@Resource annotation is null at run-time

I'm using GlassFish v3. The following field is declared in a class:

@Resource
private javax.sql.DataSource _data_source;

The foll开发者_Go百科owing is declared in web.xml:

<data-source>
  <name>java:app/env/data</name>
  <class-name>com.mysql.jdbc.Driver</class-name>
  <server-name>localhost</server-name>
  <port-number>3306</port-number>       
  <user>myUser</user>                           
  <password>myPass</password>
</data-source>

At run-time _data_source is empty. What am I doing wrong?

Could you try this:

@Resource(lookup = "java:app/env/data")
private DataSource _data_source;

See also

• DataSource Resource Definition in Java EE 6

In addition to Pascal's answer: If injection via annotations doesn't work (no Exception occurs, the fields are just null), the problem is often an old deployment descriptor version. For Glasfish v3, you can use:

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

Try using:

@Resource(lookup="java:app/env/data")
private DataSource _data_source;

Something like this should work, no xml:

@Resource(name="jdbc/__default")
private DataSource ds
...
Connection con = null {
try {
  con = ds.getConnection();
  ...
} finally {
  if (con != null) con.close()
}