HelloDatabaseWorld


1   /*-
2    * See the file LICENSE for redistribution information.
3    *
4    * Copyright (c) 2002,2006 Oracle.  All rights reserved.
5    *
6    * $Id: HelloDatabaseWorld.java,v 1.23 2006/10/31 19:56:10 mark Exp $
7    */
8   
9   package collections.hello;
10  
11  import java.io.File  ;
12  import java.util.Iterator  ;
13  import java.util.Map  ;
14  import java.util.SortedMap  ;
15  
16  import com.sleepycat.bind.serial.ClassCatalog;
17  import com.sleepycat.bind.serial.SerialBinding;
18  import com.sleepycat.bind.serial.StoredClassCatalog;
19  import com.sleepycat.bind.tuple.TupleBinding;
20  import com.sleepycat.collections.StoredSortedMap;
21  import com.sleepycat.collections.TransactionRunner;
22  import com.sleepycat.collections.TransactionWorker;
23  import com.sleepycat.je.Database;
24  import com.sleepycat.je.DatabaseConfig;
25  import com.sleepycat.je.Environment;
26  import com.sleepycat.je.EnvironmentConfig;
27  
28  /**
29   * @author Mark Hayes
30   */
31  public class HelloDatabaseWorld implements TransactionWorker {
32  
33      private static final String  [] INT_NAMES = {
34          "Hello", "Database", "World",
35      };
36      private static boolean create = true;
37  
38      private Environment env;
39      private ClassCatalog catalog;
40      private Database db;
41      private SortedMap   map;
42  
43      /** Creates the environment and runs a transaction */
44      public static void main(String  [] argv)
45          throws Exception   {
46  
47          String   dir = "./tmp";
48  
49          // environment is transactional
50          EnvironmentConfig envConfig = new EnvironmentConfig();
51          envConfig.setTransactional(true);
52          if (create) {
53              envConfig.setAllowCreate(true);
54          }
55          Environment env = new Environment(new File  (dir), envConfig);
56  
57          // create the application and run a transaction
58          HelloDatabaseWorld worker = new HelloDatabaseWorld(env);
59          TransactionRunner runner = new TransactionRunner(env);
60          try {
61              // open and access the database within a transaction
62              runner.run(worker);
63          } finally {
64              // close the database outside the transaction
65              worker.close();
66          }
67      }
68  
69      /** Creates the database for this application */
70      private HelloDatabaseWorld(Environment env)
71          throws Exception   {
72  
73          this.env = env;
74          open();
75      }
76  
77      /** Performs work within a transaction. */
78      public void doWork()
79          throws Exception   {
80  
81          writeAndRead();
82      }
83  
84      /** Opens the database and creates the Map. */
85      private void open()
86          throws Exception   {
87  
88          // use a generic database configuration
89          DatabaseConfig dbConfig = new DatabaseConfig();
90          dbConfig.setTransactional(true);
91          if (create) {
92              dbConfig.setAllowCreate(true);
93          }
94  
95          // catalog is needed for serial bindings (java serialization)
96          Database catalogDb = env.openDatabase(null, "catalog", dbConfig);
97          catalog = new StoredClassCatalog(catalogDb);
98  
99          // use Integer tuple binding for key entries
100         TupleBinding keyBinding =
101             TupleBinding.getPrimitiveBinding(Integer  .class);
102 
103         // use String serial binding for data entries
104         SerialBinding dataBinding = new SerialBinding(catalog, String  .class);
105 
106         this.db = env.openDatabase(null, "helloworld", dbConfig);
107 
108         // create a map view of the database
109         this.map = new StoredSortedMap(db, keyBinding, dataBinding, true);
110     }
111 
112     /** Closes the database. */
113     private void close()
114         throws Exception   {
115 
116         if (catalog != null) {
117             catalog.close();
118             catalog = null;
119         }
120         if (db != null) {
121             db.close();
122             db = null;
123         }
124         if (env != null) {
125             env.close();
126             env = null;
127         }
128     }
129 
130     /** Writes and reads the database via the Map. */
131     private void writeAndRead() {
132 
133         // check for existing data
134         Integer   key = new Integer  (0);
135         String   val = (String  ) map.get(key);
136         if (val == null) {
137             System.out.println("Writing data");
138             // write in reverse order to show that keys are sorted
139             for (int i = INT_NAMES.length - 1; i >= 0; i -= 1) {
140                 map.put(new Integer  (i), INT_NAMES[i]);
141             }
142         }
143         // get iterator over map entries
144         Iterator   iter = map.entrySet().iterator();
145         System.out.println("Reading data");
146         while (iter.hasNext()) {
147             Map.Entry   entry = (Map.Entry  ) iter.next();
148             System.out.println(entry.getKey().toString() + ' ' +
149                                entry.getValue());
150         }
151     }
152 }
153
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