XML學習總結

ＸＭＬ定義：

    XML（extensible Markup Language）即可扩展标记语言。

 

XML舉例：

<? xml version="1.0" encoding="utf-8" ?>
< Books >
  < book >
     < title >
      Beginning Visual C#
     </ title >
     < author >
      Karli Watson
     </ author >
     < code >
      7582
     </ code >
  </ book >
  < book  Pages ="1000" >
     <!-- This book is the book you are reading -->
     < title > Beginning Visual C# 3rd Edition </ title >
     < author > Karli Watson et al </ author >
     < code > 123456789 </ code >
  </ book >
</ Books >

 

XML主要結點類型：

根節點(文檔結點)

元素

屬性

文本

註釋

 

結點類型在XML文件中對應如下：

 

 

XML操作的動作：

 

讀取

選擇

增加

刪除

修改

替換

 

 

Xml操作的主要流程為：

 

Xpath語言：

        XPath是XML文檔的查詢語言。XML相關於數據庫，Xpath就是查詢數據的語言，即相當於SQL。詳細資料可參考(http://www.w3school.com.cn/xpath/index.asp)

 

Xpath常見的表達式如下：

表达式	描述
nodename	选取此节点的所有子节点
/	从根节点选取
//	从匹配选择的当前节点选择文档中的节点，而不考虑它们的位置
.	选取当前节点
..	选取当前节点的父节点
*	選擇任何節點
@	选取属性
@*	選擇所有屬性
athor[2]	按照索引選擇一個子節點，這裡選擇第二個author節點
text()	選擇當前節點中所有文本節點
author/text()	選擇當前節點的一個或多個子節點
//title	在文檔中選擇帶有特定名稱的所有節點，在這裡是所有的title節點
//@author	选取所有名为author的属性。
//book/title	在文檔中選擇帶有特定和特定父節點的所有節點，在這裡父節點名稱是Book,節點名稱是title
//book[author=’Jacob’]	選擇滿足條件的節點，這是authoer節點為’Jacob’的值
//book[@pages=’10’]	選擇屬性值滿足條件的節點，這裡是page屬性為10的值
//book/title | //book/ author	选取所有 book 元素的 tilte 和 author元素。

 

 例一、實現下圖功能。

 

 

 

using  System.Xml;
using  System.IO;

namespace  XmlOperate
{
     public   partial   class  Form1 : Form
    {
         public  Form1()
        {
            InitializeComponent();
             // 得到XML內容按鈕事件
            btnGet.Click  +=   new  EventHandler(btnGet_Click);
             // 創建Node按鈕事件
            btnCreateNode.Click  +=   new  EventHandler(btnCreateNode_Click);
             // 刪除節點按鈕事件
            btnDeleteNode.Click  +=   new  EventHandler(btnDeleteNode_Click);            
        }
 

         ///   <summary>
         ///  得到XML內容按鈕事件方法
         ///   </summary>
         ///   <param name="sender"></param>
         ///   <param name="e"></param>
         void  btnGet_Click( object  sender, EventArgs e)
        {
            lbXmlValue.Items.Clear();

             if  (File.Exists( @" D:\BegVCSharp\book.xml " ))
            {
                 // 加載XML文件
                XmlDocument xdDocument  =   new  XmlDocument();
                xdDocument.Load( @" D:\BegVCSharp\book.xml " );

                 // 得到主節點
                XmlElement xeRoot  =  xdDocument.DocumentElement;
                 if  (xeRoot != null )
                {
                    XmlNode xnNodeRoot  =  (XmlNode)xeRoot;
                    RecurseXmlDocument(xnNodeRoot,  0 );
                }
            }
        }

         ///   <summary>
         ///  讀取ＸＭＬ
         ///   </summary>
         ///   <param name="aXnNode"> 節點 </param>
         ///   <param name="aIndent"> 縮進大小 </param>
         private   void  RecurseXmlDocument(XmlNode aXnNode, int  aIndent)
        {
             // 判斷結點中是否有內容
             if  (aXnNode  ==   null )
            {
                 return ;
            }


             // 節點是元素時
             if  (aXnNode  is  XmlElement)
            { 
                 // 顯示根元素的名稱
                lbXmlValue.Items.Add(aXnNode.Name.PadLeft(aXnNode.Name.Length  +  aIndent));

