oralce+VO+DAO+servlet+jsp+el

       公司里至今我觉得学的东西不算多，目前所作的项目框架已经搭好，而我要做的只是添砖加瓦，用的自己的组件，项目中我觉得又回到了很久以前的“胖客户”时代。因为公司这几个组件都要用到js，所以我到目前为止java代码就很少写了，为了不忘却旧时的一点知识，故而自己编写了一个小小的例子。

    1.oracle数据库建表：

create table STUDENT
(
  ID      NUMBER not null,
  NAME    VARCHAR2(20) default '男',
  SEX     VARCHAR2(4),
  ADDRESS VARCHAR2(40),
  MEMO    VARCHAR2(60)
)     -----向表中添加几条数据

2.写一个与数据库建立的DBHelper类和一个properties文件

package db;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class DBHelper {
 private String driver;

 private String url;

 private String username;

 private String password;

 private Connection con;

 private boolean isUseTrans = false;
 
 private String configFilePath = "DBConfig.properties";// 路径

 public DBHelper() {
  readConfig();
  try {
   Class.forName(driver);
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  }
  createConnection();
 }

 public Connection getConnection(){
      return con; 
    }
 
 private void createConnection() {
  try {
   con = DriverManager.getConnection(url, username, password);
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
 
 public void beginTrans(boolean isUseTrans){
  this.isUseTrans = isUseTrans;
  try {
   if(isUseTrans){
    con.setAutoCommit(false);
   }else{
    con.setAutoCommit(true);
   }
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
 
 public void endTrans(){
  if(isUseTrans){
   try {
    con.commit();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
     this.closeConnection();
 }
 
 public void rollbackTrans(){
  if(isUseTrans){
   try {
    con.rollback();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
  this.closeConnection();
 }

 public void closeConnection() {
  try {
   if (con != null && !con.isClosed()) {
    con.close();
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
 }

 public void closeStatement(Statement s) {
  if (s != null) {
   try {
    s.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
 }

 public void closeResultSet(ResultSet rs) {
        if(rs!=null){
         try {
    rs.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
        }
 }

 public void readConfig() {
  Properties p = new Properties();
  try {
   p.load(this.getClass().getResourceAsStream("/" + configFilePath));
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }

  // 初始化
  this.driver = p.getProperty("driver");
  this.url = p.getProperty("url");
  this.username = p.getProperty("username");
  this.password = p.getProperty("password");
  
  System.out.println("qqqq"+this.driver);
  System.out.println("qqqq"+this.url);
  System.out.println("qqqq"+this.username);
  System.out.println("qqqq"+this.password);
 }
 
 
 
 
 public static void main(String[]args){
  DBHelper db=new DBHelper();
  db.readConfig();
  
 }

}

Proerties文件：DBConfig.properties

#Created by JInto - www.guh-software.de
#Tue Nov 20 16:06:28 CST 2007
driver=oracle.jdbc.driver.OracleDriver
password=xiaobo
url=jdbc:Oracle:thin:@127.0.0.1:1521:orcl
username=xiaobo

3.写一个VO：StuVO.java

package stu;

public class StuVO {
 private int id;
 private String name;
 private String sex;
 private String address;
 private String memo;
 public String getAddress() {
  return address;
 }
 public void setAddress(String address) {
  this.address = address;
 }
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getMemo() {
  return memo;
 }
 public void setMemo(String memo) {
  this.memo = memo;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public String getSex() {
  return sex;
 }
 public void setSex(String sex) {
  this.sex = sex;
 }
 

}
4.写一个DAO：StuDAO

package stu;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import db.DBHelper;

public class StuDAO {
 private DBHelper dbh;
 private Connection con;
 public StuDAO(DBHelper dbh) {
  super();
  this.dbh = dbh;
  this.con=this.dbh.getConnection();
 }
 
    public List getStu(){
     List list=new ArrayList();
     String sql="select id,name,sex,address,memo from student";
     try {
   PreparedStatement ps=con.prepareStatement(sql);
   ResultSet rs=ps.executeQuery();
   while(rs.next()){
    StuVO vo=new StuVO();
    vo.setId(rs.getInt("id"));
    vo.setAddress(rs.getString("address"));
    vo.setName(rs.getString("name"));
    vo.setSex(rs.getString("sex"));
    vo.setMemo(rs.getString("memo"));
    System.out.println(rs.getString("name"));
    list.add(vo);
    
   }
   
  } catch (SQLException e) {
   e.printStackTrace();
   System.out.println("预编译错误！");
  }
     
     
     return list;
    }
 
   
    public static void main(String[]args){
     DBHelper dbh=new DBHelper();
     StuDAO sd=new StuDAO(dbh);
     sd.getStu();
     
    }

}
5.写一个Servlet(Stunservlet.java)并配置web.xml

Stunservlet.java:

 package stu;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import db.DBHelper;

public class Stunservlet extends HttpServlet {

 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  this.doPost(request, response);

 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  String action =request.getParameter("action");
  if("query".equals(action)){
   DBHelper dbh=new DBHelper();
   StuDAO std=new StuDAO(dbh);
   dbh.beginTrans(false);
   List list=null;
   
   list=std.getStu();
   
   request.setAttribute("stulist", list);
   request.getRequestDispatcher("/test.jsp").forward(request, response);
  }

 }

}

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
 xmlns="http://java.sun.com/xml/ns/j2ee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
 http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <servlet>
    <servlet-name>Stunservlet</servlet-name>
    <servlet-class>stu.Stunservlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>Stunservlet</servlet-name>
    <url-pattern>/Stunservlet</url-pattern>
  </servlet-mapping>
</web-app>

5.jsp页面：test.jsp

在转向到test.jsp之前先建一个index.jsp用与进行转换：

index.jsp：

  <form action="<%=path%>/Stunservlet?action=query"  method="post">
  <input type="submit" value="转向" />
  </form>
  </body>

 

 

test.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
   
    <title>test</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>
<form>
<c:choose>
  <c:when test="${not empty requestScope.stulist}">
<table border="1" align="center">
   <tr>
     <td>ID</td>
     <td>姓名</td>
     <td>性别</td>
     <td>地址</td>
     <td>备注</td>
   </tr> 
   <c:forEach var="stu" items="${requestScope.stulist}">
     <tr>
     <td>${stu.id}</td>
     <td>${stu.name }</td>
     <td>${stu.sex }</td>
     <td>${stu.address}</td>
     <td>${stu.memo }</td>
     </tr>
   </c:forEach>
</table>
  </c:when>
  <c:otherwise>无记录</c:otherwise>
</c:choose>

</form>
  </body>
</html>