why use JndiObjectFactoryBean to config JNDI datas

Question

when I uss Java-base to config my JNDI. Spring 4.2.5.

But If I use JndiObjectFactoryBean to config.when I want to get the datasource,the object will be null.

@Bean
    public DataSource dataSource(){
        JndiObjectFactoryBean jndiObjectFactoryBean =new JndiObjectFactoryBean();
        jndiObjectFactoryBean.setJndiName("jdbc/SpittrDS");
        jndiObjectFactoryBean.setResourceRef(true);
        jndiObjectFactoryBean.setProxyInterface(DataSource.class);
        return (DataSource) jndiObjectFactoryBean.getObject();  //NULL!!!
    }

But if change the method to this,it work well.

@Bean
    public DataSource dataSource(){
        final JndiDataSourceLookup dsLookup = new JndiDataSourceLookup();
        dsLookup.setResourceRef(true);
        DataSource dataSource = dsLookup.getDataSource("java:comp/env/jdbc/SpittrDS");
        return dataSource;
    }

I do not know where is the problem.

Tomcat 9.0 context.xml

<Context>

    <!-- Default set of monitored resources. If one of these changes, the    -->
    <!-- web application will be reloaded.                                   -->
    <WatchedResource>WEB-INF/web.xml</WatchedResource>
    <WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>

    <!-- Uncomment this to disable session persistence across Tomcat restarts -->
    <!--
    <Manager pathname="" />
    -->

    <Resource name="jdbc/SpittrDS"
      auth="Container"
      type="javax.sql.DataSource"
      driverClassName="com.mysql.jdbc.Driver"
      url="jdbc:mysql://localhost:3306/spittrds"
      username="root"
      password="1"
      maxActive="100"
      maxIdle="20"
      minIdle="5"
      maxWait="10000"/>
</Context>

Answer 1

I landed here without realizing this was a problem I had faced in the past - Error Casting Spring's JndiObjectFactoryBean to ConnectionFactory for Solace-MQ JMS

So a workaround (not the preferred way) is to call afterPropertiesSet() on jndiObjectFactoryBean before attempting to getObject()

@Bean
    public DataSource dataSource(){
        JndiObjectFactoryBean jndiObjectFactoryBean =new JndiObjectFactoryBean();
        jndiObjectFactoryBean.setJndiName("jdbc/SpittrDS");
        jndiObjectFactoryBean.setResourceRef(true);
        jndiObjectFactoryBean.setProxyInterface(DataSource.class);
        jndiObjectFactoryBean.afterPropertiesSet();
        return (DataSource) jndiObjectFactoryBean.getObject();  //NOT NULL
    }

Answer 2

The actual lookup in JndiObjectFactoryBean is done in the lifecycle callback method. Either call the method explictly in your @Bean method like this (workaround)

    @Bean
    public DataSource dataSource(){
        JndiObjectFactoryBean jndiObjectFactoryBean =new JndiObjectFactoryBean();
        jndiObjectFactoryBean.setJndiName("jdbc/SpittrDS");
        jndiObjectFactoryBean.setResourceRef(true);
        jndiObjectFactoryBean.setProxyInterface(DataSource.class);
        jndiObjectFactoryBean.afterPropertiesSet();
        return (DataSource) jndiObjectFactoryBean.getObject();  //NULL!!!
    }

Or the better approach. Let your @Bean method return the JndiObjectFactoryBean and manage its lifecyle. Then in your dependent beans that require a DataSource inject the datasource created from the factory

    @Bean
    public JndiObjectFactoryBean dataSource(){
        JndiObjectFactoryBean jndiObjectFactoryBean =new JndiObjectFactoryBean();
        jndiObjectFactoryBean.setJndiName("jdbc/SpittrDS");
        jndiObjectFactoryBean.setResourceRef(true);
        jndiObjectFactoryBean.setProxyInterface(DataSource.class);
        return jndiObjectFactoryBean;
    }

//in your dependnecy

@Bean
public SomeBean someBean(DataSource dataSource){
   //use the injected datasource shich comes from the factory
}