Question

我有一个简单的类，并希望使用@Autowired从numberHandler对象触发该方法。但是该对象为null。有任何想法吗？

@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
 }

的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"/>

和实现类：

package com.my.lookup;

@Component
public class MyHandler implements Runnable {

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

@Override
public void run() {

    // do something
}

我是否必须使用ClassPathXmlApplicationContext（）在主类中显式定义applicationContext.xml，或者Spring是否可以在类路径中自动识别它？

Answer 1

问题是您正在实例化不由Spring管理的Startup类。您需要从Startup获取Spring管理的ApplicationContext实例。如下更改主要方法应该有效...

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

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

如何从jar文件中@autowire实现该类？

1 个答案: