jquery WebService 传接数组参数 _Ajax

jquery WebService 传递数组参数
  $.ajax({
        type: "POST",
        contentType: "application/json; charset=utf-8",
        url: "/WebService/ProductGroupService.asmx/SaveProductGroup",
        data: "{gArray:" + gArray+ ",QArray:" + QArray+ ",XArray:" + XArray+ ",PArray:" + PArray+ "}",
        dataType: 'json',
        success: function(data) {
            alert("成功");
        },
        error: function(err) {
            alert(err.responseText);
        }
    });

public bool SaveProductGroup(ArrayList gArray, ArrayList QArray, ArrayList XArray, ArrayList PArray)
        {
            Console.WriteLine(gArray[1]);
            bool result = true;
            return result;
        }

data: "{gArray:" + gArray+ ",QArray:" + QArray+ ",XArray:" + XArray+ ",PArray:" + PArray+ "}",
这样写对么？
提示无效的web方法
------解决方案--------------------
data: gArray=gArray&QArray=QArray......

Try it.

而且，必须要返回JSON格式的数据才可以，否则会一直木有反应
------解决方案--------------------
亲，你这个URL可以访问么：/WebService/ProductGroupService.asmx/SaveProductGroup