public class DBUtil {        private static final Logger logger = Logger.getLogger(DBUtil.class);        // 打开数据库连接（type: MySQL，Oracle，SQLServer）      public static Connection openConnection(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) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          return conn;      }        // 关闭数据库连接      public static void closeConnection(Connection conn) {          try {              if (conn != null) {                  conn.close();              }          } catch (Exception e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }      }        // 查询（返回 Array）      public static Object[] queryArray(QueryRunner runner, String sql, Object... params) {          Object[] result = null;          try {              result = runner.query(sql, new ArrayHandler(), params);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          printSQL(sql);          return result;      }        // 查询（返回 ArrayList）      public static List<Object[]> queryArrayList(QueryRunner runner, String sql, Object... params) {          List<Object[]> result = null;          try {              result = runner.query(sql, new ArrayListHandler(), params);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          printSQL(sql);          return result;      }        // 查询（返回 Map）      public static Map<String, Object> queryMap(QueryRunner runner, String sql, Object... params) {          Map<String, Object> result = null;          try {              result = runner.query(sql, new MapHandler(), params);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          printSQL(sql);          return result;      }        // 查询（返回 MapList）      public static List<Map<String, Object>> queryMapList(QueryRunner runner, String sql, Object... params) {          List<Map<String, Object>> result = null;          try {              result = runner.query(sql, new MapListHandler(), params);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          printSQL(sql);          return result;      }        // 查询（返回 Bean）      public static <T> T queryBean(QueryRunner runner, Class<T> cls, Map<String, String> map, String sql, Object... params) {          T result = null;          try {              if (MapUtil.isNotEmpty(map)) {                  result = runner.query(sql, new BeanHandler<T>(cls, new BasicRowProcessor(new BeanProcessor(map))), params);              } else {                  result = runner.query(sql, new BeanHandler<T>(cls), params);              }              printSQL(sql);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          return result;      }        // 查询（返回 BeanList）      public static <T> List<T> queryBeanList(QueryRunner runner, Class<T> cls, Map<String, String> map, String sql, Object... params) {          List<T> result = null;          try {              if (MapUtil.isNotEmpty(map)) {                  result = runner.query(sql, new BeanListHandler<T>(cls, new BasicRowProcessor(new BeanProcessor(map))), params);              } else {                  result = runner.query(sql, new BeanListHandler<T>(cls), params);              }              printSQL(sql);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          return result;      }        // 查询指定列名的值（单条数据）      public static Object queryColumn(QueryRunner runner, String column, String sql, Object... params) {          Object result = null;          try {              result = runner.query(sql, new ScalarHandler<Object>(column), params);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          printSQL(sql);          return result;      }        // 查询指定列名的值（多条数据）      public static <T> List<T> queryColumnList(QueryRunner runner, String column, String sql, Object... params) {          List<T> result = null;          try {              result = runner.query(sql, new ColumnListHandler<T>(column), params);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          printSQL(sql);          return result;      }        // 查询指定列名对应的记录映射      public static <T> Map<T, Map<String, Object>> queryKeyMap(QueryRunner runner, String column, String sql, Object... params) {          Map<T, Map<String, Object>> result = null;          try {              result = runner.query(sql, new KeyedHandler<T>(column), params);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          printSQL(sql);          return result;      }        // 更新（包括 UPDATE、INSERT、DELETE，返回受影响的行数）      public static int update(QueryRunner runner, Connection conn, String sql, Object... params) {          int result = 0;          try {              if (conn != null) {                  result = runner.update(conn, sql, params);              } else {                  result = runner.update(sql, params);              }              printSQL(sql);          } catch (SQLException e) {              logger.error(e.getMessage(), e);              throw new RuntimeException(e.getMessage(), e);          }          return result;      }        private static void printSQL(String sql) {          if (logger.isDebugEnabled()) {              logger.debug("SQL: " + sql);          }      }  }