java - Spring BeanFactory 作为 Swing 应用程序中的单例

Question

我目前正在重构一个大型 Swing 应用程序，以便从 XmlBeanFactory 获取一些对象。

许多不同的类可以使用它，我想知道共享这个 beanFactory 的最佳方式是什么。

• 我应该创建一个 Singleton 来共享此 XmlBeanFactory 吗？

  单例类 { 公共(public)静态 XmlBeanFactory getBeanFactory() {(...) } }

• 或者我应该向我的对象添加一些 setter (丑陋:它添加了一些依赖项......)

• 另一种解决方案？

谢谢

Answer 1

使用静态单例是一个不错的方法。我还没有找到更好的解决方案。这有点不太令人满意，因为单例在使用之前必须使用连接文件进行初始化，如果不这样做会导致 Bean 创建异常，这只是需要记住做的一件事。

public final class SpringUtil {

private static ApplicationContext context = null;
private static Set<String> alreadyLoaded = new HashSet<String>();

/**
 * Sets the spring context based off multiple wiring files. The files must exist on the classpath to be found.
 * Consider using "import resource="wiring.xml" in a single wiring file to reference other wiring files instead.
 * Note that this will destroy all previous existing wiring contexts.
 * 
 * @param wiringFiles an array of spring wiring files
 */
public static void setContext(String... wiringFiles) {
    alreadyLoaded.clear();
    alreadyLoaded.addAll(Arrays.asList(wiringFiles));
    context = new ClassPathXmlApplicationContext(wiringFiles);
}

/**
 * Adds more beans to the spring context givin an array of wiring files. The files must exist on the classpath to be
 * found.
 * 
 * @param addFiles an array of spring wiring files
 */
public static void addContext(String... addFiles) {
    if (context == null) {
        setContext(addFiles);
        return;
    }

    Set<String> notAlreadyLoaded = new HashSet<String>();
    for (String target : addFiles) {
        if (!alreadyLoaded.contains(target)) {
            notAlreadyLoaded.add(target);
        }
    }

    if (notAlreadyLoaded.size() > 0) {
        alreadyLoaded.addAll(notAlreadyLoaded);
        context = new ClassPathXmlApplicationContext(notAlreadyLoaded.toArray(new String[] {}), context);
    }
}

/**
 * Gets the current spring context for direct access.
 * 
 * @return the current spring context
 */
public static ApplicationContext getContext() {
    return context;
}

/**
 * Gets a bean from the current spring context.
 * 
 * @param beanName the name of the bean to be returned
 * @return the bean, or throws a RuntimeException if not found.
 */
public static Object getBean(final String beanName) {
    if (context == null) {
        throw new RuntimeException("Context has not been loaded.");
    }
    return getContext().getBean(beanName);
}

/**
 * Sets this singleton back to an uninitialized state, meaning it does not have any spring context and
 * {@link #getContext()} will return null. Note: this is for unit testing only and may be removed at any time.
 */
public static void reset() {
    alreadyLoaded.clear();
    context = null;
}

}

使用较新版本的 springframework，您可以使用泛型使 getBean() 返回比 Object 更具体的类，这样您就不必在获取 bean 后对其进行强制转换。