PageInfo

package com.aistart.tech.common;import java.io.Serializable;
import java.util.List;public class PageInfo<T> implements Serializable {private Integer pageNum;//当前页private Integer pageSize;//每页显示条数private Integer pageTotal;//总的页数private Integer rows;//总的条数private List<T> dataList;public Integer getPageNum() {return pageNum;}public void setPageNum(Integer pageNum) {this.pageNum = pageNum;}public Integer getPageSize() {return pageSize;}public void setPageSize(Integer pageSize) {this.pageSize = pageSize;}public Integer getPageTotal() {return pageTotal;}public void setPageTotal(Integer pageTotal) {this.pageTotal = pageTotal;}public Integer getRows() {return rows;}public void setRows(Integer rows) {this.rows = rows;}public List<T> getDataList() {return dataList;}public void setDataList(List<T> dataList) {this.dataList = dataList;}public PageInfo(Integer pageNum, Integer pageSize, Integer pageTotal, Integer rows, List<T> dataList) {this.pageNum = pageNum;this.pageSize = pageSize;this.pageTotal = pageTotal;this.rows = rows;this.dataList = dataList;}public PageInfo() {}@Overridepublic String toString() {final StringBuilder sb = new StringBuilder("PageInfo{");sb.append("pageNum=").append(pageNum);sb.append(", pageSize=").append(pageSize);sb.append(", pageTotal=").append(pageTotal);sb.append(", rows=").append(rows);sb.append(", dataList=").append(dataList);sb.append('}');return sb.toString();}
}

创建一个List<String>集合
创建一个连接
根据连接创建一个操作对象，执行sql，sql语句有两个占位符，分别代表之前页所有数量，每页数量
操作对象返回结果集
将数据存到list中
关闭

public List<String> getEmpName(int pageSize, int pageNum) throws Exception {List<String> list = new ArrayList<>();Connection connection = JDBCUtil.getConnection();PreparedStatement preparedStatement = connection.prepareStatement("select first_name from employees limit ?,?;");preparedStatement.setInt(1,pageSize*(pageNum-1));preparedStatement.setInt(2,pageSize);ResultSet resultSet = preparedStatement.executeQuery();while (resultSet.next()){list.add(resultSet.getString(1));}JDBCUtil.closeAll(connection,preparedStatement,resultSet);return list;}@Testpublic void empLimitTest() throws Exception {List<String> empName = iEmpDao.getEmpName(3, 2);PageInfo<String> stringPageInfo = new PageInfo<>();stringPageInfo.setDataList(empName);stringPageInfo.setPageNum(2);stringPageInfo.setPageSize(3);stringPageInfo.setRows(107);stringPageInfo.setPageTotal(107/3);for (String s : empName) {System.out.print(s+" ");}System.out.println(stringPageInfo);}

创建PageInfo对象
PageInfo设置每页数量和第几页
创建连接
根据连接创建操作对象，执行sql
返回结果集

public PageInfo<String> findNameAllByPage(int pageSize, int pageNum) {PageInfo<String> stringPageInfo = new PageInfo<>();stringPageInfo.setPageSize(pageSize);stringPageInfo.setPageNum(pageNum);List<String> list = new ArrayList<>();Connection connection = null;PreparedStatement preparedStatement = null;try {connection = JDBCUtil.getConnection();preparedStatement = connection.prepareStatement("select count(*) from employees;");ResultSet resultSet = preparedStatement.executeQuery();if(resultSet.next()){//获取总条目数int rows = resultSet.getInt(1);//赋值共有多少行stringPageInfo.setRows(rows);//赋值共有多少页,取整stringPageInfo.setPageTotal(rows/pageSize);}/** 跟上面一样获取一个list<string>* */stringPageInfo.setDataList(getEmpName(pageSize,pageNum));} catch (SQLException e) {throw new RuntimeException(e);} catch (Exception e) {throw new RuntimeException(e);}return stringPageInfo;}@Testpublic void limitTest(){PageInfo<String> nameAllByPage = iEmpDao.findNameAllByPage(4, 5);System.out.println(nameAllByPage);}