近期看老罗视频，做了一个简单的用户注冊系统。用户通过网页(JSP)输入用户名、真名和password，Servlet接收后通过JDBC将信息保存到MySQL中。尽管是个简单的不能再简单的东西，但麻雀虽小，五脏俱全，在此做一归纳和整理。以下先上源代码:
一、index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
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>
<title>后台管理系统</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>
<h1 align=center>欢迎您的注冊
</h1>
<br>
<font size="6"><a href="<%=path%>/pass.jsp"><font color="#0000ff">点击注冊 </font>
</a></font>
</body>
</html>
它的执行结果例如以下:
二、点击上面的“点击注冊”就跳转到了pass.jsp：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8" %>
<%
String path = request.getContextPath();
%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>后台管理系统</title>
<meta http-equiv=Content-Type content="text/html; charset=utf-8">
<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">
<style type="text/css">
.neon {
FILTER: glow(color = #002E60, strength = 3)
} DIV {
WIDTH: 70px
} BODY {
MARGIN: 0px
} BODY {
MARGIN-TOP: 0px;
SCROLLBAR-FACE-COLOR: #005fc5;
FONT-SIZE: 12px;
BACKGROUND: #ffffff;
SCROLLBAR-HIGHLIGHT-COLOR: #799ae1;
SCROLLBAR-SHADOW-COLOR: #799ae1;
SCROLLBAR-3DLIGHT-COLOR: #005fc5;
SCROLLBAR-ARROW-COLOR: #ffffff;
SCROLLBAR-TRACK-COLOR: #aabfec;
SCROLLBAR-DARKSHADOW-COLOR: #799ae1
}
</STYLE>
<LINK href="<%=path%>/images/duan_1.css" type=text/css rel=stylesheet>
<META content="MSHTML 6.00.2800.1106" name=GENERATOR>
<style type="text/css">
.style6 {
COLOR: #0000ff
} .STYLE7 {
COLOR: #003366;
font-size: 12px;
}
</style>
<script type="text/javascript">
function dosubmit() {
var th = document.form1;
if (th.username.value == "") {
alert("用户名不能为空");
th.username.focus();
return;
} if (th.realname.value == "") {
alert("姓名 不能为空");
th.realname.focus();
return;
} if (th.pswd.value == "") {
alert("password不能为空");
th.pswd.focus();
return;
}
th.action="<%=path%>/servlet/RegisterAction"
th.submit(); }
</script>
</head> <body bgColor=#ffffff
onload="MM_preloadImages('<%=path%>/images/ok_2.jpg', '<%=path%>/images/fh_2.jpg')">
<form action="" name="form1" method="post">
<table height=470 cellSpacing=0 cellPadding=0 width=580 aligen=center
border=0>
<tbody>
<tr>
<td colSpan=3 height=9 />
</tr>
<tr>
<td vAlign=top width=8 background="<%=path%>/images/dhpddw.gif"
rowSpan=2>
<!-- DWLayoutEmptyCell --> </td>
<td background="<%=path%>/images/h-1.gif" height=9></td>
<td width=9 height=9><IMG height=9
src="<%=path%>/images/jiao.gif" width=9>
</td>
</tr>
<tr>
<td vAlign=top align=right width=743 height=452>
<table cellSpacing=0 cellPadding=0 width=556 border=0>
<!-- DWLayoutTable -->
<tbody>
<tr>
<td vAligh=bottom width=548 height=27><IMG height=10
src="<%=path%>/images/jt2.gif" width=10> <span
class="1bt">用户注冊</span>
</td>
<td width=8 rowSpan=3> </td>
</tr>
<tr>
<td bgColor="#ffffff" height=22></td>
</tr>
<tr>
<td class=unnamed1 vAligh=top height=9>
<table width="99%" border=0 cellPadding=4 cellSpacing=1
bgColor="#0867b3">
<tbody>
<TR bgColor=#ffffff height=20>
<TD width=14% noWrap class="STYLE7">用户名</TD>
<TD width=24% valign="top" noWrap><INPUT class=text2
maxLength=20 size=18 name="username" minLength="1">
</TD>
<TD width=62% noWrap><span class="STYLE7">必须填写！</span>
</TD>
</TR>
<TR bgColor=#ffffff height=20>
<TD height="4" noWrap><span class="STYLE7">姓 名</span>
</TD>
<TD height="4" valign="top" noWrap><INPUT class=text2
maxLength=20 size=18 name="realname" minLength="1">
</TD>
<TD height="4" noWrap><span class="STYLE7">必须填写！</span>
</TD>
</TR>
<TR bgColor=#ffffff height=20>
<TD height="2" noWrap><span class="STYLE7">password </span>
</TD>
<TD height="2" valign="top" noWrap><INPUT
type="password" class=text2 maxLength=20 size=18
name="pswd" minLength="1">
</TD>
<TD height="2" noWrap><span class="STYLE7">必填项</span>
</TD>
</TR>
</tbody>
</table> <br>
</td>
</tr>
<TR>
<TD height=20 align="center"><a
href="javascript:dosubmit();"><img
src="<%=path%>/images/ok_1.jpg" name="Image8" width="60"
height="22" border="0"> </a> <a
href="<%=path%>/index.jsp"><img
src="<%=path%>/images/fh_1.jpg" name="Image9" width="60"
height="22" border="0"> </a>
</TD>
<TD></TD>
</TR>
</tbody>
</table>
</td>
<TD width=9 background="<%=path%>/images/s-1.gif"></TD>
</tr>
</tbody>
</table>
</form>
</body>
</html>
执行效果例如以下:
三、除上面两个jsp代码外，剩下的就是java代码了。先来看java代码的结构:
不得不说JavaWeb是一个绝好的理解MVC架构思想的载体，上述有四个包，每一个包以下一个文件。在功能的划分上有条不紊。
1、com.product.jdbc.dbutil 这个包里是基于jdbc驱动的一个工具类JdbcUtils.java,代码已经贴出来了，參见前文
2、com.product.register.action所谓的action扮演了MVC里的C的角色，即Control层，里面放的是各种Servlet。接收来自V(View)---客户端页面jsp回传的数据，然后调M层，把数据存进去。RegisterAction.java的代码:
package com.product.register.action; import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List; import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; import org.hibernate.validator.util.GetConstructor; import com.product.register.dao.RegisterDao;
import com.product.register.service.RegisterService; public class RegisterAction extends HttpServlet { /**
*
*/
private static final long serialVersionUID = 1L;
private RegisterService service; /**
* Constructor of the object.
*/
public RegisterAction() {
super();
} /**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
} /**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { this.doPost(request, response);
} /**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path = request.getContextPath();
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html; charset=utf-8");
PrintWriter out = response.getWriter();
String username = request.getParameter("username");
String realname = request.getParameter("realname");
String pswd = request.getParameter("pswd");
System.out.println("username = " + username + " realname = " + realname
+" pswd = " + pswd);
List<Object> params = new ArrayList<Object>();
params.add(username);
params.add(pswd);
params.add(realname);
boolean flag = service.registerUser(params);
if(flag){
out.println("注冊成功");
response.sendRedirect(path + "/index.jsp");
}else{
out.println("注冊失败");
}
out.flush();
out.close();
} /**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
service = new RegisterDao();
} }
3.com.product.register.service 这里的service事实上是一个接口，RegisterService.java代码:
package com.product.register.service;
import java.util.List;
public interface RegisterService {
public boolean registerUser(List<Object> params);
}
4.既然有接口就一定有接口的实现者，实现者就是com.product.register.dao下的RegisterDao.java, 负责操纵数据库，将信息存到表里。
package com.product.register.dao; import java.util.List; import com.product.jdbc.dbutil.JdbcUtils;
import com.product.register.service.RegisterService; public class RegisterDao implements RegisterService {
private JdbcUtils jdbcUtils = null;
public RegisterDao() {
// TODO Auto-generated constructor stub
jdbcUtils = new JdbcUtils();
} /* 完毕用户对注冊的Dao的编写
* @see com.product.register.service.RegisterService#registerUser(java.util.List)
*/
@Override
public boolean registerUser(List<Object> params) {
// TODO Auto-generated method stub
boolean flag = false;
jdbcUtils.getConnection();
String sql = "insert into userinfo(username, pswd, realname) values (?, ?, ?)";
try{
flag = jdbcUtils.updateByPreparedStatement(sql, params);
}catch(Exception e){
e.printStackTrace();
}
finally{
jdbcUtils.releaseConn();
} return flag;
} }
下图是输入一个用户的信息:
用Navicat打开数据库能够看到:
代码就完毕了，以下是开发要点:
1、关于中文乱码的问题，按老罗的视频一開始我的也乱码，经研究须要三个地方同一时候设置utf-8编码，第一是数据库里表的编码，第二是jsp的编码：pageEncoding="utf-8" 第三是在Servlet里同一时候设置response和request的编码，代码例如以下:
request.setCharacterEncoding("utf-8");
response.setContentType("text/html; charset=utf-8"); 记住是缺一不可哦！！！
2、关于JSP往JSP页面的跳转非常easy:
<a href="<%=path%>/pass.jsp">点击注冊</a> 超链接里直接放要跳转jsp的相对路径就可以。
3、JSP往Servlet跳转:
<a href="javascript:dosubmit();">
<img src="<%=path%>/images/ok_1.jpg" name="Image8" width="60" height="22" border="0"> </a>
也是用的href超链接，在地址里写"javascript:dosubmit();". 这就须要定义dosubmit()函数：
<script type="text/javascript">
function dosubmit() {
var th = document.form1;
if (th.username.value == "") {
alert("用户名不能为空");
th.username.focus();
return;
} if (th.realname.value == "") {
alert("姓名 不能为空");
th.realname.focus();
return;
} if (th.pswd.value == "") {
alert("password不能为空");
th.pswd.focus();
return;
}
th.action="<%=path%>/servlet/RegisterAction"
th.submit(); }
</script>
获得一个表单，然后依据input时的名字获取相应value，
<INPUT class=text2 maxLength=20 size=18 name="username" minLength="1">
4、上面能够看到jsp往servlet跳转过程中先经过javascript，接下来说白了是javascript往servlet跳转:
th.action="<%=path%>/servlet/RegisterAction"
th.submit();
5、Servlet往jsp跳转:
response.sendRedirect(path + "/index.jsp");这样的方法浏览器地址发生变化，传參数能够再URL地址里或用session，不能使用request.setAttribute来传參数。还有一种使用forward来传，具体參见这里: 链接1 链接2
6、纵观整个架构，RegisterAction是控制中枢，数据经jsp----javascript传到RegisterAction。在RegisterAction里创建了接口Service的实例RegisterDao，用Dao来存数据。
关于javaEE的各层分工，详见这里
7.由于要訪问数据库，记得将mysql-connector-java-5.1.26-bin.jar复制到WebRoot目录下的WEB-INF/lib目录下。
另外在web.xml里要配对，jsp里用到了css。其它的细节看源代码吧。