULL;
         /* get custom header data (if set) */
         std::vector headers=request->getHeaders();
             if(!headers.empty())
             {
                     for(std::vector::iterator it=headers.begin();it!=headers.end();it++)
                     {
               /* append custom headers one by one */
                         cHeaders=curl_slist_append(cHeaders,it->c_str());
                     }
            /* set custom headers for curl */
                     code = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, cHeaders);
                     if (code != CURLE_OK) {
                         break;
                     }
             }

         code = curl_easy_setopt(curl, CURLOPT_URL, request->getUrl());
         if (code != CURLE_OK)
         {
             break;
         }

         code = curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, request->getUrl());
         if (code != CURLE_OK)
         {
             break;
         }

         code = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, callback);
         if (code != CURLE_OK)
         {
             break;
         }
         //这里将response->_responseData设置为cURL回调函数中的stream参数
         code = curl_easy_setopt(curl, CURLOPT_WRITEDATA, stream);
         if (code != CURLE_OK)
         {
             break;
         }

         code = curl_easy_perform(curl);
         if (code != CURLE_OK)
         {
             break;
         }

         /* free the linked list for header data */
         curl_slist_free_all(cHeaders);

         code = curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, responseCode);
         if (code != CURLE_OK || *responseCode != 200)
         {
             code = CURLE_HTTP_RETURNED_ERROR;
         }
     } while (0);

     if (curl) {
         curl_easy_cleanup(curl);
     }

     return (code == CURLE_OK ? 0 : 1);
 }

 //这个就不说了，其实都一样的，cURL承担了所有工作
 int processPostTask(CCHttpRequest *request, write_callback callback, void *stream, int32_t *responseCode)
 {
     CURLcode code = CURL_LAST;
     CURL *curl = curl_easy_init();

     do {
         if (!configureCURL(curl)) {
             break;
         }

         /* handle custom header data */
         /* create curl linked list */
         struct curl_slist *cHeaders=NULL;
         /* get custom header data (if set) */
             std::vector headers=request->getHeaders();
             if(!headers.empty())
             {
                     for(std::vector::iterator it=headers.begin();it!=headers.end();it++)
                     {
               /* append custom headers one by one */
                         cHeaders=curl_slist_append(cHeaders,it->c_str());
                     }
            /* set custom headers for curl */
                     code = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, cHeaders);
                     if (code != CURLE_OK) {
                         break;
                     }
             }

         code = curl_easy_setopt(curl, CURLOPT_URL, request->getUrl());
         if (code != CURLE_OK) {
             break;
         }
         code = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, callback);
         if (code != CURLE_OK) {
             break;
         }
         code = curl_easy_setopt(curl, CURLOPT_WRITEDATA, stream);
         if (code != CURLE_OK) {
             break;
         }
         code = curl_easy_setopt(curl, CURLOPT_POST, 1);
         if (code != CURLE_OK) {
             break;
         }
         code = curl_easy_setopt(curl, CURLOPT_POSTFIELDS, request->getRequestData());
         if (code != CURLE_OK) {
             break;
         }
         code = curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, request->getRequestDataSize());
         if (code != CURLE_OK) {
             break;
         }
         code = curl_easy_perform(curl);
         if (code != CURLE_OK) {
             break;
         }

         /* free the linked list for header data */
         curl_slist_free_all(cHeaders);

         code = curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, responseCode);
         if (code != CURLE_OK || *responseCode != 200) {
             code = CURLE_HTTP_RETURNED_ERROR;
         }
     } while (0);
     if (curl) {
         curl_easy_cleanup(curl);
     }

     return (code == CURLE_OK ? 0 : 1);
 }

 // 返回共享实例
 CCHttpClient* CCHttpClient::getInstance()
 {
     if (s_pHttpClient == NULL) {
         s_pHttpClient = new CCHttpClient();
     }

     return s_pHttpClient;
 }

 void CCHttpClient::destroyInstance()
 {
     CCAssert(s_pHttpClient, "");
     //将CCHttpClient::dispatchResponseCallbacks()函数从CCShecduler中取消挂载
     CCDirector::sharedDirector()->getScheduler()->unscheduleSelector(schedule_selector(CCHttpClient::dispatchResponseCallbacks), s_pHttpClient);
     s_pHttpClient->release();
 }

