一、背景
这两天由于一些原因研究了研究如何在客户端C++代码中调用web服务端接口，需要访问url，并传入json数据，拿到返回值，并解析。
现在的情形是远程服务端的接口参数和返回类型都是json的字符串。所以我们主要做的就是：连接远程url、找到接口，将基本类型的数据封装成json数据传入接口，然后获取返回值，并解析返回的json数据。
这里需要用到的库就有url库、json库，大致了解了，接下来就要下载包进行配置了。
二、配置环境
首先需要安装curl库和json库，安装详情如下：
- 安装curl库
1.下载：wget http://curl.haxx.se/download/curl-7.38.0.tar.gz (如果下载不了，直接在浏览器打开这个网址下载下来)
2.解压：tar -xzvf curl-7.38.0.tar.gz
3.安装：cd curl-7.38.0 ./configure sudo make sudo make install4.查看/usr/include目录下有没有curl文件夹，没有的话需要将解压包/curl-7.38.0/include中的curl拷贝过去
5.查看/usr/local/lib/目录下有没有libcurl.so.4.3.0和libcurl.so，没有的话将/curl-7.38.0/lib/.libs/libcurl.so.4.3.0拷贝到/usr/local/lib/下，并建立软链接：ln -s libcurl.so.4.3.0 libcurl.so
6.将路径加入系统查找路径中：sudo vim /etc/ld.so.conf.d/libc.conf 将目录/usr/local/lib写入该文件中 执行sudo ldconfig7 安装完成
- 安装json库
1.下载JsonCpp：http://sourceforge.net/projects/jsoncpp/files/
2.下载scons:http://sourceforge.net/projects/scons/files/scons/2.1.0/scons-2.1.0.tar.gz/download
3.解压scons-2.1.0.tar.gz：tar -zvxf scons-2.1.0.tar.gz
4.进入解压目录scons-2.1.0，执行命令：sudo python setup.py install
5.解压jsoncpp:tar -zvxf jsoncpp-src-0.5.0.tar.gz
6.进入jsoncpp解压目录下，执行命令：sudo scons platform=linux-gcc
7.将/jsoncpp-src-0.5.0/include/目录下的json文件夹拷贝到/usr/include/
8.将jsoncpp-src-0.5.0/libs/linux-gcc-4.9.1/目录下的libjson_linux-gcc-4.9.1_libmt.so和libjson_linux-gcc-4.9.1_libmt.a 拷贝到/usr/local/lib/,并为了方便使用，将其重命名为libjson.so
三、编写代码
代码名称：getInfo.cpp
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <curl/curl.h>
#include <curl/easy.h>
#include <string.h>
#include <json/json.h>
#include <iconv.h>
#include <iostream>
#include <sstream>
using namespace std;
size_t push_string(void* buffer, size_t size, size_t nmemb, void* stream)
{
string data((const char*)buffer, (size_t) size * nmemb);
*((stringstream*) stream) << data << endl;
return size*nmemb;
}
char *send_post(char *url, char *param)
{
std::stringstream res_str;
CURL *curl_handle = NULL;
CURLcode curl_res;
curl_res = curl_global_init(CURL_GLOBAL_ALL);
// printf("param is: %s\n", param);
if(curl_res == CURLE_OK)
{
curl_handle = curl_easy_init();
if(curl_handle != NULL)
{
curl_easy_setopt(curl_handle, CURLOPT_URL, url);
curl_easy_setopt(curl_handle, CURLOPT_POST, 1);
curl_easy_setopt(curl_handle, CURLOPT_POSTFIELDSIZE, strlen(param));
curl_easy_setopt(curl_handle, CURLOPT_POSTFIELDS, param);
curl_easy_setopt(curl_handle, CURLOPT_SSL_VERIFYPEER, 0);
curl_easy_setopt(curl_handle, CURLOPT_SSL_VERIFYHOST, 0);
curl_easy_setopt(curl_handle, CURLOPT_TIMEOUT, 30);
curl_easy_setopt(curl_handle, CURLOPT_CONNECTTIMEOUT, 10L);
curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, push_string);
curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, &res_str);
curl_easy_setopt(curl_handle, CURLOPT_HEADER, 0L);
