condb.java

本远程教育系统是采用jsp技术配合SqlServer 2000数据库和Tomcat服务器开发的动态交互式网站。基本实现了用户管理

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();
		}
	}
}