linkdb.java

学校期间做的实践项目

package com.sw06701.dao;

import java.sql.*;

public class Linkdb {

  String strDriver = "org.gjt.mm.mysql.Driver";
  String strConn = "jdbc:mysql://localhost/autoportal?useUnicode=true&characterEncoding=GB2312";
  String db_usr="root";
  String db_password="123456";
  
  private Connection conn = null;
  private Statement stmt = null;
  ResultSet rs = null;

  public Linkdb() {
   //连接MySql_jdbc驱动程序
	try { 
         Class.forName(strDriver).newInstance(); 
         //System.out.println("开始数据库链接 成功");
        } catch (Exception E) { 
           // System.err.println("不能连接数据库！"); 
          } 
  }
//执行Select语句
  public ResultSet executeQuery(String sql) {
    rs = null;
    try {
      conn = DriverManager.getConnection(strConn,db_usr,db_password);
      stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
      rs = stmt.executeQuery(sql);
       }catch(SQLException ex) { 
          System.err.println("执行SQL语句出错：" + ex.getMessage());
       }
    return rs;
  }

 //执行Insert,Update语句 
  public void executeUpdate(String sql) {
    stmt = null;
    rs=null;
    try {
    //System.out.println("开始数据库链接 "+strConn);
    conn = DriverManager.getConnection(strConn,db_usr,db_password); 
    
   // System.out.println("开始数据库链接 成功 但未提交 "+sql);
   // System.out.println("开始一个数据库事务");
    conn.setAutoCommit(false);
    stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
    stmt.execute(sql);
    conn.commit();
    stmt.close();
    conn.close();
    } 
    catch(SQLException ex) { 
      System.err.println("执行SQL语句出错: " + ex.getMessage());
    }
  }

  public void closeStmt(){
    try{
      stmt.close();
     }
    catch(SQLException e){
      e.printStackTrace();
     }
  }

  public void closeConn(){
    try{
      conn.close();
     }
    catch(SQLException e){
      e.printStackTrace();
     }
  }
}