【mybatis】实现分页查询

一 .使用原生分页器的实体类

        1.1 java代码部分

                方法多  不易书写

package cn.bdqn.entity;public class Page {private Integer pageIndex;//页码private Integer pageSize;//页大小  显示多少行数据private Integer totalCounts;//数据的总行数private Integer totalPages;//总页数private Integer startRows;//起始行private String sname="";private String grade="";private String sex="";public Page() {}public Page(Integer pageIndex) {this(pageIndex, 7);}public Page(Integer pageIndex, Integer pageSize, Integer totalCounts, Integer totalPages, Integer startRows, String snane, String sex, String grade) {this.pageIndex = pageIndex;this.pageSize = pageSize;this.totalCounts = totalCounts;this.totalPages = totalPages;this.startRows = startRows;this.sname = sname;this.sex = sex;this.grade = grade;}public Page(Integer pageIndex, Integer pageSize) {this.pageIndex = pageIndex;this.pageSize = pageSize;this.setStartRows((pageIndex - 1) * pageSize);}public Integer getPageIndex() {return pageIndex;}public void setPageIndex(Integer pageIndex) {this.pageIndex = pageIndex;}public Integer getPageSize() {return pageSize;}public void setPageSize(Integer pageSize) {this.pageSize = pageSize;}public Integer getTotalCounts(int count) {return totalCounts;}public void setTotalCounts(Integer totalCounts) {this.totalCounts = totalCounts;this.setTotalPages(totalCounts % pageSize == 0 ? totalCounts / pageSize : totalCounts / pageSize + 1);}public Integer getTotalPages() {return totalPages;}public void setTotalPages(Integer totalPages) {this.totalPages = totalPages;}public Integer getStartRows() {return startRows;}public void setStartRows(Integer startRows) {this.startRows = startRows;}//    public int getPageNum() {
//        return pageNum;
//    }
//public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public String getGrade() {return grade;}public void setGrade(String grade) {this.grade = grade;}public String getSex() {return sex;}public void setSex(String grade) {this.sex = sex;}
//    @Override
//    public String toString() {
//        return "Page{" +
//                "pageIndex=" + pageIndex +
//                ", pageSize=" + pageSize +
//                ", totalCounts=" + totalCounts +
//                ", totalPages=" + totalPages +
//                ", startRows=" + startRows +
//                '}';
//    }@Overridepublic String toString() {return "Page{" +"pageIndex=" + pageIndex +", pageSize=" + pageSize +", totalCounts=" + totalCounts +", totalPages=" + totalPages +", startRows=" + startRows +", sname='" + sname + '\'' +", sex='" + sex + '\'' +", grade='" + grade + '\'' +'}';}
}

        1.2 在动态jsp页面中    用forEach  书写

<div class="a-run"><a href="<c:url context='${pageContext.request.contextPath}' value='/ServletScoreShow?pageIndex=1'/>">首页</a><c:if test="${page.pageIndex > 1}"><a href="<c:url context='${pageContext.request.contextPath}' value='/ServletScoreShow?pageIndex=${page.pageIndex - 1}' />">上一页</a></c:if><c:if test="${page.pageIndex == 1}"><a>上一页</a></c:if><c:if test="${page.pageIndex < page.totalPages}"><a href="<c:url context='${pageContext.request.contextPath}' value='/ServletScoreShow?pageIndex=${page.pageIndex + 1}'/>">下一页</a></c:if><c:if test="${page.pageIndex == page.totalPages}"><a>下一页</a></c:if><a href="<c:url context='${pageContext.request.contextPath}' value='/ServletScoreShow?pageIndex=${page.totalPages}'/>">尾页</a></div>

 二 . 使用mybatis  分页

             2.1.1  在pom.xml文件中引入依赖

       

 <!--引入分页插件--><dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper</artifactId><version>5.3.2</version></dependency>
</dependencies>

                2.1.2  在mybatis.xml中   设定标签（注意标签书写顺序）

<!--配置mybatis分页插件-->
<plugins><plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
</plugins>

三 . 测试类代码

package cn.sy;import cn.sy.entity.User;
import cn.sy.mapper.UserMapper;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;import java.io.IOException;
import java.io.InputStream;
import java.util.List;public class TestPageHelper {SqlSessionFactory factory = null;@Beforepublic void init() {try {InputStream resourceAsStream = Resources.getResourceAsStream("config/mybatis-config.xml");factory = new SqlSessionFactoryBuilder().build(resourceAsStream);} catch (IOException e) {e.printStackTrace();}}@Testpublic void test(){SqlSession sqlSession = factory.openSession(true);UserMapper mapper = sqlSession.getMapper(UserMapper.class);//pageNum : 分的页数  pageSize： 每页显示的记录数PageHelper.startPage(3,3);List<User> users = mapper.selectList();for (User user : users) {System.out.println("user = " + user);}// 创建分页信息对象  获取更多的分页信息PageInfo<User> userPageInfo = new PageInfo<>(users);// 获取分页的详细信息List<User> list = userPageInfo.getList();System.out.println("list = " + list);long total = userPageInfo.getTotal();System.out.println("total = " + total);System.out.println("*********************");System.out.println("userPageInfo = " + userPageInfo);}
}