dwr异常帮下

异常：
16:58:56,250 WARN BaseCallMarshaller:59 - Marshalling exception: Missing method or missing parameter converters: LoginServiceImpl.findByUserName
16:58:56,312 WARN BaseCallMarshaller:59 - --Erroring: batchId[0] message[java.lang.IllegalArgumentException: Missing method or missing parameter converters: LoginServiceImpl.findByUserName]
js代码

function saveFun(data) { if (data) { alert("注册成功！"); } else { alert("注册名已经存在！"); } } function OnSave() { var userMap = {}; userMap.id=1; userMap.username = myform.username.value; userMap.userpass= myform.userpass.value;alert(myform.userpass.value); LoginServiceImpl.findByUserName(userMap,saveFun); return false; }

配置文件








被调用的后台类
public boolean findByUserName(Student stu){
String hql="from Student as s where s.username=?";
List l=commdao.findList(hql,stu.getUsername());
if(l!=null&&l.size()!=0)
{
System.out.println("可以注册！");
return true;

    }
    else
        return false;
}

实体类字段
private int id;
private String username;
private String userpass;
异常：
16:58:56,250 WARN BaseCallMarshaller:59 - Marshalling exception: Missing method or missing parameter converters: LoginServiceImpl.findByUserName
16:58:56,312 WARN BaseCallMarshaller:59 - --Erroring: batchId[0] message[java.lang.IllegalArgumentException: Missing method or missing parameter converters: LoginServiceImpl.findByUserName]

Missing method or missing parameter converters: LoginServiceImpl.findByUserName

这个异常信息已经说得很清楚了，没有找到对应的方法或者是没有对应的参数转换器