XMLHelp(上)

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--- XMLHelp(上) (http://www.webasp.net/article/5/4235.htm)
-- 作者：未知
-- 发布日期： 2003-07-12
namespace XmlHelper
{
using System;
using System.Xml;
using System.Xml.XPath;
using System.Collections;
using System.Net;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Data;

/// <summary>
/// This class attempts to wrap up some common things
/// we need to do when dealing with Xml and C# classes:
/// Load, Save, Add/Remove Attributes/Elements, et al.
/// </summary>
public class XmlHelper
{
  private XmlDocument m_xmlDocument;
  private XPathNavigator m_nav;
  private string m_sLastErrorMessage;
  public enum LoadType { FromString, FromLocalFile, FromURL }
  // Constructor
  public XmlHelper()
  {
   m_sLastErrorMessage = "";
   m_xmlDocument = new XmlDocument();
  }
  // Properties...
  public string LastErrorMessage
  {
   get { return m_sLastErrorMessage; }
   set { m_sLastErrorMessage = value; }
  }
  
  public XmlNode RootNode
  {
   get { return m_xmlDocument.DocumentElement; }
  }
  
  public XmlDocument Document
  {
   get { return m_xmlDocument; }   
  }

  public XPathNavigator Navigator
  {
   get { return m_nav; }   
  }
  // delegates - more complex save operations can do it themselves...
  public delegate bool Save(string sTargetXML);
  
  /// <summary>
  /// Save the XML to a target file.
  /// </summary>
  public bool SaveToFile(string sTargetFileName)
  {
   bool bResult = false;
   
   try
   {
    m_xmlDocument.Save(sTargetFileName);
    bResult = true;
   }
   catch (XmlException e)
   {
    HandleException ( e );
   }
  
   return bResult;
  }
  
  /// <summary>
  /// Easy way to get the entire Xml string
  /// </summary>
  public override string ToString()
  {
   return m_xmlDocument.OuterXml;
  }

  private void DoPostLoadCreateInit()
  {
   m_nav = m_xmlDocument.CreateNavigator();
   MoveToRoot();
  }

  /// <summary>
  /// Easy way to load XML from a file or URL
  /// </summary>
  public bool LoadXML(string sourceXMLOrFile, LoadType loadType)
  {
   bool bLoadResult = false;
   
   try
   {
    switch (loadType)
    {
     case XmlHelper.LoadType.FromString:
      m_xmlDocument.LoadXml(sourceXMLOrFile); // loading from source XML text
      break;
     case XmlHelper.LoadType.FromLocalFile:
      m_xmlDocument.Load(sourceXMLOrFile); // loading from a file
      break;
  
     case XmlHelper.LoadType.FromURL:
     {
      string sURLContent = GetURLContent(sourceXMLOrFile);
      m_xmlDocument.LoadXml(sURLContent);
      break;
     }
    
     default:
      string sErr = "Developer note:  No LoadType case supported for " + loadType.ToString();
      throw(new Exception(sErr));
    }
    DoPostLoadCreateInit();
             
    bLoadResult = true;
   }            
   catch (Exception e)
   {
    HandleException ( e );
   }
   return bLoadResult;
  }   
   
  /// <summary>
  /// Helper method to get string content from a URL - not necessarily XML, but probably
  /// </summary>
  public string GetURLContent(string sURL)
  {
   string s = "";
   try
   {   
    HttpWebRequest webreq = (HttpWebRequest)WebRequest.Create(sURL);
    HttpWebResponse webresp = (HttpWebResponse)webreq.GetResponse();
    
    StreamReader stream = new StreamReader(webresp.GetResponseStream(), Encoding.ASCII);
    s = stream.ReadToEnd();
    stream.Close();
   }
   catch(Exception e)
   {
    HandleException ( e );
   }    
    
   return s;    
  }
  /// <summary>
  /// Helper function if navigation is used to ensure we're at the root node.
  /// </summary>
  public bool MoveToRoot()
  {
   bool bResult = false;
   try
   {
    m_nav.MoveToRoot(); // go to root node!
    bResult = true;
   }
   catch (Exception e)
   {
    HandleException ( e );    
   }
   return bResult;
  }
   
