知识准备:
JDBC访问数据库的基本步骤
(1)、将数据库的JDBC驱动加载到工程类库中。
(2)、加载JDBC驱动,并将其注册到DriverManager中。下面是一些主流数据库的JDBC驱动加载注册码:
①、oracle数据库
Class.forName(“oracle.jdbc.driver.OracleDriver”).newInstance();
②、Sql Server 7.0/2000数据库
Class.forName(“com.microsoft.jdbc.sqlserver.SQLServerDriver”).newInstance();
③、MySQL数据库
Class.forName(“com.mysql.jdbc.Driver”).newInstance();
(3)、建立数据库连接,取得Connection对象。
①、oracle数据库
String url=”jdbc:oracle:thin:@localhost:1521:orcl”;
String user=”scott”:
String password=”tiger”;
Connetion conn=DriverManager.getConnetion(url,user,password);
②、Sql Server 7.0/2000数据库
String url=”jdbc:microsoft:sqlserver://localhost:1443;DatabaseName=pubs”;
String user=”sa”;
String password=””;
Connection conn=DriverManager.getConnection(url,user,password);
③、MySQL数据库
String url=”jdbc:mysql://localhost:3306/testDB?user=root&password=root&
useUnicode=true&charaterEncoding=gb2312”;
Connection conn=DriverManager.getConnection(url);
(4)、建立Statement对象或PreparedStatement对象。
//建立Statement对象
Statement stmt=conn.createStatement();
//建立PreparedStatement对象
String sql=”select *from users where userName=? And password=?”;
PreparedStatement pstmt=conn.prepareStatement(sql);
pstmt.setString(1,”admin”);
pstmt.setString(2,”liubin”);
(5)、执行SQL语句。
//执行静态SQL查询
String sql=”select * from users”;
ResultSet rs = stmt.executeQuery(sql);
//执行insert、update、delete等语句,先定义sql
Stmt.executeUpdate(sql);
(6)、访问结果记录集ResultSet对象。
While(rs.next())
{
out.println(“你的第一个字段内容为:“+rs.getString(1));
out.println(“你的第二个字段内容为:“+rs.getString(2));
}
(7)、依次将ResultSet、Statement、PrepareStatement、Connection对象关闭,释放所有占用的资源:
rs.close();
stmt.close();
Pstmt.close();
con.close();
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%> <%@ page import="java.sql.*"%>
<html> <head> <title>在线购物</title> </head> <% //装载MySQL5.0的JDBC驱动 Class.forName("com.mysql.jdbc.Driver").newInstance(); //建立数据库连接 String url ="jdbc:mysql://localhost:3306/eshop?user=root&password=zhz&useUnicode=true&characterEncoding=gb2312"; Connection conn= DriverManager.getConnection(url); //建立一个Statement对象,用于执行SQL语句 Statement stat = conn.createStatement(); //执行查询并得到查询结果 String sql = "select * from shop"; ResultSet rs = stat.executeQuery(sql); %> <body> <h2>在线购物</h2> <hr> <table border="1" width="600"> <tr bgcolor="#dddddd"> <td align="center" width="80">商品缩图</td> <td align="center">商品摘要</td> <td align="center" width="100">在线购买</td> </tr> <% String bm,name,price,info,img; //将查询结果集中的记录输出到页面上 while (rs.next()){ //从当前记录中读取各字段的值 img = rs.getString("SP_PIC").trim(); bm = rs.getString("SP_NO").trim(); name = rs.getString("SP_NAME").trim(); price = rs.getString("SP_PRICE").trim(); info = rs.getString("SP_INFO").trim();
out.println("<tr>"); out.println("<td><img src='"+ img +"' border=0 height=60 width=60></td>"); out.println("<td>"); out.println("商品编号:"+ bm +"<br>"); out.println("商品名称:"+ name +"<br>"); out.println("商品价格:"+ price +"元<br>"); out.println("商品简介:"+ info +"<br>"); out.println("</td>"); out.println("<td><a href='buy.jsp?op=add&bm="+bm+"'>放入购物车</a></td>"); out.println("</tr>"); } %> </table> <br> <a href="cart.jsp">查看购物车</a> <a href="buy.jsp?op=clear">清空购物车</a> </body> </html>
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cart.jsp
<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%> <%@ page import="java.sql.*"%>
<html> <head> <title>我的购物车</title> </head> <% //装载MySQL5.0的JDBC驱动 Class.forName("com.mysql.jdbc.Driver").newInstance(); //建立数据库连接 Stringurl="jdbc:mysql://localhost:3306/eshop?user=root&password=zhz&useUnicode=true&characterEncoding=gb2312"; Connection conn= DriverManager.getConnection(url); //建立一个Statement对象,用于执行SQL语句 Statement stat = conn.createStatement(); //执行查询并得到查询结果 String sql = "select * from cart"; ResultSet rs = stat.executeQuery(sql); %> <body> <h2>我的购物车</h2> <hr> <table border="1" width="600"> <tr bgcolor="#dddddd"> <td align="center" width="80">商品名称</td> <td align="center">商品单价</td> <td align="center" width="100">购买数量</td> <td align="center" width="100">金额</td> <td align="center" width="100">编辑</td> </tr> <% String id,name,price,num,count; //将查询结果集中的记录输出到页面上 while (rs.next()){ //从当前记录中读取各字段的值 id = rs.getString("ID").trim(); name = rs.getString("SP_NAME").trim(); price = rs.getString("SP_PRICE").trim(); num = rs.getString("BUY_NUM").trim(); count = rs.getString("COUNT").trim();
out.println("<tr>"); out.println("<td>"+ name +"</td>"); out.println("<td>"+ price +"</td>"); out.println("<td><input type=text value="+ num +" onChange=/"updateNum('"+id+"',this.value,'"+price+"')/"></td>"); out.println("<td>"+ count +"</td>"); out.println("<td><a href='buy.jsp?op=del&id="+id+"'>退回商品架</a></td>"); out.println("</tr>"); } %> </table> <br> <a href="index.jsp">继续购物</a> <a href="buy.jsp?op=clear">清空购物车</a> </body> <script language="javascript"> function updateNum(id,num,price){ var url = "buy.jsp?op=update&id="+id+"&num="+num+"&price="+price; window.location = url; } </script> </html>
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buy.jsp
<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%> <%@ page import="java.sql.*"%>
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