springmvc ajax请求 返回 map 与model.asMap的区别

Question

@RequestMapping(value = "ajax1", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
@ResponseBody
public Map ajax1(HttpServletRequest request, Model model){

    return model.asMap();
}

ajax请求报404错误

@RequestMapping(value = "ajax2", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
@ResponseBody
public Map ajax2(HttpServletRequest request, Model model){

    return new HashMap<String, Object>();
}
ajax请求正常

翻看源码 发现 model实现linkedhashmap ，而linkedhashmap 继承hashmap

model.asMap与new HashMap有什么区别呢

求大神

Answer 1

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