struct curl_slist *pList = NULL;
pList = curl_slist_append(pList,"Content-Type: application/json;charset=utf-8");
curl_easy_setopt(curl_handle, CURLOPT_HTTPHEADER, pList);
curl_res = curl_easy_perform(curl_handle);
if(curl_res != CURLE_OK)
{
printf("curl_easy_perform error, err_msg:[%ld]\n", curl_res);
}
curl_easy_cleanup(curl_handle);
}
}
else
{
printf("CURL ERROR : %s", curl_easy_strerror(curl_res));
}
std::string str_json = res_str.str();
char *str;
str = (char *)malloc(200);
strcpy(str, str_json.c_str());
return str;
}
//解析json格式的返回值
void get_ret_info(char *res_str, char *flag, char *password, char *msg)
{
Json::Reader json_reader;
Json::Value json_value;
if(json_reader.parse(res_str, json_value))
{
std::string flag1 = json_value["id"].asString();
std::string password1 = json_value["password"].asString();
std::string msg1 = json_value["msg"].asString();
strcpy(flag, flag1.c_str());
strcpy(password, password1.c_str());
strcpy(msg, msg1.c_str());
}
}
int main(int argc, char *argv[])
{
char url[100] = "http://172.16.10.138:8888/ServerX/doRecog"; //服务端url
char param[500] = {0}; //输入参数
char *res_str; //返回数据
//构造json格式的参数
Json::Value item;
item["username"] = Json::Value("test");
item["paramdata"] = Json::Value("==2==NULL==");
item["signdata"] = Json::Value("NULL");
item["imgtype"] = Json::Value("jpg");
std::string str = item.toStyledString();
strcpy(param, );
res_str = send_post(url, (char*)str.c_str());
printf("return string is: %s", res_str);
char flag[10] = {0};
char password[30] = {0};
char msg[200] = {0};
get_ret_info(res_str, flag, password, msg);
}
三、编译
- 手动编译
g++ -c getInfo.cpp -o getInfo.o
g++ -o getInfo.exe -L /usr/local/lib -lcurl -ljson getInfo.o
- 自动编译
#x86 complie config
CC=g++
LD=g++
CFLAGS=-Wall -DLDAP_DEPRECATED=1 -I ./include/
ARCH=$(shell getconf LONG_BIT)
ifeq ($(DBGEN),1)
CFLAGS += -g
endif
ifeq ($(ARCH),32)
LIBDIR = /usr/local/lib/
BINDIR = ./
CFLAGS += -Dx86
else
LIBDIR = /usr/local/lib/
BINDIR = ./
endif
BINLIBS=-L $(LIBDIR) -lcurl -ljson
EXENAME1=getPasswd
DEBUG=
EXEEXT=.exe
TARGETBIN1 = $(EXENAME1)$(DEBUG)$(EXEEXT)
BINOBJS1 = getPasswd.o
all: $(TARGETBIN1)
.cpp.o:
$(CC) $(CFLAGS) $(XFLAGS) -c $< -o $@
.cpp.b:
$(CC) $(CFLAGS) $(XFLAGS) -c $< -o $@
$(TARGETBIN1): $(BINOBJS1)
$(LD) -o $(BINDIR)$(TARGETBIN1) $(BINOBJS1) $(BINLIBS)
clean:
rm -f *.o $(BINDIR)$(TARGETBIN1)
四、参考文章
- 安装curl:https://blog.csdn.net/makenothing/article/details/39250491
- 安装json库：https://blog.csdn.net/makenothing/article/details/39250491
- https://blog.csdn.net/weixin_39568041/article/details/83659649
- https://www.cnblogs.com/chechen/p/7261607.html
- https://blog.csdn.net/g1269420003/article/details/89349569
