curl的封装[通俗易懂]

大家好，又见面了，我是全栈君。

首先要搭建一个httpserver，这里採用tomcat6为例：

过程：新建一个Servlet，并使用tomcat的默认port号8080监听，最后写一个jsp来測试能否够訪问该server

1）新建一个Serlvet

新建完后增加写下測试代码：

public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

    /**
     * Default constructor. 
     */
    public TestServlet() {
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		this.doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setAttribute("test", "test");
		request.getRequestDispatcher("index.jsp").forward(request, response);

	}

}

该Servlet的名字是TestServlet。所以把web.xml中的内容改成下面内容

<?
xml version="1.0" encoding="UTF-8"?
><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">  <display-name>TestServlet</display-name>  <servlet>    <servlet-name>TestServlet</servlet-name>    <servlet-class>com.test.servlet.TestServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>TestServlet</servlet-name>    <url-pattern>/TestServlet</url-pattern>  </servlet-mapping></web-app>

然后编写一个訪问该Servlet后会跳转的jsp（index.jsp）

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
${test }
</body>
</html>

最后启动server。在浏览器中如输入下面地址：http://localhost:8080/TestServlet/TestServlet，能够看到訪问成功

curl的封装[通俗易懂]

其次在cocos2d-x项目中封装curl（參考Cocos2d-x高级开发教程，并添加了能够传输多个键值对），代码比較简单，直接在凝视中说明：

头文件：

//单线程发送，会堵塞
class NetworkAdaptor {
public:
	NetworkAdaptor(const string &baseUrl);//构造
	NetworkAdaptor(const char* baseUrl);//构造
	bool sendValueForKey(const char* key, const char* value, string &wirteBackBuffer);//发送一个HTTP请求
	bool sendValueForKey(const map<string, string> &content, string &wirteBackBuffer);//发送一个HTTP请求
private:
	string m_sBaseUrl;//请求的url地址
};
//多线程线程发送
class AsynNetworkAdaptor {
public:
	void sendValueForKeyToUrl(const char* key, const char* value, const string &url, string &wirteBackBuffer);//添加一个HTTP请求
	void sendValueForKeyToUrl(const map<string, string> content, const string &url, string &wirteBackBuffer);//添加一个HTTP请求
	void flushSendRequests();//批量发送HTTP请求

	CC_SYNTHESIZE_READONLY(int, m_iUnfinishedRequest, UnfinishedRequest);//发送的数量
protected:
	struct RequestInfo {//请求信息
		RequestInfo(const map<string, string> &content, const string &url, string &buffer) : content(content), url(url), buffer(buffer){}
		map<string, string> content;//发送内容
		string url;//请求的url地址
		string &buffer;//server回传的内容
	};
	vector<RequestInfo> requests;//请求容器
};

cpp文件：

//将键值对的内容转换成表单格式的内容进行传送
void translate(const map<string, string> &content, string &sendout) {
	sendout = "";
	for(map<string, string>::const_iterator it = content.begin(); it != content.end(); ++it) {
		sendout = sendout + (it->first + "=" + it->second) + "&";
	}
	sendout = sendout.substr(0, sendout.length() - 1);//去掉最后一个&字符
}
//回调函数。一定要返回服务器对应过来的字节大小
size_t writer(char* data, size_t size, size_t number, string* writeData) {
	if(writeData == NULL) {
		return 0;
	}	
	writeData->append(data, size * number);
	return size * number;
}


