反射实现增删改查（DAO层）——查询数据

先贴出代码，后续补充自己的思路、配置文件、使用方式：

/**
	 *
	 * 数据查询
	 *
	 */
	@Override
	public List<?> queryObject(List<Map<String, Object>> params,
			String tableName) {
		List<Object> objectList = new ArrayList<Object>();
		StringBuilder sql = new StringBuilder("SELECT * FROM " + tableName
				+ " WHERE 1=1");
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		ResultSet resultSet = null;

		try {
			connection = DBConnection.getConnection();
			if (params != null && params.size() > 0) {
				for (int i = 0; i < params.size(); i++) {
					Map<String, Object> map = params.get(i);
					sql.append(" AND  " + map.get("name") + " "
							+ map.get("rela") + " " + map.get("value") + " ");
				}
			}
			preparedStatement = connection.prepareStatement(sql.toString());

			resultSet = preparedStatement.executeQuery();
			ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
			// 获取数据列数
			int columnsCount = resultSetMetaData.getColumnCount();
			Field field = null;
			Object object = null;
			while (resultSet.next()) {
				/**
				 * 获取实例化对象
				 */
				object = objectClass.newInstance();

				String columnName = null;
				String columnTypeName = null;
				String columnValue = null;

				for (int i = 1; i <= columnsCount; i++) {
					columnName = resultSetMetaData.getColumnName(i);
					columnTypeName = resultSetMetaData.getColumnTypeName(i);
					columnValue = resultSet.getString(i);
					field = object.getClass().getDeclaredField(columnName);
					field.setAccessible(true);
					switch (columnTypeName) {
					case "INT":
						field.set(object, Integer.parseInt(columnValue));
						break;
					case "VARCHAR":
						field.set(object, columnValue);
						break;
					case "FLOAT":
						field.set(object, Float.parseFloat(columnValue));
						break;
					case "Date":
						field.set(object,
								new SimpleDateFormat().parse(columnValue));
						break;
					}

				}
				objectList.add(object);

			}

		} catch (SQLException e) {
			e.printStackTrace();
		} catch (NoSuchFieldException e) {
			e.printStackTrace();
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (ParseException e) {
			e.printStackTrace();
		} catch (InstantiationException e) {
			e.printStackTrace();
		} finally {
			DBConnection.close(connection, preparedStatement, resultSet);
		}
		return objectList;
	}

基本流程：（这张表结合源码备注理解应该问题不大）如果看不清楚，复制图片地址在新窗口中查看