C++

操作场景

使用C++语言调用APP认证的API时，您需要先获取SDK，参考API调用示例调用API。

前提条件

已获取API的调用信息，具体参见认证前准备。
安装openssl库。
```
apt-get install libssl-dev
```
安装curl库。
```
apt-get install libcurl4-openssl-dev
```

获取SDK

请登录API网关控制台，参考《API网关用户指南》的“SDK”章节，进入SDK页面并下载SDK。

或直接下载SDK的最新版本，获取“ApiGateway-cpp-sdk.zip”压缩包，解压后目录结构如下：

名称	说明
hasher.cpp	SDK代码
hasher.h
header.h
RequestParams.cpp
RequestParams.h
signer.cpp
signer.h
Makefile	Makefile文件
main.cpp	示例代码

调用API示例

在main.cpp中加入以下引用。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
#include "signer.h"

生成一个新的Signer，填入AppKey和AppSecret。
1. 本示例以AK和SK保存在环境变量中为例，运行本示例前请先在本地环境中设置环境变量HUAWEICLOUD_SDK_AK和HUAWEICLOUD_SDK_SK。以Linux系统为例在本地将已获取的AK/SK设置为环境变量。
  1. 打开终端，输入以下命令打开环境变量配置文件。
    vi ~/.bashrc
  2. 设置环境变量，保存文件并退出编辑器。
```
export HUAWEICLOUD_SDK_AK="已获取AK值" 
export HUAWEICLOUD_SDK_SK="已获取SK值" 
```
  3. 输入以下命令使配置文件生效。
    source ~/.bashrc
2. 生成一个新的Signer，填入已设置的环境变量。
```
// Directly writing AK/SK in code is risky. For security, encrypt your AK/SK and store them in the configuration file or environment variables.
// In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, set environment variables HUAWEICLOUD_SDK_AK and HUAWEICLOUD_SDK_SK.
Signer signer(getenv("HUAWEICLOUD_SDK_AK"), getenv("HUAWEICLOUD_SDK_SK"));
```

生成一个新的RequestParams，指定方法名、域名、请求uri、查询字符串和body。

 RequestParams* request = new RequestParams("POST", "c967a237-cd6c-470e-906f-a8655461897e.apigw.exampleRegion.com", "/app1",
        "Action=ListUsers&Version=2010-05-08", "demo");

给请求添加x-stage头，内容为环境名。如果有需要，添加需要签名的其他头域。
```
request->addHeader("x-stage", "RELEASE");
```
进行签名，执行此函数会将生成的签名头加入request变量中。
```
signer.createSignature(request);
```

使用curl库访问API，查看访问结果。

static size_t
WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
    size_t realsize = size * nmemb;
    struct MemoryStruct *mem = (struct MemoryStruct *)userp;

    mem->memory = (char*)realloc(mem->memory, mem->size + realsize + 1);
    if (mem->memory == NULL) {
        /* out of memory! */
        printf("not enough memory (realloc returned NULL)\n");
        return 0;
    }

    memcpy(&(mem->memory[mem->size]), contents, realsize);
    mem->size += realsize;
    mem->memory[mem->size] = 0;

    return realsize;
}

//send http request using curl library
int perform_request(RequestParams* request)
{
    CURL *curl;
    CURLcode res;
    struct MemoryStruct resp_header;
    resp_header.memory = (char*)malloc(1);
    resp_header.size = 0;
    struct MemoryStruct resp_body;
    resp_body.memory = (char*)malloc(1);
    resp_body.size = 0;

    curl_global_init(CURL_GLOBAL_ALL);
    curl = curl_easy_init();

    curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, request->getMethod().c_str());
    std::string url = "http://" + request->getHost() + request->getUri() + "?" + request->getQueryParams();
    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
    struct curl_slist *chunk = NULL;
    std::set<Header>::iterator it;
    for (auto header : *request->getHeaders()) {
        std::string headerEntry = header.getKey() + ": " + header.getValue();
        printf("%s\n", headerEntry.c_str());
        chunk = curl_slist_append(chunk, headerEntry.c_str());
    }
    printf("-------------\n");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk);
    curl_easy_setopt(curl, CURLOPT_COPYPOSTFIELDS, request->getPayload().c_str());
    curl_easy_setopt(curl, CURLOPT_NOBODY, 0L);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
    curl_easy_setopt(curl, CURLOPT_HEADERDATA, (void *)&resp_header);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&resp_body);
    //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
    res = curl_easy_perform(curl);
    if (res != CURLE_OK) {
        fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
    }
    else {
        long status;
        curl_easy_getinfo(curl, CURLINFO_HTTP_CODE, &status);
        printf("status %d\n", status);
        printf(resp_header.memory);
        printf(resp_body.memory);
    }
    free(resp_header.memory);
    free(resp_body.memory);
    curl_easy_cleanup(curl);

    curl_global_cleanup();

    return 0;
}