var param = {};

    param.keys = delKeys.join();//delKeys是数组，如delKeys=['a',b','c'],join函数把数组拼接成字符串，分隔符默认是,

    $.ajax({

        type: "POST",

        data: param,

        dataType: "json",//预期服务器返回的数据类型

        url: ctxpath+"/cache/deleteCache.action",

        success: function (serverData) {

            alertWin("成功删除"+serverData.data+"条");

            search();

        }

    });

@RequestMapping("/deleteCache.action")
@ResponseBody
private PageResponse deleteCache(HttpServletRequest request,@RequestParam List<String> keys) {
　　//keys可以得到正确的数组
　　//request.getParameter("keys")　得到的是"a,b,c"
}