用java和MySQL实现访客管理系统的黑名单增删改查功能的代码，并且这个代码里包含了异常处理。

以下是一个简单的访客管理系统的黑名单增删改查功能的Java代码，其中包括异常处理：

import java.sql.*;

public class Blacklist {
    private static final String DRIVER = "com.mysql.jdbc.Driver";
    private static final String URL = "jdbc:mysql://localhost:3306/guestbook";
    private static final String USER = "root";
    private static final String PASSWORD = "password";

    private Connection connection;
    private PreparedStatement preparedStatement;
    private ResultSet resultSet;

    public void addGuestToBlacklist(int guestId) {
        try {
            Class.forName(DRIVER);
            connection = DriverManager.getConnection(URL, USER, PASSWORD);
            String sql = "INSERT INTO blacklist(guest_id) VALUES(?)";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, guestId);
            preparedStatement.executeUpdate();
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnection();
        }
    }

    public void removeGuestFromBlacklist(int guestId) {
        try {
            Class.forName(DRIVER);
            connection = DriverManager.getConnection(URL, USER, PASSWORD);
            String sql = "DELETE FROM blacklist WHERE guest_id=?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, guestId);
            preparedStatement.executeUpdate();
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnection();
        }
    }

    public void updateGuestInBlacklist(int guestId, int newGuestId) {
        try {
            Class.forName(DRIVER);
            connection = DriverManager.getConnection(URL, USER, PASSWORD);
            String sql = "UPDATE blacklist SET guest_id=? WHERE guest_id=?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, newGuestId);
            preparedStatement.setInt(2, guestId);
            preparedStatement.executeUpdate();
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnection();
        }
    }

    public boolean isGuestInBlacklist(int guestId) {
        boolean isInBlacklist = false;
        try {
            Class.forName(DRIVER);
            connection = DriverManager.getConnection(URL, USER, PASSWORD);
            String sql = "SELECT * FROM blacklist WHERE guest_id=?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, guestId);
            resultSet = preparedStatement.executeQuery();
            if (resultSet.next()) {
                isInBlacklist = true;
            }
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnection();
        }
        return isInBlacklist;
    }

    private void closeConnection() {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (preparedStatement != null) {
                preparedStatement.close();
            }
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

在上面的代码中，我们使用了Java的JDBC API来连接MySQL数据库，并使用预处理语句来执行增删改查操作。在每个方法中，我们都使用了try-catch块来捕获可能发生的异常，并在最后使用finally块来关闭连接、语句和结果集。这有助于保持代码的可读性和可维护性。

值得注意的是，上面的代码只是一个示例，可能需要根据具体的需求进行修改和优化。例如，我们可能需要添加更多的方法来处理不同的业务逻辑，或使用连接池来提高性能。