batcherimpl.java

用Java实现的23个常用设计模式源代码

//$Id: BatcherImpl.java,v 1.9.2.14 2003/11/27 16:09:59 oneovthafew Exp $
package net.sf.hibernate.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashSet;
import java.util.Iterator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import net.sf.hibernate.AssertionFailure;
import net.sf.hibernate.HibernateException;
import net.sf.hibernate.JDBCException;
import net.sf.hibernate.engine.Batcher;
import net.sf.hibernate.engine.SessionFactoryImplementor;
import net.sf.hibernate.engine.SessionImplementor;
import net.sf.hibernate.util.JDBCExceptionReporter;
import net.sf.hibernate.util.StringHelper;

/**
 * Manages prepared statements and batching.
 * 
 * @author Gavin King
 */
public abstract class BatcherImpl implements Batcher {
	
	private static int openPreparedStatements;
	private static int openResultSetCount;
	
	protected static final Log log = LogFactory.getLog(BatcherImpl.class);
	
	private final SessionImplementor session;
	private final SessionFactoryImplementor factory;
	
	private PreparedStatement batchUpdate;
	private String batchUpdateSQL;
	
	private HashSet statementsToClose = new HashSet();
	private HashSet resultSetsToClose = new HashSet();
	private PreparedStatement lastQuery;
	
	public BatcherImpl(SessionImplementor session) {
		this.session = session;
		this.factory = session.getFactory();
	}
	
	protected PreparedStatement getStatement() {
		return batchUpdate;
	}
	
	public PreparedStatement prepareStatement(String sql) throws SQLException, HibernateException {
		executeBatch();
		logOpenPreparedStatement();
		return getPreparedStatement( session.connection(), sql, false );
	}
	public PreparedStatement prepareQueryStatement(String sql, boolean scrollable) throws SQLException, HibernateException {
		logOpenPreparedStatement();
		PreparedStatement ps = getPreparedStatement( session.connection(), sql, scrollable );
		setStatementFetchSize(ps);
		statementsToClose.add(ps);
		lastQuery=ps;
		return ps;
	}
	
	public void abortBatch(SQLException sqle) {
		//JDBCExceptionReporter.logExceptions(sqle);
		final PreparedStatement ps = batchUpdate;
		batchUpdate=null;
		batchUpdateSQL=null;
		try {
			closeStatement(ps);
		}
		catch (SQLException e) {
			//noncritical, swallow and let the other propagate!
			JDBCExceptionReporter.logExceptions(e);
		}
	}
	
	public ResultSet getResultSet(PreparedStatement ps) throws SQLException {
		ResultSet rs = ps.executeQuery();
		resultSetsToClose.add(rs);
		logOpenResults();
		return rs;
	}
		
	public void closeQueryStatement(PreparedStatement ps, ResultSet rs) throws SQLException {
		statementsToClose.remove(ps);
		if (rs!=null) resultSetsToClose.remove(rs);
		try {
			if (rs!=null) {
				logCloseResults();
				rs.close();
			} 
		}
		finally {
			closeQueryStatement(ps);
		}			
	}
	
	public PreparedStatement prepareBatchStatement(String sql) throws SQLException, HibernateException {
		if ( !sql.equals(batchUpdateSQL) ) {
			batchUpdate=prepareStatement(sql); // calls executeBatch()
			batchUpdateSQL=sql;
		}
		return batchUpdate;
	}
	
	public void executeBatch() throws HibernateException {
		if (batchUpdate!=null) {
			final PreparedStatement ps = batchUpdate;
			batchUpdate=null;
			batchUpdateSQL=null;
			try {
				try {
					doExecuteBatch(ps);
				}
				finally {
					closeStatement(ps);
				}
			}
			catch (SQLException sqle) {
				throw new JDBCException("Could not execute JDBC batch update", sqle);
			}
		}
	}
	
	public void closeStatement(PreparedStatement ps) throws SQLException {
		logClosePreparedStatement();
		closePreparedStatement(ps);
	}
	
	private void closeQueryStatement(PreparedStatement ps) throws SQLException {

		try {
			//work around a bug in all known connection pools....
			if ( ps.getMaxRows()!=0 ) ps.setMaxRows(0);
			if ( ps.getQueryTimeout()!=0 ) ps.setQueryTimeout(0);
		}
		catch (Exception e) {
			log.warn("exception clearing maxRows/queryTimeout", e);
			ps.close(); //just close it; do NOT try to return it to the pool!
			return; //NOTE: early exit!
		}
		
		closeStatement(ps);
	}
	
	public void closeStatements() {
		try {
			if (batchUpdate!=null) batchUpdate.close();
		}
		catch (SQLException sqle) {
			//no big deal
			log.warn("Could not close a JDBC prepared statement", sqle);
		}
		batchUpdate=null;
		batchUpdateSQL=null;

