@RequestMapping("/testServletAPI")
public void testServletAPI(HttpServletRequest request,
HttpServletResponse response,HttpSession session,
Writer out) throws IOException{
System.out.println(request);
System.out.println(response);
System.out.println(session);
out.write("hello");
}
代码解析： 很明显，要使用Sevlet的一些API，只要直接将其作为参数传入即可。你需要request，就传入request， 需要session，就传入session。springmvc支持传入的Sevlet原生api一共有以下这些：
1. HttpServletRequest
2. HttpServletResponse
3. HttpSession
4. java.security.Principal
5. Locale
6. InputStream
7. OutputStream
8. Reader
9. Writer
