How to configure Tomcat to connect with MySQL

Question

Could someone provide a few details on how to configure Tomcat to access MySQL?

1. In which directory within Tomcat do I place mysql-connector-java-5.1.13-bin? Should I place it under Tomcat 6.0\webapps\myapp\WEB-INF\lib?

2. Do I need to add configuration to context.xml or server.xml?

3. Should I create a web.xml file and place it under Tomcat 6.0\webapps\myapp\WEB-INF? If so, then what should the contents of this file look like?

Answer 1

1: Where to place mysql-connector-java-5.1.13-bin in Tomcat directory? Should I place it under Tomcat 6.0\webapps\myapp\WEB-INF\lib?

That depends on where the connections are to be managed. Normally you would like to create a connection pooled JNDI datasource to improve connecting performance. In that case, Tomcat is managing the connections and need to have access to the JDBC driver. You should then drop the JAR file in Tomcat/lib.

But if you're doing it the basic way using DriverManager#getConnection(), then it in fact don't matter if you drop it in Tomcat/lib or YourApp/WEB-INF/lib. You however need to realize that the one in Tomcat/lib will apply for all deployed webapps and that the one in YourApp/WEB-INF/lib will override the one in Tomcat/lib for only the particular webapp.

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2: Do I need to confirgure context.xml or server.xml files?

That depends on where the connections are to be managed. When using a JNDI datasource, it suffices to configure it using YourApp/META-INF/context.xml like follows (just create file if not exist):

<?xml version="1.0" encoding="UTF-8"?>
<Context>
    <Resource
        name="jdbc/yourdb" type="javax.sql.DataSource"
        maxActive="100" maxIdle="30" maxWait="10000" 
        url="jdbc:mysql://localhost:3306/yourdb"
        driverClassName="com.mysql.jdbc.Driver"
        username="yourname" password="yourpass"
    />
</Context>

and the YourApp/WEB-INF/web.xml as follows:

<resource-env-ref>
    <resource-env-ref-name>jdbc/yourdb</resource-env-ref-name>
    <resource-env-ref-type>javax.sql.DataSource</resource-env-ref-type>
</resource-env-ref>

If you're doing it the basic DriverManager way, then it's all up to you. Hardcoded, properties file, XML file, etcetera. You should manage it youself. Tomcat won't (and can't) do anything useful for you.

Noted should be that the YourApp/META-INF/context.xml is specific to Tomcat and clones. Each servletcontainer/appserver has its own way of defining JNDI resources. In Glassfish for example, you'd like to do that through the webbased admin interface.

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3: Should I write web.xml file and need to place under Tomcat 6.0\webapps\myapp\WEB-INF? If Yes, then what should be the contents of file?

You should always supply one. It's not only to configure resources, but also to define servlets, filters, listeners and that kind of mandatory stuff to run your webapp. This file is part of the standard Servlet API.

See also:

• Is it safe to use a static java.sql.Connection instance in a multithreaded system?
• How should I connect to JDBC database / datasource in a servlet based application?
• Where do I have to place the JDBC driver for Tomcat's connection pool?
• DAO Tutorial - basic JDBC/DAO tutorial, targeted on Tomcat/JSP/Servlet