Commons DBCP example source code file (PoolingDataSource.java)

This example Commons DBCP source code file (PoolingDataSource.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons DBCP tags/keywords

callablestatement, connection, connection, delegatingconnection, delegatingpreparedstatement, io, jdbc, poolingdatasource, preparedstatement, preparedstatement, sql, sqlexception, sqlexception, statement, string, string, unsupportedoperationexception, util

The Commons DBCP PoolingDataSource.java source code

/*
 * 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 org.apache.commons.dbcp;

import java.io.PrintWriter;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.Statement;
import java.util.Map;
import java.util.NoSuchElementException;

import javax.sql.DataSource;

import org.apache.commons.pool.ObjectPool;

/**
 * A simple {@link DataSource} implementation that obtains
 * {@link Connection}s from the specified {@link ObjectPool}.
 *
 * @author Rodney Waldhoff
 * @author Glenn L. Nielsen
 * @author James House
 * @author Dirk Verbeeck
 * @version $Revision: 895844 $ $Date: 2010-01-04 20:50:04 -0500 (Mon, 04 Jan 2010) $
 */
public class PoolingDataSource implements DataSource {

    /** Controls access to the underlying connection */
    private boolean accessToUnderlyingConnectionAllowed = false; 

    public PoolingDataSource() {
        this(null);
    }

    public PoolingDataSource(ObjectPool pool) {
        _pool = pool;
    }

    public void setPool(ObjectPool pool) throws IllegalStateException, NullPointerException {
        if(null != _pool) {
            throw new IllegalStateException("Pool already set");
        } else if(null == pool) {
            throw new NullPointerException("Pool must not be null.");
        } else {
            _pool = pool;
        }
    }

    /**
     * Returns the value of the accessToUnderlyingConnectionAllowed property.
     * 
     * @return true if access to the underlying is allowed, false otherwise.
     */
    public boolean isAccessToUnderlyingConnectionAllowed() {
        return this.accessToUnderlyingConnectionAllowed;
    }

    /**
     * Sets the value of the accessToUnderlyingConnectionAllowed property.
     * It controls if the PoolGuard allows access to the underlying connection.
     * (Default: false)
     * 
     * @param allow Access to the underlying connection is granted when true.
     */
    public void setAccessToUnderlyingConnectionAllowed(boolean allow) {
        this.accessToUnderlyingConnectionAllowed = allow;
    }

    /* JDBC_4_ANT_KEY_BEGIN */
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }

    public <T> T unwrap(Class iface) throws SQLException {
        throw new SQLException("PoolingDataSource is not a wrapper.");
    }
    /* JDBC_4_ANT_KEY_END */
    
    //--- DataSource methods -----------------------------------------

    /**
     * Return a {@link java.sql.Connection} from my pool,
     * according to the contract specified by {@link ObjectPool#borrowObject}.
     */
    public Connection getConnection() throws SQLException {
        try {
            Connection conn = (Connection)(_pool.borrowObject());
            if (conn != null) {
                conn = new PoolGuardConnectionWrapper(conn);
            } 
            return conn;
        } catch(SQLException e) {
            throw e;
        } catch(NoSuchElementException e) {
            throw new SQLNestedException("Cannot get a connection, pool error " + e.getMessage(), e);
        } catch(RuntimeException e) {
            throw e;
        } catch(Exception e) {
            throw new SQLNestedException("Cannot get a connection, general error", e);
        }
    }

    /**
     * Throws {@link UnsupportedOperationException}
     * @throws UnsupportedOperationException
     */
    public Connection getConnection(String uname, String passwd) throws SQLException {
        throw new UnsupportedOperationException();
    }

    /**
     * Returns my log writer.
     * @return my log writer
     * @see DataSource#getLogWriter
     */
    public PrintWriter getLogWriter() {
        return _logWriter;
    }

    /**
     * Throws {@link UnsupportedOperationException}.
     * @throws UnsupportedOperationException As this
     *   implementation does not support this feature.
     */
    public int getLoginTimeout() {
        throw new UnsupportedOperationException("Login timeout is not supported.");
    }

    /**
     * Throws {@link UnsupportedOperationException}.
     * @throws UnsupportedOperationException As this
     *   implementation does not support this feature.
     */
    public void setLoginTimeout(int seconds) {
        throw new UnsupportedOperationException("Login timeout is not supported.");
    }

    /**
     * Sets my log writer.
     * @see DataSource#setLogWriter
     */
    public void setLogWriter(PrintWriter out) {
        _logWriter = out;
    }

    /** My log writer. */
    protected PrintWriter _logWriter = null;

    protected ObjectPool _pool = null;

    /**
     * PoolGuardConnectionWrapper is a Connection wrapper that makes sure a 
     * closed connection cannot be used anymore.
     */
    private class PoolGuardConnectionWrapper extends DelegatingConnection {

        private Connection delegate;
    
