JDBC编程-白红宇

Java数据库连接（JDBC）的实现详解

JDBC（Java DataBase Connectivity）是Java语言访问数据库的一种标准API，其核心在于通过数据库 URL连接到数据库系统。本文将详细介绍JDBC编程的实现步骤、常用类及其应用实例。

1. 获取数据库连接的基础步骤

数据库连接是应用程序与数据库之间的桥梁，建立连接的关键在于正确配置数据库 URL和加载相应的数据库驱动。

使用JDBC获取数据库连接的步骤如下：

achers实现如下伪代码进行优化：

创建数据库连接的核心逻辑可以通过以下方法实现：

public class JdbcUtil {    private final String userName;    private final String password;    private final String database;    private final String host;    private final Integer port;    public JdbcUtil(String userName, String password, String database, String host, Integer port) {        this.userName = userName;        this.password = password;        this.database = database;        this.host = host;        this.port = port;    }    // 获得数据库连接    public Connection getConnection() {        try {            Class.forName("com.mysql.jdbc.Driver");        } catch (ClassNotFoundException e) {            e.printStackTrace();        }        String url = String.format(            "jdbc:mysql://%s:%d/%s?user=%s&password=%s",            host,            port,            database,            userName,            password        );        try {            return DriverManager.getConnection(url);        } catch (SQLException e) {            e.printStackTrace();        }        return null;    }    // 创建预编译语句    public PreparedStatement getPreparedStatement(Connection connection, String sql) {        try {            return connection.prepareStatement(sql);        } catch (SQLException e) {            e.printStackTrace();        }        return null;    }    // 执行数据库操作    public int update(PreparedStatement preparedStatement) {        try {            return preparedStatement.executeUpdate();        } catch (SQLException e) {            e.printStackTrace();        }        return 0;    }    // 关闭数据库资源    public void doClose(ResultSet resultSet, PreparedStatement preparedStatement, Connection connection) {        if (resultSet != null) {            try {                resultSet.close();            } catch (SQLException e) {                e.printStackTrace();            }        }        if (preparedStatement != null) {            try {                preparedStatement.close();            } catch (SQLException e) {                e.printStackTrace();            }        }        if (connection != null) {            try {                connection.close();            } catch (SQLException e) {                e.printStackTrace();            }        }    }}2. 数据库操作的实现类

2. 数据库操作的实现类

基于上述JdbcUtil类，可以对数据库进行 CRUD（增删改查）操作。以下是MemoGroupDaoImpl的实现代码：

public class MemoGroupDaoImpl implements MemoGroupDao {    private JdbcUtil jdbcUtil;    public MemoGroupDaoImpl(JdbcUtil jdbcUtil) {        this.jdbcUtil = jdbcUtil;    }    @Override    public boolean insert(MemoGroup memoGroup) {        String sql = "insert into memo_group(name, created_time) values(?,?)";        Connection connection = jdbcUtil.getConnection();        PreparedStatement preparedStatement = jdbcUtil.getPreparedStatement(connection, sql);        try {            preparedStatement.setString(1, memoGroup.getName());            preparedStatement.setDate(2, new Date(memoGroup.getCreatedTime().getTime()));            int effect = jdbcUtil.update(preparedStatement);            return effect == 1;        } catch (SQLException e) {            e.printStackTrace();        } finally {            jdbcUtil.doClose(null, preparedStatement, connection);        }        return false;    }    @Override    public boolean update(MemoGroup memoGroup) {        String sql = "update memo_group set name = ? where id = ?";        Connection connection = jdbcUtil.getConnection();        PreparedStatement preparedStatement = jdbcUtil.getPreparedStatement(connection, sql);        try {            preparedStatement.setString(1, memoGroup.getName());            preparedStatement.setInt(2, memoGroup.getId());            int effect = jdbcUtil.update(preparedStatement);            return effect == 1;        } catch (SQLException e) {            e.printStackTrace();        } finally {            jdbcUtil.doClose(null, preparedStatement, connection);        }        return false;    }    @Override    public boolean delete(int id) {        String sql = "delete from memo_group where id = ?";        Connection connection = jdbcUtil.getConnection();        PreparedStatement preparedStatement = jdbcUtil.getPreparedStatement(connection, sql);        try {            preparedStatement.setInt(1, id);            int effect = jdbcUtil.update(preparedStatement);            return effect == 1;        } catch (SQLException e) {            e.printStackTrace();        } finally {            jdbcUtil.doClose(null, preparedStatement, connection);        }        return false;    }    @Override    public MemoGroup queryById(int id) {        String sql = "select * from memo_group where id = ?";        Connection connection = jdbcUtil.getConnection();        PreparedStatement preparedStatement = jdbcUtil.getPreparedStatement(connection, sql);        ResultSet resultSet = null;        try {            preparedStatement.setInt(1, id);            resultSet = jdbcUtil.query(preparedStatement);            if (resultSet.next()) {                MemoGroup memoGroup = new MemoGroup();                memoGroup.setId(resultSet.getInt("id"));                memoGroup.setName(resultSet.getString("name"));                memoGroup.setCreatedTime(resultSet.getDate("created_time"));                memoGroup.setModifyTime(resultSet.getDate("modify_time"));                return memoGroup;            } else {                return null;            }        } catch (SQLException e) {            e.printStackTrace();        } finally {            jdbcUtil.doClose(resultSet, preparedStatement, connection);        }        return null;    }    @Override    public List
    
      queryAll() {        String sql = "select * from memo_group";        Connection connection = jdbcUtil.getConnection();        PreparedStatement preparedStatement = jdbcUtil.getPreparedStatement(connection, sql);        ResultSet resultSet = null;        List
     
       memoGroups = new ArrayList<>();        try {            resultSet = jdbcUtil.query(preparedStatement);            while (resultSet.next()) {                MemoGroup memoGroup = new MemoGroup();                memoGroup.setId(resultSet.getInt("id"));                memoGroup.setName(resultSet.getString("name"));                memoGroup.setCreatedTime(resultSet.getDate("created_time"));                memoGroup.setModifyTime(resultSet.getDate("modify_time"));                memoGroups.add(memoGroup);            }        } catch (SQLException e) {            e.printStackTrace();        } finally {            jdbcUtil.doClose(resultSet, preparedStatement, connection);        }        return memoGroups;    }}

3. 注意事项

在实际应用中，建议使用连接池优化数据库连接管理。每次获取连接时请记得闭合资源，以避免资源泄漏。此外，对于敏感信息如数据库密码，请妥善处理保护。

希望以上内容对您有所帮助，如果需要进一步的Clrify或修正，请随时与我联系。