反射实现增删改查（DAO层）——插入数据

Posted 2020-11-07 云中志

先贴出代码，后续补充自己的思路、配置文件、使用方式：

/**
     *  插入数据
     */
    @Override
    public void addObject(Object object, String tableName) {
        StringBuilder sql = new StringBuilder("INSERT " + tableName
                + " VALUES(");
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        // 用于存放传入的对象的参数，默认将id值（主键）的key设为0，方便条件设置
        Map<Integer, Object> fieldsValues = new HashMap<Integer, Object>();
        try {
            for (int i = 0; i < fields.length; i++) {
                fields[i].setAccessible(true);
                fieldsValues.put(i, fields[i].get(object));
                sql.append("?");
                if (i < (fields.length - 1))
                    sql.append(", ");

            }
            sql.append(")");
            connection = DBConnection.getConnection();

            preparedStatement = connection.prepareStatement(sql.toString());
            Class<?> fieldClass = null;
            for (int i = 1; i <= fieldsValues.size(); i++) {
                /**
                 * 获取存入map中对象的参数的类类型，根据类类型选择preparedStatement的set方法
                 */
                if (fieldsValues.get(i - 1) != null) {
                    fieldClass = fieldsValues.get(i - 1).getClass();
                    // 如果类类型为String.class，则执行setString
                    if (fieldClass.equals(String.class)) {
                        preparedStatement.setString(i,
                                (String) fieldsValues.get(i - 1));
                    }
                    // 如果类类型为Float.class，则执行setString
                    if (fieldClass.equals(Float.class)) {
                        preparedStatement.setFloat(i,
                                (Float) fieldsValues.get(i - 1));
                    }
                    // 如果类类型为Integer.class，则执行setString
                    if (fieldClass.equals(Integer.class)) {
                        preparedStatement.setInt(i,
                                (Integer) fieldsValues.get(i - 1));
                    }
                    // 如果类类型为Timestamp.class，则执行setString
                    if (fieldClass.equals(Timestamp.class)) {
                        preparedStatement.setTimestamp(i, new Timestamp(
                                ((Date) fieldsValues.get(i - 1)).getTime()));
                    }

                } else {
                    preparedStatement.setObject(i, null);
                }

            }
            // 执行sql语句，返回更新参数
            int columnsCount = preparedStatement.executeUpdate();
            System.out.println("有" + columnsCount + "条数据被更新！");

        } catch (SQLException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (NumberFormatException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            DBConnection.close(connection, preparedStatement, null);
        }

    }