How to @autowire implementation of the class from a jar file?

Question

I have a simple class and would like to use @Autowired to trigger the method from numberHandler object. However the object is null. Any ideas?

@Component
public class Startup implements UncaughtExceptionHandler {

@Autowired
private MyHandler myHandler;

public static void main(String[] args) {

    startup = new Startup();
    startup(args);

}

public static void startup(String[] args) {

    startup = new Startup();

}
private void start() {
     ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
     myHandler.run(); //NULL
 }

applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
   xmlns:util="http://www.springframework.org/schema/util"
   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd">

<context:annotation-config />
<context:component-scan base-package="com.my.lookup"/>  

and the implementation class:

package com.my.lookup;

@Component
public class MyHandler implements Runnable {

private static Logger LOGGER = LoggerFactory.getLogger(MyHandler.class);

@Override
public void run() {

    // do something
}

Do I have to explicit define applicationContext.xml in main class with ClassPathXmlApplicationContext() or is there way for Spring to automatically recognize it in my classpath?

Answer 1

The problem is you are instantiating the Startup class which is not managed by Spring. You need to get the Startup instance managed by Spring from your ApplicationContext . Changing your main method as follows should work...

public static void main(String[] args) {
    ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
    startup = context.getBean(Startup.class);
    startup.start();
}

private void start() {
    myHandler.run();
}