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