Initialcontext in a standalone Java program

Question

I'm using a JNDI for creating connection pool. It works great in a web application. I believe the InitialContext is provided by the tomcat server.

Context initContext  = new InitialContext(); Context envContext  = (Context)initContext.lookup("java:/comp/env"); dataSource = (DataSource)envContext.lookup("jdbc/testdb"); 

But when I try to call the same utility from a standalone Java program, the initContext object is null. How can I explicitly provide all the necessary properties that Context object is expecting.

Error : javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file: java.naming.factory.initial

Answer 1

Here is an example adapted from the accepted answer but doing everything inline to avoid creating extra classes.

public static void main(String[] args) {     setupInitialContext();     //do something that looks up a datasource }  private static void setupInitialContext() {     try {         NamingManager.setInitialContextFactoryBuilder(new InitialContextFactoryBuilder() {              @Override             public InitialContextFactory createInitialContextFactory(Hashtable<?, ?> environment) throws NamingException {                 return new InitialContextFactory() {                      @Override                     public Context getInitialContext(Hashtable<?, ?> environment) throws NamingException {                         return new InitialContext(){                              private Hashtable<String, DataSource> dataSources = new Hashtable<>();                              @Override                             public Object lookup(String name) throws NamingException {                                  if (dataSources.isEmpty()) { //init datasources                                     MysqlConnectionPoolDataSource ds = new MysqlConnectionPoolDataSource();                                     ds.setURL("jdbc:mysql://localhost:3306/mydb");                                     ds.setUser("mydbuser");                                     ds.setPassword("mydbpass");                                     dataSources.put("jdbc/mydbname", ds);                                      //add more datasources to the list as necessary                                 }                                  if (dataSources.containsKey(name)) {                                     return dataSources.get(name);                                 }                                  throw new NamingException("Unable to find datasource: "+name);                             }                         };                     }                  };             }          });     }     catch (NamingException ne) {         ne.printStackTrace();     } } 

Answer 2

You could also create your own custom context.

LocalContext ctx = LocalContextFactory.createLocalContext(); ctx.addDataSource("jdbc/testdb", driverName, url, usr, pwd); 

See Running Beans Locally that use Application Server Data Sources for more details.

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UPDATE

You can use the class org.springframework.mock.jndi.SimpleNamingContextBuilder of Spring. e.g.:

• Setup:

  SimpleNamingContextBuilder builder = new SimpleNamingContextBuilder(); builder.bind("jdbc/Oracle", ods); builder.activate(); 

• Use:

  DataSource ds = InitialContext.doLookup("jdbc/Oracle");