// 不使用这种传参：var data = "username="+vm.username+"&password="+vm.password+"&captcha="+vm.captcha;
		login: function (event) {
			$.ajax({
				type: "POST",
			    url: "sys/login",
                data: { // 改为使用json方式传参。则问题解决。
                    "username": vm.username,
                    "password": vm.password,
                    "captcha": vm.captcha
                },
			    dataType: "json",
			    success: function(result){
					if(result.errorCode == 0){//登录成功
						parent.location.href ='index.html';
					}else{
						vm.error = true;
						vm.errorMsg = result.msg;
						
						vm.refreshCode();
					}
				}
			});
		}