//获得分页栏。注意indexSize为奇数,这样也比较好看

//totalNum:数据库总记录数，pageSize:每页显示的记录数，indexSize:要显示几个页码，比如下边显示 1 2 3 4 5 indexSize就=5， page:当前页码

function getPageIndex(totalNum, pageSize, indexSize, page) {

    var pageIndex = "";

    //如果总记录数大于页码显示数量才进行计算

    if (totalNum > pageSize) {

        var totalPage = 0;

        if (totalNum % pageSize == 0) {

            totalPage = totalNum / pageSize;

        }

        else {

            totalPage = Math.floor(totalNum / pageSize) + 1;

        }

        //情况1 总页数<页码数

        if (totalPage < indexSize) {

            for (var i = 1; i <= totalPage; i++) {

                pageIndex += "<li";

                if (i == page) {

                    pageIndex += " class='active'";

                }

                pageIndex += ">";

                pageIndex += "<a>" + i + "</a>";

                pageIndex += "</li>";

            }

        }

        //情况2 总页数>页码数 并且 当前页数位于最后后半段 如 25 26 27 28 29的28页

        else if (totalPage > indexSize && totalPage - page <= ((indexSize - 1) / 2)) {

            for (var i = totalPage - indexSize + 1; i <= totalPage; i++) {

                pageIndex += "<li";

                if (i == page) {

                    pageIndex += " class='active'";

                }

                pageIndex += ">";

                pageIndex += "<a>" + i + "</a>";

                pageIndex += "</li>\n";

            }

        }

        //情况3 总页数>页码数 并且 当前页数位于最前前半段 如 1 2 3 4 5的2页

        else if (totalPage > indexSize && page <= ((indexSize + 1) / 2)) {

            for (var i = 1; i <= indexSize; i++) {

                pageIndex += "<li";

                if (i == page) {

                    pageIndex += " class='active'";

                }

                pageIndex += ">";

                pageIndex += "<a>" + i + "</a>";

                pageIndex += "</li>\n";

            }

        }

        //正常情况

        else {

            for (var i = parseInt(page) - Math.floor(indexSize / 2); i <= parseInt(page) + Math.floor(indexSize / 2); i++) {

                pageIndex += "<li";

                if (i == page) {

                    pageIndex += " class='active'";

                }

                pageIndex += ">";

                pageIndex += "<a>" + i + "</a>";

                pageIndex += "</li>\n";

            }

        }

        //上一页 下一页

        if (page == 1) {

            pageIndex = "<li class='disabled'><a>上一页</a></li>" + pageIndex + "<li><a>下一页</a></li>";

        } else if (page == totalPage) {

            pageIndex = "<li><a>上一页</a></li>" + pageIndex + "<li class='disabled'><a>下一页</a></li>";

        } else {

            pageIndex = "<li><a>上一页</a></li>" + pageIndex + "<li><a>下一页</a></li>";

        }

    }

    return pageIndex;

}