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Java > Open Source Codes > org > apache > turbine > modules > ScheduledJobLoader


1 package org.apache.turbine.modules;
2
3 /*
4  * Copyright 2001-2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License")
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 import java.util.List JavaDoc;
20
21 import org.apache.commons.logging.Log;
22 import org.apache.commons.logging.LogFactory;
23
24 import org.apache.turbine.Turbine;
25 import org.apache.turbine.TurbineConstants;
26 import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService;
27 import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker;
28 import org.apache.turbine.services.schedule.JobEntry;
29 import org.apache.turbine.util.ObjectUtils;
30 import org.apache.turbine.util.RunData;
31
32 /**
33  * ScheduledJobs loader class.
34  *
35  * @author <a HREF="mailto:mbryson@mindspring.com">Dave Bryson</a>
36  * @author <a HREF="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
37  * @version $Id: ScheduledJobLoader.java,v 1.7.2.3 2004/08/16 22:57:50 henning Exp $
38  */
39 public class ScheduledJobLoader
40     extends GenericLoader
41 {
42     /** Logging */
43     private static Log log = LogFactory.getLog(ScheduledJobLoader.class);
44
45     /** The single instance of this class. */
46     private static ScheduledJobLoader instance =
47         new ScheduledJobLoader(Turbine.getConfiguration()
48             .getInt(TurbineConstants.SCHEDULED_JOB_CACHE_SIZE_KEY,
49                 TurbineConstants.SCHEDULED_JOB_CACHE_SIZE_DEFAULT));
50
51     /** The Assembler Broker Service */
52     private static AssemblerBrokerService ab = TurbineAssemblerBroker.getService();
53
54     /**
55      * These ctor's are private to force clients to use getInstance()
56      * to access this class.
57      */
58     private ScheduledJobLoader()
59     {
60         super();
61     }
62
63     /**
64      * These ctor's are private to force clients to use getInstance()
65      * to access this class.
66      */
67     private ScheduledJobLoader(int i)
68     {
69         super(i);
70     }
71
72     /**
73      * Adds an instance of an object into the hashtable.
74      *
75      * @param name Name of object.
76      * @param job Job to be associated with name.
77      */
78     private void addInstance(String JavaDoc name, ScheduledJob job)
79     {
80         if (cache())
81         {
82             this.put(name, (ScheduledJob) job);
83         }
84     }
85
86     /**
87      * Attempts to load and execute the external ScheduledJob.
88      *
89      * @param job The JobEntry.
90      * @param name Name of object that will execute the job.
91      * @exception Exception a generic exception.
92      */
93     public void exec(JobEntry job, String JavaDoc name)
94             throws Exception JavaDoc
95     {
96         // Execute job
97 getInstance(name).run(job);
98     }
99
100     /**
101      * Attempts to load and execute the external ScheduledJob.
102      *
103      * HELP! - THIS IS UGLY!
104      *
105      * I want the cache stuff from GenericLoader, BUT, I don't think
106      * the scheduler needs the Rundata object. The scheduler runs
107      * independently of an HTTP request. This should not extend
108      * GenericLoader! Thoughts??
109      *
110      * @param data Turbine information.
111      * @param name Name of object that will execute the job.
112      * @exception Exception a generic exception.
113      */
114     public void exec(RunData data, String JavaDoc name)
115             throws Exception JavaDoc
116     {
117         throw new Exception JavaDoc("RunData objects not accepted for Scheduled jobs");
118     }
119
120     /**
121      * Pulls out an instance of the object by name. Name is just the
122      * single name of the object.
123      *
124      * @param name Name of object instance.
125      * @return An ScheduledJob with the specified name, or null.
126      * @exception Exception a generic exception.
127      */
128     public ScheduledJob getInstance(String JavaDoc name)
129             throws Exception JavaDoc
130     {
131         ScheduledJob job = null;
132
133         // Check if the screen is already in the cache
134 if (cache() && this.containsKey(name))
135         {
136             job = (ScheduledJob) this.get(name);
137             log.debug("Found Job " + name + " in the cache!");
138         }
139         else
140         {
141             log.debug("Loading Job " + name + " from the Assembler Broker");
142
143             try
144             {
145                 if (ab != null)
146                 {
147                     // Attempt to load the job
148 job = (ScheduledJob) ab.getAssembler(
149                         AssemblerBrokerService.SCHEDULEDJOB_TYPE, name);
150                 }
151             }
152             catch (ClassCastException JavaDoc cce)
153             {
154                 // This can alternatively let this exception be thrown
155 // So that the ClassCastException is shown in the
156 // browser window. Like this it shows "Screen not Found"
157 job = null;
158             }
159
160             if (job == null)
161             {
162                 // If we did not find a screen we should try and give
163 // the user a reason for that...
164 // FIX ME: The AssemblerFactories should each add it's
165 // own string here...
166 List JavaDoc packages = Turbine.getConfiguration()
167                     .getList(TurbineConstants.MODULE_PACKAGES);
168
169                 ObjectUtils.addOnce(packages, GenericLoader.getBasePackage());
170
171                 throw new ClassNotFoundException JavaDoc(
172                         "\n\n\tRequested ScheduledJob not found: " + name +
173                         "\n\tTurbine looked in the following " +
174                         "modules.packages path: \n\t" + packages.toString() + "\n");
175             }
176             else if (cache())
177             {
178                 // The new instance is added to the cache
179 addInstance(name, job);
180             }
181         }
182         return job;
183     }
184
185     /**
186      * The method through which this class is accessed.
187      *
188      * @return The single instance of this class.
189      */
190     public static ScheduledJobLoader getInstance()
191     {
192         return instance;
193     }
194 }
195
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