ServiceLocator的實現
/*
* Created on 2004-8-25 by simba.
*
*/
package com.simba.blog.util;
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import javax.servlet.ServletContext;
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import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
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import com.opensymphony.webwork.ServletActionContext;
import com.simba.blog.service.BlogService;
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/**
* @author simba
*
* email: simbasun@msn.com
*/
public class ServiceLocator
{
//the catalog service bean name
private static final String BLOG_SERVICE_BEAN_NAME = "blogService";
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//the user service bean name
private static final String USER_SERVICE_BEAN_NAME = "userService";
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//the logger for this class
private Log logger = LogFactory.getLog(this.getClass());
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//the Spring application context
private ApplicationContext appContext;
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//the cached catalog service
private BlogService blogService;
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//the cached user service
//private UserService userService;
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/**
* Constructor.
* <p>
* The following steps being done:
* <ul>
* <li>retrieve Spring application context from servlet context.
* <li>look up <code>CatalogService</code> from Spring application
* context.
* <li>look up <code>UserService</code> from Spring applicatino context.
* </ul>
*/
public ServiceLocator()
{
/*InputStream is = getClass().getResourceAsStream("springapp-servlet.xml");
XmlBeanFactory bf = new XmlBeanFactory(is);
blogService = (BlogService) bf.getBean("blogService");*/
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ServletContext context = ServletActionContext.getServletContext();
this.appContext = WebApplicationContextUtils.getRequiredWebApplicationContext(context);
this.blogService = (BlogService)this.lookupService(BLOG_SERVICE_BEAN_NAME);
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/*
* this.userService = (UserService)this.lookupService(USER_SERVICE_BEAN_NAME);
*/
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this.logger.info("Service locator bean is initialized");
}
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/**
* Lookup service based on service bean name.
*
* @param serviceBeanName the service bean name
* @return the service bean
*/
public Object lookupService(String serviceBeanName)
{
return appContext.getBean(serviceBeanName);
}
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/**
* @return Returns the blogService.
*/
public BlogService getBlogService()
{
return blogService;
}
}
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[in web.xml]
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<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/daoContext.xml /WEB-INF/applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- OR USE THE CONTEXTLOADERSERVLET INSTEAD OF THE LISTENER
<servlet>
<servlet-name>context</servlet-name>
<servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
-->