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Tomcat connection pool with MyBatis

I was wondering if anyone has any code examples for setting up a connection pool in Tomcat (7 or later) using MyBatis as the ORM.
I presume I need to add a resource to my context.xml file in my Tomcat conf folder and then link that to MyBatis. I've had a look and any tutorials I have found seem to be Spring specific. Does anyone have a simple tutorial or can they outline the steps required to get this up and running?

There is this old entry in the iBatis FAQ that should still be applicable to myBatis: How do I use a JNDI DataSource with iBATIS in Tomcat?.
You can google for the details to configure a datasource in your Tomcat version, then configure MyBatis as well (it's different than the iBatis configuration):
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="JNDI">
<property name="data_source" value="java:comp/env/jdbc/yourDatasourceName"/>
</dataSource>
</environment>

There are a number of ways you can do this. I am assuming that you mean to implement Tomcat (as opposed to Spring) managed connection pooling. I have tested on MySQl/Spring 4/Mybatis-spring 1.1 stack.
Figure out the connection pooling mechanism you want to implement (C3P0/DBCP etc).
If you want to use your database as a JNDI data source, then you have to declare it as a resource in Tomcat settings. There are a number of ways to do this. You can follow this well written guide Tomcat JNDI connection pooling. I generally add the following entry in context.xml located in the META-INF directory of my app:
<Context>
<Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource" maxTotal="100" maxIdle="30" maxWaitMillis="10000" username="javauser" password="javadude" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost:3306/javatest"/>
</Context>
This file is used by Tomcat to invoke its own default connection pool, which in this case would be DBCP 2. You can tweak its settings by adding more parameters (like removeAbandonedOnBorrow=true) in the Resource element above. You should put the driver jar (eg MySQL Connector Jar) of your database in Tomcat's lib folder.
After this, depending on your Mybatis implementation (XML or bean based), you can inject this data source into Mybatis. If you are doing it the bean way, you can do it like this:
<bean id="dbDataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:comp/env/jdbc/TestDB"/>
</bean>
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dbDataSource" />
</bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dbDataSource" />
<property name="typeAliasesPackage" value="com.example.model"/>
<property name="mapperLocations" value="classpath*:*.xml" />
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.example.dao" />
</bean>
MapperScannerConfigurer is necessary because it searches the directories given to it to find mapper xml files. You can also use the old way of defining a mybatis-config.xml file by injecting the file's location in the sqlSessionFactory bean in its configLocation property.

Tomcat Connection Pool - Factory Setting

I have been learning about how to set up Tomcat's connection pool through this website. So I made a context.xml file and put it in the directory META-INF. This is what I have right now.
<?xml version="1.0" encoding="UTF-8"?>
<Context>
<Resource name="jdbc/gmustudent" auth="Container"
type="javax.sql.DataSource" driverClassName="com.mysql.jdbc.Driver"
username="root" password="root"
url="jdbc:mysql://localhost:3306/official"
maxActive="100" maxIdle="10" minIdle="5" initialSize="5" maxWait="10000" />
</Context>
However I would like to specify the class name of the factory. But everytime I add this attribute
factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
I get a huge pile of errors in my console. Here are some of them in no particular order.
WARNING: Failed to register in JMX: javax.naming.NamingException: com.mysql.jdbc.Driver
WARNING: Unexpected exception resolving reference java.sql.SQLException: com.mysql.jdbc.Driver
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:gmustudent' did not find a matching property.
So when I do not specify a factory the site works just fine. But when I do errors are thrown and nothing works. I did some research on stack overflow and found this post. Because of this I changed my tomcat version from 7.0.11 to the most recent but am still getting the error. So then I thought maybe it is some kind of clash with my factory in my server.xml file but I am not nearly experienced to make that call. But here is the resource in my server.xml file
<Resource auth="Container" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" name="UserDatabase" pathname="conf/tomcat-users.xml" type="org.apache.catalina.UserDatabase"/>
So is this clashing with the factory in my context.xml file? Or am I totally wrong here? In a nut shell I would like to find out how to specify a factory in my context.xml file without getting a huge error. Thank you for reading.

You can actually manage the entire connection in your web app using Spring if you want. Here is an example using PostgreSQL:
<?xml version="1.0" encoding="windows-1252"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="myDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.postgresql.Driver"/>
<property name="url" value="jdbc:postgresql://localhost/mydb"/>
<property name="username" value="postgres"/>
<property name="password" value="postgres"/>
</bean>
</beans>
You can just put that in WEB-INF/classes and load it using:
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/mycontext.xml");
I wouldn't even bother with having Tomcat manage it at this point.

How to use JNDI DataSource provided by Tomcat in Spring?

