c语言使用ekhtml库解析html

c语言使用ekhtml库解析html

El-Kabong 是一个快速的，不带验证的，SAX接口的HTML解析器。 它的目标是提供一个快速，轻量级的解析HTML的库，对于语法不正确的标签也可以识别。
可从sourceforge下载源码：http://sourceforge.net/projects/ekhtml/
* 最新版本ekhtml-0.3.2.

下载完毕后，解压开，进入到解压开的目录下，输入./configure && make编译文档。这些都在INSTALL文件里，可以参考一下。

然后，在src目录下的.lib目录下会有一个libekhtml.a的文件，这个文件就是ekhtml的静态链接库。静态链接库可以看成是.o文件的集合。

最后输入sudo make install就可以将ekhtml库安装到计算机上，ekhtml.h头文件在/usr/local/include目录下，静态链接库和动态链接库在/usr/local/lib目录下。

使用时，包含头文件ekhtml.h就可以了，在链接时要记得加上，/usr/local/lib/libekhtml.a文件。

下面是链接库的官方文档：

Libraries have been installed in:
   /usr/local/lib
If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR'
flag during linking and do at least one of the following:
   - add LIBDIR to the `LD_LIBRARY_PATH' environment variable
     during execution
   - add LIBDIR to the `LD_RUN_PATH' environment variable
     during linking
   - use the `-Wl,--rpath -Wl,LIBDIR' linker flag
   - have your system administrator add LIBDIR to `/etc/ld.so.conf'
See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.

这个是官方给的测试程序：

编译命令为：gcc -o tester tester.c /usr/local/lib/libekhtml.a

/*
 * Copyright (c) 2002, Jon Travis
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#include "ekhtml.h"

#define MAGIC_DOODIE 0xf9d33bc1

typedef struct {
    unsigned int n_starttags;
    unsigned int n_endtags;
    unsigned int n_comments;
    unsigned int n_data;
    unsigned int magic_doodie;
    unsigned int only_parse;
} tester_cbdata;

static void handle_starttag_way(void *cbdata, ekhtml_string_t *tag,
                                ekhtml_attr_t *attrs)
{
    printf("GOT WAY START!n");
}

static void handle_starttag(void *cbdata, ekhtml_string_t *tag,
			    ekhtml_attr_t *attrs)
{
    ekhtml_attr_t *attr;
    tester_cbdata *tdata = cbdata;
    
    assert(tdata->magic_doodie == MAGIC_DOODIE);
    tdata->n_starttags++;
    if(tdata->only_parse)
        return;
    
    printf("START: "%.*s"n", (int)tag->len, tag->str);
    for(attr=attrs; attr; attr=attr->next) {
        printf("ATTRIBUTE: "%.*s" = ", (int)attr->name.len, attr->name.str);
        if(!attr->isBoolean)
            printf(""%.*s"n", (int)attr->val.len, attr->val.str);
        else
            printf(""%.*s"n", (int)attr->name.len, attr->name.str);
    }
}

static void handle_endtag(void *cbdata, ekhtml_string_t *str){
    tester_cbdata *tdata = cbdata;
    
    assert(tdata->magic_doodie == MAGIC_DOODIE);
    tdata->n_endtags++;
    if(tdata->only_parse)
        return;
    
    printf("END: "%.*s"n", (int)str->len, str->str);
}

static void handle_comment(void *cbdata, ekhtml_string_t *str){
    tester_cbdata *tdata = cbdata;
    
    assert(tdata->magic_doodie == MAGIC_DOODIE);
    tdata->n_comments++;
    if(tdata->only_parse)
        return;
    
    printf("COMMENT: "%.*s"n", (int)str->len, str->str);
}

static void handle_data(void *cbdata, ekhtml_string_t *str){
    tester_cbdata *tdata = cbdata;
    
    assert(tdata->magic_doodie == MAGIC_DOODIE);
    tdata->n_data++;
    if(tdata->only_parse)
        return;
    
    fwrite(str->str, str->len, 1, stdout);
}

int main(int argc, char *argv[]){
    tester_cbdata cbdata;
    ekhtml_parser_t *ekparser;
    char *buf;
    size_t nbuf;
    int feedsize;
    
