JavaBean连接数据库
程序员文章站
2022-06-15 09:10:53
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JavaBean技术不但实现了表现层和商务逻辑层的分离,而且提高了JSP的效率和代码重用的程度,是JSP编程中常用的技术
下面是一个简单的JavaBean实例
java代码:
package com.javaBean.vo;
public class FirstJavaBean {
private String firstPorperty=new String("");
public FirstJavaBean(){
}
public String getFirstProperty(){
return firstPorperty;
}
public void setFirstProperty(String value){
firstPorperty=value;
}
}
JSP页面:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@page import="java.sql.ResultSet"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<jsp:useBean id="abc" scope="session" class="com.javaBean.vo.FirstJavaBean"/>
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%request.setCharacterEncoding("UTF-8");
abc.setFirstProperty("简单实例!!!"); %>
<%=abc.getFirstProperty() %>
</body>
</html>
下面用JavaBean实现对数据库的查询 数据的更新(Mysql数据库)
java代码:
package MyBean;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Dbcon {
public static Statement getStatement(){
Statement stmt=null;
Connection con=null;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
con=DriverManager.getConnection("jdbc:mysql://localhost/person?user=root&password=");
stmt=con.createStatement();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}catch(Exception e){
System.out.println("数据库连接失败!!!"+e.getMessage());
}
return stmt;
}
/**
* 执行sql语句的数据库查询
* @param sql
* @return
*/
public ResultSet executeQuery(String sql){
ResultSet rs=null;
try {
rs=getStatement().executeQuery(sql);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("数据库查询失败!!!"+e.getMessage());
}
return rs;
}
/**
* 执行sql语句的数据库更新
*/
public int executeUpdate(String sql){
int i=0;
try {
i=getStatement().executeUpdate(sql);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("执行更新错误!!!"+e.getMessage());
}
return i;
}
}
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@page import="java.sql.ResultSet"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<jsp:useBean id="abc" scope="session" class="MyBean.Dbcon"/>
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%
ResultSet rs=abc.executeQuery("select * from student");
while(rs.next()){%>
<%=rs.getString(2) %>
<%}
%>
</body>
</html>