UsePoolBackedDataSource


1   import java.sql.*;
2   import javax.sql.DataSource  ;
3   import com.mchange.v2.c3p0.DataSources;
4   
5   
6   /**
7    *  This example shows how to programmatically get and directly use
8    *  an pool-backed DataSource
9    */
10  public final class UsePoolBackedDataSource
11  {
12  
13      public static void main(String  [] argv)
14      {
15      try
16          {
17          // Note: your JDBC driver must be loaded [via Class.forName( ... ) or -Djdbc.properties]
18          // prior to acquiring your DataSource!
19  
20          // Acquire the DataSource... this is the only c3p0 specific code here
21          DataSource   unpooled = DataSources.unpooledDataSource("jdbc:postgresql://localhost/test",
22                                       "swaldman",
23                                       "test");
24          DataSource   pooled = DataSources.pooledDataSource( unpooled );
25  
26  
27  
28          // get hold of a Connection an do stuff, in the usual way
29          Connection con  = null;
30          Statement  stmt = null;
31          ResultSet  rs   = null;
32          try
33              {
34              con = pooled.getConnection();
35              stmt = con.createStatement();
36              rs = stmt.executeQuery("SELECT * FROM foo");
37              while (rs.next())
38                  System.out.println( rs.getString(1) );
39              }
40          finally
41              {
42              //i try to be neurotic about ResourceManagement,
43              //explicitly closing each resource
44              //but if you are in the habit of only closing
45              //parent resources (e.g. the Connection) and
46              //letting them close their children, all
47              //c3p0 DataSources will properly deal.
48              attemptClose(rs);
49              attemptClose(stmt);
50              attemptClose(con);
51              }
52          }
53      catch (Exception   e)
54          { e.printStackTrace(); }
55      }
56  
57      static void attemptClose(ResultSet o)
58      {
59      try
60          { if (o != null) o.close();}
61      catch (Exception   e)
62          { e.printStackTrace();}
63      }
64  
65      static void attemptClose(Statement o)
66      {
67      try
68          { if (o != null) o.close();}
69      catch (Exception   e)
70          { e.printStackTrace();}
71      }
72  
73      static void attemptClose(Connection o)
74      {
75      try
76          { if (o != null) o.close();}
77      catch (Exception   e)
78          { e.printStackTrace();}
79      }
80  
81      private UsePoolBackedDataSource()
82      {}
83  }
84
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