前文说到，新项目中，用到的是SpringMVC + jdbcTemplate，前台是EasyUI，发现同事以前封装分页是逻辑分页，于是，自己动手封装了下物理分页。
这个是核心分页实体：
import java.io.Serializable;
import java.util.List;
import java.util.Map;
import org.apache.commons.lang.StringUtils;
import org.springframework.jdbc.core.JdbcTemplate;
/**
* 分页实体
* @author lyh
* @version 2013-10-10
* @see Pagination
* @since
*/
public class Pagination implements Serializable
{
/**
* 序列号<br>
*/
private static final long serialVersionUID = -2554565760258955645L;
/**
* 每页显示的记录数
*/
private int numPerPage;
/**
* 记录总数 （命名必须为total 对应easyui分页）
*/
private int total;
/**
* 总页数
*/
private int totalPages;
/**
* 当前页码
*/
private int currentPage;
/**
* 记录起始行数
*/
private int startIndex;
/**
* 记录结束行数
*/
private int lastIndex;
/**
* 结果集存放List （命名必须为rows 对应easyui分页）
*/
private List<Map<String,Object>> rows;
/**
* 构造函数
* @param sql sql语句
* @param currentPage 当前页码
* @param numPerPage 每页显示记录数
* @param jdbcTemplate JdbcTemplate实例
*/
public Pagination(String sql, int currentPage, int numPerPage, JdbcTemplate jdbcTemplate)
{
if (jdbcTemplate == null)
{
throw new IllegalArgumentException(
"jdbcTemplate is null , pls initialize ... ");
}
else if (StringUtils.isBlank(sql))
{
throw new IllegalArgumentException("sql is blank , pls initialize ... ");
}
//设置每页显示记录数
setNumPerPage(numPerPage);
//设置当前页数
setCurrentPage(currentPage);
//计算总记录数SQL
StringBuffer totalSQL = new StringBuffer(" select count(1) from ( ");
totalSQL.append(sql);
totalSQL.append(" ) ");
//总记录数
setTotal(jdbcTemplate.queryForInt(totalSQL.toString()));
//计算总页数
setTotalPages();
//计算起始行数
setStartIndex();
//计算结束行数
setLastIndex();
//拼装oracle的分页语句 （其他DB修改此处的分页关键词即可）
StringBuffer paginationSQL = new StringBuffer(" select * from ( ");
paginationSQL.append(" select row_limit.*,rownum rownum_ from ( ");
paginationSQL.append(sql);
paginationSQL.append(" ) row_limit where rownum <= " + lastIndex);
paginationSQL.append(" ) where rownum_ > " + startIndex);
//装入结果集（key转为小写）
setRows(ConvertMapkey.listKeyToLower(jdbcTemplate.queryForList(
paginationSQL.toString())));
}
/**
* 根据总记录数和每页显示记录数 计算总页数
*
* @see
*/
private void setTotalPages()
{
if (total % numPerPage == 0)
{
this.totalPages = total / numPerPage;
}
else
{
this.totalPages = (total / numPerPage) + 1;
}
}
/**
* 根据当前页和每页显示记录条数 计算记录开始行数
*
* @see
*/
private void setStartIndex()
{
this.startIndex = (currentPage - 1) * numPerPage;
}
/**
* 计算记录结束行数
*
* @see
*/
private void setLastIndex()
{
if (total < numPerPage)
{
this.lastIndex = total;
}
else if ((total % numPerPage == 0)
|| (total % numPerPage != 0 && currentPage < totalPages))
{
this.lastIndex = currentPage * numPerPage;
}
else if (total % numPerPage != 0 && currentPage == totalPages)
{
this.lastIndex = total;
}
}
//setter and getter
public int getCurrentPage()
{
return currentPage;
}
public void setCurrentPage(int currentPage)
{
this.currentPage = currentPage;
}
public int getNumPerPage()
{
return numPerPage;
}
public void setNumPerPage(int numPerPage)
{
this.numPerPage = numPerPage;
}
public List<Map<String,Object>> getRows()
{
return rows;
}
public void setRows(List<Map<String,Object>> rows)
{
this.rows = rows;
}
public int getTotalPages()
{
return totalPages;
}
public int getTotal()
{
return total;
}
public void setTotal(int total)
{
this.total = total;
}
public int getStartIndex()
{
return startIndex;
}
public int getLastIndex()
{
return lastIndex;
}
}
Map转化工具类：
public class ConvertMapkey {
/**
* 把map对象的key全部转为小写形式
* @param map
* @return
*/
public static Map<String, Object> keyToLower(Map<String, Object> map) {
Map<String, Object> r = new HashMap<String, Object>();
if (map == null || map.size() == 0)
return r;
for (Map.Entry<String, Object> entry : map.entrySet()) {
r.put(entry.getKey().toLowerCase(), entry.getValue());
}
return r;
}
/**
* 把list map中map对象的key全部转为小写形式
