VC++ 下使用 xml 文件导入导出数据

最新推荐文章于 2023-07-04 21:08:51 发布

Akron

最新推荐文章于 2023-07-04 21:08:51 发布

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文章标签： xml vc++ object float class null

本文链接：https://blog.youkuaiyun.com/Akron/article/details/2734392

本文介绍了如何在VC++环境下利用XML进行数据的导入和导出。通过定义不同数据类型如INT, FLOAT, STR等，并实现ToXML方法，实现了数据到XML的转换。同时，使用IXMLDOMDocument接口解析XML文件，将数据加载到CCollectionType集合类中，简化了操作。" 114295379,10700328,Java字符流详解：编码解码与缓冲流,"['Java IO', '字符输入流', '字符输出流', '编码转换', '缓冲流']

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XML (eXtensible Markup Language) 是一种简单的数据存储语言，使用一系列简单的标记描述数据，虽然XML占用的空间比二进制数据要占用更多的空间，但XML极其简单易于掌握和使用。更重要的是，xml 可以描述非常复杂的数据结构，比如树状结构。

为了建立一个通用，易于扩展，易于使用的数据导入导出应用，首先得定义一些数据类型用于存储 int, float, string, array 等基本数据类型。

#pragma once

#include "Collection.h"

class CDataType

{

public:

CString Id;

CDataType(void) {}

virtual ~CDataType() {}

virtual char* GetTypeName() { return ""; }

virtual int& Integer() { ::AfxThrowInvalidArgException(); }

virtual float& Float() { ::AfxThrowInvalidArgException(); }

virtual CString& String() { ::AfxThrowInvalidArgException(); }

virtual CDataType& operator[](LPCTSTR key) { ::AfxThrowInvalidArgException(); }

virtual CDataType& operator[](int index) { ::AfxThrowInvalidArgException(); }

virtual bool IsCollection() { return false; }

virtual CString& ToXML(CString& s) { return s; }

};

class CIntegerType: public CDataType

{

int m_Object;

public:

CIntegerType(int value) { m_Object = value; }

virtual char* GetTypeName() { return "INT"; }

virtual int& Integer() { return m_Object; }

virtual CString& ToXML(CString& s) {

s.Format("<INT ID=/"%s/" V=/"%d/" />", Id, m_Object);

return s;

}

};

class CFloatType: public CDataType

{

float m_Object;

public:

CFloatType(float value) { m_Object = value; }

virtual char* GetTypeName() { return "FLOAT"; }

virtual float& Float() { return m_Object; }

virtual CString& ToXML(CString& s) {

s.Format("<FLOAT ID=/"%s/" V=/"%g/" />", Id, m_Object);

return s;

}

};

class CStringType: public CDataType

{

CString m_Object;

public:

CStringType(LPCTSTR value) { m_Object = value; }

virtual char* GetTypeName() { return "STR"; }

virtual CString& String() { return m_Object; }

virtual CString& ToXML(CString& s) {

s.Format("<STR ID=/"%s/" V=/"%s/" />", Id, m_Object);

return s;

}

};

class CStringArrayType: public CDataType

{

CArray<CString*, CString*> m_Object;

public:

CStringArrayType() {}

virtual char* GetTypeName() { return "STRs"; }

void Add(LPCTSTR value) { m_Object.Add(new CString(value)); }

CString& GetAt(int index) { return *m_Object[index]; }

int GetCount() { return (int) m_Object.GetCount(); }

virtual ~CStringArrayType(void) { for (int i=0; i<m_Object.GetCount(); i++) delete m_Object[i]; }

virtual CString& ToXML(CString& s) {

s.Format("<STRs ID=/"%s/"", Id);

for (int i=0; i<m_Object.GetCount(); i++) {

s.Format("%s V%d=/"%s/"", s, i, GetAt(i));

}

return s;

