针对不同表的通用的查询操作

/**
 * @program: Connection
 * @description: 针对不同表的通用的查询操作
 * @author: Mr.Fan
 * @create: 2021-05-29 11:39
 **/
public class PreparedStatementQueryTest {

    public  <T> T getInstance(Class<T> clazz, String sql, Object ...args){
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            conn = JDBCUtils.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            rs = ps.executeQuery();
            //获取结果集的元数据：ResultSetMetaData
            ResultSetMetaData metaData = rs.getMetaData();
            //获取结果集中的列数
            int columnCount = metaData.getColumnCount();

            if(rs.next()){
                T t = clazz.newInstance();



                for (int i = 0; i < columnCount; i++) {
                    Object columnValue = rs.getObject(i + 1);

                    //获取每个列的列名
                    String columnName = metaData.getColumnName(i+1);

                    //给t对象指定的columnName属性赋值为columnValue,通过反射
                    Field field = clazz.getDeclaredField(columnName);
                    field.setAccessible(true);
                    field.set(t, columnValue);

                    //给book对象的某个属性赋值为value
                }
                return t;

            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        JDBCUtils.closeResource(conn, ps, rs);
        return null;
    }
}