Hl7引擎的目標主要是解決將資料按HL7協議的要求標準化，和標準業務的整合和不同系統間標準業務資料的同步。在多年的醫院資訊化過程中，HL7標準組織和解析最複雜了，下面是我用了多年HL7引擎解析，主要有兩個版本1.C#,2.JAVA版的。

 本次公開JAVA的

引擎類：

package com.xxxx.hl7;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

public class HL7ToXmlConverter {
	
	public static String ConvertToXml(String sHL7)
    {
		Document document = ConvertToXmlObject(sHL7);  
		String hl7str = document.asXML();		
        return hl7str;
    }
	
	public static String ConvertToXml(Document document)
    {
		String hl7str = document.asXML();		
        return hl7str;
    }
	
	
	public static Document ConvertToXmlObject(String sHL7)
    {
		 Document document = CreateXmlDoc();
	       
		//把HL7分成段
         String[] sHL7Lines = sHL7.split("\n");


         //去掉XML的關鍵字
         for (int i = 0; i < sHL7Lines.length; i++)
         {
             sHL7Lines[i] = sHL7Lines[i].replace("^~\\&", "").replace("MSH", "MSH|");
         }
		 
         for (int i = 0; i < sHL7Lines.length; i++)
         {
             // 判斷是否空行
             if (sHL7Lines[i] != null)
             {
            	 String sHL7Line = sHL7Lines[i];

                 //通過/r 或/n 回車符分隔
                 String[] sFields = GetMessgeFields(sHL7Line);
                 
              // 為段（一行）建立第一級節點                 
                 Element el = document.getRootElement().addElement(sFields[0]);
                 
              // 迴圈每一行
                 Boolean isMsh=true;
                 for (int a = 1; a < sFields.length; a++)
                 {
                	 
                	
                	 
                	//是否包括HL7的連線符^~\\&
                     if (sFields[a].indexOf('^')>0 || sFields[a].indexOf('~')>0 || sFields[a].indexOf('\\')>0 || sFields[a].indexOf('&')>0 )
                     {//0:如果這一行有任一分隔符
                    	 
                    	 //開始操作~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                    	 
                    	 //通過~分隔
                         String[] sComponents = GetRepetitions(sFields[a]);
                         if (sComponents.length > 1)
                         {//1:如果可以分隔 0001^郭靖^體檢號^EQ^AND~0002^東一區^病區號^EQ^AND
                        	 
                        	 for (int b = 0; b < sComponents.length; b++)
                             {
                        		// Element fieldEl1 = el.addElement(sFields[0] + "." + a);
                        		 CreateComponents(el,sComponents[b],sFields[0],a,b);   
                             }
                        	 
                        	 
                         }
                         else
                         {//1：如果真的只有一個值的 0001^郭靖^體檢號^EQ^AND
                        	// 為欄位建立第二級節點
                        	// Element fieldEl = el.addElement(sFields[0] + "." + a);
                        	 CreateComponents(el,sFields[a],sFields[0],a,0);
                        	 
                        	 
                        	 
                        	 //fieldEl.setText(sFields[a]+"11111111111111");
                         }
                    	 
                    	 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                     }
                     
                     else
                     {//0:如果這一行沒有任何分隔符
                    	// 為欄位建立第二級節點
                    	Element fieldEl = el.addElement(sFields[0] + "." + a);
                        fieldEl.setText(sFields[a]);
                    	 
                    	 
                     }
                	 
                 }
                 
                 
             }//end if
             
         }//end for 
		
         
       //修改MSH.1 和 MSH.2的值
       document.selectSingleNode("HL7Message/MSH/MSH.1").setText("|");
       document.selectSingleNode("HL7Message/MSH/MSH.2").setText("~^\\&");
       //  document.selectNodes("MSH/MSH.1");
         
         
	    return document;
    }
	
	
	@SuppressWarnings("unused")
	private static Element CreateComponents(final Element el,final String hl7Components,String sField,int a,int b)
	{	
		 	Element componentEl = el.addElement(sField + "." + a);
    		// Element componentEl =el;//.addElement(sField + "." + a + "." + b);
    		 
    		 //&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
    		//通過&分隔 
             String[] subComponents = GetSubComponents(hl7Components);
             if (subComponents.length > 1)
             {//2.如果有字組，一般是沒有的。。。  子分組 用&很少用
            	 
             }
             else
             {//2.如果沒有了，就用^分組
            	   String[] sRepetitions = GetComponents(hl7Components);
                   if (sRepetitions.length > 1)
                   {
                       Element repetitionEl = null;
                       for (int c = 0; c < sRepetitions.length; c++)
                       {
                           repetitionEl = componentEl.addElement(sField + "." + a + "." + (c+1));
                           repetitionEl.setText(sRepetitions[c]);
                       }
                   }
                   else
                   {
                       componentEl.setText(hl7Components);
                   }
            	 