		Iterator iter = resultSetsToClose.iterator();
		while ( iter.hasNext() ) {
			try {
				logCloseResults();
				( (ResultSet) iter.next() ).close();
			}
			catch (SQLException e) {
				// no big deal
				log.warn("Could not close a JDBC result set", e);
			}
		}
		resultSetsToClose.clear();
		
		iter = statementsToClose.iterator();
		while ( iter.hasNext() ) {
			try {
				closeQueryStatement( (PreparedStatement) iter.next() );
			}
			catch (SQLException e) {
				// no big deal
				log.warn("Could not close a JDBC statement", e);
			}
		}
		statementsToClose.clear();
	}
	
	protected abstract void doExecuteBatch(PreparedStatement ps) throws SQLException, HibernateException;
	
	private static void logOpenPreparedStatement() {
		if ( log.isTraceEnabled() ) {
			log.trace( "about to open: " + openPreparedStatements + " open PreparedStatements, " + openResultSetCount + " open ResultSets" );
			openPreparedStatements++;
		}
	}
	
	private static void logClosePreparedStatement() {
		if ( log.isTraceEnabled() ) openPreparedStatements--;
		log.trace( "done closing: " + openPreparedStatements + " open PreparedStatements, " + openResultSetCount + " open ResultSets" );
	}
	
	private static void logOpenResults() {
		if ( log.isTraceEnabled() ) openResultSetCount++;
	}
	private static void logCloseResults() {
		if ( log.isTraceEnabled() ) openResultSetCount--;
	}

	protected SessionImplementor getSession() {
		return session;
	}

	protected SessionFactoryImplementor getFactory() {
		return factory;
	}

	private PreparedStatement getPreparedStatement(final Connection conn, final String sql, boolean scrollable) throws SQLException {
		
		if ( scrollable && !factory.isScrollableResultSetsEnabled() ) {
			throw new AssertionFailure("Hibernate tried to grab a scrollable result set");
		}
		
		// note: if we're not using JDBC2, don't return a scrollable PS
		// clients *must* be prepared to handle this case!
		
		if ( log.isDebugEnabled() ) log.debug(
			(scrollable ? "scrollable " : StringHelper.EMPTY_STRING ) + "prepared statement get: " + sql
		);
		if ( factory.isShowSqlEnabled() ) System.out.println("Hibernate: " + sql);
		
		try {
			log.trace("preparing statement");
			return scrollable ?
				conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY) :
				conn.prepareStatement(sql);
		}
		catch (SQLException sqle) {
			JDBCExceptionReporter.logExceptions(sqle);
			throw sqle;
		}
	}
	
	private void closePreparedStatement(PreparedStatement ps) throws SQLException {
		try {
			log.trace("closing statement");
			if (ps!=null) ps.close(); //null check not absolutely necessary!
		}
		catch (SQLException sqle) {
			JDBCExceptionReporter.logExceptions(sqle);
			throw sqle;
		}

	}

	private void setStatementFetchSize(PreparedStatement statement) throws SQLException {
		Integer statementFetchSize = factory.getJdbcFetchSize();
		if (statementFetchSize!=null) statement.setFetchSize( statementFetchSize.intValue() );
	}
	
	public Connection openConnection() throws HibernateException {
		try {
			return factory.getConnectionProvider().getConnection();
		}
		catch (SQLException sqle) {
			throw new JDBCException("Cannot open connection", sqle);
		}
	}
	
	public void closeConnection(Connection conn) throws HibernateException {
		try {
			if ( !conn.isClosed() ) {
				JDBCExceptionReporter.logWarnings( conn.getWarnings() );
				conn.clearWarnings();
			}
			factory.getConnectionProvider().closeConnection(conn);
		}
		catch (SQLException sqle) {
			throw new JDBCException("Cannot close connection", sqle);
		}
	}
	
	public void cancelLastQuery() throws HibernateException {
		try {
			if (lastQuery!=null) lastQuery.cancel();
		}
		catch (SQLException sqle) {
			throw new JDBCException("Could not cancel query", sqle);
		}
	}
		
}