Quick look of JNDI (Java Naming and Directory Interface)

saladlam

Salad Lam

Posted on October 21, 2024

Quick look of JNDI (Java Naming and Directory Interface)

Simple to say, programmer can use the same JNDI interface to query the following

  • lookup resources provided by application server, such as data source
  • search LDAP entries
  • lookup DNS records

Brief introduction is here.

The code

Resources of the application server are placed under "java:comp/env" prefix. Assume that a data source is on

java:/comp/env/jdbc/db1
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To get that data source

javax.naming.Context initialContext = new javax.naming.InitialContext();
javax.naming.Context subContext = (javax.naming.Context) initialContext.lookup("java:comp/env");
DataSource dataSource = (DataSource) subContext.lookup("jdbc/db1");
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Or you may get the instance directly by providing the full path

javax.naming.Context initialContext = new javax.naming.InitialContext();
DataSource dataSource = (DataSource) initialContext.lookup("java:comp/env/jdbc/db1");
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Spring boot integration

Just add a line into application.properties

spring.datasource.jndi-name=java:/comp/env/jdbc/db1
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The related bean is created by org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration

@Configuration(proxyBeanMethods = false)
@AutoConfigureBefore({ XADataSourceAutoConfiguration.class, DataSourceAutoConfiguration.class })
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
@ConditionalOnProperty(prefix = "spring.datasource", name = "jndi-name")
@EnableConfigurationProperties(DataSourceProperties.class)
public class JndiDataSourceAutoConfiguration {

    @Bean(destroyMethod = "")
    @ConditionalOnMissingBean
    public DataSource dataSource(DataSourceProperties properties, ApplicationContext context) {
        JndiDataSourceLookup dataSourceLookup = new JndiDataSourceLookup();
        DataSource dataSource = dataSourceLookup.getDataSource(properties.getJndiName());
        excludeMBeanIfNecessary(dataSource, "dataSource", context);
        return dataSource;
    }

    private void excludeMBeanIfNecessary(Object candidate, String beanName, ApplicationContext context) {
        for (MBeanExporter mbeanExporter : context.getBeansOfType(MBeanExporter.class).values()) {
            if (JmxUtils.isMBean(candidate.getClass())) {
                mbeanExporter.addExcludedBean(beanName);
            }
        }
    }

}
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πŸ’– πŸ’ͺ πŸ™… 🚩
saladlam
Salad Lam

Posted on October 21, 2024

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