为什么，编译时出错 提示：包javax.servlet不存在(20分)

请看下面一段。为什么，编译时出错 提示：包javax.servlet不存在
环境变量 classpath是这样的：.;D:/jdk1.3.0_03/lib;D:/jdk1.3.0_03/lib/tools.jar;D:/jakarta-tomcat-4.1.18/common/lib/servlet.jar
package xbook.common ;

import java.lang.* ;
import java.sql.* ;
import javax.servlet.* ;
import xbook.common.* ;

public class SQLBridge {
private ConnPool connPool ;
private Connection conn ;
private ResultSet rs ;
private ResultSetMetaData rsmd ;
private Statement stmt ;
private String driverName ;
private String jdbcURL ;
private String username ;
private String password ;

// -------------------------------------- Constructor --------------------------------------
public SQLBridge() {
connPool=null ;
conn=null ;
rs=null ;
rsmd=null ;
stmt=null ;
}
// -----------------------------------------------------------------------------------------
private void clearResult() throws SQLException {
if( rs!=null ) rs.close() ;
rs=null ;
if( stmt!=null ) stmt.close() ;
stmt=null ;
rsmd=null ;
}

public void closeDB() throws SQLException {
clearResult() ;
if( connPool!=null ) {
connPool.returnConnection() ;
connPool=null ;
}
else
{
if( conn==null )
throw new SQLException( "This connection has been closed already." ) ;
if( conn.isClosed() )
throw new SQLException( "This connection has been closed." ) ;
conn.close() ;
}
conn=null ;
}

public int execSQL( String sqlStmt )
throws SQLException {
if( conn==null || conn.isClosed() )
throw new SQLException( "This connection has not been established yet." ) ;
if( sqlStmt==null )
throw new SQLException( "SQL-statement is null." ) ;
clearResult() ;
conn.setAutoCommit( true ) ;
stmt=conn.createStatement() ;
if( sqlStmt.toUpperCase().startsWith( "SELECT" ) ) {
rs=stmt.executeQuery( sqlStmt ) ;
rsmd=rs.getMetaData() ;
return -1 ;
}
else
{
int numRow=stmt.executeUpdate( sqlStmt ) ;
clearResult() ;
return numRow ;
}
}

public void execUpdate( String[] sqlStmts )
throws SQLException {
if( conn==null || conn.isClosed() )
throw new SQLException( "The connection has not been established yet." ) ;
if( sqlStmts==null || sqlStmts.length==0 )
throw new SQLException( "SQL-statement is null." ) ;
clearResult() ;
conn.setAutoCommit( false ) ;
try {
for( int i=0 ;
i<sqlStmts.length ;
i++ ) {
stmt=conn.createStatement() ;
stmt.executeUpdate( sqlStmts ) ;
stmt.close() ;
}
conn.commit() ;
}
catch( SQLException ex ) {
conn.rollback() ;
throw ex ;
}
}

public int getColumnCount()
throws SQLException {
if( rsmd==null )
throw new SQLException( "ResultSet is null." ) ;
return rsmd.getColumnCount() ;
}

public String[] getColumnNames()
throws SQLException {
if( rsmd==null )
throw new SQLException( "ResultSet is null." ) ;
String[] columnNames=new String[ getColumnCount() ] ;
for( int i=1 ;
i<=columnNames.length ;
i++ )
columnNames[i-1]=rsmd.getColumnName( i ) ;
return columnNames ;
}

protected Object getField( int column, boolean convertToString )
throws SQLException {
if( rs==null || rsmd==null )
throw new SQLException( "ResultSet is null." ) ;

switch( rsmd.getColumnType( column ) ) {
case Types.BIGINT :
if( convertToString )
return String.valueOf( rs.getLong(column) ) ;
else

return new Long( rs.getLong(column) ) ;

case Types.BINARY :
if( convertToString )
return Byte.toString( rs.getByte(column) ) ;
else

return new Byte( rs.getByte(column) ) ;

case Types.BIT :
if( convertToString )
return String.valueOf( rs.getBoolean(column) ) ;
else

return new Boolean( rs.getBoolean(column) ) ;

case Types.CHAR :
return rs.getString(column) ;

case Types.DATE :
if( convertToString )
return ( rs.getDate(column) ).toString() ;
else

return rs.getDate(column) ;

case Types.DECIMAL :
if( convertToString )
return ( rs.getBigDecimal( column, rsmd.getScale(column) ) ).toString() ;
else

