java分页(基于mybatis)

该分页功能中心思想：

001、为Page类设置 当前页，总记录数，每页记录数

002、将查询的结果集复制给Page的属性容器

003、向前台页面返回Page

做到这三点，其他过程可自己发挥

1、系统常量类

public class Conv 
{
	 // 每页显示条数	
	public static int pageSize=10;	

      //登录后放在Session中的User信息
}

 2、Page类，包含了可以存放List的容器

public class Page 
{
	/**当前页*/
	private int curPage;
	/**总页数*/
	private int total;
	/**总的记录数*/
	private int sum;
	/**结果集*/
	private List result;

	public Page(){}
	
	public Page(int curPage,int sum) {
		this.curPage = curPage;
		this.sum = sum;
		int totalPage = 
(int) Math.ceil(sum/Double.parseDouble(Conv.pageSize + ""));
		if (totalPage == 0)
			totalPage = 1;
		this.total=totalPage;
	}



	public int getCurPage() {
		return curPage;
	}

	public void setCurPage(int curPage) {
		this.curPage = curPage;
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}

	public int getSum() {
		return sum;
	}

	public void setSum(int sum) {
		this.sum = sum;
	}

	public List getResult() {
		return result;
	}

	public void setResult(List result) {
		this.result = result;
	}
}

 3、UnitService类获取SqlSession，利用mybatis的RowBounds进行分页，执行sql语句获得结果集

public class UnitService 
{
		private static UnitService unitService = null;
		Logger LOG = Logger.getLogger(DeptService.class);
		private UnitService(){}
		public static UnitService getInstance(){
			if(unitService==null){
				unitService=new UnitService();
			}
			return unitService;
		}
		
		
		//分页查询单位
		public Page queryQyDw(Map<String,Object> params,int currentPage,int pageSize) throws Exception{
			List<QyDw> units = null;
			int count = 0;
			SqlSession session=MybatisUtil.getSqlSessionFactory().openSession();
			try{
				IunitDao manager=session.getMapper(IunitDao.class);
				units=(List<QyDw>)session.selectList("com.xinfeijinxin.qy.dao.IunitDao.queryQyDw", params,new RowBounds((start-1)*Conv.pageSize, limit));
				count = manager.queryQyDwCount();
			}catch(Exception e){
				
			}finally{
				session.close();
			}
			

			Page page=new Page(start,count);		//初始化分页数据
			page.setResult(units);					//封装对象
			return page;
		}
}

 4、IunitDao.java 对应UnitDao.xml查询语句

public interface IunitDao 
{

	/**
	 * 查询单位列表
	 */
	public List<QyDw> queryQyDw(Map<String,Object> map);
}

 5、UnitDao.xml

<?xml version="1.0" encoding="UTF-8" ?> 
<!DOCTYPE mapper 
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 
<!-- namespace应对应接口路径-->
<mapper namespace="com.xinfeijinxin.qy.dao.IunitDao">

<!--查询记录，map参数可以根据情况去掉-->
  <select id="queryQyDw" parameterType="map" resultType="com.xinfeijinxin.qy.bean.QyDw">
    select dwid,dwmc,dwjc,sjdw,dwlx from qy_dw where 1=1
      
    <if test="keyword!=null and keyword !=''">
     and dwmc like CONCAT('%','${keyword}','%' )
    </if>
    
    <if test="keyword!=null and keyword !=''">
    and dwjc like CONCAT('%','${keyword}','%' )
    </if>
    
    <if test="keyword!=null and keyword !=''">
    and sjdw like CONCAT('%','${keyword}','%' )
    </if>
    
    <if test="keyword!=null and keyword !=''">
    and dwlx like CONCAT('%','${keyword}','%' )
    </if>
  </select>


<!-- 查询记录总数-->
<select id="queryQyDwCount" resultType="int">
     select count(*) from qy_dw
  </select>

