封装JDBCUtils--用反射得到对应的对象集合

/**
	 * 将查询的结果转换成对象,然后将这些对象包装成一个集合
	 * @param 
	 * @param t
	 * @param sql
	 * @param args
	 * @return
	 * @throws Exception
	 */
	public static <T> List<T> getList(Class<T> cla, String sql, Object... args) throws Exception {
		List<T> list = new ArrayList<T>();
		Connection connection = null;
		PreparedStatement st = null;
		ResultSet rs = null;
		try {
            //得到连接
			connection = getConnection();
			st = connection.prepareStatement(sql);
			for (int i = 1; i <= args.length; i++) {
				st.setObject(i, args[i - 1]);
			}
			//得到结果集
			rs = st.executeQuery();  
             //将每一列的列名都存里一个集合中
           	 List<String>  colLabels = new ArrayList<>();
			ResultSetMetaData rsmd = rs.getMetaData();
			int col = rsmd.getColumnCount();
			for (int i = 0; i < col; i++) {
				 colLabels.add(rsmd.getColumnName(i + 1));
			}
     
            //结果集中的每一行数据都转换成Map集合,键为列名
             Map<String, Object> map = null;
			while (rs.next()) {			
				map = new HashMap<String, Object>();
				for (String colName : colLabels) {
					map.put(colName, rs.getObject(colName));
				}
			
                 //每个map集合都转换成相应的对象
				T object = cla.newInstance();//反射得到 Class的实例 object
				for (Map.Entry<String, Object> entry : map.entrySet()) {
                      //属性名
					String propertyName = entry.getKey();
                      //属性值
					Object value = entry.getValue();
					setProperty(object, propertyName,value);	
				}		      
                 // 将转换后的对象存入集合
				list.add(object);
			}   
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			//关闭资源
			JDBCTools.release(connection, st, rs);
		}
		return list;
	}