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19
20
21 package org.apache.mailet.base;
22
23 import javax.mail.MessagingException;
24
25 import org.apache.mailet.Mail;
26 import org.apache.mailet.Mailet;
27 import org.apache.mailet.MailetConfig;
28 import org.apache.mailet.MailetContext;
29
30 import java.util.ArrayList;
31 import java.util.Collection;
32 import java.util.HashSet;
33 import java.util.Iterator;
34
35 /**
36 * GenericMailet makes writing mailets easier. It provides simple
37 * versions of the lifecycle methods init and destroy and of the methods
38 * in the MailetConfig interface. GenericMailet also implements the log
39 * method, declared in the MailetContext interface.
40 * <p>
41 * To write a generic mailet, you need only override the abstract service
42 * method.
43 *
44 * @version 1.0.0, 24/04/1999
45 */
46 public abstract class GenericMailet implements Mailet, MailetConfig {
47 private MailetConfig config = null;
48
49 /**
50 * Called by the mailer container to indicate to a mailet that the
51 * mailet is being taken out of service.
52 */
53 public void destroy() {
54 //Do nothing
55 }
56
57 /**
58 * <p>Gets a boolean valued init parameter.</p>
59 * <p>A convenience method. The result is parsed
60 * from the value of the named parameter in the {@link MailetConfig}.</p>
61 * @param name name of the init parameter to be queried
62 * @param defaultValue this value will be substituted when the named value
63 * cannot be parse or when the init parameter is absent
64 * @return true when the init parameter is <code>true</code> (ignoring case);
65 * false when the init parameter is <code>false</code> (ignoring case);
66 * otherwise the default value
67 * @throws NullPointerException before {@link #init(MailetConfig)}
68 */
69 public boolean getInitParameter(String name, boolean defaultValue) {
70 if (config == null) {
71 throw new NullPointerException("Mailet configuration must be set before getInitParameter is called.");
72 }
73 return MailetUtil.getInitParameter(config, name, defaultValue);
74 }
75
76 /**
77 * Returns a String containing the value of the named initialization
78 * parameter, or null if the parameter does not exist.
79 * <p>
80 * This method is supplied for convenience. It gets the value of the
81 * named parameter from the mailet's MailetConfig object.
82 *
83 * @param name - a String specifying the name of the initialization parameter
84 * @return a String containing the value of the initalization parameter
85 */
86 public String getInitParameter(String name) {
87 return config.getInitParameter(name);
88 }
89
90 /**
91 * Returns a String containing the value of the named initialization
92 * parameter, or defValue if the parameter does not exist.
93 * <p>
94 * This method is supplied for convenience. It gets the value of the
95 * named parameter from the mailet's MailetConfig object.
96 *
97 * @param name - a String specifying the name of the initialization parameter
98 * @param defValue - a String specifying the default value when the parameter
99 * is not present
100 * @return a String containing the value of the initalization parameter
101 */
102 public String getInitParameter(String name, String defValue) {
103 String res = config.getInitParameter(name);
104 if (res == null) {
105 return defValue;
106 } else {
107 return res;
108 }
109 }
110
111 /**
112 * Returns the names of the mailet's initialization parameters as an
113 * Iterator of String objects, or an empty Iterator if the mailet has no
114 * initialization parameters.
115 * <p>
116 * This method is supplied for convenience. It gets the parameter names from
117 * the mailet's MailetConfig object.
118 *
119 * @return an Iterator of String objects containing the names of
120 * the mailet's initialization parameters
121 */
122 public Iterator getInitParameterNames() {
123 return config.getInitParameterNames();
124 }
125
126 /**
127 * Returns this Mailet's MailetConfig object.
128 *
129 * @return the MailetConfig object that initialized this mailet
130 */
131 public MailetConfig getMailetConfig() {
132 return config;
133 }
134
135 /**
136 * Returns a reference to the MailetContext in which this mailet is
137 * running.
138 *
139 * @return the MailetContext object passed to this mailet by the init method
140 */
141 public MailetContext getMailetContext() {
142 return getMailetConfig().getMailetContext();
143 }
144
145 /**
146 * Returns information about the mailet, such as author, version, and
147 * copyright. By default, this method returns an empty string. Override
148 * this method to have it return a meaningful value.