* @param listmap
* @return
*/
public static List<Map<String, Object>> listKeyToLower(List<Map<String, Object>> listmap) {
List<Map<String, Object>> r = new ArrayList<Map<String, Object>>();
if (listmap == null || listmap.size() == 0)
return r;
for (Map<String, Object> map : listmap) {
r.add(keyToLower(map));
}
return r;
}
}
DAO层 Service层：
return new Pagination(sqlFetchRows, page, rows, jdbcTemplate);
Controller层：
@RequestMapping(value = "/list_school")
@ResponseBody
public Pagination listSchool(HttpServletRequest request) {
Pagination p = null;
try {
int page = Integer.parseInt(request.getParameter("page"));
int rows = Integer.parseInt(request.getParameter("rows"));
String school_code = request.getParameter("s_school_code");
String school_name = request.getParameter("s_school_name");
//page：当前页 rows：每页显示记录条数 区别结果集存放List-rows
p = schoolService.pageData(page, rows, school_id, school_code, school_name);
} catch (Exception e) {
logger.error(e);
}
return p;
}
注意：Controller返回的 Pagination实体在会转为JSON（故实体中一定不能含有jdbcTemplate字段，jdbcTemplate只能通过方法形式注入），然后在EasyUi中展示。
通过FireFox 可以发现上述返回的分页实体的JSON。
JS部分：
// 查询
$('#btn_02010100').click(function() {
$('#basedg').datagrid('load');
});
$('#basedg').datagrid({
animate: true, //是否动画展开折叠
checkbox: true, //全选复选框
checkOnSelect: true, //选中复选框的同时选中行
selectOnCheck: true, //选中行的同时选中复选框
singleSelect: false, //是否单选
collapsible: true, //是否可折叠
height: 'auto', //自动高度
iconCls: 'icon-save', //样式图标
idField: 'school_id', //主索引，唯一标识字段
loadMsg: '数据载入中，请稍候......',
maximizable: true,
nowrap: true, //截断内文
pagination: true, //分页
pageList: [10,15,20,25,30],
rownumbers: true, //是否显示列数,
url: basePath + '/school/list_school',
frozenColumns: [[
{field:'ck',checkbox:true},
{field:'school_id',title:'唯一id',hidden:true},
{field:'school_code',title:'学校代码',80},
{field:'school_name',title:'学校名称',200}
]],
columns: [[
{field:'schooling_length',title:'学制',100},
{field:'telephone',title:'联系电话',120},
{field:'school_address',title:'学校地址',300},
{field:'establishment_date',title:'建校年月',80,
formatter:function (value) {
return value == null ? '' : (new Date(value).format('yyyy-MM-dd'));
}
}
]],
onBeforeLoad: function (param) {
param.s_school_code = $('#s_school_code').searchbox('getValue');
param.s_school_name = $('#s_school_name').searchbox('getValue');
}
});
}
JSP页面：
<table id="basedg" toolbar="#toolbar" pagination="true"></table> <div id="toolbar"> <div id="searchbar"> <table cellspacing="0" cellpadding="0"> <tr> <td>查询条件：</td> <td> <input id="s_school_code" class="easyui-searchbox" data-options="prompt:'学校代码'"></input> </td> <td> <input id="s_school_name" class="easyui-searchbox" data-options="prompt:'学校名称'"></input> </td> </tr> </table> </div> <a href="javascript:void(0)" id="btn_02010100" class="easyui-linkbutton" iconCls="icon-search" plain="true">查询</a> </div>
最终效果：
每次查询时的触发SQL如下：
log Begining method: com.ruhuiyun.studentmanager.service.SchoolService.pageData 2013-10-11 10:40:18,345 [qtp14565508-22] DEBUG [org.springframework.jdbc.core.JdbcTemplate] - Executing SQL query [ select count(1) from ( SELECT school_id, school_code, school_name, schooling_length, school_address, telephone, establishment_date FROM T_SCHOOL WHERE 1 = 1 AND instr(school_name, '无锡') > 0 ) ] 2013-10-11 10:40:18,349 [qtp14565508-22] DEBUG [org.springframework.jdbc.core.JdbcTemplate] - Executing SQL query [ select * from ( select row_limit.*,rownum rownum_ from ( SELECT school_id, school_code, school_name, schooling_length, school_address, telephone, establishment_date FROM T_SCHOOL WHERE 1 = 1 AND instr(school_name, '无锡') > 0 ) row_limit where rownum <= 2 ) where rownum_ > 0] 2013-10-11 10:40:18,353 [qtp14565508-22] INFO [com.ruhuiyun.studentmanager.aop.LogAdvice] - log Ending method: com.ruhuiyun.studentmanager.service.SchoolService.pageData
一曲终了~~