return rs.getBigDecimal( column, rsmd.getScale(column) );

case Types.DOUBLE :
if( convertToString )
return String.valueOf( rs.getDouble(column) ) ;
else

return newdo
uble( rs.getDouble(column) ) ;

case Types.FLOAT :
if( convertToString )
return String.valueOf( rs.getDouble(column) ) ;
else

return new Float( rs.getDouble(column) ) ;

case Types.INTEGER :
if( convertToString )
return String.valueOf( rs.getInt(column) ) ;
else

return new Integer( rs.getInt(column) ) ;

case Types.LONGVARBINARY :
if( convertToString )
return ( rs.getBinaryStream(column) ).toString() ;
else

return rs.getBinaryStream(column) ;

case Types.LONGVARCHAR :
return rs.getString(column) ;

case Types.NULL :
if( convertToString )
return "NULL" ;
else

return null ;

case Types.NUMERIC :
if( convertToString )
return ( rs.getBigDecimal( column, rsmd.getScale(column) ) ).toString() ;
else

return rs.getBigDecimal( column, rsmd.getScale(column) ) ;

case Types.REAL :
if( convertToString )
return String.valueOf( rs.getFloat(column) ) ;
else

return new Float( rs.getFloat(column) ) ;

case Types.SMALLINT :
if( convertToString )
return String.valueOf( rs.getShort(column) ) ;
else

return new Short( rs.getShort(column) ) ;

case Types.TIME :
if( convertToString )
return ( rs.getTime(column) ).toString() ;
else

return rs.getTime(column) ;

case Types.TIMESTAMP :
if( convertToString )
return ( rs.getTimestamp(column) ).toString() ;
else

return rs.getTimestamp(column) ;

case Types.TINYINT :
if( convertToString )
return String.valueOf( rs.getByte(column) ) ;
else

return new Byte( rs.getByte(column) ) ;

case Types.VARBINARY :
if( convertToString )
return ( rs.getBytes(column) ).toString() ;
else

return rs.getBytes(column) ;

case Types.VARCHAR :
return rs.getString(column) ;

default :
if( convertToString )
return ( rs.getObject(column) ).toString() ;
else

return rs.getObject(column) ;
}
}

public Object getField( int column )
throws SQLException {
return getField( column, false ) ;
}

public Object getField( String fieldName )
throws SQLException {
return getField( rs.findColumn( fieldName ) ,false ) ;
}

public String getFieldString( int column )
throws SQLException {
return (String)getField( column, true ) ;
}

public String getFieldString( String fieldName )
throws SQLException {
return (String)getField( rs.findColumn( fieldName ) ,true ) ;
}

public boolean nextRow()
throws SQLException {
if( rs==null )
throw new SQLException( "ResultSet is null." ) ;
return rs.next() ;
}

public void openDB( String drvName ,String url ,
String uname ,String passwd )
throws SQLException {
if( conn!=null &amp;&amp;
!conn.isClosed() )
throw new SQLException( "The connection has been established already." ) ;
clearResult() ;
try {
Class.forName( drvName ) ;
}
catch( ClassNotFoundException ex ) {
throw new SQLException( ex.toString() ) ;
}
conn=DriverManager.getConnection( url ,uname ,passwd ) ;
}

public void openDB( ConnPool pool )
throws SQLException {
if( conn!=null &amp;&amp;
!conn.isClosed() )
throw new SQLException( "The connection has been established already." ) ;
if( pool==null )
throw new SQLException( "The connection pool cannot be found." ) ;
clearResult() ;
connPool=pool ;
conn=connPool.getConnection() ;
}

public void setConnectionSwitch( String on_off )
throws ServletException {
try {
if( on_off.equalsIgnoreCase( "ON" ) ) {
if( connPool==null )
openDB( driverName, jdbcURL, username, password ) ;
else

openDB( connPool ) ;
}
else
if( on_off.equalsIgnoreCase( "OFF" ) )
closeDB() ;
}
catch( SQLException ex ) {
throw new ServletException( ex.toString() ) ;
}
}

public void setConnPool( ConnPool pool ) {
connPool=pool ;
}

public void setDriverName( String drvName ) {
driverName=drvName ;
}

public void setJdbcURL( String url ) {
jdbcURL=url ;
}

public void setUserName( String uname ) {
username=uname ;
}

public void setPassword( String passwd ) {
password=passwd ;
}
}

装j2ee

照理说应该没错的

接受答案了.