    if(argc < 2){
        fprintf(stderr, "Syntax: %s <feedsize> [1|0 (to print debug)]n", 
                argv[0]);
        return -1;
    }
    
    feedsize = atoi(argv[1]);
    
    ekparser = ekhtml_parser_new(NULL);
    
    cbdata.n_starttags  = 0;
    cbdata.n_endtags    = 0;
    cbdata.n_comments   = 0;
    cbdata.n_data       = 0;
    cbdata.magic_doodie = MAGIC_DOODIE;
    cbdata.only_parse   = argc == 3;
    
    ekhtml_parser_datacb_set(ekparser, handle_data);
    ekhtml_parser_commentcb_set(ekparser, handle_comment);
    ekhtml_parser_startcb_add(ekparser, "WAY", handle_starttag_way);
    ekhtml_parser_startcb_add(ekparser, NULL, handle_starttag);
    ekhtml_parser_endcb_add(ekparser, NULL, handle_endtag);
    ekhtml_parser_cbdata_set(ekparser, &cbdata);
    buf = malloc(feedsize);
    
    while((nbuf = fread(buf, 1, feedsize, stdin))){
        ekhtml_string_t str;

        str.str = buf;
        str.len = nbuf;
        ekhtml_parser_feed(ekparser, &str);
        ekhtml_parser_flush(ekparser, 0);
    }
    ekhtml_parser_flush(ekparser, 1);
    ekhtml_parser_destroy(ekparser);
    free(buf);
    
    if(argc == 3){
        fprintf(stderr, 
                "# starttags: %un"
                "# endtags:   %un"
                "# comments:  %un"
                "# data:      %un", cbdata.n_starttags,
                cbdata.n_endtags, cbdata.n_comments, cbdata.n_data);
    }
    
    return 0;
}

下面来介绍一下ekhtml函数的使用（官方的文档在docs文件夹下）：

ekhtml中有两个结构体，一个是ekhtml_attr_t，用来表示标签的属性，定义如下：

typedef struct ekhtml_attr_t {
    ekhtml_string_t       name;       /**< Name of the attribute             */
    ekhtml_string_t       val;        /**< Value of the attribute            */
    unsigned int          isBoolean;  /**< True of the attribute is boolean  */
    struct ekhtml_attr_t *next;  /**< Pointer to next attribute in the list  */
} ekhtml_attr_t;

这个结构体将会传递给回调函数，属性的名字和属性的值都是ekhtml_string_t类型，是另一个结构体，官方说是因为速度的原因没有使用''结尾的字符串。

ekhtml_string_t的定义如下：

typedef struct ekhtml_string_t {
    const char *str;    /**< Actual string data          */
    size_t      len;    /**< Length of the data in `str` */
} ekhtml_string_t;

ekhtml_string_t表示一个字符串，不过这个字符串用len字段表明这个字符串的长度。

常用函数：

1，ekhtml_parser_t *ekhtml_parser_new(void *cbdata)

创建一个解析html的对象，返回其指针，参数时要传递给回调函数的参数。

ekhtml_parser_t是一个html的解析对象，有兴趣可以参见源代码中它的定义。

可以先不设置，然后使用ekhtml_parser_cbdata_set函数来设置。

2，void ekhtml_parser_datacb_set(ekhtml_parser_t *parser, ekhtml_data_cb_t cb)

这个用来设置标签内的内容处理的回调函数，标签内容和设置的回调函数参数会传递给回调函数。

ekhtml_data_cb_t是一个函数的指针类型，定义为：

typedef void (*ekhtml_data_cb_t)(void *cbdata, ekhtml_string_t *data);

cbdata为自己设置的回调函数参数，ekhtml_string_t为标签内容。

3，void ekhtml_parser_commentcb_set(ekhtml_parser_t *parser, ekhtml_data_cb_t cb)

我把ekhtml的源代码放到了我的github上，方便下载：https://github.com/gwq5210/ekhtml.git

参考：

1）http://blog.csdn.net/jq0123/article/details/1328786