It is said that in the Spring javadoc article about DriverManagerDataSource class, that this class is very simple and that it is recommended
to use a JNDI DataSource provided by the container. Such a DataSource can be exposed as a DataSource bean in a Spring ApplicationContext via JndiObjectFactoryBean
The question is: how do I accomplish this?
For example, if I wish to have DataSource bean to access my custom MySQL database, what would I require then? What should I write in the context configuration, etc?

If using Spring's XML schema based configuration, setup in the Spring context like this:
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:jee="http://www.springframework.org/schema/jee" xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd">
...
<jee:jndi-lookup id="dbDataSource"
jndi-name="jdbc/DatabaseName"
expected-type="javax.sql.DataSource" />
Alternatively, setup using simple bean configuration like this:
<bean id="DatabaseName" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:comp/env/jdbc/DatabaseName"/>
</bean>
You can declare the JNDI resource in tomcat's server.xml using something like this:
<GlobalNamingResources>
<Resource name="jdbc/DatabaseName"
auth="Container"
type="javax.sql.DataSource"
username="dbUser"
password="dbPassword"
url="jdbc:postgresql://localhost/dbname"
driverClassName="org.postgresql.Driver"
initialSize="20"
maxWaitMillis="15000"
maxTotal="75"
maxIdle="20"
maxAge="7200000"
testOnBorrow="true"
validationQuery="select 1"
/>
</GlobalNamingResources>
And reference the JNDI resource from Tomcat's web context.xml like this:
<ResourceLink name="jdbc/DatabaseName"
global="jdbc/DatabaseName"
type="javax.sql.DataSource"/>
Reference documentation:
Tomcat 8 JNDI Datasource HOW-TO
Tomcat 8 Context Resource Links Reference
Spring 4 JEE JNDI Lookup XML Schema Reference
Spring 4 JndiObjectFactoryBean Javadoc
Edit: This answer has been updated for Tomcat 8 and Spring 4. There have been a few property name changes for Tomcat's default datasource resource pool setup.

With Spring's JavaConfig mechanism, you can do it like so:
#Configuration
public class MainConfig {
...
#Bean
DataSource dataSource() {
DataSource dataSource = null;
JndiTemplate jndi = new JndiTemplate();
try {
dataSource = jndi.lookup("java:comp/env/jdbc/yourname", DataSource.class);
} catch (NamingException e) {
logger.error("NamingException for java:comp/env/jdbc/yourname", e);
}
return dataSource;
}
}

Assuming you have a "sampleDS" datasource definition inside your tomcat configuration, you can add following lines to your applicationContext.xml to access the datasource using JNDI.
<jee:jndi-lookup expected-type="javax.sql.DataSource" id="springBeanIdForSampleDS" jndi-name="sampleDS"/>
You have to define the namespace and schema location for jee prefix using:
xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd"

Documentation: C.2.3.1 <jee:jndi-lookup/> (simple)
Example:
<jee:jndi-lookup id="dataSource" jndi-name="jdbc/MyDataSource"/>
You just need to find out what JNDI name your appserver has bound the datasource to. This is entirely server-specific, consult the docs on your server to find out how.
Remember to declare the jee namespace at the top of your beans file, as described in C.2.3 The jee schema.

Another feature:
instead of of server.xml, you can add "Resource" tag in
your_application/META-INF/Context.xml
(according to tomcat docs)
like this:
<Context>
<Resource name="jdbc/DatabaseName" auth="Container" type="javax.sql.DataSource"
username="dbUsername" password="dbPasswd"
url="jdbc:postgresql://localhost/dbname"
driverClassName="org.postgresql.Driver"
initialSize="5" maxWait="5000"
maxActive="120" maxIdle="5"
validationQuery="select 1"
poolPreparedStatements="true"/>
</Context>

According to Apache Tomcat 7 JNDI Datasource HOW-TO page there must be a resource configuration in web.xml:
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
That works for me

In your spring class, You can inject a bean annotated like as
#Autowired
#Qualifier("dbDataSource")
private DataSource dataSource;
and You add this in your context.xml
<beans:bean id="dbDataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
<beans:property name="jndiName" value="java:comp/env/jdbc/MyLocalDB"/>
</beans:bean>
You can declare the JNDI resource in tomcat's server.xml using
<Resource name="jdbc/TestDB"
global="jdbc/TestDB"
auth="Container"
type="javax.sql.DataSource"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/TestDB"
username="pankaj"
password="pankaj123"
maxActive="100"
maxIdle="20"
minIdle="5"
maxWait="10000"/>
back to context.xml de spring add this
<ResourceLink name="jdbc/MyLocalDB"
global="jdbc/TestDB"
auth="Container"
type="javax.sql.DataSource" />
if, like this exmple you are injecting connection to database, make sure that MySQL jar is present in the tomcat lib directory, otherwise tomcat will not be able to create the MySQL database connection pool.