</mapper>

 6、Action封装前台数据

public class UnitAction extends BaseAction 
{
     //getter setter（）。。。。
	private List<QyDw> units=null; 
	private Page page=null;
	private QyDw unit;

//分页查询单位
	public String list()
	{
		// 分页信息设置，接受前台参数
		if (page == null)
			page = new Page();
		// 如果当前页为0，则设置当前页为1
		if (page.getCurPage() == 0) {
			page.setCurPage(1);
		}
		try{
			Map<String,Object> map=new HashMap<String,Object>();
			//map.put("keyword","学");
                      
                      //将page传至前台
			page=UnitService.getInstance().queryQyDw(map, page.getCurPage(), Conv.pageSize);
		}catch(DBException e){
			logger.error(e.getMessage());
		}
             return LIST;
       }
}

 7、BaseAction，设置统一返回的字符串，获取request和response

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.log4j.Logger;
import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

public class BaseAction extends ActionSupport{
	protected HttpServletRequest request; // request
	protected HttpServletResponse response; // response
	protected ServletContext servletConext; // servletContext
	protected HttpSession session; // session
	public final String SUCCESS = "success";	//成功
	protected String ADD = "add"; // 返回增加
	protected String DELETE = "delete"; // 返回删除
	protected String UPDATE = "update"; // 返回修改
	protected String LIST = "list"; // 返回修改
	protected String EXCEPTION="exception"; 	//返回异常
	
	Logger logger = Logger.getLogger(BaseAction.class);
	
	
	public HttpServletRequest getRequest() {
		return ServletActionContext.getRequest();
	}

	public void setRequest(HttpServletRequest request) {
		this.request = request;
	}

	public HttpServletResponse getResponse() {
		return ServletActionContext.getResponse();
	}

	public void setResponse(HttpServletResponse response) {
		this.response = response;
	}

	public ServletContext getServletConext() {
		return ServletActionContext.getServletContext();
	}

	public void setServletConext(ServletContext servletConext) {
		this.servletConext = servletConext;
	}

	public HttpSession getSession() {
		return ServletActionContext.getRequest().getSession();
	}
	
}

 8、前台链接

<div class="btn" style="text-align: center;">
					<s:if test="page.curPage <= 1">
						<img src="images/firstpage2.png" />
						<img src="images/prepage2.png" />
					</s:if>
					<s:else>
						<a href="admin/Unit_list.action?page.curPage=1"><img
								src="images/firstpage.png" /> </a>
						<a
							href="admin/Unit_list.action?page.curPage=<s:property value="%{page.curPage-1}" />"><img
								src="images/prepage.png" /> </a>
					</s:else>
					<s:if test="page.curPage < page.total">
						<a
							href="admin/Unit_list.action?page.curPage=<s:property value="%{page.curPage+1}" />"><img
								src="images/nextpage.PNG" /> </a>
						<a
							href="admin/Unit_list.action?page.curPage=<s:property value="%{page.total}" />"><img
								src="images/lastpage.png" /> </a>
					</s:if>
					<s:else>
						<img src="images/nextpage2.PNG" />
						<img src="images/lastpage2.png" />
					</s:else>
					<select id="page" name="page.curPage"
						style="width: 50px; vertical-align: middle;" onchange="jump()">
						<s:bean name="org.apache.struts2.util.Counter" id="counter">
							<s:param name="first" value="1" />
							<s:param name="last" value="page.total" />
							<s:iterator>
								<option value="<s:property value="current-1" />">
									<s:property value="current-1" />
								</option>
							</s:iterator>
						</s:bean>
					</select>
			<script type="text/javascript">
				var num = '${page.curPage}';
				document.getElementById('page').options[num - 1].selected = true;
			</script>

				第
				<s:property value="%{page.curPage}" />
				页 共
				<s:property value="%{page.total}" />
				页 共
				<s:property value="%{page.sum}" />
				记录
			</div>