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Java > Open Source Codes > de > laures > cewolf > taglib > DataContainer


1 /*
2  * Created on 13.04.2003
3  *
4  * To change the template for this generated file go to
5  * Window>Preferences>Java>Code Generation>Code and Comments
6  */
7 package de.laures.cewolf.taglib;
8
9 import java.io.Serializable JavaDoc;
10 import java.util.Date JavaDoc;
11 import java.util.Map JavaDoc;
12
13 import org.apache.commons.logging.Log;
14 import org.apache.commons.logging.LogFactory;
15 import org.jfree.data.general.Dataset;
16
17 import de.laures.cewolf.DatasetProduceException;
18 import de.laures.cewolf.DatasetProducer;
19 import de.laures.cewolf.taglib.util.DatasetProductionTimeStore;
20 import de.laures.cewolf.taglib.util.KeyGenerator;
21 import de.laures.cewolf.util.Assert;
22
23 /**
24  * @author guido
25  *
26  * To change the template for this generated type comment go to
27  * Window>Preferences>Java>Code Generation>Code and Comments
28  */
29 public class DataContainer implements DataAware, Serializable JavaDoc {
30
31     private static transient final Log log = LogFactory.getLog(ChartImageDefinition.class);
32
33     private transient Dataset data;
34     private transient DatasetProducer producer;
35
36     private Map JavaDoc datasetProductionParams;
37     private long datasetProduceTime;
38     private boolean useCache = true;
39
40     public void setDataProductionConfig(DatasetProducer dsp, Map JavaDoc params, boolean useCache) {
41         log.debug("setDataProductionConfig");
42         producer = dsp;
43         datasetProductionParams = params;
44         this.useCache = useCache;
45         checkDataProductionNeed();
46     }
47
48     public Object JavaDoc getDataset() throws DatasetProduceException {
49         Assert.check(producer != null, "you need to specifiy a producer for the data of the chart.");
50         log.debug("getting data..");
51         if (data == null) {
52             log.debug("producing new dataset for " + producer.getProducerId());
53             data = (Dataset) producer.produceDataset(datasetProductionParams);
54             DatasetProductionTimeStore dataCache = DatasetProductionTimeStore.getInstance();
55             dataCache.addEntry(producer.getProducerId(), datasetProductionParams, new Date JavaDoc(datasetProduceTime));
56         }
57         Assert.check(data != null, "your producer of type " + producer.getClass().getName() + " produced a null dataset.");
58         return data;
59     }
60
61     /**
62      * This method checks if there has been a dataset production
63      * for the same DatasetProvider and parameters. If so the DatasetProducer
64      * is consulted to check the expiry of this data.
65      * If the data has expired the retrieval of a cached image of this
66      * ChartDefinition is avoided by setting the datasetProduceTime to the
67      * actual time. After this the hash code of this object can not be
68      * present in the image cache and so a new image with new data will
69      * be rendered.
70      * If the data did not expire the last dataset production time is stored
71      * as a memeber to reach the same hash code for this object as the one
72      * before if possible.
73      * This method is called during serialization to ensure the same serialized
74      * representation of this and a eventually formally stored object.
75      */
76     private void checkDataProductionNeed() {
77         log.debug("checking data actuality..." + producer + ", " + datasetProductionParams);
78         final String JavaDoc prodId = producer.getProducerId();
79         log.debug(prodId + ", " + KeyGenerator.generateKey((Serializable JavaDoc)datasetProductionParams));
80         log.debug("useCache = " + useCache);
81         DatasetProductionTimeStore dataCache = DatasetProductionTimeStore.getInstance();
82         if (useCache && dataCache.containsEntry(prodId, datasetProductionParams)) {
83             Date JavaDoc produceTime = dataCache.getProductionTime(prodId, datasetProductionParams);
84             log.debug("cached data available.");
85             // cached data available
86 if (!producer.hasExpired(datasetProductionParams, produceTime)) {
87                 log.debug("cached data is still valid.");
88                 this.datasetProduceTime = produceTime.getTime();
89                 return;
90             }
91             dataCache.removeEntry(prodId, datasetProductionParams);
92         }
93         datasetProduceTime = System.currentTimeMillis();
94     }
95
96 }
97
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