I found this solution very helpful in a clean way to remove xml configuration entirely.
Please check this db configuration using JNDI and spring framework.
http://www.unotions.com/design/how-to-create-oracleothersql-db-configuration-using-spring-and-maven/
By this article, it explain how easy to create a db confguration based on database jndi(db/test) configuration. once you are done with configuration then all the db repositories are loaded using this jndi. I did find useful. If #Pierre has issue with this then let me know. It's complete solution to write db configuration.

Tomcat6 MySql JDBC Datasource configuration

I've always used Spring's dependency injection to get datasource objects and use them in my DAOs, but now, I have to write an app without that.
With Spring I can write something like this:
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://127.0.0.1/app?characterEncoding=UTF-8" />
<property name="username" value="u" />
<property name="password" value="p" />
</bean>
But how can I use datasource in my DAOs without Spring or anything? I'm using servlets and JSPs only. Performance is very important factor.

Believe it or not, people were writing applications before Spring and some are still not using it :) In your case, you could use Tomcat connection pool (and there is a complete configuration example for MySQL in the documentation). Let me summarize it:
First, put your driver in $CATALINA_HOME/lib.
Then, configure a JNDI DataSource in Tomcat by adding a declaration for your resource to your Context:
<Context path="/DBTest" docBase="DBTest"
debug="5" reloadable="true" crossContext="true">
<!-- maxActive: 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 -1 for no limit.
-->
<!-- maxIdle: Maximum number of idle dB connections to retain in pool.
Set to -1 for no limit. See also the DBCP documentation on this
and the minEvictableIdleTimeMillis configuration parameter.
-->
<!-- maxWait: 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.
-->
<!-- username and password: MySQL dB username and password for dB connections -->
<!-- driverClassName: Class name for the old mm.mysql JDBC driver is
org.gjt.mm.mysql.Driver - we recommend using Connector/J though.
Class name for the official MySQL Connector/J driver is com.mysql.jdbc.Driver.
-->
<!-- url: The JDBC connection url for connecting to your MySQL dB.
-->
<Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="javauser" password="javadude" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/javatest"/>
</Context>
Declare this resource in your web.xml:
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<description>MySQL Test App</description>
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
And get the datasource with a JNDI lookup in your application:
Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
DataSource ds = (DataSource) envCtx.lookup("jdbc/TestDB");
Connection conn = ds.getConnection();
... use this connection to access the database ...
conn.close();
Note that such lookup is usually coded in a ServiceLocator (when you can't have a a DI container or a framework inject it for you).

I used to get error with sybase, I had missing META-INF folder in WebContent folder. Putting context.xml in that fixed the error Cannot create JDBC driver of class '' for connect URL 'null'...
// www.abbulkmailer.com
My context.xml looks like
<Context path="/reports" docBase="reports" debug="5" reloadable="true" crossContext="true">
<Resource name='jdbc/ASCSybaseConnection'
auth='Container'
type='javax.sql.DataSource'
username='fdd'
password='555'
driverClassName='com.sybase.jdbc2.jdbc.SybDriver'
maxActive='100'
maxIdle='100'
minIdle='10'
removeAbandoned="true"
removeAbandonedTimeout="60"
testOnBorrow="true"
logAbandoned="true"
url='jdbc:sybase:Tds:1.3.4.5:654/DB'/>
</Context>

You can declare your data source as a JNDI object and retrieve a datasource via a JNDI lookup:
DataSource ds = (DataSource)
envCtx.lookup("jdbc/EmployeeDB");
as documented here and here.
That's as bare-bones as you can get, so from there on, performance is completely up to you.

Tomcat vs Weblogic JNDI Lookup

The Weblogic servers we are using have been configured to allow JNDI datasource names like "appds".
For development (localhost), we might be running Tomcat and when declared in the <context> section of server.xml, Tomcat will hang JNDI datasources on "java:comp/env/jdbc/*" in the JNDI tree.
Problem: in Weblogic, the JNDI lookup is "appds" whilst in Tomcat, it seems that that I must provide the formal "java:comp/env/jdbc/appds". I'm afraid the Tomcat version is an implicit standard but unfortunately, I can't change Weblogic's config ... so that means we end up with two different spring config files (we're using spring 2.5) to facilitate the different environments.
Is there an elegant way to address this. Can I look JNDI names up directly in Tomcat? Can Spring take a name and look in both places? Google searches or suggestions would be great.

