源码看DBCPConnectionProvider与BasicDataSource的渊源

package com.syscatech.util.db.hibernate;import java.io.PrintWriter;
import java.io.StringWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.Properties;

import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.HibernateException;
import org.hibernate.cfg.Environment;
import org.hibernate.connection.ConnectionProvider;
import org.hibernate.connection.ConnectionProviderFactory;


public class DBCPConnectionProvider implements ConnectionProvider {

    private static final Log log = LogFactory.getLog(DBCPConnectionProvider.class);
    private static final String PREFIX = "hibernate.dbcp.";
    private static BasicDataSource ds;

    // Old Environment property for backward-compatibility (property removed in Hibernate3)
    private static final String DBCP_PS_MAXACTIVE = "hibernate.dbcp.ps.maxActive";

    // Property doesn't exists in Hibernate2
    private static final String AUTOCOMMIT = "hibernate.connection.autocommit";

    public void configure(Properties props) throws HibernateException {
        try {
            log.debug("Configure DBCPConnectionProvider");
           
            // DBCP properties used to create the BasicDataSource
            Properties dbcpProperties = new Properties();

            // DriverClass & url
            String jdbcDriverClass = props.getProperty(Environment.DRIVER);
            String jdbcUrl = props.getProperty(Environment.URL);
            dbcpProperties.put("driverClassName", jdbcDriverClass);
            dbcpProperties.put("url", jdbcUrl);
           
            // Username / password
            String username = props.getProperty(Environment.USER);
            String password = props.getProperty(Environment.PASS);
            dbcpProperties.put("username", username);
            dbcpProperties.put("password", password);

            // Isolation level
            String isolationLevel = props.getProperty(Environment.ISOLATION);
            if ((isolationLevel != null) && (isolationLevel.trim().length() > 0)) {
                dbcpProperties.put("defaultTransactionIsolation", isolationLevel);
            }
           
            // Turn off autocommit (unless autocommit property is set)
            String autocommit = props.getProperty(AUTOCOMMIT);
            if ((autocommit != null) && (autocommit.trim().length() > 0)) {
                dbcpProperties.put("defaultAutoCommit", autocommit);
            } else {
                dbcpProperties.put("defaultAutoCommit", String.valueOf(Boolean.FALSE));
            }

            // Pool size
            String poolSize = props.getProperty(Environment.POOL_SIZE);
            if ((poolSize != null) && (poolSize.trim().length() > 0)
                && (Integer.parseInt(poolSize) > 0))  {
                dbcpProperties.put("maxActive", poolSize);
            }

            // Copy all "driver" properties into "connectionProperties"
            Properties driverProps = ConnectionProviderFactory.getConnectionProperties(props);
            if (driverProps.size() > 0) {
                StringBuffer connectionProperties = new StringBuffer();
                for (Iterator iter = driverProps.keySet().iterator(); iter.hasNext();) {
                    String key = (String) iter.next();
                    String value = driverProps.getProperty(key);
                    connectionProperties.append(key).append('=').append(value);
                    if (iter.hasNext()) {
                        connectionProperties.append(';');
                    }
                }
                dbcpProperties.put("connectionProperties", connectionProperties.toString());
            }

            // Copy all DBCP properties removing the prefix
            for (Iterator iter = props.keySet().iterator() ; iter.hasNext() ;) {
                String key = String.valueOf(iter.next());
                if (key.startsWith(PREFIX)) {
                    String property = key.substring(PREFIX.length());
                    String value = props.getProperty(key);
                    dbcpProperties.put(property, value);
                }
            }
           
            // Backward-compatibility
            if (props.getProperty(DBCP_PS_MAXACTIVE) != null) {
                dbcpProperties.put("poolPreparedStatements", String.valueOf(Boolean.TRUE));
                dbcpProperties.put("maxOpenPreparedStatements", props.getProperty(DBCP_PS_MAXACTIVE));
            }
           
            // Some debug info
            if (log.isDebugEnabled()) {
                log.debug("Creating a DBCP BasicDataSource with the following DBCP factory properties:");
                StringWriter sw = new StringWriter();
                dbcpProperties.list(new PrintWriter(sw, true));
                log.debug(sw.toString());
            }

            // Let the factory create the pool
         ds = (BasicDataSource) BasicDataSourceFactory.createDataSource(dbcpProperties);           
            // The BasicDataSource has lazy initialization
            // borrowing a connection will start the DataSource
            // and make sure it is configured correctly.
            Connection conn = ds.getConnection();
            conn.close();

            // Log pool statistics before continuing.
            logStatistics();
        }
        catch (Exception e) {
            String message = "Could not create a DBCP pool";
            log.fatal(message, e);
            if (ds != null) {
                try {
                    ds.close();
                }
                catch (Exception e2) {
                    // ignore
                }
                ds = null;
            }
            throw new HibernateException(message, e);
        }
        log.debug("Configure DBCPConnectionProvider complete");
    }
   
    public static BasicDataSource getDataSource(){
       
        return ds;
    }
   
    public Connection getConnection() throws SQLException {
        Connection conn = null;
        try {
                conn = ds.getConnection();
        }
        finally {
            logStatistics();
        }
        return conn;
    }

    public void closeConnection(Connection conn) throws SQLException {
        try {
            conn.close();
        }
        finally {
            logStatistics();
        }
    }

    public void close() throws HibernateException {
        log.debug("Close DBCPConnectionProvider");
        logStatistics();
        try {
            if (ds != null) {
                ds.close();
                    ds = null;
            }
            else {
                log.warn("Cannot close DBCP pool (not initialized)");
            }
        }
        catch (Exception e) {
            throw new HibernateException("Could not close DBCP pool", e);
        }
        log.debug("Close DBCPConnectionProvider complete");
    }
   
    protected void logStatistics() {
        if (log.isInfoEnabled()) {
            log.info("active: " + ds.getNumActive() + " (max: " + ds.getMaxActive() + ")   "
                    + "idle: " + ds.getNumIdle() + "(max: " + ds.getMaxIdle() + ")");
        }
    }
   
}