仅在设置对象的属性后如何加载Spring Bean？

Question

I have an object called ApplicationProperties . The object has private fields and public getter methods. Very trivial.

    if (properties == null) {
        properties = new ApplicationProperties();
        SettingsLoader settingsLoader = new SettingsLoader(properties);
        settingsLoader.loadApplicationSettings();
    }
    return properties;

I also have Spring Beans, some of which depend on ApplicationProperties for reading some path etc. This is working fine for a long period of time. The JDK is Oracle JDK 1.6 . But recently when I deployed in OpenJDK 1.7 ICEDTEA I got some NullPointerException as the application properties being used by a spring bean has null fields(Not initialized fully).

May be parallel class loading is done in case of Open JDK(Not sure about it).

How do I ensure that all spring beans(more than 200 in number - and many through annotations) are instantiated only after the ApplicationProperties is fully ready?

Answer 1

将属性对象作为构造函数依赖项注入到需要它的所有Bean。

Answer 2

The class ApplicationProperties is a non-bean which was not under the control of the Spring IoC. For some reasons the code which was working fine on Oracle JDK 1.6 and higher versions but did not work on Open JDK 1.7 ICEDTEA and I was getting some NullPointerException .

For reference I am posting the solution as answer.

As the non-bean class properties need to be loaded completely before beans are created, I delegated the loading part to a separate thread and it worked fine for me.

public class SettingsLoader implements Runnable {
    //Other methods go here
    @Override
    public void run() {
        loadApplicationSettings();
    }
}

And inside the constructor of the ApplicationProperties

    private ApplicationProperties() {
        SettingsLoader settingsLoader = new SettingsLoader(this);
        Thread loader = new Thread(settingsLoader);
        loader.setName("Settings Loader");
        logger.info("Settings Loader is initiated. Loading application settings.");
        loader.setPriority(Thread.MAX_PRIORITY);
        try {
            loader.start();
            loader.join();
        } catch (InterruptedException ex) {
            logger.error("Application settings loader is interrupted. Exception is", ex);
        }
    }

With this the current thread waits until the thread loader has done its job of setting application properties fields.