處理模型數據 Spring mvc ModelAndView

將模型數據暴露給視圖是Spring MVC框架的一項重要工作，SpringMVC提供了多種途徑輸出模型數據：

1.ModelAndView

2.@ModelAttribute

3.Map及Model

4.@SessionAttributes

例子如下：

package com.wondersgroup.hs.test.controller;

import java.util.Map;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.wondersgroup.hs.test.model.User;

@Controller
@RequestMapping("/mavc")
public class ModelAndViewController {
	/**
	 * 處理模型數據1：ModelAndView
	 * @return
	 */
	@RequestMapping("method1")
	public ModelAndView method1(){
		ModelAndView mav = new ModelAndView();
		User u = new User();
		u.setUserName("1");
		mav.addObject("user1", u);
		mav.setViewName("modelandview");
		return mav;
	}
	
	/**
	 * 處理模型數據2：@ModelAttribute
	 * @param user
	 * @return
	 */
	@RequestMapping("method2")
	public String method2(@ModelAttribute("user")User user){
		user.setUserName("湯姆");
		return "/mavc/handle61";
	}
	
	@ModelAttribute("user")
	public User getUser(){
		User user = new User();
		user.setUserName("湯姆");
		return user;
	}
	/**
	 * 處理模型數據3：Map及Model
	 * @param map
	 * @return
	 */
	@RequestMapping("method3")
	public String method3(Map<String,Object> map){
		User user = new User();
		user.setRealName("湯姆");
		map.put("user", user);
		return "/mavc/method3";
	}
	@RequestMapping("method4")
	public String method4(ModelMap modelMap){
		User user = new User();
		user.setRealName("湯姆");
		modelMap.put("user", user);
		return "/mavc/method4";
	}
	
	/**
	 * 處理模型數據4：@SessionAttributes("user")
	 * 詳見SessionAttributesController
	 * */
}

package com.wondersgroup.hs.test.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.bind.support.SessionStatus;

import com.wondersgroup.hs.test.model.User;

@Controller
@RequestMapping("/sac")
@SessionAttributes("user")
public class SessionAttributesController {
	
	@ModelAttribute("user")
	public User getUser(){
		User user = new User();
		user.setUserName("湯姆");
		return user;
	}
	
	@RequestMapping("method1")
	public String method1(@ModelAttribute("user") User user){
		user.setUserName("Tom");
		return "redirect:method2";
	}
	@RequestMapping("method2")
	public String method2(ModelMap modelMap,SessionStatus sessionStatus){
		User user = (User)modelMap.get("User");
		if(user != null){
			user.setUserName("Tim");
			sessionStatus.setComplete();
		}
		return "sac/method2";
	}
}