}

};

class CIntegerArrayType: public CDataType

{

CArray<int, int&> m_Object;

public:

virtual char* GetTypeName() { return "INTs"; }

int& GetAt(int index) { return m_Object[index]; }

void Add(int value) { m_Object.Add(value); }

int GetCount() { return (int) m_Object.GetCount(); }

virtual CString& ToXML(CString& s) {

s.Format("<INTs ID=/"%s/"", Id);

for (int i=0; i<m_Object.GetCount(); i++) {

s.Format("%s V%d=/"%d/"", s, i, GetAt(i));

}

return s;

}

};

class CFloatArrayType: public CDataType

{

CArray<float, float&> m_Object;

public:

virtual char* GetTypeName() { return "FLOATs"; }

void Add(float value) { m_Object.Add(value); }

float& GetAt(int index) { return m_Object[index]; }

int GetCount() { return (int) m_Object.GetCount(); }

virtual CString& ToXML(CString& s) {

s.Format("<INTs ID=/"%s/"", Id);

for (int i=0; i<m_Object.GetCount(); i++) {

s.Format("%s V%d=/"%g/"", s, i, GetAt(i));

}

return s;

}

};

class CCollectionType: public CDataType

{

CCollection<CDataType> m_Object;

public:

CCollectionType() {}

virtual ~CCollectionType(void) { DeleteAll(); }

virtual CCollectionType& Collection() { return *this; }

virtual char* GetTypeName() { return "SETs"; }

virtual bool IsCollection() { return true; }

void Add(LPCTSTR key, CDataType* object) { m_Object.Add(key, object)->Id = key; }

void Add(LPCTSTR key, int value) { m_Object.Add(key, new CIntegerType(value))->Id = key; }

void Add(LPCTSTR key, float value) { m_Object.Add(key, new CFloatType(value))->Id = key; }

void Add(LPCTSTR key, LPCTSTR value) { m_Object.Add(key, new CStringType(value))->Id = key; }

int GetCount() { return m_Object.GetCount(); }

CDataType& operator[](LPCTSTR key) { return m_Object[key]; }

CDataType& operator[](int index) { return m_Object[index]; }

CDataType* GetAt(LPCTSTR key) { return m_Object.GetAt(key); }

CDataType* GetAt(int index) { return m_Object.GetAt(index); }

void RemoveAll() { return m_Object.RemoveAll(); }

void DeleteAll() { return m_Object.DeleteAll(); }

virtual CString& ToXML(CString& s) {

s.Format("<SETs ID=/"%s/">", Id, m_Object);

return s;

}

};

CCollectionType 是一个可以使用字符名称以及索引查询的CDataType 集合类，由于CCollectionType 是从CDataType 派生，所以CcollectionType 可以被加入到CcollectionType 中，用以形成树状结构。

VC++ 下带有 xml 的解析 IXMLDOMDocument, 虽然没有 C# 下简单，但是在MSXML2 namespace 下的封装类，则相当简单.

bool CXMLFile::Load(LPCTSTR fileName, CCollectionType& collection)

{

try {

if FAILED(::CoInitialize(NULL))

return false;

MSXML2::IXMLDOMDocumentPtr pXMLDoc = NULL;

if FAILED(pXMLDoc.CreateInstance("Msxml2.DOMDocument.4.0"))

return false;

if (! pXMLDoc->load(CComVariant(fileName)))

return false;

MSXML2::IXMLDOMElementPtr pElement = pXMLDoc->documentElement;

if (collection.Id != pElement->nodeName.GetBSTR())

return false;

return ParseObjects(pElement->childNodes, collection);

}

catch (...) { return false; }

}

bool CXMLFile::ParseObjects(MSXML2::IXMLDOMNodeListPtr nodes, CCollectionType& collection)

{

try {

MSXML2::IXMLDOMNodePtr node;

int length = nodes->length;

for (long n=0; n<length; n++) {

node = nodes->item[n];

CString type(node->nodeName.GetBSTR());

if (node->attributes->length < 1) return false;