                 if  (aXnNode.Attributes != null )
                {
                     // 得到屬性
                     foreach  (XmlAttribute xaAttribute  in  aXnNode.Attributes)
                    {
                         string  sText  =   "" ;
                        sText  =  xaAttribute.Name;
                        lbXmlValue.Items.Add(sText.PadLeft(sText.Length  +  aIndent + 2 ));
                        sText  =  xaAttribute.Value;
                        lbXmlValue.Items.Add(sText.PadLeft(sText.Length  +  aIndent + 4 ));
                    } 
                }
                 // 根元素中是否有子元素
                 if  (aXnNode.HasChildNodes)
                {                  
                     // 有子節點，遍歷子節點
                    RecurseXmlDocument(aXnNode.FirstChild, aIndent + 2 );
                }
                 // 判斷下個節點是為空
                 if  (aXnNode.NextSibling  !=   null )
                {                    
                    RecurseXmlDocument(aXnNode.NextSibling, aIndent);
                }
            } 
             else   if  (aXnNode  is  XmlText)
            {
                 // 顯示節點中的內容
                 string  sText  =  ((XmlText)aXnNode).Value;
                lbXmlValue.Items.Add(sText.PadLeft(sText.Length  +  aIndent));
            }
             else   if  (aXnNode  is  XmlComment)
            {
                 string  sText  =  aXnNode.Value;
                lbXmlValue.Items.Add(sText.PadLeft(sText.Length  +  aIndent));

                 // 如果不加下邊的遍歷，資料只會得出備註中的內容，不會得出子節點內容
                 if  (aXnNode.HasChildNodes)
                {
                     // 有子節點，遍歷子節點
                    RecurseXmlDocument(aXnNode.FirstChild, aIndent  +   2 );
                }
                 if  (aXnNode.NextSibling  !=   null )
                {
                    RecurseXmlDocument(aXnNode.NextSibling, aIndent);
                }
            }

        }

         ///   <summary>
         ///  創建Node按鈕事件方法
         ///   </summary>
         ///   <param name="sender"></param>
         ///   <param name="e"></param>
         void  btnCreateNode_Click( object  sender, EventArgs e)
        {
             // 加載XML文件
            XmlDocument xdDocument  =   new  XmlDocument();
            xdDocument.Load( @" D:\BegVCSharp\book.xml " );

             // 得到主節點
            XmlElement xeRoot  =  xdDocument.DocumentElement;

             // 創建節點
            XmlElement newBook  =  xdDocument.CreateElement( " book " );
            XmlElement newTitle  =  xdDocument.CreateElement( " title " );
            XmlElement newAuthor  =  xdDocument.CreateElement( " author " );
            XmlElement newCode  =  xdDocument.CreateElement( " code " );            
             // 創建屬性
            XmlAttribute xaNewAttribute  =  xdDocument.CreateAttribute( " Pages " );
            xaNewAttribute.Value  =   " 1000 " ;

            XmlText title  =  xdDocument.CreateTextNode( " Beginning Visual C# 3rd Edition " );
            XmlText author  =  xdDocument.CreateTextNode( " Karli Watson et al " );
            XmlText code  =  xdDocument.CreateTextNode( " 123456789 " );
             // 創建備註
            XmlComment comment  =  xdDocument.CreateComment( " This book is the book you are reading " );




             // 元素插入ＸＭＬ樹中
            newBook.AppendChild(comment);
            newBook.Attributes.Append(xaNewAttribute);
            newBook.AppendChild(newTitle);
            newBook.AppendChild(newAuthor);
            newBook.AppendChild(newCode);
            newTitle.AppendChild(title);
            newAuthor.AppendChild(author);
            newCode.AppendChild(code);

             // 插入某節點後邊
            xeRoot.InsertAfter(newBook, xeRoot.FirstChild);

             // 保存結果
            xdDocument.Save( @" D:\BegVCSharp\book.xml " );

        }

         ///   <summary>
         ///  刪除節點按鈕事件
         ///   </summary>
         ///   <param name="sender"></param>
         ///   <param name="e"></param>
         void  btnDeleteNode_Click( object  sender, EventArgs e)
        {
             // 加載XML文件
            XmlDocument xdDocument  =   new  XmlDocument();
            xdDocument.Load( @" D:\BegVCSharp\book.xml " );

             // 得到主節點
            XmlElement xeRoot  =  xdDocument.DocumentElement;

             if  (xeRoot.HasChildNodes)
            {
                 // 得到最後一個節點
                XmlNode xnBook  =  xeRoot.LastChild;
                 // 刪除最後一個結點
                xeRoot.RemoveChild(xnBook);
                 // 保存結果
                xdDocument.Save( @" D:\BegVCSharp\book.xml " );
            }
        }
    }
}

 

 

例二、用Xpath執行相關查詢

using  System.Xml;

namespace  XmlIoManage
{
     public   partial   class  Form1 : Form
    {
         public  Form1()
        {
            InitializeComponent();
             string  sXmlPath  =   @" D:\BegVCSharp\XPathQuery.xml " ;
            XmlDocument xdDocument  =   new  XmlDocument();
            xdDocument.Load(sXmlPath);
            XmlNode xnNode  =  xdDocument.DocumentElement;
    
            GetXmlListAttribute(xnNode,  " //@pages " );
            GetXmlElementList(xnNode,  " //book " );
        }