            	 
             }
             //&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
    	
		return el;
		
	}
	
	
	
	  /// <summary>
    /// 通過|分隔 欄位
    /// </summary>
    /// <param name="s"></param>
    /// <returns></returns>
    private static String[] GetMessgeFields(String s)
    {
        return s.split("\\|");
    }

    /// <summary>
    /// 通過^分隔 組欄位
    /// </summary>
    /// <param name="s"></param>
    /// <returns></returns>
    private static String[] GetComponents(String s)
    {
        return s.split("\\^");
    }

    /// <summary>
    /// 通過&分隔 子分組組欄位
    /// </summary>
    /// <param name="s"></param>
    /// <returns></returns>
    private static String[] GetSubComponents(String s)
    {
        return s.split("&");
    }

    /// <summary>
    /// 通過~分隔 重複
    /// </summary>
    /// <param name="s"></param>
    /// <returns></returns>
    private static String[] GetRepetitions(String s)
    {
        return s.split("~");
    }

    /// <summary>
    /// 建立XML物件
    /// </summary>
    /// <returns></returns>
    private static Document CreateXmlDoc()
    {
    	Document output = DocumentHelper.createDocument();   
    	//生成一個接點   
        Element rootNode = output.addElement("HL7Message");   
        return output;
    }
	
	
	
    public static String GetText(Document document, String path)
    {
    	Node node = document.selectSingleNode("HL7Message/"+path);      
        if (node != null)
        {
            return node.getText();
        }
        else
        {
            return null;
        }
    }
    public static String GetText(Document document, String path,int index)
    {
    	List nodes = document.selectNodes("HL7Message/"+path);  
        if(nodes!=null)
        {
        	return ((Node)nodes.get(index)).getText();
        }
        else
        {
        	return null;
        }

    }
    
    public static List GetTexts(Document document, String path)
    {  
        List nodes = document.selectNodes("HL7Message/"+path);  
        return nodes;
        

    }


	
	
	
	
	
	
	
	
	
	 public static void writeDocument(Document document, String filepath){   
	        try{   
	            //讀取檔案   
	          //  FileWriter fileWriter = new FileWriter(filepath);   
	            Writer writer = new OutputStreamWriter(new FileOutputStream(filepath),"utf-8");

	            //設定檔案編碼   
	            OutputFormat xmlFormat = new OutputFormat();   
	            xmlFormat.setEncoding("utf-8");   
	            //建立寫檔案方法   
	            XMLWriter xmlWriter = new XMLWriter(writer,xmlFormat);   
	            //寫入檔案   
	            xmlWriter.write(document);   
	            //關閉   
	            xmlWriter.close();   
	        }catch(IOException e){   
	            System.out.println("檔案沒有找到");   
	            e.printStackTrace();   
	        }   
	    }   


}
 

單元測試呼叫類：

 String  myHL7string="MSH|^~\\&|455755610_0100||0200||20110624160404|000|QRY^A19^QRY_A19|0123456001|P|2.6\nQRD|||||||||0001^郭靖^體檢號^EQ^AND~0002^東一區^病區號^EQ^AND\nQRF||20110627|20110803";
		  Document document = HL7ToXmlConverter.ConvertToXmlObject(myHL7string);
		  
		  //獲取事件
		  String eventName = HL7ToXmlConverter.GetText(document, "MSH/MSH.9/MSH.9.3");
		  System.out.println("eventName:"+eventName);
		  
		  
		 //  List nodeValue = document.selectNodes("MSH.1");
		  String nodeValue = document.selectSingleNode("HL7Message/MSH/MSH.1").getText();
          String nodeValue2 = document.selectSingleNode("HL7Message/MSH/MSH.3").getText();      
		 // DocumentElement.SelectNodes(path);
          System.out.println(nodeValue+":"+nodeValue2);
          
          
          String value = HL7ToXmlConverter.GetText(document, "QRD/QRD.9/QRD.9.1",0);
          String value1 = HL7ToXmlConverter.GetText(document, "QRD/QRD.9/QRD.9.1",1);
          String value2 = HL7ToXmlConverter.GetText(document, "QRD/QRD.9/QRD.9.1");
          System.out.println(value+":"+value1+":"+value2);
		  
          List<Node> list = HL7ToXmlConverter.GetTexts(document, "QRD/QRD.9/QRD.9.1");
          for(Node node : list)
          {
        	  System.out.println(":"+node.getText());
          }
          
          
          System.out.println(HL7ToXmlConverter.ConvertToXml(myHL7string));