  /// <summary>
  /// Gets an ArrayList of XmlNode children using an xPath expression
  /// </summary>
  public ArrayList GetChildNodesFromCriteria(string xPathExpression)
  {
   ArrayList al = new ArrayList();
   try
   {
    XmlNodeList nl = m_xmlDocument.SelectNodes(xPathExpression);
   
    if ( nl != null )
    {
     for ( int i=0; i<nl.Count; i++ )
      al.Add (nl.Item(i));
    }    
   }
   catch (Exception e)
   {
    HandleException ( e );      
   }
     
   return al;
  }
  /// <summary>
  /// Get first child node given an XPath expression
  /// </summary>
  public XmlNode GetFirstChildNodeFromCriteria (string xPathExpression)
  {
   
   XmlNode node = null;
   
   try
   {
    node = m_xmlDocument.SelectSingleNode(xPathExpression);
   }
   catch (Exception e)
   {
    HandleException ( e );      
   }
   
   return node;
  }
      
  /// <summary>
  /// Get the Attribute value from a given XmlNode
  /// </summary>
  public string GetAttributeValue(XmlNode node, string sAttributeName)
  {
   string sVal = "";
   try
   {
    XmlAttributeCollection attribColl = node.Attributes;
    XmlAttribute attrib = attribColl[sAttributeName, ""];
    sVal = Decode(attrib.Value);
   }       
   catch (Exception e)
   {
    HandleException ( e );
   }
    
   return sVal;
  }
  /// <summary>
  /// Get the Attribute int32 (int) value from a given XmlNode
  /// </summary>
  public int GetAttributeInt32Value(XmlNode node, string sAttributeName)
  {
   string sVal = GetAttributeValue ( node, sAttributeName);
    
   return sVal != "" ? Convert.ToInt32(sVal) : 0;
  }
  /// <summary>
  /// Get the Attribute floating point/Single value from a given XmlNode
  /// </summary>
  public float GetAttributeFloatValue(XmlNode node, string sAttributeName)
  {
   string sVal = GetAttributeValue ( node, sAttributeName);
   return sVal != "" ? Convert.ToSingle(sVal) : 0;
  }
  /// <summary>
  /// Get the Attribute double value from a given XmlNode
  /// </summary>
  public double GetAttributeDoubleValue(XmlNode node, string sAttributeName)
  {
   string sVal = GetAttributeValue ( node, sAttributeName);
   return sVal != "" ? Convert.ToDouble(sVal) : 0.00;
  }
  /// <summary>
  /// Get the Attribute boolean value from a given XmlNode
  /// </summary>
  public bool GetAttributeBooleanValue(XmlNode node, string sAttributeName)
  {
   string sVal = GetAttributeValue ( node, sAttributeName);
   return sVal != "" ? Convert.ToBoolean(sVal) : false;
  }
  /// <summary>
  /// Get the Element value from a given XmlNode
  /// </summary>
  public string GetElementValue(XmlNode xmlNode)
  {
   string sVal = "";
   
