深入理解springMVC中的Model和Session属性

目录

• springMVC的范围
• spring的@MODELATTRIBUTE
• spring Model和Request后边的原因
• Spring的@SESSIONATTRIBUTE
• 控制对话属性

@Controller
public class MyController {
 @ModelAttribute("myRequestObject")
 public MyCommandBean addStuffToRequestScope() {
  System.out.println("Inside of addStuffToRequestScope");
  MyCommandBean bean = new MyCommandBean("Hello World",42);
  return bean;
 }
 @RequestMapping("/dosomething")
 public String requestHandlingMethod(Model model, HttpServletRequest request) {
  System.out.println("Inside of dosomething handler method");
  System.out.println("--- Model data ---");
  Map modelMap = model.asMap();
  for (Object modelKey : modelMap.keySet()) {
   Object modelValue = modelMap.get(modelKey);
   System.out.println(modelKey + " -- " + modelValue);
  }
  System.out.println("=== Request data ===");
  java.util.Enumeration reqEnum = request.getAttributeNames();
  while (reqEnum.hasMoreElements()) {
   String s = reqEnum.nextElement();
   System.out.println(s);
   System.out.println("==" + request.getAttribute(s));
  }
  return "nextpage";
 }
         //  ... the rest of the controller
}

Inside of addStuffToRequestScope
Inside of dosomething handler method
--- Model data ---
myRequestObject -- MyCommandBean [someString=Hello World, someNumber=42]
=== Request data ===
org.springframework.web.servlet.DispatcherServlet.THEME_SOURCE
==WebApplicationContext for namespace 'dispatcher-servlet': startup date [Sun Oct 13 21:40:56 CDT 2013]; root of context hierarchy
org.springframework.web.servlet.DispatcherServlet.THEME_RESOLVER
==org.springframework.web.servlet.theme.FixedThemeResolver@204af48c
org.springframework.web.servlet.DispatcherServlet.CONTEXT
==WebApplicationContext for namespace 'dispatcher-servlet': startup date [Sun Oct 13 21:40:56 CDT 2013]; root of context hierarchy
org.springframework.web.servlet.HandlerMapping.pathWithinHandlerMapping
==dosomething.request
org.springframework.web.servlet.HandlerMapping.bestMatchingPattern
==/dosomething.*
org.springframework.web.servlet.DispatcherServlet.LOCALE_RESOLVER
==org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver@18fd23e4

Request Scope (key==values)
<%
 java.util.Enumeration<String> reqEnum = request.getAttributeNames();
 while (reqEnum.hasMoreElements()) {
  String s = reqEnum.nextElement();
  out.print(s);
  out.println("==" + request.getAttribute(s));
%><br />
<%
 }
%>

do something
Request Scope(key==values)

Session Scope (key==values)
<%
  java.util.Enumeration<String> sessEnum = request.getSession()
 .getAttributeNames();
  while (sessEnum.hasMoreElements()) {
 String s = sessEnum.nextElement();
 out.print(s);
 out.println("==" + request.getSession().getAttribute(s));
%><br />
<%
  }
%>

@Controller
@SessionAttributes("myRequestObject")
public class MyController {
  ...
}

@SuppressWarnings("rawtypes")
@RequestMapping("/dosomething")
public String requestHandlingMethod(Model model, HttpServletRequest request, HttpSession session) {
  System.out.println("Inside of dosomething handler method");
  System.out.println("--- Model data ---");
  Map modelMap = model.asMap();
  for (Object modelKey : modelMap.keySet()) {
 Object modelValue = modelMap.get(modelKey);
 System.out.println(modelKey + " -- " + modelValue);
  }
  System.out.println("=== Request data ===");
  java.util.Enumeration<String> reqEnum = request.getAttributeNames();
  while (reqEnum.hasMoreElements()) {
 String s = reqEnum.nextElement();
 System.out.println(s);
 System.out.println("==" + request.getAttribute(s));
  }
  System.out.println("*** Session data ***");
  Enumeration<String> e = session.getAttributeNames();
  while (e.hasMoreElements()){
 String s = e.nextElement();
 System.out.println(s);
 System.out.println("**" + session.getAttribute(s));
  } 
  return "nextpage";
}

do something
Request Scope(key == values)
Session Scope(key == values)