SpringMVC域对象共享数据

@RequestMapping("/testServletAPI")
public String testServletAPI(HttpServletRequest request){
request.setAttribute("testScope", "hello,servletAPI");
return "success";
}

直接在大括号里面加上request中的键

@RequestMapping("/testModelAndView")
public ModelAndView testModelAndView(){

ModelAndView mav = new ModelAndView();
//向请求域共享数据
mav.addObject("testScope", "hello,ModelAndView");
//设置视图，实现页面跳转
mav.setViewName("success");
return mav;
}

注：如果使用了ModelAndView，方法返回值必须是ModelAndView，它需要返回让前端控制器解析

@RequestMapping("/testModel")
public String testModel(Model model){
model.addAttribute("testScope", "hello,Model");
return "success";
}

@RequestMapping("/testMap")
public String testMap(Map map){
map.put("testScope", "hello,Map");
return "success";
}

注：声明的map必须放在形参中 

@RequestMapping("/testModelMap")
public String testModelMap(ModelMap modelMap){
modelMap.addAttribute("testScope", "hello,ModelMap");
return "success";
}

注：声明的ModelMap必须放在形参中 

Model、ModelMap、Map类型的参数其实本质上都是 BindingAwareModelMap 类型的

public interface Model{}
public class ModelMap extends LinkedHashMap {}
public class ExtendedModelMap extends ModelMap implements Model {}
public class BindingAwareModelMap extends ExtendedModelMap {}

 以上六种方式，最终都会封装成ModelAndView

@RequestMapping("/testSession")
public String testSession(HttpSession session){
session.setAttribute("testSessionScope", "hello,session");
return "success";
}

@RequestMapping("/testApplication")
public String testApplication(HttpSession session){
ServletContext application = session.getServletContext();
application.setAttribute("testApplicationScope", "hello,application");
return "success";
}