远程教育系统教室管理

package condb; import java.sql.*; public class ConDB{ private static Connection con; private Statement stmt; private ResultSet rs; private static final String drivername="com.microsoft.jdbc.sqlserver.SQLServerDriver"; private static final String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=YCJX;user=sa;password=sa"; public ConDB(){ } public static synchronized Connection getCon() throws Exception { try{ Class.forName(drivername); con=DriverManager.getConnection(url); return con; } catch(SQLException e){ System.err.println(e.getMessage()); throw e; } } public Statement getStmtread(){ try{ con=getCon(); stmt=con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY); return stmt; } catch(Exception e){ System.err.println(e.getMessage()); e.printStackTrace(); } return null; } public ResultSet getRs(String sql) throws Exception{ stmt=getStmtread(); rs=stmt.executeQuery(sql); return rs; } public int executeUpdate(String sql){ int i=-1; stmt = getStmtread(); try{ i = stmt.executeUpdate(sql); } catch(Exception e) { System.err.println(e.getMessage()); e.printStackTrace(); } return i; } public void close(){ try{ if(rs != null){ rs.close(); rs=null; } } catch(Exception e){ System.err.println(e.getMessage()); e.printStackTrace(); } try{ if(stmt != null){ stmt.close(); stmt=null; } } catch(Exception e){ System.err.println(e.getMessage()); e.printStackTrace(); } try{ if(con != null){ con.close(); con=null; } } catch(Exception e){ System.err.println(e.getMessage()); e.printStackTrace(); } } }