   try
   {
    sVal = Decode(xmlNode.InnerXml);
   }       
   catch (Exception e)
   {
    HandleException ( e );
   }
   return sVal;
  }
  /// <summary>
  /// Get the Element Int32 value from a given XmlNode
  /// </summary>
  public int GetElementInt32Value(XmlNode xmlNode)
  {
   string sVal = GetElementValue (xmlNode);
   return sVal != "" ? Convert.ToInt32(sVal) : 0;
  }
  /// <summary>
  /// Get the Element float/single floating point value from a given XmlNode
  /// </summary>
  public float GetElementFloatValue(XmlNode xmlNode)
  {
   string sVal = GetElementValue (xmlNode);
   return sVal != "" ? Convert.ToSingle(sVal) : 0;
  }
  /// <summary>
  /// Get the Element Double value from a given XmlNode
  /// </summary>
  public double GetElementDoubleValue(XmlNode xmlNode)
  {
   string sVal = GetElementValue (xmlNode);
   return sVal != "" ? Convert.ToDouble(sVal) : 0.00;
  }
  /// <summary>
  /// Get the Element Boolean value from a given XmlNode
  /// </summary>
  public bool GetElementBooleanValue(XmlNode xmlNode)
  {
   string sVal = GetElementValue (xmlNode);
   return sVal != "" ? Convert.ToBoolean(sVal) : false;
  }
  /// <summary>
  /// Get the first Child Element value from a given XmlNode
  /// </summary>
  public string GetChildElementValue(XmlNode parentNode, string sElementName)
  {
   string sVal = "";
   try
   {
    XmlNodeList childNodes = parentNode.ChildNodes;
    foreach (XmlNode childNode in childNodes)
    {
     if (childNode.Name == sElementName)
     {
      sVal = GetElementValue ( childNode );
      break;  
     }
    }
   }       
   catch (Exception e)
   {
    HandleException ( e );
   }
   return sVal;
  }
  /// <summary>
  /// Get the Child Element int32 value from a given XmlNode and ElementName
  /// </summary>
  public int GetChildElementInt32Value(XmlNode parentNode, string sElementName)
  {
   string sVal = GetChildElementValue (parentNode, sElementName);
   return sVal != "" ? Convert.ToInt32(sVal) : 0;
  }
  /// <summary>
  /// Get the Child Element floating point/single value from a given XmlNode and ElementName
  /// </summary>
  public float GetChildElementFloatValue(XmlNode parentNode, string sElementName)
  {
   string sVal = GetChildElementValue (parentNode, sElementName);
   return sVal != "" ? Convert.ToSingle(sVal) : 0;
  }
  /// <summary>
  /// Get the Child Element double value from a given XmlNode and ElementName
  /// </summary>
  public double GetChildElementDoubleValue(XmlNode parentNode, string sElementName)
  {
   string sVal = GetChildElementValue (parentNode, sElementName);
   return sVal != "" ? Convert.ToDouble(sVal) : 0.00;
  }
  /// <summary>
  /// Get the Child Element boolean value from a given XmlNode and ElementName
  /// </summary>
  public bool GetChildElementBooleanValue(XmlNode parentNode, string sElementName)
  {
   string sVal = GetChildElementValue (parentNode, sElementName);
   return sVal != "" ? Convert.ToBoolean(sVal) : false;
  }
  /// <summary>
  /// Returns the first XmlNode object matching this element name
  /// <seealso cref='GetFirstChildXmlNode'/>
  /// </summary>
  public XmlNode GetFirstChildXmlNodeFromRoot(string sElementName)
  {
   // TODO:  isn't there a better/faster/more effiecient way to do this?  couldn't find it sifting through documentation!
   XmlNodeList nodeList = GetChildNodesFromRoot(sElementName);
   if (nodeList.Count > 0)
    return nodeList[0];
   
   return null;
  }

  /// <summary>
  /// Returns the first XmlNode object matching this element name
  /// NOTE:  this doesn't seem to work if parent is Root!  Use GetFirstChildXmlNodeFromRoot
  /// <seealso cref='GetFirstChildXmlNodeFromRoot'/>
  /// </summary>
  public XmlNode GetFirstChildXmlNode(XmlNode parentNode, string sElementName)
  {
   // NOTE:  this doesn't seem to work if parent is Root!  Use GetFirstChildXmlNodeFromRoot
   XmlNode foundChildNode = null;
   try
   {
    XmlNodeList childNodes = parentNode.ChildNodes;
    foreach (XmlNode childNode in childNodes)
    {
     if (childNode.Name == sElementName)
     {
      foundChildNode = childNode;
      break;  
     }
    }
   }       
   catch (Exception e)
   {
    HandleException ( e );
   }
   return foundChildNode;
  }
  /// <summary>
  /// Returns an XmlNodeList of child nodes matching this element name
  /// </summary>
  public XmlNodeList GetChildNodesFromRoot(string sElementName)
  {
   return m_xmlDocument.GetElementsByTagName(sElementName);
  }
  
  /// <summary>
  /// Returns an ArrayList (boxed XmlNode objects) of child nodes matching this element name
  /// This function is recursive in that it will find ALL the children, even if their in
  /// sub folders (sub child nodes)
  /// </summary>
  public ArrayList GetRecursiveChildNodesFromParent(XmlNode parentNode, string sElementName)
  {
   ArrayList elementList = new ArrayList();
    
   try
   {
    XmlNodeList children = parentNode.ChildNodes;
    foreach (XmlNode child in children)
    {
     if (child.Name == sElementName)
      elementList.Add(child);
     
     if (child.HasChildNodes == true)
     {
      ArrayList childrenList = GetRecursiveChildNodesFromParent(child, sElementName);
      if (childrenList.Count > 0)
      {
       foreach (XmlNode subChild in childrenList)
        elementList.Add(subChild);
      }
     }
    }
   }
   catch (Exception e)
   {
    HandleException ( e );
   }
       
   return elementList;
  }
  
   
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