JavaBean接続データベース

5788 ワード

JavaBeanテクノロジーは,表現層とビジネスロジック層の分離を実現するだけでなく,JSPの効率とコード再利用の程度を向上させ,JSPプログラミングでよく用いられるテクノロジーである.
 
簡単なJavaBeanの例を次に示します
JAvaコード:
 
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ページ:
 
<%@ 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("    !!!"); %>
  <%=abc.getFirstProperty() %>
  </body>
</html>

  次にJavaBeanを用いてデータベースのクエリーデータの更新(Mysqlデータベース)を実現する.
JAvaコード:
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("       !!!"+e.getMessage());
		}
		return stmt;
	}
	
	/**
	 *   sql        
	 * @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("       !!!"+e.getMessage());
		}
		return rs;
	}
	
	/**
	 *   sql        
	 */
	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("      !!!"+e.getMessage());
		}
		return i;
	}

}
 
jspページ:
<%@ 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>