REST接口调用客户端开发库例子

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最近在写微服务相关的东西，微服务对外公布的rest api如何让不同语言的开发者方便调用呢？本文简单实现了个rest接口客户端调用库，可简单满足vc、qt、java开发者通过指定网关及其代理的微服务名访问具体的rest接口的需求。

vc

vc下用的是大名鼎鼎的libcurl库封装rest调用，libcurl怎么用vc编译看上一篇文章，下面直接上代码吧

restcli.h

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#ifndef RESTCLI_H
#define RESTCLI_H

#include <iostream>
#include <string>
#include <map>
using namespace std;

class RestClient
{
public:
    RestClient();
    RestClient(string address, int port, string serviceName);
    void SetAuth(string appKey, string appSecret);
    void SetTimeout(int connTimeout, int timeout);
    bool Get(string path, string &result);
    bool Post(string path, string &result, string postData="");
protected:
    void genBasePath();
    void genAuthParam();
    string getUrl(string path);
private:
    string address;
    int port;
    string serviceName;
    string appKey;
    string appSecret;
    int connTimeout;
    int timeout;
    string basePath;
    string authParam;
};
#endif // RESTCLI_H

restcli.cpp

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#include "restcli.h"
#include "curl.h"
#include <sstream>

static int writer(char *data, size_t size, size_t nmemb, std::string *writerData)
{
    if(writerData == NULL)
        return 0;
    writerData->append(data, size*nmemb);
    return size * nmemb;
}

RestClient::RestClient()
{
    this->address = "localhost";
    this->port = 80;
    this->serviceName = "";
    this->appKey = "";
    this->appSecret = "";
    this->connTimeout = -1;
    this->timeout = -1;
    genBasePath();
    genAuthParam();
}
RestClient::RestClient(string address, int port, string serviceName)
{
    this->address = address;
    this->port = port;
    this->serviceName = serviceName;
    this->appKey = "";
    this->appSecret = "";
    this->connTimeout = -1;
    this->timeout = -1;
    genBasePath();
    genAuthParam();
}
void RestClient::genBasePath()
{
    ostringstream osPort;
    osPort<<this->port;
    this->basePath = "http://" + this->address + ":" + osPort.str() + "/";
    if (this->serviceName.size() > 0)
        this->basePath += this->serviceName + string("/");
}
void RestClient::genAuthParam()
{
    if (appKey.size() > 0) {
        authParam = "appKey=" + appKey + "&appSecret=" + appSecret;
    }
}
string RestClient::getUrl(string path)
{
    string url = basePath + path;
    if (authParam.size() == 0)
        return url;
    int pos = path.find("?");
    if (pos >= 0) {
        url += "&" + authParam;
    } else {
        url += "?" + authParam;
    }
    return url;
}
void RestClient::SetAuth(string appKey, string appSecret)
{
    this->appKey = appKey;
    this->appSecret = appSecret;
}
void RestClient::SetTimeout(int connTimeout, int timeout)
{
    this->connTimeout = connTimeout;
    this->timeout = timeout;
}

bool RestClient::Get(string path, string &result)
{
    CURLcode code;
    CURL* curl = curl_easy_init();
    if (curl == NULL)
        return false;
    string url = getUrl(path);
    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writer);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &result);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, this->connTimeout);
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, this->timeout);
    code = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
    if(code != CURLE_OK)
        return false;

    return true;
}
bool RestClient::Post(string path, string &result, string postData)
{
    CURLcode code;
    CURL* curl = curl_easy_init();
    if (curl == NULL)
        return false;
    curl_easy_setopt(curl, CURLOPT_URL, getUrl(path).c_str());
    curl_easy_setopt(curl, CURLOPT_POST, 1);
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postData.c_str());
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writer);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &result);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, this->connTimeout);
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, this->timeout);
    code = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
    if(code != CURLE_OK)
        return false;

    return true;
}

qt

之所以用libcurl进行http请求处理的一个重要原因就是为了想在vc下和qt下可以复用一套代码，所以qt的代码和vc的是一样的。具体qt的工程文件x.pro怎么写见上一篇文章

java

java处理http请求就简单多了，如果是springMVC工程下直接用个restTemplate就完成了，下面还是用java下最普遍使用的httpclient库实现。我建立maven工程，引入httpclient依赖4.5.5

