[libexpat]_[XML处理]_[C/C++使用libexpat库以数据流(SAX模型)的方式读取(解析)大XML文件]

优点:

1.当处理大文件XML时，只读取特定的数据。

2.速度快。

3.内存占用少。

缺点:

1.只支持XML文件,HTML文件不支持。

2.需要自己实现特定的存储结构。

以下是编译的Makefile文件:

CP="cp -u"

.build-post: test.exe
	${CP} E:/software/Lib/file/xml-expat-2.0.1/win32/release/share/libexpat-1.dll .

test.exe:test.o
	g++ -o test.exe test.o -LE:/software/Lib/file/xml-expat-2.0.1/win32/release/share -lexpat

test.o:test.cpp
	g++ -IE:/software/Lib/file/xml-expat-2.0.1/win32/release/share/include -c test.cpp -o test.o

以下是源代码：

#include <stdio.h>
#include <string>
#include <iostream>
#include <string.h>

#include "expat.h"

using namespace std;

#define XML_FMT_INT_MOD "l"


static bool sectPrStart = false;
static void StartElementHandler(void *userData,const XML_Char *name,
                                const XML_Char **atts)
{
	if(!strcmp("w:sectPr",name))
	{	
		sectPrStart = true;
		for (int i = 0; atts[i] != 0; i += 2)
		{
			cout << "name: " << atts[i] << endl;
			cout << "value: " << atts[i+1] << endl;
		}
	}
}

static void EndElementHandler(void *userData,const XML_Char *name)
{
	if(!strcmp("w:sectPr",name))
	{
		sectPrStart = false;
		cout << "End element name: " << name << endl;
	}
}

static void CharacterDataHandler(void *userData,const XML_Char *s,
                                 int len)
{
	if(sectPrStart && s)
	{
		string str(s,len);
		cout << "inner Text: " << str << endl;
	}
}

int main(int argc, char *argv[])
{
	cout << "Start............................." << endl;
	int i = 0;

	XML_Parser parser = XML_ParserCreate(NULL);
	XML_SetUserData(parser, &i);
	XML_SetElementHandler(parser, &StartElementHandler,&EndElementHandler);
	{
		XML_SetCharacterDataHandler(parser,&CharacterDataHandler);
	}

	int WRITEBUFFERSIZE = 5242880; // 5Mb buffer
	int size_buf = WRITEBUFFERSIZE;
	void* buf = malloc(size_buf);
	
	const char* file_path = argv[1];
	FILE* file = fopen(file_path,"r");
	
	int ret = 0;
	while(!feof(file))
	{
		ret = fread(buf,1,size_buf,file);
		cout << "ret: " << ret << endl;
		if (XML_Parse(parser, (char*) buf, ret, 0) == XML_STATUS_ERROR)
		{
			fprintf(stderr, "%s at line %" XML_FMT_INT_MOD "u ->%s\n",
					XML_ErrorString(XML_GetErrorCode(parser)),
					XML_GetCurrentLineNumber(parser), file_path);
			break;
		}
	}
	//last call
	XML_Parse(parser, (char*) 0, 0, 1);

	free(buf);
	XML_ParserFree(parser);
	fclose(file);
	cout << "End............................." << endl;
	return 0;
}