错误信息：
DefaultHandlerExceptionResolver : Resolved [org.springframework.web.HttpRequestMethodNotSupportedException: Request method 'POST' not supported]

==================================
controller代码：
@RequestMapping(value = "login",method = RequestMethod.POST)
public String login( @Param("username") String username,@Param("password") String password)
{
System.out.print(username+password);
user u=us.getuser(username,password);
if(u!=null)
{
return "forward:index.html";
}
return "redirect:login.html";
}

======================
前台：
<form id="signupForm" method="post" action="/login">
<h4 class="no-margins">登录：</h4>
<input type="text" name="username" class="form-control uname" placeholder="用户名"/>
<input type="password" name="password" class="form-control pword m-b" placeholder="密码"/>

            <button class="btn btn-success btn-block">登录</button>
        </form>

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求大神告诉我错在哪里