java分页查询接口的实现

java分页查询接口的实现

分页要传入当前所在页数和每页显示记录数，再分页查询数据库，部分代码如下所示。

传入参数实体类：

public class MessageReq {    private String memberId;//会员id    private int currentPage;//当前页    private int pageSize;//一页多少条记录    private int startIndex;//从哪一行开始    private int endIndex;//从哪一行结束    public String getMemberId() {        return memberId;    }    public void setMemberId(String memberId) {        this.memberId = memberId;    }    public int getCurrentPage() {        return currentPage;    }       public int getStartIndex() {        return startIndex;    }    public int getEndIndex() {        return endIndex;    }    public void setCurrentPage(int currentPage) {        this.currentPage = currentPage;    }    public void setStartIndex(int startIndex) {        this.startIndex = startIndex;    }    public void setEndIndex(int endIndex) {        this.endIndex = endIndex;    }    public int getPageSize() {        return pageSize;    }    public void setPageSize(int pageSize) {        this.pageSize = pageSize;    }    //根据当前所在页数和每页显示记录数计算出startIndex和endIndex    public void setStartIndexEndIndex(){         this.startIndex=(this.getCurrentPage()-1)*this.getPageSize();         this.endIndex= (this.getCurrentPage()-1)*this.getPageSize()+this.getPageSize();    }}

分页工具类：

public class Page<T>{    private int currentPage = 1; // 当前页    private int pageSize = 20; //每页显示记录数    private int startRecord = 1; //起始查询记录    private int totalPage = 0; //总页数    private int totalRecord = 0; //总记录数    private List<T> datas;    public Page(){}    public Page(int currentPage, int pageSize) {        this.currentPage = currentPage;        this.pageSize = pageSize;        if(this.currentPage <= 0) {            this.currentPage = 1;        }        if(this.pageSize <=0) {            this.pageSize = 1;        }    }    public Page(int currentPage, int pageSize, int totalRecord) {        this(currentPage, pageSize);        this.totalRecord = totalRecord;        if(this.totalRecord <=0) {            this.totalRecord = 1;        }    }    public int getCurrentPage() {        if(currentPage <= 0) {            return 1;        }        return currentPage;    }    public void setCurrentPage(int currentPage) {        this.currentPage = currentPage;    }    public int getPageSize() {        return pageSize;    }    public void setPageSize(int pageSize) {        this.pageSize = pageSize;    }    public int getTotalRecord() {        if(totalRecord < 0) {            return 0;        }        return totalRecord;    }    public void setTotalRecord(int totalRecord) {        this.totalRecord = totalRecord;    }    public List<T> getDatas() {        return datas;    }    public void setDatas(List<T> datas) {        this.datas = datas;    }    public int getTotalPage() {        if(totalRecord <= 0) {            return 0;        }        int size = totalRecord / pageSize;//总条数/每页显示的条数=总页数        int mod = totalRecord % pageSize;//最后一页的条数        if(mod != 0) {            size++;        }        totalPage = size;        return totalPage;    }    public int getStartRecord() {        startRecord = (getCurrentPage() - 1) * pageSize;        return startRecord;    }}

Manager层

public interface MessageManager {    //分页查询消息    public Page<Message> queryMessage(MessageReq req);}

@Componentpublic class MessageManagerImpl implements MessageManager{    @Autowired    private MessageMapper messageMapper;    @Override    public Page<Message> queryMessage(MessageReq req) {        Page<Message> page = new Page<Message>();        int pageCount = messageMapper.getMessageNum(req.getMemberId());//得到总条数        page = initPage(page, pageCount, req);        List<Message> message= messageMapper.queryMessage(req);        if (!message.isEmpty()) {            page.setDatas(message);        }        return page;    }    private Page<Message> initPage(Page<Message> page, int pageCount,            MessageReq messageReq) {        page.setTotalRecord(pageCount);        page.setCurrentPage(messageReq.getCurrentPage());        page.setPageSize(messageReq.getPageSize());        messageReq.setStartIndexEndIndex();        return page;        }   }

Dao层

public interface MessageMapper {    //分页查询    public List<Message> queryMessage(Messagereq);    //查询总条数    public int getMessageNum(String memberId);}

mybatis的.xml文件

<?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" ><mapper namespace="com.sf.ccsp.member.dao.mapper.MessageMapper">   <resultMap id="MessageResultMap" type="com.sf.ccsp.member.dao.domain.message.Message" >      <result column="ID" property="id" jdbcType="VARCHAR" />      <result column="MEMBERID" property="memberId" jdbcType="VARCHAR" />      <result column="MESSAGE_CLASSIFY" property="messageClassify" jdbcType="VARCHAR" />      <result column="MESSAGE_CODE" property="messageCode" jdbcType="VARCHAR" />      <result column="MESSAGE_CONTENT" property="messageContent" jdbcType="VARCHAR" />      <result column="MESSAGE_STATUS" property="messageStatus" jdbcType="VARCHAR" />   </resultMap>   <select id="queryMessage" resultMap="MessageResultMap" parameterType="com.sf.ccsp.member.client.request.MessageReq">     select *     from cx_customer_message     where MEMBERID = #{memberId, jdbcType=VARCHAR}     and ISVALID = '1'     LIMIT #{startIndex,jdbcType=INTEGER},#{pageSize,jdbcType=INTEGER}     </select>    <select id="getMessageNum" resultType="INTEGER" parameterType="String">      select count(*)      from cx_customer_message      where MEMBERID = #{memberId, jdbcType=VARCHAR}    </select></mapper>