使用libxml2创建和解析xml文件
毕业设计需要用到xml文件来组织和存放数据，
对于Linux环境下，有libxml2可供使用。
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经过一段时间查询文档和网站，
基本掌握创建xml文档和解析xml的操作，
简单做一下记录。
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创建xml
例子如下：
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#include <stdio.h>#include <libxml/parser.h>#include <libxml/tree.h>int main(int argc, char **argv){ xmlDocPtr doc = NULL; xmlNodePtr root_node = NULL, node = NULL, node1 = NULL; doc = xmlNewDoc(BAD_CAST "1.0"); // create a new xml document. root_node = xmlNewNode(NULL, BAD_CAST "root"); // create a root node. xmlDocSetRootElement(doc, root_node); xmlNewChild(root_node, NULL, BAD_CAST "node1", BAD_CAST "content of node1"); //xmlNewChild(root_node, NULL, BAD_CAST "node2", NULL); node = xmlNewChild(root_node, NULL, BAD_CAST "node3", BAD_CAST "node3 has attributes"); xmlNewProp(node, BAD_CAST "attribute", BAD_CAST "yes"); node = xmlNewNode(NULL, BAD_CAST "node4"); node1 = xmlNewText(BAD_CAST "other way to create content (which is also a node)"); xmlAddChild(node, node1); xmlAddChild(root_node, node); xmlSaveFormatFileEnc(argc > 1 ? argv[1] : "-", doc, "UTF-8", 1); xmlFreeDoc(doc); xmlCleanupParser(); xmlMemoryDump(); return(0);}?libxml的api使用 const unsigned char* 。
而string literal 只能隐式转换到 const char*。
所以libxml提供一个BAD_CAST用来作显示转换。
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代码应该不难看懂，生成的xml文件如下：
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<?xml version="1.0" encoding="UTF-8"?><root> <node1>content of node1</node1> <node3 attribute="yes">node3 has attributes</node3> <node4>other way to create content (which is also a node)</node4></root>
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xml文件和创建xml的代码对照着看就很容易看懂如何生成节点以及属性了。
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解析xml
代码如下：
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#include <stdio.h>#include <stdlib.h>#include <string.h>#include <libxml/parser.h>#include <libxml/xmlmemory.h>int main(int argc, char **argv){ xmlDocPtr doc; xmlNodePtr curNode; xmlKeepBlanksDefault(0); doc = xmlReadFile("mine.xml", "UTF-8", XML_PARSE_RECOVER); // open a xml doc. curNode = xmlDocGetRootElement(doc); // get root element. if (curNode == NULL) { fprintf(stderr, "open file failed. \n"); xmlFreeDoc (doc); return -1; } if (xmlStrcmp(curNode->name, "root")) // if the same,xmlStrcmp return 0, else return 1 { fprintf(stderr, "check rootElement failed. \n"); xmlFreeDoc (doc); return -1; } curNode = curNode->children; // move to root element's children. char *nodeName; char *content; if (curNode != NULL) { nodeName = (char *) curNode->name; content = (char *) xmlNodeGetContent(curNode); printf ("Current node name:%s,\t the content is:%s.\n\n", nodeName, content); } curNode = curNode->next; char *attr; if (curNode != NULL) { nodeName = (char *) curNode->name; content = (char *) xmlNodeGetContent(curNode); attr = (char *) xmlGetProp(curNode, (const xmlChar *)"attribute"); // get node attribute printf ("Current node name:%s,\t the content is:%s,\t AND THE ATTR IS:%s.\n\n", nodeName, content,attr); } curNode = curNode->next; if (curNode != NULL) { nodeName = (char *) curNode->name; content = (char *) xmlNodeGetContent(curNode); printf ("Current node name:%s,\t the content is:%s.\n\n", nodeName, content); } xmlFree(curNode); xmlFreeDoc(doc); return 1;}?
上面的代码是简单的按生成的xml结构来解析，
正确的用法应该是写成一个函数来调用，
可以解析任何的已知根节点的xml文件。
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解析的结果输入如下：
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[nigelzeng@ubuntu xml-learning]$ ./xml-mine-parse Current node name:node1, the content is:content of node1.Current node name:node3, the content is:node3 has attributes, AND THE ATTR IS:yes.Current node name:node4, the content is:other way to create content (which is also a node).
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参考：
http://xmlsoft.org/index.html
http://www.cppblog.com/lymons/archive/2009/03/30/37553.html
http://www.4ucode.com/Study/Topic/1622022
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