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19 
20 package org.apache.james.mime4j.field;
21 
22 import java.util.regex.Matcher;
23 import java.util.regex.Pattern;
24 
25 /**
26  * The base class of all field classes.
27  *
28  *
29  * @version $Id: Field.java,v 1.6 2004/10/25 07:26:46 ntherning Exp $
30  */
31 public abstract class Field {
32     public static final String SENDER = "Sender";
33     public static final String FROM = "From";
34     public static final String TO = "To";
35     public static final String CC = "Cc";
36     public static final String BCC = "Bcc";
37     public static final String REPLY_TO = "Reply-To";
38     public static final String RESENT_SENDER = "Resent-Sender";
39     public static final String RESENT_FROM = "Resent-From";
40     public static final String RESENT_TO = "Resent-To";
41     public static final String RESENT_CC = "Resent-Cc";
42     public static final String RESENT_BCC = "Resent-Bcc";
43 
44     public static final String DATE = "Date";
45     public static final String RESENT_DATE = "Resent-Date";
46 
47     public static final String SUBJECT = "Subject";
48     public static final String CONTENT_TYPE = "Content-Type";
49     public static final String CONTENT_TRANSFER_ENCODING =
50                                         "Content-Transfer-Encoding";
51 
52     private static final String FIELD_NAME_PATTERN =
53         "^([\\x21-\\x39\\x3b-\\x7e]+)[ \t]*:";
54     private static final Pattern fieldNamePattern =
55         Pattern.compile(FIELD_NAME_PATTERN);
56 
57     private static final DefaultFieldParser parser = new DefaultFieldParser();
58 
59     private final String name;
60     private final String body;
61     private final String raw;
62 
Field(final String name, final String body, final String raw)63     protected Field(final String name, final String body, final String raw) {
64         this.name = name;
65         this.body = body;
66         this.raw = raw;
67     }
68 
69     /**
70      * Parses the given string and returns an instance of the
71      * <code>Field</code> class. The type of the class returned depends on
72      * the field name:
73      * <table>
74      *      <tr>
75      *          <td><em>Field name</em></td><td><em>Class returned</em></td>
76      *          <td>Content-Type</td><td>org.apache.james.mime4j.field.ContentTypeField</td>
77      *          <td>other</td><td>org.apache.james.mime4j.field.UnstructuredField</td>
78      *      </tr>
79      * </table>
80      *
81      * @param s the string to parse.
82      * @return a <code>Field</code> instance.
83      * @throws IllegalArgumentException on parse errors.
84      */
parse(final String raw)85     public static Field parse(final String raw) {
86 
87         /*
88          * Unfold the field.
89          */
90         final String unfolded = raw.replaceAll("\r|\n", "");
91 
92         /*
93          * Split into name and value.
94          */
95         final Matcher fieldMatcher = fieldNamePattern.matcher(unfolded);
96         if (!fieldMatcher.find()) {
97             throw new IllegalArgumentException("Invalid field in string");
98         }
99         final String name = fieldMatcher.group(1);
100 
101         String body = unfolded.substring(fieldMatcher.end());
102         if (body.length() > 0 && body.charAt(0) == ' ') {
103             body = body.substring(1);
104         }
105 
106         return parser.parse(name, body, raw);
107     }
108 
109     /**
110      * Gets the default parser used to parse fields.
111      * @return the default field parser
112      */
getParser()113     public static DefaultFieldParser getParser() {
114         return parser;
115     }
116 
117     /**
118      * Gets the name of the field (<code>Subject</code>,
119      * <code>From</code>, etc).
120      *
121      * @return the field name.
122      */
getName()123     public String getName() {
124         return name;
125     }
126 
127     /**
128      * Gets the original raw field string.
129      *
130      * @return the original raw field string.
131      */
getRaw()132     public String getRaw() {
133         return raw;
134     }
135 
136     /**
137      * Gets the unfolded, unparsed and possibly encoded (see RFC 2047) field
138      * body string.
139      *
140      * @return the unfolded unparsed field body string.
141      */
getBody()142     public String getBody() {
143         return body;
144     }
145 
146     /**
147      * Determines if this is a <code>Content-Type</code> field.
148      *
149      * @return <code>true</code> if this is a <code>Content-Type</code> field,
150      *         <code>false</code> otherwise.
151      */
isContentType()152     public boolean isContentType() {
153         return CONTENT_TYPE.equalsIgnoreCase(name);
154     }
155 
156     /**
157      * Determines if this is a <code>Subject</code> field.
158      *
159      * @return <code>true</code> if this is a <code>Subject</code> field,
160      *         <code>false</code> otherwise.
161      */
isSubject()162     public boolean isSubject() {
163         return SUBJECT.equalsIgnoreCase(name);
164     }
165 
166     /**
167      * Determines if this is a <code>From</code> field.
168      *
169      * @return <code>true</code> if this is a <code>From</code> field,
170      *         <code>false</code> otherwise.
171      */
isFrom()172     public boolean isFrom() {
173         return FROM.equalsIgnoreCase(name);
174     }
175 
176     /**
177      * Determines if this is a <code>To</code> field.
178      *
179      * @return <code>true</code> if this is a <code>To</code> field,
180      *         <code>false</code> otherwise.
181      */
isTo()182     public boolean isTo() {
183         return TO.equalsIgnoreCase(name);
184     }
185 
186     /**
187      * @see #getRaw()
188      */
toString()189     public String toString() {
190         return raw;
191     }
192 }
193