java mysql通用分页类

import java.sql.*;
import java.util.*;

public class PageHelper {
    private int pageNum; // 当前页码
    private int pageSize; // 每页显示的数据量
    private Connection conn; // 数据库连接

    public PageHelper(int pageNum, int pageSize, Connection conn) {
        this.pageNum = pageNum;
        this.pageSize = pageSize;
        this.conn = conn;
    }

    public List<Map<String, Object>> getPage(String sql) throws SQLException {
        List<Map<String, Object>> resultList = new ArrayList<>();
        PreparedStatement pstmt = null;
        ResultSet rs = null;

        try {
            // 计算偏移量
            int offset = (pageNum - 1) * pageSize;
            // 构造分页SQL语句
            String pageSql = sql + " LIMIT " + pageSize + " OFFSET " + offset;
            pstmt = conn.prepareStatement(pageSql);
            rs = pstmt.executeQuery();

            ResultSetMetaData metaData = rs.getMetaData();
            int columnCount = metaData.getColumnCount();

            while (rs.next()) {
                Map<String, Object> rowMap = new HashMap<>();
                for (int i = 1; i <= columnCount; i++) {
                    rowMap.put(metaData.getColumnName(i), rs.getObject(i));
                }
                resultList.add(rowMap);
            }
        } finally {
            if (rs != null) rs.close();
            if (pstmt != null) pstmt.close();
        }

        return resultList;
    }
}