ajax请求成功后返回的data如何比较

ajax请求成功后返回的data怎么比较?

 function login(){
    $.ajax({
    'url':'${ctx}/user.do?method=login',
    'data':{'email':$('#email').val(),'password':$('#password').val()},
    'type':'post',
    'dataType':'Json',
    'success':function(data,statusText){
    alert(data);//success
    alert(data=='success');//false
    if(data=='success'){
    alert('进来了~！');
    closeBg();
    }
    if(data=='fail'){
    $('#msg').html('账号或者密码错误');
    }
    }
    });
    
    }

@RequestMapping(params="method=login")
public void login(HttpServletRequest request,HttpServletResponse response) throws Exception{
System.out.println("here");
String email=request.getParameter("email");
String password=request.getParameter("password");
User user=userService.findByEmail(email, password);
System.out.println("user:"+user);
PrintWriter out=response.getWriter();
if(user!=null){
request.getSession().setAttribute("user", user);
out.println("success");
out.close();
}
else{
out.println("fail");
out.close();
}
}

 out.println  这个方法会多个换行符
用 
out.print