PreparedStatement针对不同表的通用查询操作

PreparedStatement针对不同表的通用查询操作

public class PreparedStatementQueryTest {


        @Test
    public void testGetForList(){
        String sql="select id,name,email from customers where id<?";
        List<Customer> list = getForList(Customer.class, sql, 12);
        list.forEach(System.out::println);
    }
    public<T> List<T> getForList(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 rsmd = rs.getMetaData();
           //通过ResultSetMetaData获取结果集中的列数
           int columnCount = rsmd.getColumnCount();
           ArrayList<T> list = new ArrayList<>();
           while (rs.next()) {
               T t = clazz.newInstance();
               for (int i = 0; i < columnCount; i++) {
                   //获取每个列的值
                   Object columnValue = rs.getObject(i + 1);

                   //获取每个列的别名
                   String columnName = rsmd.getColumnLabel(i + 1);

                   //给cust对象指定的columnName属性，赋值为columnValue
                   Field field = clazz.getDeclaredField(columnName);
                   field.setAccessible(true);
                   field.set(t, columnValue);
               }
               list.add(t);
           }
           return list;
       }catch (Exception e){
           e.printStackTrace();
       }finally {
           JDBCUtils.closeResource(conn,ps,rs);
       }
       return null;
    }