Java Workshop--(4)WEB系统设计篇

在这个练习里，我们用一个Servlet、一个Javabean和两个Jsp来实现一个基本的WEB系统框架。不涉及一些具体模式的说明。可以说是一个系统的小小的架构，说起架构不知道大家对架构的定义是怎么想的，架构等于高层设计嘛？有一个网站说架构等于组件和连接器，并定义了一种架构语言（ADL）。不过设计模式不同于架构，但是象MVC这样的模式来说可以算是一个小系统的架构吧。
这里系统的流程是这样的，当Servlet接受了一个Get请求的时候，创建一个Bean对象，把它存储在一个session里面，调用Get.jsp。当Servlet接受了一个Post请求的时候，它找到Bean对象的Session，然后显示一个Post.jsp。我们先来看一下Servelt的代码：

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class StaffServlet extends javax/servlet/http/HttpServlet.java.html" target="_blank">HttpServlet {
public void doGet(javax/servlet/http/HttpServletRequest.java.html" target="_blank">HttpServletRequest req, javax/servlet/http/HttpServletResponse.java.html" target="_blank">HttpServletResponse res)
throws java/io/IOException.java.html" target="_blank">IOException, javax/servlet/ServletException.java.html" target="_blank">ServletException
{
StaffBean bean = new StaffBean();
bean.setID("10");
bean.setName("Sanders");
javax/servlet/http/HttpSession.java.html" target="_blank">HttpSession session = req.getSession(true);
session.setAttribute("staffBean", bean);
javax/servlet/ServletContext.java.html" target="_blank">ServletContext ctxt = getServletContext();
javax/servlet/RequestDispatcher.java.html" target="_blank">RequestDispatcher rd = ctxt.getRequestDispatcher("/jsp/Get.jsp");
if(rd != null){
rd.forward(req, res);
}
}
public void doPost(javax/servlet/http/HttpServletRequest.java.html" target="_blank">HttpServletRequest req, javax/servlet/http/HttpServletResponse.java.html" target="_blank">HttpServletResponse res)
throws java/io/IOException.java.html" target="_blank">IOException, javax/servlet/ServletException.java.html" target="_blank">ServletException
{
javax/servlet/http/HttpSession.java.html" target="_blank">HttpSession session = req.getSession(true);
StaffBean bean = (StaffBean)session.getAttribute("staffBean");
bean.setDept("SERVICE DIV.");
bean.setJob("ITS");
bean.setYears("7");
javax/servlet/ServletContext.java.html" target="_blank">ServletContext ctxt = getServletContext();
javax/servlet/RequestDispatcher.java.html" target="_blank">RequestDispatcher rd = ctxt.getRequestDispatcher("/jsp/Post.jsp");
if(rd != null){
rd.forward(req, res);
}
}
}

这里用了forward这个方法来吧请求forward到另外的资源中，这里我们用了jsp文件。
然后定义两个jsp文件
get.jsp

<html>
<body>
<form>
<jsp:useBean id="staffBean" class="StaffBean" scope="session" />
<table border="1">
<tbody>
<tr>
<td width="120">Employee ID</td>
<td width="100">Name</td>
</tr>
<tr>
<td><jsp:getProperty name="staffBean" property="ID" /></td>
<td><jsp:getProperty name="staffBean" property="name" /></td>
</tr>
</tbody>
</table>
<form action="/servlet/StaffServlet" method="POST">
<input type=submit value="Detail">
</form>
</body>
</html>
post.jsp
<jsp:useBean id="staffBean" class="jpc.StaffBean" scope="session" />
<table border="1"><tbody>
<tr>
<td width="120">Employee ID</td>
<td width="100">Name</td>
<td width="100">Department</td>
<td width="50">Job Title</td>
<td width="200">Years of Continuous Employment</td>
</tr>
<tr>
<td><jsp:getProperty name="staffBean" property="ID" /></td>
<td><jsp:getProperty name="staffBean" property="name" /></td>
<td><jsp:getProperty name="staffBean" property="dept" /></td>
<td><jsp:getProperty name="staffBean" property="job" /></td>
<td><jsp:getProperty name="staffBean" property="years" /></td>
</tr>
</tbody></table>

这里是java 文件：

public class StaffBean {
private java/lang/String.java.html" target="_blank">String ID;
private java/lang/String.java.html" target="_blank">String name;
private java/lang/String.java.html" target="_blank">String dept;
private java/lang/String.java.html" target="_blank">String job;
private java/lang/String.java.html" target="_blank">String years;
public StaffBean () {
}
public java/lang/String.java.html" target="_blank">String getID() {
return ID;
}
public void setID(java/lang/String.java.html" target="_blank">String str) {
ID = str;
}
public java/lang/String.java.html" target="_blank">String getName() {
return name;
}
public void setName(java/lang/String.java.html" target="_blank">String str) {
name = str;
}
public java/lang/String.java.html" target="_blank">String getDept() {
return dept;
}
public void setDept(java/lang/String.java.html" target="_blank">String str) {
dept = str;
}
public java/lang/String.java.html" target="_blank">String getJob() {
return job;
}
public void setJob(java/lang/String.java.html" target="_blank">String str) {
job = str;
}
public java/lang/String.java.html" target="_blank">String getYears() {
return years;
}
public void setYears(java/lang/String.java.html" target="_blank">String str) {
years = str;
}
}

这个例子比较简单，不过本人觉得对于刚刚起步学java web开发的人有一定的参考价值，没有数据库，直接把四个文件放到tomcat相应的目录中就可以执行了。虽然在页面上永远看到的是一个Servlet，其他的文件都是用这个servlet来调用。Jsp的页面页比较整洁，没有过多的<%%>代码和html混合在一起。一个对象的所有属性的设置和取出均用Databean的各个方法来实现。