GenericMailet


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17  
18  package org.apache.mailet;
19  
20  import javax.mail.MessagingException  ;
21  import java.util.Iterator  ;
22  
23  /**
24   * GenericMailet makes writing mailets easier. It provides simple
25   * versions of the lifecycle methods init and destroy and of the methods
26   * in the MailetConfig interface. GenericMailet also implements the log
27   * method, declared in the MailetContext interface.
28   * <p>
29   * To write a generic mailet, you need only override the abstract service
30   * method.
31   *
32   * @version 1.0.0, 24/04/1999
33   */
34  public abstract class GenericMailet implements Mailet, MailetConfig {
35      private MailetConfig config = null;
36  
37      /**
38       * Called by the mailer container to indicate to a mailet that the
39       * mailet is being taken out of service.
40       */
41      public void destroy() {
42          //Do nothing
43      }
44  
45      /**
46       * Returns a String containing the value of the named initialization
47       * parameter, or null if the parameter does not exist.
48       * <p>
49       * This method is supplied for convenience. It gets the value of the
50       * named parameter from the mailet's MailetConfig object.
51       *
52       * @param name - a String specifying the name of the initialization parameter
53       * @return a String containing the value of the initalization parameter
54       */
55      public String   getInitParameter(String   name) {
56          return config.getInitParameter(name);
57      }
58  
59      /**
60       * Returns the names of the mailet's initialization parameters as an
61       * Iterator of String objects, or an empty Iterator if the mailet has no
62       * initialization parameters.
63       * <p>
64       * This method is supplied for convenience. It gets the parameter names from
65       * the mailet's MailetConfig object.
66       *
67       * @return an Iterator of String objects containing the names of
68       *          the mailet's initialization parameters
69       */
70      public Iterator   getInitParameterNames() {
71          return config.getInitParameterNames();
72      }
73  
74      /**
75       * Returns this Mailet's MailetConfig object.
76       *
77       * @return the MailetConfig object that initialized this mailet
78       */
79      public MailetConfig getMailetConfig() {
80          return config;
81      }
82  
83      /**
84       * Returns a reference to the MailetContext in which this mailet is
85       * running.
86       *
87       * @return the MailetContext object passed to this mailet by the init method
88       */
89      public MailetContext getMailetContext() {
90          return getMailetConfig().getMailetContext();
91      }
92  
93      /**
94       * Returns information about the mailet, such as author, version, and
95       * copyright.  By default, this method returns an empty string. Override
96       * this method to have it return a meaningful value.
97       *
98       * @return information about this mailet, by default an empty string
99       */
100     public String   getMailetInfo() {
101         return "";
102     }
103 
104     /**
105      * Returns the name of this mailet instance.
106      *
107      * @return the name of this mailet instance
108      */
109     public String   getMailetName() {
110         return config.getMailetName();
111     }
112 
113 
114     /**
115      * <p>Called by the mailet container to indicate to a mailet that the
116      * mailet is being placed into service.</p>
117      *
118      * <p>This implementation stores the MailetConfig object it receives from
119      * the mailet container for later use. When overriding this form of the
120      * method, call super.init(config).</p>
121      *
122      * @param MailetConfig newconfig - the MailetConfig object that contains
123      *          configutation information for this mailet
124      * @throws MessagingException
125      *          if an exception occurs that interrupts the mailet's normal operation
126      */
127     public void init(MailetConfig newConfig) throws MessagingException   {
128         config = newConfig;
129         init();
130     }
131 
132     /**
133      * <p>A convenience method which can be overridden so that there's no
134      * need to call super.init(config).</p>
135      *
136      * Instead of overriding init(MailetConfig), simply override this
137      * method and it will be called by GenericMailet.init(MailetConfig config).
138      * The MailetConfig object can still be retrieved via getMailetConfig().
139      *
140      * @throws MessagingException
141      *          if an exception occurs that interrupts the mailet's normal operation
142      */
143     public void init() throws MessagingException   {
144         //Do nothing... can be overriden
145     }
146 
147     /**
148      * Writes the specified message to a mailet log file, prepended by
149      * the mailet's name.
150      *
151      * @param message - a String specifying the message to be written to the log file
152      */
153     public void log(String   message) {
154         StringBuffer   logBuffer =
155             new StringBuffer  (256)
156                     .append(getMailetName())
157                     .append(": ")
158                     .append(message);
159         getMailetContext().log(logBuffer.toString());
160     }
161 
162     /**
163      * Writes an explanatory message and a stack trace for a given Throwable
164      * exception to the mailet log file, prepended by the mailet's name.
165      *
166      * @param message - a String that describes the error or exception
167      * @param t - the java.lang.Throwable to be logged
168      */
169     public void log(String   message, Throwable   t) {
170         StringBuffer   logBuffer =
171             new StringBuffer  (256)
172                     .append(config.getMailetName())
173                     .append(": ")
174                     .append(message);
175         getMailetContext().log(logBuffer.toString(), t);
176     }
177 
178     /**
179      * <p>Called by the mailet container to allow the mailet to process a
180      * message.</p>
181      *
182      * <p>This method is declared abstract so subclasses must override it.</p>
183      *
184      * @param mail - the Mail object that contains the MimeMessage and
185      *          routing information
186      * @throws javax.mail.MessagingException - if an exception occurs that interferes with the mailet's normal operation
187      */
188     public abstract void service(Mail mail) throws javax.mail.MessagingException  ;
189 }
190 
191 
192
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