NetworkAdaptor::NetworkAdaptor(const string& baseUrl) {
	this->m_sBaseUrl =  baseUrl;
}
NetworkAdaptor::NetworkAdaptor(const char* baseUrl) {
	this->m_sBaseUrl =  string(baseUrl);
}
bool NetworkAdaptor::sendValueForKey(const char* key, const char* value, string &wirteBackBuffer) {
	map<string, string> content;
	content.insert(make_pair(key, value));
	sendValueForKey(content, wirteBackBuffer);
	return true;
}
bool NetworkAdaptor::sendValueForKey(const map<string, string> &content, string &wirteBackBuffer) {
	CURL* curl = curl_easy_init();//初始化curl
	if(curl) {
		string sendout;
		translate(content, sendout);
		//配置curl的请求參数
		curl_easy_setopt(curl, CURLOPT_URL, m_sBaseUrl.c_str());
		curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
		curl_easy_setopt(curl, CURLOPT_POST, 1);//post方式
		curl_easy_setopt(curl, CURLOPT_POSTFIELDS, sendout.c_str());
		curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writer);
		curl_easy_setopt(curl, CURLOPT_WRITEDATA, &wirteBackBuffer);
	
		int res = curl_easy_perform(curl);
		curl_easy_cleanup(curl);

		if(res == CURLE_OK) {
			CCLog("get data from server : %s", wirteBackBuffer.c_str());
			return true;
		}else {
			CCLog("curl post error");
		}
	}else {
		CCLog("curl init fail");
	}
	return false;
}


void AsynNetworkAdaptor::sendValueForKeyToUrl(const char* key, const char* value, const string &url, string &wirteBackBuffer) {
	map<string, string> content;
	content.insert(make_pair(key, value));
	sendValueForKeyToUrl(content, url, wirteBackBuffer);
}
void AsynNetworkAdaptor::sendValueForKeyToUrl(const map<string, string> content, const string &url, string &wirteBackBuffer) {
	RequestInfo info(content, url, wirteBackBuffer);
	requests.push_back(info);//将请求放到请求容器中
}
void AsynNetworkAdaptor::flushSendRequests() {
	CURLM* curlm = curl_multi_init();
	if(curlm) {
		for(unsigned int i = 0; i < requests.size(); ++i) {//将请求容器中的请求批量发送到服务端
			CURL* curl = curl_easy_init();
			if(curl) {
				string sendout;
				translate(requests[i].content, sendout);
				curl_easy_setopt(curl, CURLOPT_URL, requests[i].url.c_str());
				curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
				curl_easy_setopt(curl, CURLOPT_POST, 1);
				curl_easy_setopt(curl, CURLOPT_POSTFIELDS, sendout.c_str());
				curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writer);
				curl_easy_setopt(curl, CURLOPT_WRITEDATA, &requests[i].buffer);
				int res = curl_easy_perform(curl);

				curl_multi_add_handle(curlm, curl);
				curl_easy_cleanup(curl);

			}else {
				CCLog("curl init fail");
				break;
			}
		}
		
		CURLMcode curlm_code = CURLM_CALL_MULTI_PERFORM;
		while(CURLM_CALL_MULTI_PERFORM == curlm_code) {
			curlm_code = curl_multi_perform(curlm, &m_iUnfinishedRequest);
		}
		if (curlm_code != CURLM_OK) {
			CCLog("curlm post error");

		}
		curl_multi_cleanup(curlm);
	}else {
		CCLog("curlm init fail");
	}
}

最后写一个測试用例：

	NetworkAdaptor n("http://localhost:8080/TestServlet/TestServlet");
	string v;
	map<string, string> m;
	m.insert(make_pair("name", "myName"));
	m.insert(make_pair("password", "myPassword"));
	n.sendValueForKey(m, v);
	CCLog("%s", v.c_str());

改动server端的代码。使其不跳转。并给client响应一句话

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//request.setAttribute("testt", "test");
		//request.getRequestDispatcher("index.jsp").forward(request, response);
		String name = request.getParameter("name");
		String password = request.getParameter("password");
		System.out.println("name: " + name + " , password: " + password);//输出从client发送过来的内容
		
		response.getWriter().print("server have get data");//给client响应一句话
	}

如在控制台看到下面測试结果。则表明訪问成功：

服务端：

curl的封装[通俗易懂]