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public class RestClient {
	String address = "localhost";
	int port = 80;
	String serviceName = "";
	String appKey = "";
	String appSecret = "";
	int connTimeout = -1;
	int timeout = -1;
	String basePath = "";
	String authParam = "";

	public RestClient() {
		genBasePath();
		genAuthParam();
	}

	public RestClient(String address, int port, String serviceName) {
		this.address = address;
		this.port = port;
		this.serviceName = serviceName;
		genBasePath();
		genAuthParam();
	}

	public void SetAuth(String appKey, String appSecret) {
		this.appKey = appKey;
		this.appSecret = appSecret;
	}

	public void SetTimeout(int connTimeout, int timeout) {
		this.connTimeout = connTimeout;
		this.timeout = timeout;
	}

	public boolean Get(String path, StringBuilder result) {
		boolean ret = false;
		CloseableHttpClient httpClient = HttpClients.createDefault();
		RequestConfig requestConfig = RequestConfig.custom()
				.setConnectTimeout(connTimeout)
				.setConnectionRequestTimeout(connTimeout)
				.setSocketTimeout(timeout).setRedirectsEnabled(true).build();
		String url = getUrl(path);
		HttpGet httpGet = new HttpGet(url);
		httpGet.setConfig(requestConfig);
		try {
			HttpResponse httpResponse = httpClient.execute(httpGet);
			int statusCode = httpResponse.getStatusLine().getStatusCode();
			String s = EntityUtils.toString(httpResponse.getEntity(), "UTF-8");
			if (statusCode == 200) {
				result.append(s);
				ret = true;
			} else {
				ret = false;
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				httpClient.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return ret;
	}

	public boolean Post(String path, StringBuilder result, String postData) {
		boolean ret = false;
		CloseableHttpClient httpClient = HttpClients.createDefault();
		RequestConfig requestConfig = RequestConfig.custom()
				.setConnectTimeout(connTimeout)
				.setConnectionRequestTimeout(connTimeout)
				.setSocketTimeout(timeout).setRedirectsEnabled(true).build();
		String url = getUrl(path);
		HttpPost httpPost = new HttpPost(url);
		httpPost.setConfig(requestConfig);
		List<BasicNameValuePair> list = new ArrayList<BasicNameValuePair>();
		String[] params = postData.split("&");
		for (String param : params) {
			String[] nv = param.split("=");
			if (nv.length == 2) {
				list.add(new BasicNameValuePair(nv[0], nv[1]));
			}
		}
		try {
			UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list,
					"UTF-8");
			httpPost.setEntity(entity);
			HttpResponse httpResponse = httpClient.execute(httpPost);
			int statusCode = httpResponse.getStatusLine().getStatusCode();
			String s = EntityUtils.toString(httpResponse.getEntity(), "UTF-8");
			if (statusCode == 200) {
				result.append(s);
				ret = true;
			} else {
				ret = false;
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return ret;
	}

	private String getUrl(String path) {
		String url = basePath + path;
		if (authParam.length() == 0)
			return url;
		int pos = path.indexOf("?");
		if (pos >= 0) {
			url += "&" + authParam;
		} else {
			url += "?" + authParam;
		}
		return url;
	}

	private void genAuthParam() {
		if (appKey.length() > 0) {
			authParam = "appKey=" + appKey + "&appSecret=" + appSecret;
		}
	}

	private void genBasePath() {
		if (port == 80) {
			this.basePath = "http://" + this.address + "/";
		} else {
			this.basePath = "http://" + this.address + ":" + port + "/";
		}
		if (this.serviceName.length() > 0)
			this.basePath += this.serviceName + "/";
	}

	public static void testGet() throws Exception {
		CloseableHttpClient httpClient = HttpClients.createDefault();
		HttpGet httpGet = new HttpGet("http://www.baidu.com/");
		HttpResponse httpRes = httpClient.execute(httpGet);
		String result = EntityUtils.toString(httpRes.getEntity(), "UTF-8");
		System.out.println(result);
		httpClient.close();
	}

	public static void main(String[] args) throws Exception {
		// RestClient.testGet();
		RestClient rc = new RestClient("www.baidu.com", 80, "");
		StringBuilder sb = new StringBuilder("");
		boolean b = rc.Get("", sb);

		System.out.println(b);
		System.out.println(sb);
	}
}

建maven工程的一个重要原因是想封装的rest访问库只要提供一个jar包就可以，如果普通工程恐怕要附带提供其他如httpclient.jar的包。~标记一下以后写maven的文章~

参考文章

*下面这些文章是我写上面这些时看过的，记录下来以备后看
libcurl

qt

httpclient