        PoolGuardConnectionWrapper(Connection delegate) {
            super(delegate);
            this.delegate = delegate;
        }

        protected void checkOpen() throws SQLException {
            if(delegate == null) {
                throw new SQLException("Connection is closed.");
            }
        }
    
        public void close() throws SQLException {
            if (delegate != null) {
                this.delegate.close();
                this.delegate = null;
                super.setDelegate(null);
            }
        }

        public boolean isClosed() throws SQLException {
            if (delegate == null) {
                return true;
            }
            return delegate.isClosed();
        }

        public void clearWarnings() throws SQLException {
            checkOpen();
            delegate.clearWarnings();
        }

        public void commit() throws SQLException {
            checkOpen();
            delegate.commit();
        }

        public Statement createStatement() throws SQLException {
            checkOpen();
            return new DelegatingStatement(this, delegate.createStatement());
        }

        public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
            checkOpen();
            return new DelegatingStatement(this, delegate.createStatement(resultSetType, resultSetConcurrency));
        }

        public boolean innermostDelegateEquals(Connection c) {
            Connection innerCon = super.getInnermostDelegate();
            if (innerCon == null) {
                return c == null;
            } else {
                return innerCon.equals(c);
            }
        }
        
        public boolean getAutoCommit() throws SQLException {
            checkOpen();
            return delegate.getAutoCommit();
        }

        public String getCatalog() throws SQLException {
            checkOpen();
            return delegate.getCatalog();
        }

        public DatabaseMetaData getMetaData() throws SQLException {
            checkOpen();
            return delegate.getMetaData();
        }

        public int getTransactionIsolation() throws SQLException {
            checkOpen();
            return delegate.getTransactionIsolation();
        }

        public Map getTypeMap() throws SQLException {
            checkOpen();
            return delegate.getTypeMap();
        }

        public SQLWarning getWarnings() throws SQLException {
            checkOpen();
            return delegate.getWarnings();
        }

        public int hashCode() {
            if (delegate == null){
                return 0;
            }
            return delegate.hashCode();
        }
        
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (obj == this) {
                return true;
            }
            // Use superclass accessor to skip access test
            Connection conn = super.getInnermostDelegate();
            if (conn == null) {
                return false;
            }
            if (obj instanceof DelegatingConnection) {    
                DelegatingConnection c = (DelegatingConnection) obj;
                return c.innermostDelegateEquals(conn);
            }
            else {
                return conn.equals(obj);
            }
        }

        public boolean isReadOnly() throws SQLException {
            checkOpen();
            return delegate.isReadOnly();
        }

        public String nativeSQL(String sql) throws SQLException {
            checkOpen();
            return delegate.nativeSQL(sql);
        }

        public CallableStatement prepareCall(String sql) throws SQLException {
            checkOpen();
            return new DelegatingCallableStatement(this, delegate.prepareCall(sql));
        }

        public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
            checkOpen();
            return new DelegatingCallableStatement(this, delegate.prepareCall(sql, resultSetType, resultSetConcurrency));
        }

        public PreparedStatement prepareStatement(String sql) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql));
        }

        public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, resultSetType, resultSetConcurrency));
        }

        public void rollback() throws SQLException {
            checkOpen();
            delegate.rollback();
        }

        public void setAutoCommit(boolean autoCommit) throws SQLException {
            checkOpen();
            delegate.setAutoCommit(autoCommit);
        }

        public void setCatalog(String catalog) throws SQLException {
            checkOpen();
            delegate.setCatalog(catalog);
        }

        public void setReadOnly(boolean readOnly) throws SQLException {
            checkOpen();
            delegate.setReadOnly(readOnly);
        }

        public void setTransactionIsolation(int level) throws SQLException {
            checkOpen();
            delegate.setTransactionIsolation(level);
        }

        public void setTypeMap(Map map) throws SQLException {
            checkOpen();
            delegate.setTypeMap(map);
        }

        public String toString() {
            if (delegate == null){
                return "NULL";
            }
            return delegate.toString();
        }

        public int getHoldability() throws SQLException {
            checkOpen();
            return delegate.getHoldability();
        }
    
        public void setHoldability(int holdability) throws SQLException {
            checkOpen();
            delegate.setHoldability(holdability);
        }

        public java.sql.Savepoint setSavepoint() throws SQLException {
            checkOpen();
            return delegate.setSavepoint();
        }

        public java.sql.Savepoint setSavepoint(String name) throws SQLException {
            checkOpen();
            return delegate.setSavepoint(name);
        }

        public void releaseSavepoint(java.sql.Savepoint savepoint) throws SQLException {
            checkOpen();
            delegate.releaseSavepoint(savepoint);
        }

        public void rollback(java.sql.Savepoint savepoint) throws SQLException {
            checkOpen();
            delegate.rollback(savepoint);
        }

        public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            checkOpen();
            return new DelegatingStatement(this, delegate.createStatement(resultSetType, resultSetConcurrency, resultSetHoldability));
        }

        public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            checkOpen();
            return new DelegatingCallableStatement(this, delegate.prepareCall(sql, resultSetType, resultSetConcurrency, resultSetHoldability));
        }

        public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, autoGeneratedKeys));
        }

        public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this,delegate.prepareStatement(sql, resultSetType, resultSetConcurrency, resultSetHoldability));
        }

        public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, columnIndexes));
        }

        public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, columnNames));
        }

        /**
         * @see org.apache.commons.dbcp.DelegatingConnection#getDelegate()
         */
        public Connection getDelegate() {
            if (isAccessToUnderlyingConnectionAllowed()) {
                return super.getDelegate();
            } else {
                return null;
            }
        }

        /**
         * @see org.apache.commons.dbcp.DelegatingConnection#getInnermostDelegate()
         */
        public Connection getInnermostDelegate() {
            if (isAccessToUnderlyingConnectionAllowed()) {
                return super.getInnermostDelegate();
            } else {
                return null;
            }
        }
    }
}