Connection Pooling, DB, DBCP, Tomcat, Webserver, Java, JDBC
Problem:
Connection-Pooling in Tomcat nutzen
Ursache:
-
Lösung:
Nutzung von Commons DBCP (http://jakarta.apache.org/commons/dbcp/index.html). Es kann über den Parameter poolPreparedStatements auch Caching von PreparedStatements aktiviert werden.
1) In der server.xml die Datasource definieren
<Resource name="jdbc/DB2PooledDS"
auth="Container"
type="javax.sql.DataSource"/>
<ResourceParams name="jdbc/DB2PooledDS">
<parameter>
<name>factory</name>
<value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
</parameter>
<!-- Maximum number of dB connections in pool. Make sure you
configure your mysqld max_connections large enough to handle
all of your db connections. Set to 0 for no limit.
-->
<parameter>
<name>maxActive</name>
<value>100</value>
</parameter>
<!-- Maximum number of idle dB connections to retain in pool.
Set to 0 for no limit.
-->
<parameter>
<name>maxIdle</name>
<value>30</value>
</parameter>
<!-- Maximum time to wait for a dB connection to become available
in ms, in this example 10 seconds. An Exception is thrown if
this timeout is exceeded. Set to -1 to wait indefinitely.
-->
<parameter>
<name>maxWait</name>
<value>10000</value>
</parameter>
<!-- MySQL dB username and password for dB connections -->
<parameter>
<name>username</name>
<value>myuser</value>
</parameter>
<parameter>
<name>password</name>
<value>mypass</value>
</parameter>
<!-- Class name for mm.mysql JDBC driver -->
<parameter>
<name>driverClassName</name>
<value>COM.ibm.db2.jdbc.app.DB2Driver</value>
</parameter>
<!-- Prepared Statement Pooling aktivieren -->
<parameter>
<name>poolPreparedStatements</name>
<value>true</value>
</parameter>
<parameter>
<name>maxOpenPreparedStatements</name>
<value>50</value>
</parameter>
<!-- The JDBC connection url for connecting to your MySQL dB.
The autoReconnect=true argument to the url makes sure that the
mm.mysql JDBC Driver will automatically reconnect if mysqld closed the
connection. mysqld by default closes idle connections after 8 hours.
-->
<parameter>
<name>url</name>
<value>jdbc:db2:mydb</value>
</parameter>
</ResourceParams>
2) In web.xml der Anwendung angeben
<web-app id="WebApp">
...
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/DB2PooledDS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
3) Connection im Java-Code öffenen über JNDI
try {
InitialContext initCtx = new InitialContext();
Context ctx = (Context) initCtx.lookup(“java:comp/env”);
//Context ctx = new InitialContext();
if (ctx == null) {
logger.error("No InitialContext available");
} else {
dataSource = (DataSource) ctx.lookup(“jdbc/DB2PooledDS”);
}
} catch (NamingException ne) {
logger.error(ne);
}
try {
Connection conn = getDataSource().getConnection();
} catch (SQLException e) {
logger.error(e);
}
