dbconn.java

一本jsp自学教材

package test;
import java.sql.*;
public class DBConn{
   //驱动程序名、数据库用户名、密码、数据库名、表名
  String driverName="com.mysql.jdbc.Driver";
  String username="root";
  String password="123456";
  String dbName="study";
  //连接字符串 
  String url="jdbc:mysql://localhost/"+dbName+"?characterEncoding=GBK";
  private Connection conn;
  private Statement stmt;
  private PreparedStatement pstmt;
  ResultSet rs=null;
  public DBConn()
   {
     try{
     //加载驱动程序
     Class.forName("com.mysql.jdbc.Driver");
     //建立同数据库的连接对象
     conn=DriverManager.getConnection(url,username,password);
    }
    catch(Exception e)
    {
      System.out.print(e.toString()); 
    } 
  }
  public synchronized Statement getStmt()throws Exception
   {
     stmt=conn.createStatement();
     return stmt;
   }
  //创建预处理会话对象
  public synchronized PreparedStatement getPstmt(String sql)throws Exception
   {
     pstmt=conn.prepareStatement(sql);
     return pstmt;
   }
  //执行查询操作
  public synchronized ResultSet query(String sql)throws Exception
 {
  try{  
    stmt=conn.createStatement(); 
    rs=stmt.executeQuery(sql);
    return rs;
   }
  catch(Exception e)
  {
   System.out.println(e.toString());
   return null;
  }
 } 
 //执行更新操作
public synchronized int update(String sql)throws Exception
 {
   int nn;
   try{
   stmt=conn.createStatement();
   nn=this.stmt.executeUpdate(sql); 
  }
  catch(Exception e)
  {
   System.out.println(e.toString());
   nn=0;   
  }
  return nn;
 }
}