抓取url的超链接程序（使用到libcurl和libxml2）

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <string>
#include <vector>
#include <curl/curl.h>
#include <libxml/HTMLparser.h>

using namespace std;

#ifdef _MSC_VER
#define COMPARE(a, b) (!stricmp((a), (b)))
#else
#define COMPARE(a, b) (!strcasecmp((a), (b)))
#endif

typedef struct LinkStringDefined
{
    string url;
    string anthor_text;
} LinkString;

typedef struct ContextDefined
{
    ContextDefined(): addTitle(false) { }
    bool addTitle;
    string title;
    string url;
    vector<LinkString> terms;
} Context;

static char errorBuffer[CURL_ERROR_SIZE];
static string buffer;
static int writer(char *, size_t, size_t, string *);
static bool init(CURL *&, char *);
static void parseHtml(const string &, vector<LinkString> &);
static void StartElement(void *, const xmlChar *, const xmlChar **);
static void EndElement(void *, const xmlChar *);
static void Characters(void *, const xmlChar *, int);
static void CdataBlock(void *, const xmlChar *, int);

int main(int argc, char* argv[])
{
    CURL *conn = NULL;
    CURLcode code;
    vector<LinkString> arr;
    if (argc != 2)
    {
        fprintf(stderr, "Usage: %s <url>\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    curl_global_init(CURL_GLOBAL_DEFAULT);
    if (!init(conn, argv[1]))
    {
        fprintf(stderr, "Connection initializion failed\n");
        exit(EXIT_FAILURE);
    }
    code = curl_easy_perform(conn);
    curl_easy_cleanup(conn);
    if (code != CURLE_OK)
    {
        fprintf(stderr, "Failed to get '%s' [%s]\n", argv[1], errorBuffer);
        exit(EXIT_FAILURE);
    }
    parseHtml(buffer, arr);
    int arr_size = arr.size();
    for(int i = 0; i < arr_size; i ++)
    {
        cout << arr[i].anthor_text << "\t" << arr[i].url << endl;
    }
    return 0;
}

static bool init(CURL *&conn, char *url)
{
    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, &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 long sizes = size * nmemb;
    if (writerData == NULL) return 0;
    writerData->append(data, sizes);
    return sizes;
}

static htmlSAXHandler saxHandler =
{
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    StartElement,
    EndElement,
    NULL,
    Characters,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    CdataBlock,
    NULL
};

static void parseHtml(const string &html, vector<LinkString> &arr)
{
    htmlParserCtxtPtr ctxt;
    Context context;
    ctxt = htmlCreatePushParserCtxt(&saxHandler, &context, "", 0, "", XML_CHAR_ENCODING_NONE);
    htmlParseChunk(ctxt, html.c_str(), html.size(), 0);
    htmlParseChunk(ctxt, "", 0, 1);
    htmlFreeParserCtxt(ctxt);
    arr = context.terms;
}

static void StartElement(void *voidContext, const xmlChar *name, const xmlChar **attributes)
{
//    int sz_att = sizeof(**attributes) / sizeof(xmlChar);
    Context *context = (Context *)voidContext;
    if (COMPARE((char *)name, "a"))
    {
        context->url = (char *)attributes[1];
        context->title = "";
        context->addTitle = true;
    }
}

static void EndElement(void *voidContext, const xmlChar *name)
{
    Context *context = (Context *)voidContext;
    if (COMPARE((char *)name, "a"))
    {
        context->url = "";
        context->addTitle = false;
    }
}

static void handleCharacters(Context *context, const xmlChar *chars, int length)
{
    LinkString linkString;
    if (context->addTitle)
    {
        context->title.append((char *)chars, length);
        linkString.anthor_text = context->title;
        linkString.url = context->url;
        context->terms.push_back(linkString);
    }
}

static void Characters(void *voidContext, const xmlChar *chars, int length)
{
    Context *context = (Context *)voidContext;
    handleCharacters(context, chars, length);
}

static void CdataBlock(void *voidContext, const xmlChar *chars, int length)
{
    Context *context = (Context *)voidContext;
    handleCharacters(context, chars, length);
}

CXX = g++

WARNING = -Wall
GDBDEBUG = -g
LIBS = -L.
DEFAULT_INCLUDE = -I. -I/usr/include
ADDED_INCLUDE= -I /usr/include/libxml2
OPTIMIZE = -O2

allprog = get_url_info
object1 = get_url_info.o
complied = $(CXX) $(GDBDEBUG) $(WARNING) $(OPTIMIZE) $(DEFAULT_INCLUDE) $(ADDED_INCLUDE) -c $*.cpp

all : ${allprog}
.cpp.o :
    $(complied)
get_url_info : $(object1)
    $(CXX) $(GDBDEBUG) $(WARNING) -lcurl -lxml2 $(OPTIMIZE) -o get_url_info $(object1)

.PHONY : cleanall clean cleanobj
cleanall :
    -rm *.o ${allprog}
clean :
    -rm $(object1) get_url_info
cleanobj :
    -rm *.o