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1   /**
2   The contents of this file are subject to the Mozilla Public License Version 1.1
3   (the "License"); you may not use this file except in compliance with the License.
4   You may obtain a copy of the License at http://www.mozilla.org/MPL/
5   Software distributed under the License is distributed on an "AS IS" basis,
6   WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the
7   specific language governing rights and limitations under the License.
8   
9   The Original Code is "GroupPointer.java".  Description:
10  "A GroupPointer is used when parsing traditionally encoded HL7 messages"
11  
12  The Initial Developer of the Original Code is University Health Network. Copyright (C)
13  2001.  All Rights Reserved.
14  
15  Contributor(s): ______________________________________.
16  
17  Alternatively, the contents of this file may be used under the terms of the
18  GNU General Public License (the  "GPL"), in which case the provisions of the GPL are
19  applicable instead of those above.  If you wish to allow use of your version of this
20  file only under the terms of the GPL and not to allow others to use your version
21  of this file under the MPL, indicate your decision by deleting  the provisions above
22  and replace  them with the notice and other provisions required by the GPL License.
23  If you do not delete the provisions above, a recipient may use your version of
24  this file under either the MPL or the GPL.
25  
26  */
27  
28  package ca.uhn.hl7v2.parser;
29  
30  import java.util.StringTokenizer;
31  
32  /**
33   * Detects message encoding (ER7 / XML) without relying on any
34   * external dependencies
35   */
36  public final class EncodingDetector {
37  
38  	/**
39  	 * Non instantiable
40  	 */
41  	private EncodingDetector() {
42  		// nothing
43  	}
44  
45      /**
46       * Throws an exception if the message is not ER7 encoded
47       *
48       * @param theMessage message to be examined
49       * @throws RuntimeException if message is not ER7-encoded
50       */
51  	public static void assertEr7Encoded(String theMessage) {
52          // quit if the string is too short
53          if (theMessage.length() < 4)
54              throw new RuntimeException("The message is less than 4 characters long");
55  
56          // string should start with "MSH"
57          if (!theMessage.startsWith("MSH"))
58              throw new RuntimeException("The message does not start with MSH");
59  
60          // 4th character of each segment should be field delimiter
61          char fourthChar = theMessage.charAt(3);
62          StringTokenizer st = new StringTokenizer(theMessage, String.valueOf(PipeParser.SEGMENT_DELIMITER), false);
63          while (st.hasMoreTokens()) {
64              String x = st.nextToken();
65              if (x.length() > 0) {
66                  if (Character.isWhitespace(x.charAt(0)))
67                      x = PipeParser.stripLeadingWhitespace(x);
68                  if (x.length() >= 4 && x.charAt(3) != fourthChar)
69                      throw new RuntimeException(String.format(
70                              "The 4th character should have been a %c, but it was a %c", x.charAt(3), fourthChar));
71              }
72          }
73  
74          // should be at least 11 field delimiters (because MSH-12 is required)
75          int nextFieldDelimLoc = 0;
76          for (int i = 0; i < 11; i++) {
77              nextFieldDelimLoc = theMessage.indexOf(fourthChar, nextFieldDelimLoc + 1);
78              if (nextFieldDelimLoc < 0)
79                  throw new RuntimeException("Expected to find required field MSH-12");
80          }
81  	    
82  	}
83  	
84  	/**
85  	 * Returns true if the message is ER7 (pipe-and-hat) encoded
86       *
87       * @param theMessage message to be examined
88       * @return true if message is ER7-encoded
89       */
90      public static boolean isEr7Encoded(String theMessage) {
91          try {
92              assertEr7Encoded(theMessage);
93              return true;
94          } catch (Exception e) {
95              return false;
96          }
97  	}
98  
99      /**
100      * Throws an exception if the message is not XML encoded
101      *
102      * @param theMessage message to be examined
103      * @throws RuntimeException if message is not XML-encoded
104      */
105     public static void assertXmlEncoded(String theMessage) {
106         if (!theMessage.contains("MSH.1>")) throw new RuntimeException("Expected to find MSH.1");
107         if (!theMessage.contains("MSH.2>")) throw new RuntimeException("Expected to find MSH.2");
108     }
109 
110     /**
111      * Returns true if the message is XML encoded. Note that this 
112      * message does not perform a very robust check, and does not
113      * validate for well-formedness. It is only intended to perform
114      * a simple check for XML vs. ER7 messages.
115      *
116      * @param theMessage message to be examined
117      * @return true if message is XML-encoded
118      */
119 	public static boolean isXmlEncoded(String theMessage) {
120         try {
121             assertXmlEncoded(theMessage);
122             return true;
123         } catch (Exception e) {
124             return false;
125         }
126 	}
127 
128 	
129 }