/** * Copyright (C) 2015-2017, Zhichun Wu * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package com.github.cassandra.jdbc; import java.sql.SQLException; import java.sql.SQLWarning; import java.sql.Wrapper; /** * Base class for JDBC implementations of Connection, Statement and ResultSet. * * @author Zhichun Wu */ public abstract class BaseJdbcObject implements AutoCloseable, Wrapper { /** * List of chained SQL warnings. */ private SQLWarning _warning; /** * This indicates whether this object has been closed. */ protected boolean closed; /** * Quiet mode suggests if the driver should throw SQLException for * unsupported operation. By default it is true but can be customized by * passing "quiet=false" in connection properties. */ protected final boolean quiet; protected BaseJdbcObject(boolean quiet) { this.closed = false; this.quiet = quiet; } /** * Idempotent close method. * * @return SQLException if any */ protected abstract SQLException tryClose(); /** * This returns the underlying object actually doing the work. * * @return underlying object */ protected abstract Object unwrap(); /** * Validate instance state - mainly checking if this has been closed. * * @throws SQLException when state is invalid(e.g. closed * connection/statement/resultset) */ protected void validateState() throws SQLException { if (closed) { throw CassandraErrors.resourceClosedException(this); } } /** * Append a warning to the end of chained SQL warnings. * * @param warning warning to be appended to the warnings list */ public void appendWarning(SQLWarning warning) { if (warning != null) { if (_warning == null) { _warning = warning; } else { SQLWarning w = _warning; SQLWarning prevWarning = w; do { if (w == warning) { break; } else { prevWarning = w; } } while ((w = w.getNextWarning()) != null); if (prevWarning != w) { prevWarning.setNextWarning(warning); } } } } public void clearWarnings() throws SQLException { // validateState(); _warning = null; } public void close() throws SQLException { clearWarnings(); closed = true; SQLException exception = tryClose(); if (!quiet && exception != null) { throw exception; } } public SQLWarning getWarnings() throws SQLException { validateState(); return _warning; } public boolean isClosed() throws SQLException { return closed; } public boolean isWrapperFor(Class<?> iface) throws SQLException { Object innerObj = unwrap(); return innerObj != null && innerObj.getClass().isAssignableFrom(iface); } public <T> T unwrap(Class<T> iface) throws SQLException { return iface.cast(unwrap()); } }