68 lines
2.2 KiB
Markdown
68 lines
2.2 KiB
Markdown
---
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layout: default_docs
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title: Data Sources and JNDI
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header: Chapter 11. Connection Pools and Data Sources
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resource: media
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previoustitle: Tomcat setup
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previous: tomcat.html
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nexttitle: Chapter 12. Further Reading
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next: reading.html
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---
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All the `ConnectionPoolDataSource` and `DataSource` implementations can be stored
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in JNDI. In the case of the nonpooling implementations, a new instance will be
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created every time the object is retrieved from JNDI, with the same settings as
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the instance that was stored. For the pooling implementations, the same instance
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will be retrieved as long as it is available (e.g., not a different JVM retrieving
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the pool from JNDI), or a new instance with the same settings created otherwise.
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In the application server environment, typically the application server's
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`DataSource` instance will be stored in JNDI, instead of the PostgreSQL™
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`ConnectionPoolDataSource` implementation.
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In an application environment, the application may store the `DataSource` in JNDI
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so that it doesn't have to make a reference to the `DataSource` available to all
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application components that may need to use it. An example of this is shown in
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[Example 11.2, “`DataSource` JNDI Code Example”](jndi.html#ds-jndi).
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<a name="ds-jndi"></a>
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**Example 11.2. `DataSource` JNDI Code Example**
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Application code to initialize a pooling `DataSource` and add it to JNDI might
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look like this:
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`PGPoolingDataSource source = new PGPoolingDataSource();`
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`source.setDataSourceName("A Data Source");`
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`source.setServerName("localhost");`
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`source.setDatabaseName("test");`
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`source.setUser("testuser");`
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`source.setPassword("testpassword");`
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`source.setMaxConnections(10);`
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`new InitialContext().rebind("DataSource", source);`
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Then code to use a connection from the pool might look like this:
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<pre><code>
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Connection conn = null;
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try
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{
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DataSource source = (DataSource)new InitialContext().lookup("DataSource");
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conn = source.getConnection();
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// use connection
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}
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catch (SQLException e)
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{
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// log error
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}
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catch (NamingException e)
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{
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// DataSource wasn't found in JNDI
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}
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finally
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{
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if (con != null)
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{
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try { conn.close(); } catch (SQLException e) {}
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}
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}
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</code></pre> |