用Get方式访问

//客户端代码

 <form id="form1" runat="server">
        <asp:ScriptManager ID="ScriptManager1" runat="server" ScriptMode="Debug">
            <Services>
                <asp:ServiceReference Path="Services/UseHttpGetService.asmx" InlineScript="true" />
            </Services>
        </asp:ScriptManager>
        
        <input type="button" value="Get Random" onclick="getRandom()" />
        <input type="button" value="Get Range Random" onclick="getRandom(50, 100)" />
        
        <script language="javascript" type="text/javascript">
            function getRandom(minValue, maxValue)
            {
                if (arguments.length != 2)
                {
                    UseHttpGetService.GetRandom(onSucceeded);
                }
                else
                {
                    UseHttpGetService.GetRangeRandom(minValue, maxValue, onSucceeded);
                }
            }
            
            function onSucceeded(result)
            {
                alert(result);
            }
        </script>
    </form>

//WebService

    [WebMethod]
    public int GetRandom()
    {
        return new Random(DateTime.Now.Millisecond).Next();
    }

    [WebMethod]
    //使用Get方式
    [ScriptMethod(UseHttpGet=true)]
    public int GetRangeRandom(int minValue, int maxValue)
    {
        return new Random(DateTime.Now.Millisecond).Next(minValue, maxValue);
    }