CComVariant id = node->attributes->item[0]->nodeValue;

if (type == "INT") {

if (node->attributes->length < 2) return false;

CComVariant value = node->attributes->item[1]->nodeValue;

int v = ::atoi((LPCTSTR) CString(value.bstrVal));

collection.Add(CString(id.bstrVal), v);

}

else if (type == "FLOAT") {

if (node->attributes->length < 2) return false;

CComVariant value = node->attributes->item[1]->nodeValue;

float v = (float) ::atof((LPSTR) value.bstrVal);

collection.Add(CString(id.bstrVal), v);

}

else if (type == "INTs") {

if (node->attributes->length < 2) return false;

CIntegerArrayType* v = new CIntegerArrayType;

int cout = node->attributes->length - 1;

for (int i=1; i<node->attributes->length; i++) {

CComVariant value = node->attributes->item[i]->nodeValue;

v->Add(::atoi((LPSTR) value.bstrVal));

}

collection.Add(CString(id.bstrVal), v);

}

else if (type == "STRs") {

if (node->attributes->length < 2) return false;

CStringArrayType* v = new CStringArrayType;

int cout = node->attributes->length - 1;

for (int i=1; i<node->attributes->length; i++) {

CComVariant value = node->attributes->item[i]->nodeValue;

v->Add(CString(value.bstrVal));

}

collection.Add(CString(id.bstrVal), v);

}

else if (type == "STR") {

if (node->attributes->length < 2) return false;

CComVariant value = node->attributes->item[1]->nodeValue;

collection.Add(CString(id.bstrVal), (LPCTSTR) CString(value.bstrVal));

}

else if (type == "SETs") {

CCollectionType* v = new CCollectionType();

collection.Add(CString(id.bstrVal), v);

if (! ParseObjects(node->childNodes, *v))

return false;

}

else {

}

catch(...) { return false; }

return true;

}

bool CXMLFile::Save(CStdioFile& file, CCollectionType& collection)

{

try {

m_IndentCount = 0;

file.WriteString("<");

file.WriteString(collection.Id);

file.WriteString(">/n");

SaveObjects(file, collection);

file.WriteString("</");

file.WriteString(collection.Id);

file.WriteString(">");

file.Close();

return true;

}

catch (...) { return false; }

}

bool CXMLFile::SaveObjects(CStdioFile& file, CCollectionType& collection)

{

try {

m_IndentCount++;

CString s;

for (int i=0; i<collection.GetCount(); i++) {

CDataType* v= collection.GetAt(i);

for (int n=0; n<m_IndentCount; n++)

file.WriteString(" ");

file.WriteString(v->ToXML(s) + "/n");

if (v->IsCollection()) {

SaveObjects(file, *(CCollectionType*) v);

for (int n=0; n<m_IndentCount; n++)

file.WriteString(" ");

file.WriteString("</SETs>/n");

}

m_IndentCount--;

return true;

}

catch (...) { return false; }

}

最终的使用变得非常简单：

CFileDialog openFile(TRUE, NULL, NULL, OFN_HIDEREADONLY,

_T("XML File (*.xml)|*.xml|All Files (*.*)|*.*||"), NULL);

if (openFile.DoModal() == IDOK) {

CXMLFile file;

CCollectionType collection;

collection.Id = _T("DEVICE");

if (! file.Load(openFile.GetFileName(), collection)) {

::MessageBox(NULL, _T(" Cannot open the file for write. "), NULL, MB_ICONSTOP | MB_OK);

return;

}

m_Text.SetWindowText(collection["APPLICATION"]["SYSTEM"]["VERSION"].String());

CString fileName = openFile.GetFileName() + "_";

CStdioFile outfile;

if( !outfile.Open(fileName, CFile::modeCreate|CFile::modeWrite|CFile::typeText)) {

::MessageBox(NULL, _T(" Cannot open the file for write. "), NULL, MB_ICONSTOP | MB_OK);

return;

}

file.Save(outfile, collection);