Explanation of several return forms of springMVC

package com.boventech.learning.controller;  
  
import java.util.HashMap;  
import java.util.Map;  
  
import org.springframework.stereotype.Controller;  
import org.springframework.ui.Model;  
import org.springframework.web.bind.annotation.RequestMapping;  
import org.springframework.web.bind.annotation.RequestMethod;  
import org.springframework.web.bind.annotation.RequestParam;  
import org.springframework.web.bind.annotation.ResponseBody;  
import org.springframework.web.servlet.ModelAndView;  
  
import com.boventech.learning.entity.User;  
  
/**
 * MVCReturn
 * @author peng.xia
 *
 */  
@Controller  
@RequestMapping("/MVCReturn")  
public class SpringMVCReturnController {  
      
    @RequestMapping(value="/index1",method=RequestMethod.GET)  
    public ModelAndView index(){  
        ModelAndView modelAndView = new ModelAndView("/user/index");  
        modelAndView.addObject("name", "xxx");  
        return modelAndView;  
    }  
    //For the ModelAndView constructor, you can specify the name of the returned page, or you can use the setViewName method to set the page you want to jump to;  
      
    @RequestMapping(value="/index2",method=RequestMethod.GET)  
    public ModelAndView index2(){  
        ModelAndView modelAndView = new ModelAndView();  
        modelAndView.addObject("name", "xxx");  
        modelAndView.setViewName("/user/index");  
        return modelAndView;  
    }  
    //returns a ModelAndView object containing a model and a view;  
      
    /**
     * Model a model object,
     * Mainly includes spring-packaged model and modelMap, as well as java.util.Map,
     * When no view is returned, the view name will be determined by requestToViewNameTranslator;  
     * @return
     */  
    @RequestMapping(value="/index3",method=RequestMethod.GET)  
    public Map<String, String> index3(){  
        Map<String, String> map = new HashMap<String, String>();  
        map.put("1", "1");  
        //map.put is equivalent to request.setAttribute method  
        return map;  
    }  
    //The view of the response should also be the view of the request. Equivalent to void return.  
      
    //return String  
    //Use through model  
    @RequestMapping(value="/index4",method = RequestMethod.GET)  
    public String index(Model model) {  
        String retVal = "user/index";  
        User user = new User();  
        user.setName("XXX");  
        model.addAttribute("user", user);  
        return retVal;  
    }  
      
    //By cooperating with @ResponseBody, the content or object is returned as the HTTP response body (suitable for instant verification);  
    @RequestMapping(value = "/valid", method = RequestMethod.GET)  
    @ResponseBody  
    public String valid(@RequestParam(value = "userId", required = false) Integer userId,  
            @RequestParam(value = "name") String name) {  
        return String.valueOf(true);  
    }  
    //The return string represents a view name. At this time, if you need a model in the process of rendering the view, you can add a model parameter to the processor, and then add a value to the model in the method body.  
      
       
    @RequestMapping(method=RequestMethod.GET)  
    public void index5(){  
        ModelAndView modelAndView = new ModelAndView();  
        modelAndView.addObject("xxx", "xxx");  
    }  
    //The returned result page is still: /type  
    //At this time, we generally write the return result in HttpServletResponse, if not,  
    //spring will use RequestToViewNameTranslator to return a corresponding view name. If a model is needed at this time, the processing method is the same as the case of returning a string.  
  
}  

Reprinted from: http://blog.csdn.net/sunhuwh/article/details/41727257