封装 Apache Commons 的 DbUtils 实现的数据库操作工具类

使用 DBUtil 工具类可加快编写 JDBC 代码的开发速度，非常轻量级，非常好用！

注意：这里是 DBUtil 的基础版，若要查看高级版，请阅读《DBUtil 代码细节》。

DBUtil.java

public class DBUtil {
    private static final QueryRunner runner = new QueryRunner();

    // 打开数据库连接（type: MySQL，Oracle，SQLServer）
    public static Connection openConn(String type, String host, String port, String name, String username, String password) {
        Connection conn = null;
        try {
            String driver;
            String url;
            if (type.equalsIgnoreCase("MySQL")) {
                driver = "com.mysql.jdbc.Driver";
                url = "jdbc:mysql://" + host + ":" + port + "/" + name;
            } else if (type.equalsIgnoreCase("Oracle")) {
                driver = "oracle.jdbc.driver.OracleDriver";
                url = "jdbc:oracle:thin:@" + host + ":" + port + ":" + name;
            } else if (type.equalsIgnoreCase("SQLServer")) {
                driver = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
                url = "jdbc:sqlserver://" + host + ":" + port + ";databaseName=" + name;
            } else {
                throw new RuntimeException();
            }
            Class.forName(driver);
            conn = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }

    // 关闭数据库连接
    public static void closeConn(Connection conn) {
        try {
            if (conn != null) {
                conn.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    // 查询（返回Array结果）
    public static Object[] queryArray(Connection conn, String sql, Object... params) {
        Object[] result = null;
        try {
            result = runner.query(conn, sql, new ArrayHandler(), params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询（返回ArrayList结果）
    public static List<Object[]> queryArrayList(Connection conn, String sql, Object... params) {
        List<Object[]> result = null;
        try {
            result = runner.query(conn, sql, new ArrayListHandler(), params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询（返回Map结果）
    public static Map<String, Object> queryMap(Connection conn, String sql, Object... params) {
        Map<String, Object> result = null;
        try {
            result = runner.query(conn, sql, new MapHandler(), params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询（返回MapList结果）
    public static List<Map<String, Object>> queryMapList(Connection conn, String sql, Object... params) {
        List<Map<String, Object>> result = null;
        try {
            result = runner.query(conn, sql, new MapListHandler(), params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询（返回Bean结果）
    public static <T> T queryBean(Class<T> cls, Map<String, String> map, Connection conn, String sql, Object... params) {
        T result = null;
        try {
            if (MapUtil.isNotEmpty(map)) {
                result = runner.query(conn, sql, new BeanHandler<T>(cls, new BasicRowProcessor(new BeanProcessor(map))), params);
            } else {
                result = runner.query(conn, sql, new BeanHandler<T>(cls), params);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询（返回BeanList结果）
    public static <T> List<T> queryBeanList(Class<T> cls, Map<String, String> map, Connection conn, String sql, Object... params) {
        List<T> result = null;
        try {
            if (MapUtil.isNotEmpty(map)) {
                result = runner.query(conn, sql, new BeanListHandler<T>(cls, new BasicRowProcessor(new BeanProcessor(map))), params);
            } else {
                result = runner.query(conn, sql, new BeanListHandler<T>(cls), params);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询指定列名的值（单条数据）
    public static <T> T queryColumn(String column, Connection conn, String sql, Object... params) {
        T result = null;
        try {
            result = runner.query(conn, sql, new ScalarHandler<T>(column), params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询指定列名的值（多条数据）
    public static <T> List<T> queryColumnList(String column, Connection conn, String sql, Object... params) {
        List<T> result = null;
        try {
            result = runner.query(conn, sql, new ColumnListHandler<T>(column), params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 查询指定列名对应的记录映射
    public static <T> Map<T, Map<String, Object>> queryKeyMap(String column, Connection conn, String sql, Object... params) {
        Map<T, Map<String, Object>> result = null;
        try {
            result = runner.query(conn, sql, new KeyedHandler<T>(column), params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    // 更新（包括UPDATE、INSERT、DELETE，返回受影响的行数）
    public static int update(Connection conn, String sql, Object... params) {
        int result = 0;
        try {
            result = runner.update(conn, sql, params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }
}

MapUtil.java

public class MapUtil {
    // 判断Map是否非空
    public static boolean isNotEmpty(Map<?, ?> map) {
        return MapUtils.isNotEmpty(map);
    }

    // 判断Map是否为空
    public static boolean isEmpty(Map<?, ?> map) {
        return MapUtils.isEmpty(map);
    }
}