最后更新于 .

本篇主要是一些使用示例,由于部分代码是来源网上,原作者已经无法考证,所以如有原作者看到,可以告诉我,我给注明~

上一篇链接--libcurl的使用总结(一)

另:文末附有所有代码的打包下载,均在suse 10下编译运行通过

1.下载文件到本地

/*==============================================
#  Author:          DanteZhu - http://www.vimer.cn
#  Email:           dantezhu@vip.qq.com
#  FileName:        test_download.cpp
#  Version:         1.0
#  LastChange:      2010-03-09 14:20:44
#  Description:     
#  History:         
============================================*/
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include "curl/curl.h"
using namespace std;
static char errorBuffer[CURL_ERROR_SIZE];
static int writer(char *, size_t, size_t, string *);
static bool init(CURL *&, char *,string *);
int main()
{
    CURL *conn = NULL;
    CURLcode code;
    string buffer;
    curl_global_init(CURL_GLOBAL_DEFAULT);
    char* url="172.16.211.50/cc2/cc/getfile.php";
    if (!init(conn,url,&buffer ))
    {
        fprintf(stderr, "Connection initializion failed\n");
        exit(EXIT_FAILURE);
    }
    code = curl_easy_perform(conn);
    if (code != CURLE_OK)
    {
        fprintf(stderr, "Failed to get '%s' [%s]\n", url, errorBuffer);
        exit(EXIT_FAILURE);
    }
    FILE * file = fopen("1.gif","wb");
    fseek(file,0,SEEK_SET);
    fwrite(buffer.c_str(),1,buffer.size(),file);
    fclose(file);
    curl_easy_cleanup(conn);
    printf("%s\n",buffer.c_str());
    return 0;
}
static bool init(CURL *&conn, char *url,string *p_buffer)
{
    CURLcode code;
    conn = curl_easy_init();
    if (conn == NULL)
    {
        fprintf(stderr, "Failed to create CURL connection\n");
        exit(EXIT_FAILURE);
    }
    code = curl_easy_setopt(conn, CURLOPT_ERRORBUFFER, errorBuffer);
    if (code != CURLE_OK)
    {
        fprintf(stderr, "Failed to set error buffer [%d]\n", code);
        return false;
    }
    code = curl_easy_setopt(conn, CURLOPT_URL, url);
    if (code != CURLE_OK)
    {
        fprintf(stderr, "Failed to set URL [%s]\n", errorBuffer);
        return false;
    }
    code = curl_easy_setopt(conn, CURLOPT_FOLLOWLOCATION, 1);
    if (code != CURLE_OK)
    {
        fprintf(stderr, "Failed to set redirect option [%s]\n", errorBuffer);
        return false;
    }
    code = curl_easy_setopt(conn, CURLOPT_WRITEFUNCTION, writer);
    if (code != CURLE_OK)
    {
        fprintf(stderr, "Failed to set writer [%s]\n", errorBuffer);
        return false;
    }
    code = curl_easy_setopt(conn, CURLOPT_WRITEDATA, p_buffer);
    if (code != CURLE_OK)
    {
        fprintf(stderr, "Failed to set write data [%s]\n", errorBuffer);
        return false;
    }
    return true;
}
static int writer(char *data, size_t size, size_t nmemb, string *writerData)
{
    unsigned long sizes = size * nmemb;
    if (writerData == NULL) return 0;
    writerData->append(data, sizes);
    return sizes;
}

2.通过multipart/form-data方式上传文件
模仿的HTML代码:

<html>
    <head>
        <meta http-equiv=content-type content="text/html;charset=gb2312">
        <title>File Upload</title>
    </head>
<body>
    <form action="/?fileupload" method="post" id="uplodfile" name="uploadfile"  enctype="multipart/form-data" >
        <input type="file" id="file" name="upload" style="width:300px">
        <input name="submit" type="submit" value="OK" >
    </form>
</body>
</html>

C代码:

