The default value is Note that this attribute name differs between pool implementations and documentation is often incorrect. Default value is 30 seconds. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.
NOTE - for a true value to have any effect, the validationQuery or validatorClassName parameter must be set to a non-null string. In order to have a more efficient validation, see validationInterval. Default value is false. If specified, this query does not have to return any data, it just can't throw a SQLException.
The default value is null. We are also initializing the value of the bar property, which will cause setBar 23 to be called before the new bean is returned. Because we are not initializing the foo property although we could have , the bean will contain whatever default value is set up by its constructor. Some beans have properties with types that cannot automatically be converted from a string value. In cases were those beans provide methods to set the properties from a string value, the Tomcat BeanFactory can be configured to use these methods.
The configuration is done with the forceString attribute. The bean has two properties, both are of type InetAddress. The first property local has an additional setter taking a string argument. By default the Tomcat BeanFactory would try to use the automatically detected setter with the same argument type as the property type and then throw a NamingException, because it is not prepared to convert the given string attribute value to InetAddress.
We can tell the Tomcat BeanFactory to use the other setter like that:. The bean property remote can also be set from a string, but one has to use the non-standard method name host.
To set local and remote use the following configuration:. Multiple property descriptions can be combined in forceString by concatenation with comma as a separator. Each property description consists of either only the property name in which case the BeanFactory calls the setter method.
For properties of types String or of primitive type or of their associated primitive wrapper classes using forceString is not needed. The correct setter will be automatically detected and argument conversion will be applied. UserDatabase resources are typically configured as global resources for use by a UserDatabase realm. A typical XML would look like:. It should look something like this:. The pathname attribute can be a URL, an absolute path or a relative path. The readonly attribute is optional and defaults to true if not supplied.
If the XML is writeable then it will be written to when Tomcat starts. Ensure that these are appropriate to maintain the security of your installation. If referenced in a Realm, the UserDatabase will, by default, monitor pathname for changes and reload the file if a change in the last modified time is observed. This can be disabled by setting the watchSource attribute to false.
Configure a UserDatabase Realm to use this resource as described in the Realm configuration documentation. In many web applications, sending electronic mail messages is a required part of the system's functionality. The Java Mail API makes this process relatively straightforward, but requires many configuration details that the client application must be aware of including the name of the SMTP host to be used for message sending.
Tomcat includes a standard resource factory that will create javax. Session session instances for you, already configured to connect to an SMTP server. In this way, the application is totally insulated from changes in the email server configuration environment - it simply asks for, and receives, a preconfigured session whenever needed.
A typical web. Note that the application uses the same resource reference name that was declared in the web application deployment descriptor. Customize the value of the mail. Additional resource attributes and values will be converted to properties and values and passed to javax. Properties as part of the java. Properties collection. Here then are some example configurations that have been posted to tomcat-user for popular databases and some general tips for db usage.
Please let us know if you have any other tested configurations that you feel may be of use to the wider audience, or if you feel we can improve this section in anyway.
You will most likely need to modify older JNDI resource configurations to match the syntax in the example below in order to make them work in Tomcat 9. See Tomcat Migration Guide for details. Also, please note that JNDI DataSource configuration in general, and this tutorial in particular, assumes that you have read and understood the Context and Host configuration references, including the section about Automatic Application Deployment in the latter reference.
DriverManager supports the service provider mechanism. Driver file are automatically discovered, loaded and registered, relieving you from the need to load the database driver explicitly before you create a JDBC connection. However, the implementation is fundamentally broken in all Java versions for a servlet container environment. The problem is that java. DriverManager will scan for the drivers only once. This is enabled by default. It means that only libraries visible to the common class loader and its parents will be scanned for database drivers.
If you are considering disabling this feature, note that the scan would be triggered by the first web application that is using JDBC, leading to failures when this web application is reloaded and for other web applications that rely on this feature. The list of drivers in java. DriverManager is also a known source of memory leaks. Any Drivers registered by a web application must be deregistered when the web application stops.
Tomcat will attempt to automatically discover and deregister any JDBC drivers loaded by the web application class loader when the web application stops. However, it is expected that applications do this for themselves via a ServletContextListener. The default database connection pool implementation in Apache Tomcat relies on the libraries from the Apache Commons project. The following libraries are used:. However, only the classes needed for connection pooling have been included, and the packages have been renamed to avoid interfering with applications.
See the DBCP 2 documentation for a complete list of configuration parameters. A database connection pool creates and manages a pool of connections to a database. Recycling and reusing already existing connections to a database is more efficient than opening a new connection.
There is one problem with connection pooling. A web application has to explicitly close ResultSet's, Statement's, and Connection's. Failure of a web application to close these resources can result in them never being available again for reuse, a database connection pool "leak".
This can eventually result in your web application database connections failing if there are no more available connections. There is a solution to this problem. Not only can it recover them, but also generate a stack trace for the code which opened these resources and never closed them. The default for both of these attributes is false.
Note that removeAbandonedOnMaintenance has no effect unless pool maintenance is enabled by setting timeBetweenEvictionRunsMillis to a positive value.
See the DBCP 2 documentation for full documentation on these attributes.
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