149 *
150 * @return information about this mailet, by default an empty string
151 */
152 public String getMailetInfo() {
153 return "";
154 }
155
156 /**
157 * Returns the name of this mailet instance.
158 *
159 * @return the name of this mailet instance
160 */
161 public String getMailetName() {
162 return config.getMailetName();
163 }
164
165
166 /**
167 * <p>Called by the mailet container to indicate to a mailet that the
168 * mailet is being placed into service.</p>
169 *
170 * <p>This implementation stores the MailetConfig object it receives from
171 * the mailet container for later use. When overriding this form of the
172 * method, call super.init(config).</p>
173 *
174 * @param newConfig - the MailetConfig object that contains
175 * configutation information for this mailet
176 * @throws MessagingException
177 * if an exception occurs that interrupts the mailet's normal operation
178 */
179 public void init(MailetConfig newConfig) throws MessagingException {
180 config = newConfig;
181 init();
182 }
183
184 /**
185 * <p>A convenience method which can be overridden so that there's no
186 * need to call super.init(config).</p>
187 *
188 * Instead of overriding init(MailetConfig), simply override this
189 * method and it will be called by GenericMailet.init(MailetConfig config).
190 * The MailetConfig object can still be retrieved via getMailetConfig().
191 *
192 * @throws MessagingException
193 * if an exception occurs that interrupts the mailet's normal operation
194 */
195 public void init() throws MessagingException {
196 //Do nothing... can be overriden
197 }
198
199 /**
200 * Writes the specified message to a mailet log file.
201 *
202 * @param message - a String specifying the message to be written to the log file
203 */
204 public void log(String message) {
205 getMailetContext().log(message);
206 }
207
208 /**
209 * Writes an explanatory message and a stack trace for a given Throwable
210 * exception to the mailet log file.
211 *
212 * @param message - a String that describes the error or exception
213 * @param t - the java.lang.Throwable to be logged
214 */
215 public void log(String message, Throwable t) {
216 getMailetContext().log(message, t);
217 }
218
219 /**
220 * <p>Called by the mailet container to allow the mailet to process a
221 * message.</p>
222 *
223 * <p>This method is declared abstract so subclasses must override it.</p>
224 *
225 * @param mail - the Mail object that contains the MimeMessage and
226 * routing information
227 * @throws javax.mail.MessagingException - if an exception occurs that interferes with the mailet's normal operation
228 */
229 public abstract void service(Mail mail) throws javax.mail.MessagingException;
230
231
232
233 /**
234 * Utility method: Checks if there are unallowed init parameters specified in the
235 * configuration file against the String[] allowedInitParameters.
236 * @param allowedArray array of strings containing the allowed parameter names
237 * @throws MessagingException if an unknown parameter name is found
238 */
239 protected final void checkInitParameters(String[] allowedArray) throws MessagingException {
240 // if null then no check is requested
241 if (allowedArray == null) {
242 return;
243 }
244
245 Collection allowed = new HashSet();
246 Collection bad = new ArrayList();
247
248 for (int i = 0; i < allowedArray.length; i++) {
249 allowed.add(allowedArray[i]);
250 }
251
252 Iterator iterator = getInitParameterNames();
253 while (iterator.hasNext()) {
254 String parameter = (String) iterator.next();
255 if (!allowed.contains(parameter)) {
256 bad.add(parameter);
257 }
258 }
259
260 if (bad.size() > 0) {
261 throw new MessagingException("Unexpected init parameters found: "
262 + arrayToString(bad.toArray()));
263 }
264 }
265
266 /**
267 * Utility method for obtaining a string representation of an array of Objects.
268 */
269 protected final String arrayToString(Object[] array) {
270 if (array == null) {
271 return "null";
272 }
273 StringBuffer sb = new StringBuffer(1024);
274 sb.append("[");
275 for (int i = 0; i < array.length; i++) {
276 if (i > 0) {
277 sb.append(",");
278 }
279 sb.append(array[i]);
280 }
281 sb.append("]");
282 return sb.toString();
283 }
284
285 }
286
287