         ///   <summary>
         ///  得到指定結點的Text值
         ///   </summary>
         ///   <param name="aXnNode"></param>
         ///   <param name="asAttributeFilter"></param>
         private   void  GetXmlElementList(XmlNode aXnNode,  string  asAttributeFilter)
        {
            List < string >  lElementTextlist  =   new  List < string > ();
             if  (aXnNode  ==   null )
            {
                 return ;
            }
            XmlNodeList xnlNodeList  =  aXnNode.SelectNodes(asAttributeFilter);
            lElementTextlist  =  ReadXmlElementText(xnlNodeList);
        }

         ///   <summary>
         ///  讀取節點Text值
         ///   </summary>
         ///   <param name="aXnlNodeList"></param>
         ///   <returns></returns>
         private  List < string >  ReadXmlElementText(XmlNodeList aXnlNodeList)
        {
            List < string >  lElementTextlist  =   new  List < string > ();
             if  (aXnlNodeList == null )
            {
                 return  lElementTextlist;
            }
             foreach  (XmlNode xnNode  in  aXnlNodeList)
            {
                 string  sText  =  RecurseXmlDocument(xnNode);
                lElementTextlist.Add(sText);
            }
             return  lElementTextlist;
        }

         string  sNodeInderText  =   "" ;
         ///   <summary>
         ///  返回第一個Text值
         ///   </summary>
         ///   <param name="aXnNode"></param>
         ///   <returns></returns>
         private   string  RecurseXmlDocument(XmlNode aXnNode)
        {            
             if  (aXnNode  ==   null )
            {
                 return   "" ;
            }
             if  (aXnNode  is  XmlElement)
            {
                 if  (aXnNode.HasChildNodes)
                {
                    RecurseXmlDocument(aXnNode.FirstChild);
                }
            }
             else   if  (aXnNode  is  XmlText)
            {
                sNodeInderText  =  ((XmlText)aXnNode).Value;
            }
            sNodeInderText += sNodeInderText.Trim();
             return  sNodeInderText;
        }


         ///   <summary>
         ///  得到所有指定屬性的值
         ///   </summary>
         ///   <param name="aXnNode"> aXnNode </param>
         ///   <param name="asAttributeFilter"> 屬性過慮值 </param>
         private   void  GetXmlListAttribute(XmlNode aXnNode,  string  asAttributeFilter)
        {
             // 存放得到屬性列表
            List < string >  lAttributeList  =   new  List < string > ();
             if  (aXnNode  ==   null )
            {
                 return ;
            }
            XmlNodeList xnlNodeList  =  aXnNode.SelectNodes(asAttributeFilter);
            lAttributeList  =  ReadXmlAttributeList(xnlNodeList);
        }

         ///   <summary>
         ///  得到屬性列表
         ///   </summary>
         ///   <param name="aXaNodeList"> XmlNodeList </param>
         ///   <returns> 得到的屬性列表 </returns>
         private  List < string >  ReadXmlAttributeList(XmlNodeList aXaNodeList)
        {
             // 存放得到屬性列表
            List < string >  lAttributeList  =   new  List < string > ();
             if  (aXaNodeList  ==   null )
            {
                 return  lAttributeList;
            }
             foreach  (XmlNode xnNode  in  aXaNodeList)
            {
                 if  (xnNode  is  XmlAttribute)
                {
                    XmlAttribute xaAttribute  =  (XmlAttribute)xnNode;

                    lAttributeList.Add(xaAttribute.Value);
                }
            }
             return  lAttributeList;
        }




         ///   <summary>
         ///  選擇單個結點屬性
         ///   </summary>
         ///   <param name="aXnNode"> 被查詢的Xml </param>
         ///   <param name="asAttributeFilter"> Xpth條件 </param>
         private   void  GetXmlSingleAttribute(XmlNode aXnNode,  string  asAttributeFilter)
        {
             if  (aXnNode == null )
            {
                 return ;
            }
            XmlNode xnSelectNode  =  aXnNode.SelectSingleNode(asAttributeFilter);
             string  sResult  =  ReadXmlSingleAttribute(xnSelectNode);
        }
         ///   <summary>
         ///  讀取XML單點的屬性方法
         ///   </summary>
         ///   <param name="aXnNode"> XmlNode </param>
         ///   <returns> 得到的屬性值 </returns>
         private   string  ReadXmlSingleAttribute(XmlNode aXnNode)
        {
             string  sRetrunValue  =   "" ;
             if  (aXnNode == null )
            {
                 return  sRetrunValue;
            }
             if  (aXnNode  is  XmlElement)
            {
                 if  (aXnNode.Attributes != null )
                {
                     foreach  (XmlAttribute xaAttribute  in  aXnNode.Attributes)
                    {
                        sRetrunValue  =  xaAttribute.Value;
                    }
                }               
            }
             return  sRetrunValue;
        }
    }
}