自己封装的JDBC类

た入场券 2021-09-07 22:30 343阅读 0赞

> ### 对JDBC进行一些简单的封装，可以方便在项目中调用，同时也减少了重复代码量，降低代码的冗余度，提高代码的可读性和美观。 ###

## ##

package JdbcUtil;
    import java.sql.*;
    /**
     * 简述：
     *数据库管理类
     * @author:LiYansheng
     * @date:2021/04/26 19:31
     * @version:
     */
    public class ConnectionManager {
        /**
         * 连接数据库的四大必需属性
         */
        private static final String driver = "com.mysql.cj.jdbc.Driver";
        private static final String url = "jdbc:mysql://localhost:3306/book_management?useSSL=false&serverTimezone=Asia/Shanghai";
        private static final String user = "root";
        private static final String psd = "root";
    
        /**
         * 静态块加载驱动
         */
        static {
            try {
                Class.forName(driver);
                System.out.println("加载驱动成功！");
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
                System.out.println("加载驱动失败！");
            }
        }
        /**
         * 返回一个连接对象
         * @return
         */
        public static Connection getConnection() {
            Connection connection = null;
            try {
                connection = DriverManager.getConnection(url, user, psd);
            } catch (SQLException e) {
                e.printStackTrace();
            }
            return connection;
        }
        /**
         * 通用查询方法,返回结果集
         * @param sql
         * @param objects
         * @return
         * @throws SQLException
         */
        public static ResultSet query(String sql, Object[] objects) throws SQLException {
            Connection conn = ConnectionManager.getConnection();
            PreparedStatement pst = conn.prepareStatement(sql);
            ResultSet resultSet=null;
    //        判断Object是否为空，为空直接执行sql语句
            if (objects == null) {
                resultSet = pst.executeQuery();
            } else {
                for (int i = 0; i < objects.length; i++) {
                    pst.setObject(i+1,objects[i]);
                }
                resultSet = pst.executeQuery();
            }
            return resultSet;
        }
        /**
         * 通用增删改方法
         * @param sql
         * @param objects
         * @return
         * @throws SQLException
         */
        public static int Update(String sql,Object[] objects) throws SQLException {
            Connection conn = ConnectionManager.getConnection();
            PreparedStatement pst = conn.prepareStatement(sql);
    //      判断数组是否为空
            try {
                if (objects == null || objects.equals("")) {
                    return pst.executeUpdate();
                } else {
                    for (int i = 0; i < objects.length; i++) {
                        pst.setObject(i + 1, objects[i]);
                    }
                    return pst.executeUpdate();
                }
            } finally {
                closeall(conn, pst);
            }
    
        }
        /**
         * 返回结果集的二维数组形式，这个在JavaGUI里创建了表格要调用显示数据库的数据时可以用到
         * @param set
         * @return
         * @throws SQLException
         */
        public static Object[][] getSetArrays(ResultSet set) throws SQLException {
            Object[][] objects;
            set.last();
            int rowcount = set.getRow();
            ResultSetMetaData rsm = set.getMetaData();
            int colcount = rsm.getColumnCount();//获取列数
    //            创建二维数组
            objects = new Object[rowcount][colcount+1];
            set.first();
            for (int i = 0; i < rowcount; i++) {
                objects[i][0]=i+1;//给每一行的第一列添加序号
                for (int j = 1; j < colcount+1; j++) {
                    objects[i][j] = set.getObject(j);
                }
                set.next();
            }
            return objects;
        }
    
        /**
         * 关闭资源
         * @param resultSet
         * @param statement
         * @param connection
         */
        public static void closeAll(ResultSet resultSet, Statement statement, Connection connection) {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (statement != null) {
                    statement.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
    
            try {
                if (connection != null && (!connection.isClosed())) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        public static void closeAll(ResultSet resultSet, PreparedStatement preparedStatement, Connection connection) {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
    
            try {
                if (connection != null && (!connection.isClosed())) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        public static void closeall(Connection c, PreparedStatement p) throws SQLException {
            c.close();
            p.close();
        }
        
        
    
    }

> 记录 一下。。。