How to use a single JNDI name in your web app
I've struggled with this for a few months myself. The best solution is to make your application portable so you have the same JNDI name in both Tomcat and Weblogic.
In order to do that, you change your web.xml and spring-beans.xml to point to a single jndi name, and provide a mapping to each vendor specific jndi name.
I've placed each file below.
You need:
A <resource-ref /> entry in web.xml for your app to use a single name
A file WEB-INF/weblogic.xml to map your jndi name to the resource managed by WebLogic
A file META-INF/context.xml to map your jndi name to the resource managed by Tomcat
This can be either in the Tomcat installation or in your app.
As a general rule, prefer to have your jndi names in your app like jdbc/MyDataSource and jms/ConnFactory and avoid prefixing them with java:comp/env/.
Also, data sources and connection factories are best managed by the container and used with JNDI. It's a common mistake to instantiate database connection pools in your application.
spring
<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd">
<jee:jndi-lookup jndi-name="jdbc/appds"
id="dataSource" />
</beans>
web.xml
<resource-ref>
<description>My data source</description>
<res-ref-name>jdbc/appds</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
weblogic.xml
<?xml version="1.0" encoding="UTF-8" ?>
<weblogic-web-app
xmlns="http://xmlns.oracle.com/weblogic/weblogic-web-app"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://xmlns.oracle.com/weblogic/weblogic-web-app http://http://www.oracle.com/technology/weblogic/weblogic-web-app/1.1/weblogic-web-app.xsd">
<resource-description>
<jndi-name>appds</jndi-name>
<res-ref-name>jdbc/appds</res-ref-name>
</resource-description>
</weblogic-web-app>
META-INF/context.xml (for Tomcat)
<Context>
<ResourceLink global="jdbc/appds" name="jdbc/appds" type="javax.sql.DataSource"/>
</Context>

JndiLocatorSupport has a property resourceRef. When setting this true, "java:comp/env/" prefix will be prepended automatically. So I believe it would be correct to differentiate this parameter when moving from Tomcat to Weblogic.

I've managed the trick with Tomcat and WebLogic using Spring. Here is a description of how it worked for me.

The following config works in Tomcat and Weblogic for me.
In Spring:
<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
<!-- This will prepend 'java:comp/env/' for Tomcat, but still fall back to the short name for Weblogic -->
<property name="resourceRef" value="true" />
<property name="jndiName" value="jdbc/AgriShare" />
</bean>
In Weblogic Admin Console create a JDBC resource named jdbc/AgriShare. Under 'Targets', MAKE SURE YOU TARGET THE DATASOURCE TO THE SERVER YOU ARE DEPLOYING YOUR APP TO!. This particular point cost me some time just now...

How about an evironment variable? Set developers machines with the tomcat name and production with the Weblogic name. You can even set your code to use a default one (WebLogic) in case the variable don't exist.

How are you referencing the resource in spring?
This is what we have for tomcat:
context:
<Resource name="jms/ConnectionFactory" auth="Container" type="org.apache.activemq.ActiveMQConnectionFactory" description="
JMS Connection Factory"
factory="org.apache.activemq.jndi.JNDIReferenceFactory" brokerURL="tcp://localhost:61615" brokerName="StandaloneAc
tiveMQBroker"/>
spring:
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">
<jee:jndi-lookup jndi-name="jms/ConnectionFactory" id="connectionFactory" resource-ref="true"
expected-type="javax.jms.ConnectionFactory" lookup-on-startup="false"/>
The jee namespace comes from:
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.0.xsd

Setting up DataSource in the application itself is not that crazy :) I would say that is even mandatory if application is meant to be deployed on a grid. River, GigaSpaces, or similar.
Note: I do not say connection settings have to be hardcoded inside of WAR, they need to be supplied at deployment time/runtime. This simplifies management of cloud instances since there is only on place to configure.
Configuring resources at the container makes sense only if multiple applications are deployed there and they can use shared resource.
Again, in cloud type of deployments there is only one application per servlet container instance.

My application also had a similar problem and this is how I solved it:
1) WEB-INF/classes/application.properties contains the entry:
ds.jndi=java:comp/env/jdbc/tcds
2) On the WLS machine, I have an entry in the /etc/sysenv file:
ds.jndi=wlsds
3) I configured spring to lookup the JNDI vis the property ${ds.jndi}, using a PropertyPlaceholderConfigurer bean with classpath:application.properties and file:/etc/sysenv as locations. I also set the ignoreResourceNotFound to true so that developers need not have /etc/sysenv on their machines.
4) I run an integration test using Cargo+Jetty and I could not properly set up a JNDI environment there. So I have a fallback BasicDataSource configured too using the defaultObject property of JndiObjectFactoryBean.