http://blog.csdn.net/wangjintao1988/article/details/8003573,这个里面说明了实现思路，并且编码方式的转换是基于Java的。最近正在学习linux socket编程，因此想通过linux实现这个功能，字体编码从GB2312到ASCII字符的转换时曾经尝试用iconv，但一直无法正确转换，自己写了一个函数。

这个code如下：down.c

<pre class="cpp" name="code">#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <string.h>
#include <sys/socket.h>
#include <iconv.h>
#define MAX_SIZE 1024
#define SEVER_PORT 80
/*
*将GB3212格式转换为ASCII字符，并且在其中插入服务器需要的%
*/
int zh2b(char *inbuf,int inbytes,char *outbuf,int outbytes)
{
        int len = 0;
        char ch[8];
        int i;
        printf("\n===========ascii===========\n");
        for(i=0;i<inbytes;i++)
        {
                sprintf(ch,"%0x",inbuf[i]);
                outbuf[len++] = '%';
                outbuf[len++] = ch[6];
                outbuf[len++] = ch[7];
        }
        outbuf[len] = '\0';
        for(i=0;i<len;i++)
        {
                if(outbuf[i]>='a'&&outbuf[i]<='z')
                        outbuf[i] -= 32;
        }
        printf("\n===============end================\n");
        printf("%s\n",outbuf);
}
/*
* 向服务器发送的GET请求
*/
void obtion_head_msg(const char *music,const char *artist,char *head_msg)
{

        sprintf(head_msg,"GET /x?op=12&count=1&title=");
        strcat(head_msg,music);
        strcat(head_msg,"$$");
        strcat(head_msg,artist);
        strcat(head_msg,"$$$$");
        strcat(head_msg," HTTP/1.1\n");
        strcat(head_msg,"Host: box.zhangmen.baidu.com\n");
        strcat(head_msg,"User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:29.0) Gecko/20100101 Firefox/29.0\n");
        strcat(head_msg,"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\n");
        strcat(head_msg,"Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3\n");
        strcat(head_msg,"Accept-Encoding: gzip, deflate\n");
        strcat(head_msg,"Connection:close\n\n");

}
int main(int argc,char* argv[])
{
        int sockfd,numbytes;
        char buf[MAX_SIZE];
        struct hostent *h;
        char requestMsg[MAX_SIZE]={'\n'};
        char music[64];

        char artist[64];
        int music_len=64;
        int artist_len=64;
        struct sockaddr_in sever_addr;
        if(argc != 3)
        {
                fprintf(stderr,"please input music info:example\n\n ./down music artist \n\n");
                exit(1);
        }

        zh2b(argv[1],strlen(argv[1]),music,music_len);
        zh2b(argv[2],strlen(argv[2]),artist,artist_len);
        printf("before:music:%s,artist:%s\n",argv[1],argv[2]);
        printf("after: music:%s,artist:%s\n",music,artist);

        if((h=gethostbyname("box.zhangmen.baidu.com")) == NULL)
        {
                herror("gethostbyname");
                exit(1);
        }

        printf("Host name :%s\n",h->h_name);
        printf("IP Address:%s",inet_ntoa(*((struct in_addr *)h->h_addr)));
if((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1)
        {
                perror("socket error\n");
                goto ERROR_;
        }

        sever_addr.sin_family = AF_INET;
        sever_addr.sin_port = htons(SEVER_PORT);
        sever_addr.sin_addr = *((struct in_addr *)h->h_addr);
        bzero(&(sever_addr.sin_zero),8);

        if(connect(sockfd,(struct sockaddr *)&sever_addr,sizeof(struct sockaddr)) == -1)
        {
                perror("connect error \n");
                goto ERROR_;
        }

        obtion_head_msg(music,artist,requestMsg);
        printf("%s\n",requestMsg);

        if(send(sockfd,requestMsg,strlen(requestMsg),0)==-1)
        {
                perror("send error \n");
                goto ERROR_;
        }

        numbytes = recv(sockfd,buf,MAX_SIZE,0);
        if(numbytes == -1)
        {
                perror("recv error\n");
                goto ERROR_;
        }
        printf("\n\n=============================start html=======================\n\n");
      while(numbytes > 0)
        {
                printf("%s",buf);
                numbytes = recv(sockfd,buf,MAX_SIZE,0);
        }
        printf("\n\n=============================end html=======================\n\n");
        return 0;
ERROR_:
        exit(1);

}

之后编译：gcc -o down down.c

 ./down 童话 光良

便可以下载百度服务器发送过来的html，可以根据其中的内容结合这篇文档http://blog.csdn.net/wangjintao1988/article/details/8003573,进行解析出歌曲的下载路径，然后再次用socket或者其他编程方式下载。

注意事项

1.服务器GET请求中，汉字必须转化为ASCII字符并且用%隔开，如：童话（%E7%AB%A5%E8%AF%9D），光良（%E5%85%89%E8%89%AF），括号中是服务器识别的格式

2.GET请求的格式：

GET /x?op=12&count=1&title=%E7%AB%A5%E8%AF%9D$$%E5%85%89%E8%89%AF$$$$ HTTP/1.1
Host: box.zhangmen.baidu.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:29.0) Gecko/20100101 Firefox/29.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Connection:close

这个可以在火狐浏览器中通过firebug插件查看你发送的GET请求，如下图：输入http://box.zhangmen.baidu.com/x?op=12&count=1&title=%E7%AB%A5%E8%AF%9D$$%E5%85%89%E8%89%AF$$$$