Question

我在一个我实现的SystemEventListener中遇到了问题。我正在使用注释@Value从属性文件中注入一个值。问题是注释@Value在应用程序的其他部分（例如@Controller）中运行良好但在此SystemEventListener中运行不正常。它也适用于tomcat，但不适用于Websphere 8.5。

你知道它可能是什么吗？

实施

public class PreRenderViewListener implements SystemEventListener {

    @Value("${path}/fileName.properties")
    private String filePath;

面-config.xml中

<system-event-listener>
            <system-event-listener-class>com.package.PreRenderViewListener</system-event-listener-class>
            <system-event-class>javax.faces.event.PreRenderViewEvent</system-event-class>
</system-event-listener>

解析器是一个扩展了PropertyPlaceholderConfigurer类的bean，它运行良好。

<bean id="uxMasterConfigBean" class="com.csc.cscip.ux.common.util.UXPropertiesConfigurer">
        <property name="ignoreUnresolvablePlaceholders" value="true" />
        <property name="ignoreResourceNotFound" value="true" />
        <property name="locations">
            <list>
                <value>classpath:/resources/master/ux.default.configuration.properties</value>
                <value>${ux.master.configuration.file.path}</value>
            </list>
        </property>
    </bean>

此配置在Tomcat中运行良好，因此我认为这不是代码中的问题，可能是与Websphere 8.5相关的问题。我一直在互联网上寻找这个问题，但我没有找到这样的东西。

感谢您的帮助！

Answer 1

正如M. Deinum所说，

PreRenderViewListener是一个JSF（faces）托管bean而不是春天管理的bean所以@Value不应该工作。

因此，要让它工作，你必须让你的PreRenderViewListener“被Spring认可”，这意味着它必须是一个Spring组件。
我现在正在使用的解决方案（我希望得到关于它的评论）是使用将在faces config中注册的multicaster org.springframework.web.jsf.DelegatingPhaseListenerMulticaster，并将所有工作委托给其他Spring bean实施SystemEventListener 这是多播器的代码（它的灵感来自于提到的Spring多功能器）。

package org.example.listeners;
import java.util.Collection;

import javax.faces.context.FacesContext;
import javax.faces.event.AbortProcessingException;
import javax.faces.event.SystemEvent;
import javax.faces.event.SystemEventListener;

import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.jsf.FacesContextUtils;


public class DelegatingSystemEventListenerMulticaster implements SystemEventListener{

@Override
public void processEvent(SystemEvent event) throws AbortProcessingException {
    for (SystemEventListener listener : getDelegates(FacesContext.getCurrentInstance())) {
        if(listener.isListenerForSource(event.getSource())){
            listener.processEvent(event);
        }
    }

}

@Override
public boolean isListenerForSource(Object source) {
    for (SystemEventListener listener : getDelegates(FacesContext.getCurrentInstance())) {
        if(listener.isListenerForSource(source)){
          return true;
        }
    }
    return false;
}


/**
 * Obtain the delegate PhaseListener beans from the Spring root WebApplicationContext.
 * @param facesContext the current JSF context
 * @return a Collection of PhaseListener objects
 * @see #getBeanFactory
 * @see org.springframework.beans.factory.ListableBeanFactory#getBeansOfType(Class)
 */
protected Collection<SystemEventListener> getDelegates(FacesContext facesContext) {
    ListableBeanFactory bf = getBeanFactory(facesContext);
    return BeanFactoryUtils.beansOfTypeIncludingAncestors(bf, SystemEventListener.class, true, false).values();
}

/**
 * Retrieve the Spring BeanFactory to delegate bean name resolution to.
 * <p>The default implementation delegates to {@code getWebApplicationContext}.
 * Can be overridden to provide an arbitrary ListableBeanFactory reference to
 * resolve against; usually, this will be a full Spring ApplicationContext.
 * @param facesContext the current JSF context
 * @return the Spring ListableBeanFactory (never {@code null})
 * @see #getWebApplicationContext
 */
protected ListableBeanFactory getBeanFactory(FacesContext facesContext) {
    return getWebApplicationContext(facesContext);
}

/**
 * Retrieve the web application context to delegate bean name resolution to.
 * <p>The default implementation delegates to FacesContextUtils.
 * @param facesContext the current JSF context
 * @return the Spring web application context (never {@code null})
 * @see FacesContextUtils#getRequiredWebApplicationContext
 */
protected WebApplicationContext getWebApplicationContext(FacesContext facesContext) {
    return FacesContextUtils.getRequiredWebApplicationContext(facesContext);
}

}

在faces-config.xml：

<system-event-listener>
        <system-event-listener-class>org.example.listeners.DelegatingSystemEventListenerMulticaster</system-event-listener-class>
<!--Use any event you want here -->
        <system-event-class>javax.faces.event.PostAddToViewEvent</system-event-class>
    </system-event-listener>

最后，创建您的SystemEventListener bean，例如：

@Component
public class FooComponentListener  implements SystemEventListener{

@Autowired
private FooService fooService;

@Override
public void processEvent(SystemEvent event) throws AbortProcessingException {
    //Do your business
}

@Override
public boolean isListenerForSource(Object source) {
//Or any other condition
    return (source instanceof HtmlInputText || source instanceof HtmlOutputText || source instanceof HtmlOutputLabel);
}


}

我希望这会有所帮助，即使有点迟了。

Websphere 8.5上的SystemEventListener + @Value null

1 个答案: