Struts的Acion中如何取得Spring管理的bean

package com.maywide.sett.commons.web.struts;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionServlet;
import org.apache.struts.actions.DispatchAction;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;


import com.xxx.data.admin.domain.logic.SysAdminFacade;
import com.xxx.sett.commons.LoginInfo;
import com.xxx.sett.commons.constant.ForwardType;
import com.xxx.sett.commons.constant.MessageKey;
import com.xxx.sett.commons.constant.ReqAttributeType;
import com.xxx.sett.commons.utils.EncodeEx;
import com.xxx.sett.commons.utils.StringUtils;
import com.xxx.sett.domain.logic.SettBusiFacade;
import com.xxx.sett.domain.logic.SettBusiconfFacade;


/**
 * 
 *
 * <p>Looks up the Spring WebApplicationContext via the ServletContext
 * and obtains the PetStoreFacade implementation from it, making it
 * available to subclasses via a protected getter method.
 *
 * <p>As alternative to such a base class, consider using Spring's
 * ActionSupport class for Struts, which pre-implements
 * WebApplicationContext lookup in a generic fashion.
 *
 * @author Juergen Hoeller
 * @since 30.11.2003
 * @see #getPetStore
 * @see org.springframework.web.context.support.WebApplicationContextUtils#getRequiredWebApplicationContext
 * @see org.springframework.web.struts.ActionSupport
 */
public abstract class BaseAction extends DispatchAction {    
    
private static Logger logger = Logger.getLogger(BaseAction.class);
    
private SettBusiFacade settBusiFacade;

private SettBusiconfFacade settBusiconfFacade;

private SysAdminFacade sysAdminFacade;


public SysAdminFacade getSysAdminFacade() {
return sysAdminFacade;
}


public SettBusiconfFacade getSettBusiconfFacade() {
return settBusiconfFacade;
}


public void setServlet(ActionServlet actionServlet) {
super.setServlet(actionServlet);
if (actionServlet != null) {
ServletContext servletContext = actionServlet.getServletContext();
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);

this.settBusiFacade = (SettBusiFacade) wac.getBean("settBusiFacade");
this.settBusiconfFacade=(SettBusiconfFacade)wac.getBean("settBusiconfFacade");
this.sysAdminFacade=(SysAdminFacade) wac.getBean("sysAdminFacade");
}
}

public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
String isCscomm = request.getParameter("CSCOMM");
if (isCscomm != null && isCscomm.equalsIgnoreCase("true")) {
EncodeEx.change(form);
}
String ajaxkind = request.getParameter("ajaxkind");
if (ajaxkind != null && ajaxkind.equalsIgnoreCase("wfajax")) {
EncodeEx.wfAjaxchange(form);
}
  
request.setAttribute(MessageKey.COR_MESSAGE, "");
try {
return super.execute(mapping, form, request, response);
} catch (Exception ex) {
ex.printStackTrace();
log.info(ex.getMessage());
ActionForward forward = mapping.findForward(ForwardType.SUCCESS);
request.setAttribute(MessageKey.COR_MESSAGE, ex.getMessage());
saveError(request, ex);
if (forward != null) {
return forward;
} else {
return mapping.findForward(ForwardType.SUCCESS);
}
}
}


public SettBusiFacade getSettBusiFacade() {
return settBusiFacade;
}


public void saveError(HttpServletRequest request, Exception ex) {
request.setAttribute(MessageKey.ERR_MESSAGE, ex.getMessage());
request.setAttribute(MessageKey.DETAIL, ex.toString());
}

public ActionForward doNew(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
return mapping.findForward(ForwardType.CONTENT);
}

}

 问题来了，setServlet这个方法有时什么时候被调用，又是在什么地方被调用的呢？为了搞清楚这个问题，我们有必要剖析一下struts1.3.8的源码，从http://struts.apache.org/download.cgi上可以当下来。

        首先要从ActionServlet的init方法看起，需要关注的有这么几行代码：

            // Initialize modules as needed
            ModuleConfig moduleConfig = initModuleConfig("", config);

            initModuleMessageResources(moduleConfig);
            initModulePlugIns(moduleConfig);
            initModuleFormBeans(moduleConfig);
            initModuleForwards(moduleConfig);
            initModuleExceptionConfigs(moduleConfig);
            initModuleActions(moduleConfig);

        ModuleConfig这个类其实就是负责解析装配struts config配置文件的类，在initModuleConfig方法中调用了ModuleConfigFactory这个工厂类来创建一个ModuleConfig实例，继续往下看，根据方法名你也能猜到initModuleActions是用来干吗的，在这个方法中通过调用ModuleConfigImp的findActionConfigs方法加载和初始化Action类的，检查一番，发现除了加载配置文件中的Action类之外似乎额外的动作不多，显然我想要找的东西不在这里。
        接下来要看的自然是doGet和doPost方法了，方法内部均是调用另外的一个process方法，在这个方法里，我们看到了如下一段代码：
        ModuleConfig config = getModuleConfig(request);

        RequestProcessor processor = getProcessorForModule(config);

        if (processor == null) {
            processor = getRequestProcessor(config);
        }

        processor.process(request, response);

        看来关键就在于RequestProcessor的process方法了，看到
        // Create or acquire the Action instance to process this request
        Action action = processActionCreate(request, response, mapping);

        你应该心中有数，离胜利不远了，果然，在processActionCreate方法里
        if (instance.getServlet() == null) {
            instance.setServlet(this.servlet);
        }
        终于找到了！就是在这里将ActionServlet对象塞入了Action中。

        其实对于技术框架源码的剖析并不是很难，关键在于把握主线，对于一些旁枝末节可以稍后关注。虽然细节上还有待进一步深入探索，但一开始理清脉络才是最重要的，宏观上没有把握，微观上的行为很可能就是盲目的，其实做任何事都是这样的啊。

2.Struts Action 的setServlet() 方法是自动运行的吗？

这个方法会在action初始化的时候调用，这样在action初始化的时候就把spring管理的bean付给了action（作为action的全局变量），但是要注意的是在action中只有无状态的对象才能作为action的全局变量哦.private PetStoreFacade petStore;   public void setServlet(ActionServlet actionServlet) {           super.setServlet(actionServlet);           if (actionServlet != null) {               ServletContext servletContext = actionServlet.getServletContext();               WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);               this.petStore = (PetStoreFacade) wac.getBean("petStore");           }                    System.out.println("俺已经初始化了么？");         }  启动tomcat时候,没有输出该语句. 我进入首页后,点击 Enter the Store,控制台输出了该语句,此时执行的DoNothingAction 其代码如下: 代码public class DoNothingAction extends BaseAction {       /* Public Methods */      public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {       return mapping.findForward("success");     }   }  所以看来确实是在Action初始化的时候执行的该方法. 不过每次执行一个BaseAction子类,setServlet()方法就要执行一次.

参考资料：http://www.javaeye.com/topic/40646 

http://blog.csdn.net/xiehl/article/details/5514668