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昨天做了个解析xml文件的接口,百度了boost的接口,再结合自己踩过的坑,特做此记录。
先上代码,看看如何获取到xml文件节点属性和内容:
xml文件如下:
data1
12 "jack" "0001"
hello2
13 "toni" "0002"
disk 333
14 "hate" "0003"
代码如下:
#includeusing namespace std;
#include#includeusing namespace boost::property_tree;
string& trim(string &s)
{if (s.empty())
{return s;
}
string blanks("\f\v\r\t\n ");
s.erase(0, s.find_first_not_of(blanks));
s.erase(s.find_last_not_of(blanks) + 1);
return s;
}
int main(int argc, char **argv)
{ptree pt;
const char *filename = "t.xml";
read_xml(filename, pt);
const ptree &strages = pt.get_child("root");
for (auto it = strages.begin(); it != strages.end(); ++it)
{if (it->first != "strage") { cout<< it->first<< endl;
continue;
}
ptree strage = it->second;
string &data = strage.data();
data = trim(data);
string name = strage.get(".name");
int alias = strage.get(".alias");
float classId = strage.get(".classId");
printf("data: %s\nname: %s alias: %d classId: %f\n", data.c_str(), name.c_str(), alias, classId);
const ptree& idChild = strage.get_child("id");
const ptree& nameChild = strage.get_child("name");
const ptree& codeChild = strage.get_child("code");
const string& child_id = idChild.data();
const string& child_name = nameChild.data();
const string& child_code = codeChild.data();
printf("id: %s name: %s code: %s\n", child_id.c_str(), child_name.c_str(), child_code.c_str());
}
return 0;
}
运行结果如下:
data: data1
name: asd alias: 13 classId: 13.220000
id: 12 name: "jack" code: "0001"
data: hello2
name: abbasd alias: 14 classId: 14.220000
id: 13 name: "toni" code: "0002"
data: disk 333
name: assasd alias: 15 classId: 15.440000
id: 14 name: "hate" code: "0003"
大的坑:
在遍历子节点时,如果父节点本身带有属性,会多出一个的子节点,所以要判断一下子节点的first是否等于子节点的名称(
不用怀疑,当获取某个节点的内容时,由于xml的缩进换行美化效果,会造成内容前面或后面会有回车换行,甚至可能由于手动编辑过,会有我们看不到的制表符/t或空格,所以在获取内容时,往往需要去除两端空白。
第三个坑:
获取xml的某个节点的属性xmlattr时,如果该属性不存在,会抛异常,所以建议使用时给默认值可以避免抛出异常,如果属性必须存在,可以用try语句。
下面演示获取具体某个节点:
#include#include#include#includeusing namespace boost::property_tree;
using namespace std;
ptree *get_node_by_attr(ptree &nodes, const string label, const string attr, const string value)
{for (ptree::iterator it = nodes.begin(); it != nodes.end(); it++)
{if (it->first != label)
{continue;
}
ptree &item = it->second;
string name = item.get(string(".") + attr, "");
if (name == value)
{return &item;
}
}
return NULL;
}
string& trim(string &s)
{if (s.empty())
{return s;
}
string blanks("\f\v\r\t\n ");
s.erase(0, s.find_first_not_of(blanks));
s.erase(s.find_last_not_of(blanks) + 1);
return s;
}
int main(int argc, char **argv)
{ptree pt;
xml_parser::read_xml(string("t.xml"), pt, xml_parser::no_comments);
ptree &child = pt.get_child("root");
const string label = "strage";
const string attr = "name";
const string value = "abbasd";
ptree *node = get_node_by_attr(child, label, attr, value);
if (NULL == node)
{cout<< "没有name=" + attr + "的" + label + "节点"<(".name");
int alias = strage.get(".alias");
float classId = strage.get(".classId");
printf("data: %s\nname: %s alias: %d classId: %f\n", data.c_str(), name.c_str(), alias, classId);
const ptree& idChild = strage.get_child("id");
const ptree& nameChild = strage.get_child("name");
const ptree& codeChild = strage.get_child("code");
const string& child_id = idChild.data();
const string& child_name = nameChild.data();
const string& child_code = codeChild.data();
printf("id: %s name: %s code: %s\n", child_id.c_str(), child_name.c_str(), child_code.c_str());
return 0;
}
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