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javaservletsannotationsjndi

Life cycle/length of a DataSource injected with @Resource annotation

I'm far from an expert of the intricacies of Resource Injection, and of indeed DataSources in Java, but I generally understand the process of doing a lookup for a predefined JNDI resource to get a datasource from.

Using Resource Injection as an alternate method, the below syntax works:

@Resource(name="jdbc/Foo")
private javax.sql.DataSource con;

However, I am using this in a servlet and as such wondering, how long this injected connection object's value will exist? Presumably, as it's simply an object within the servlet, it will inject when the servlet is first instantiated and exist for the same duration as the servlet (assuming I don't manually change it). Is this correct? Or does the servlet re-inject the resource everytime the servlet is used?

Thanks

Solution

  • A servlet container only ever creates one instance of your servlet. The IoC container you're using will then instantiate and inject the DataSource, so the value in con will remain the same for the life of your servlet, ie. the life of the application.

    As to the underlying connection the DataSource is trying to make will, that's up to your datasource.