/*=============================================
#  Author:          DanteZhu - http://www.vimer.cn
#  Email:           dantezhu@vip.qq.com
#  FileName:        test.cpp
#  Version:         1.0
#  LastChange:      2010-03-08 20:23:23
#  Description:     
#  History:         
============================================*/
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "curl/curl.h"
using namespace std;
#define MAX_BUFF_LEN 1048576 /*1M*/
#define POST_URL "172.16.211.50/cc2/cc/setfile.php"
int check_file_existed(char *filename)
{
    struct stat st;
     return (stat( filename, &st )==0 && S_ISREG(st.st_mode));
}
int get_file_size(char *filename)
{
    int file_len = 0;
    int fd = 0;
    fd = open(filename, O_RDONLY);
    if(fd < 0)
    {
        perror("open");
        exit(-1);
    }
    file_len = lseek(fd, 0, SEEK_END);
    if(file_len < 0)
    {
        perror("lseek");
        exit(-1);
    }
    return file_len;
}
int http_post_file(const char *url, const char *filename)
{
    CURL *curl = NULL;
    CURLcode res;
    int timeout = 5;
    struct curl_httppost *post=NULL;
    struct curl_httppost *last=NULL;
    struct curl_slist *headerlist=NULL;
    if(filename == NULL || url == NULL)
        return -1;
    printf("URL: %s\n", url);
    printf("filename: %s\n", filename);
    /* Add simple file section */
    if( curl_formadd(&post, &last, CURLFORM_COPYNAME, "content",
                CURLFORM_FILE, filename, CURLFORM_END) != 0)
    {
        fprintf(stderr, "curl_formadd error.\n");
        goto out;
    }
    /* Fill in the submit field too, even if this is rarely needed */
    curl_formadd(&post, &last,
            CURLFORM_COPYNAME, "submit",
            CURLFORM_COPYCONTENTS, "OK",
            CURLFORM_END);
    //curl_global_init(CURL_GLOBAL_ALL);
    curl = curl_easy_init();
    if(curl == NULL)
    {
        fprintf(stderr, "curl_easy_init() error.\n");
        goto out;
    }
    curl_easy_setopt(curl, CURLOPT_HEADER, 0);
    curl_easy_setopt(curl, CURLOPT_URL, url); /*Set URL*/
    curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, timeout);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 1);
    res = curl_easy_perform(curl);
    if(res != CURLE_OK)
    {
        fprintf(stderr, "curl_easy_perform[%d] error.\n", res);
        goto out;
    }
    curl_easy_cleanup(curl);
out:
    curl_formfree(post);
    //curl_global_cleanup();
    return 0;
}
int main(int argc, char *argv[])
{
    char buff[MAX_BUFF_LEN]={0};
    //Check Argument
    //argv[1] upload filename
    if(argc != 2)
    {
        fprintf(stderr, "Usage: %s filename\n", argv[0]);
        return 1;
    }
    //Check File Existed
    if(!check_file_existed(argv[1]))
    {
        fprintf(stderr, "File Not Existed.\n");
        return 1;
    }
    //Check File Size
    if( get_file_size(argv[1]) >= MAX_BUFF_LEN)
    {
        fprintf(stderr, "File Size is Big!\n");
        return 1;
    }
    //POST File
    http_post_file(POST_URL, argv[1]);
    return 0;
}

3)makefile的编写(注意链接的库,及库的顺序)

#=========================================
#  Author:          DanteZhu - http://www.vimer.cn
#  Email:           dantezhu@vip.qq.com
#  FileName:        makefile
#  Version:         1.0
#  LastChange:      2010-03-09 14:46:48
#  Description:     
#  History:         
#=========================================
CXX = g++
TARGET =  test_download test_post
C_FLAGS += -g -Wall
INC+=-I../include -I /home/dantezhu/curl-7.20.0/include/
LIB+=-L. -lcurl -lz -lrt -lcrypto -lssl
LIB_FLAGS = -pthread
all: $(TARGET)
test_download:  test_download.o
    $(CXX) -o $@ $^  $(LIB_FLAGS) $(LIB) $(C_FLAGS)
test_post:  test_post.o
    $(CXX) -o $@ $^  $(LIB_FLAGS) $(LIB) $(C_FLAGS)
.cpp.o:
    $(CXX) -c -o $*.o $(INC) $(C_FLAGS) $*.cpp
.cc.o:
    $(CXX) -c -o $*.o $(INC) $(C_FLAGS) $*.cc
clean:
    -rm -f *.o $(TARGET)

附:代码程序打包下载

 

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