 CCHttpClient::CCHttpClient()
 : _timeoutForConnect(30)
 , _timeoutForRead(60)
 {
     //将成员函数dispatchTesponseCallbacks()挂载至CCSheduler
     CCDirector::sharedDirector()->getScheduler()->scheduleSelector(
                     schedule_selector(CCHttpClient::dispatchResponseCallbacks), this, 0, false);
     //初始化为停止调度，由工作线程接收到了数据之后启用调度
     CCDirector::sharedDirector()->getScheduler()->pauseTarget(this);
 }

 CCHttpClient::~CCHttpClient()
 {
     need_quit = true;

     if (s_pSem != NULL) {
         sem_post(s_pSem);
     }

     s_pHttpClient = NULL;
 }

 //只有在第一次调用send()时调用，去初始化队列、创建线程、初始化互斥变量等
 bool CCHttpClient::lazyInitThreadSemphore()
 {
     if (s_pSem != NULL) {
         return true;
     } else {
 #if CC_ASYNC_HTTPREQUEST_USE_NAMED_SEMAPHORE
         s_pSem = sem_open(CC_ASYNC_HTTPREQUEST_SEMAPHORE, O_CREAT, 0644, 0);
         if (s_pSem == SEM_FAILED) {
             CCLog("Open HttpRequest Semaphore failed");
             s_pSem = NULL;
             return false;
         }
 #else
         int semRet = sem_init(&s_sem, 0, 0);
         if (semRet < 0) {
             CCLog("Init HttpRequest Semaphore failed");
             return false;
         }

         s_pSem = &s_sem;
 #endif

         s_requestQueue = new CCArray();
         s_requestQueue->init();

         s_responseQueue = new CCArray();
         s_responseQueue->init();

         pthread_mutex_init(&s_requestQueueMutex, NULL);
         pthread_mutex_init(&s_responseQueueMutex, NULL);

         pthread_create(&s_networkThread, NULL, networkThread, NULL);
         pthread_detach(s_networkThread);

         need_quit = false;
     }

     return true;
 }

 //Add a get task to queue
 void CCHttpClient::send(CCHttpRequest* request)
 {
     //第一次调用的时候初始化
     if (false == lazyInitThreadSemphore())
     {
         return;
     }

     if (!request)
     {
         return;
     }
     //将当前需要处理的request个数++
     ++s_asyncRequestCount;
     //在这里对request进行第一次retain，
     request->retain();
     //这里request的引用次数为1
     pthread_mutex_lock(&s_requestQueueMutex);//request队列加锁
     s_requestQueue->addObject(request);//push到request队列
     pthread_mutex_unlock(&s_requestQueueMutex);//解锁

     // 发送信号唤醒工作线程
     sem_post(s_pSem);
 }

 // 将response队列数据分发
 void CCHttpClient::dispatchResponseCallbacks(float delta)
 {
     // CCLog("CCHttpClient::dispatchResponseCallbacks is running");

     CCHttpResponse* response = NULL;

     pthread_mutex_lock(&s_responseQueueMutex);//给response队列上锁
     if (s_responseQueue->count())
     {
         response = dynamic_cast(s_responseQueue->objectAtIndex(0));//取出response
         s_responseQueue->removeObjectAtIndex(0);//将其从response队列移除
     }
     pthread_mutex_unlock(&s_responseQueueMutex);//解锁

     if (response)
     {
         --s_asyncRequestCount;

         CCHttpRequest *request = response->getHttpRequest();
         CCObject *pTarget = request->getTarget();//获取request回调函数的对象
         SEL_CallFuncND pSelector = request->getSelector();//获取回调函数

         if (pTarget && pSelector)
         {
             (pTarget->*pSelector)((CCNode *)this, response);//调用回调函数，并把本单例对象和response传递给我们设置在request中的回调函数
         }

         response->release();
     }

     if (0 == s_asyncRequestCount) //如果没有没有请求，停止调度
     {
         CCDirector::sharedDirector()->getScheduler()->pauseTarget(this);
     }

 }

      花了大半天时间，终于写的差不多了，其实我当初是想看看cocos2d-x是怎样封装socket这一块的，结果是这样，用的cURL库。。。
      这篇文章是我的处女做，哪里有不好的地方大家提出来共同进步，欢迎交流

      本人今年刚毕业，接触cocos2d-x也才两个月（写的不好不要扔砖就好），前一个多月一直在搞粒子系统这块，这几天把改造后的粒子系统工具开发完了，时间稍微多点，就看看其他的模块了，看完了收获也不少，由于经常逛csdn，拜读大神的文章，所以就想着咱也来发表一遍学习心得吧，这样既可以提高自己，也可以和大家交流交流心得，更重要的是我发现写博客可以提升学习的兴趣

      好了，就到这里了，以后有时间再继续