dbconn.java

汽车展销的网站开发

package Bean;
import java.sql.*;
import java.io.*;

public class DbConn{
	Connection conn=null;
	ResultSet rs=null;
	Statement stmt=null;
	String strUrl="jdbc:odbc:car";
	
	public DbConn(){
	}
    //建立数据库连接
	public void open() throws Exception{
		try{
			//加载JDBC-ODBC桥驱动程序
			Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
			//建立数据源car的连接
			conn=DriverManager.getConnection(strUrl);
		}catch(Exception e){
			System.out.println(e.getMessage());
		}
	}
	
	//执行数据库的查询操作，返回ResultSet类型的值
	public ResultSet executeQuery(String sql){
		stmt=null;
		rs=null;
		try{
			stmt=conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
			rs=stmt.executeQuery(sql);
			return rs;
		}catch(SQLException e){
			System.out.println(e.getMessage());
		}
		return null;
	}
	
	//执行数据库的更新操作，包括更、删、改
	public int executeUpdate(String sql){
    stmt=null;
    rs=null;
    int i=0;
    try{
        stmt=conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
              ResultSet.CONCUR_READ_ONLY);
        i=stmt.executeUpdate(sql);
        return i;
       }
   catch(SQLException e) {
         System.err.println(e.getMessage());
         }
        return 0; 
     }
     
     //从指定的结果集rs中返回某字段str的值
     public String getString(ResultSet rs,String str){
     	try{
     		return rs.getString(str);
     	}catch(Exception ex){
     		System.err.println(ex.getMessage());
     		return null;
     	}
     }
     
     //数据编码的转换
     public static String toGBK(String str){
     	try{
     		if(str==null)
     			str="";
     		else
     			str=new String(str.getBytes("ISO-8859-1"),"GBK");
     	}catch(Exception e){
     		System.out.println(e.getMessage());
     	}
     	return str;
     }
     
     //关闭数据库连接
     public void close(){
     	try{
     		stmt.close();
     		conn.close();
     	}catch(SQLException e){
     		System.out.println(e.getMessage());
     	}
     }
}