用设计模式开发J2EE系统

package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import org.apache.jasper.runtime.*;
public class HelloWorld_jsp extends HttpJspBase {
......
public void _jspService(HttpServletRequest request,
HttpServletResponse response)throws java.io.IOException, ServletException
{
JspFactory _jspxFactory = null;
javax.servlet.jsp.PageContext pageContext = null;
HttpSession session = null;
ServletContext application = null;
ServletConfig config = null;
JspWriter out = null;
Object page = this;
JspWriter _jspx_out = null;
try {
_jspxFactory = JspFactory.getDefaultFactory();
response.setContentType("text/html;charset=ISO-8859-1");
pageContext = _jspxFactory.getPageContext(this, request, response,null, true, 8192, true);
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();
_jspx_out = out;
//执行JSP中的JAVA代码
……
//把JSP中的HTML代码输出到out对象中
out.print(……);
} catch (Throwable t) {
out = _jspx_out;
if (out != null && out.getBufferSize() != 0)
out.clearBuffer();
if (pageContext != null) pageContext.handlePageException(t);
} finally {
if (_jspxFactory != null) _jspxFactory.releasePageContext(pageContext);
}
}
}

二　传统的设计方法及其弊端

<html>
<%@ page contentType="text/html;charset=gb2312"%>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>实例首页</title>
</head>
<body>
<table border="0" width="100%">
<tr> <td><div align="center">
<a href="showallarticle.jsp">显示文章</a> <!—代码（1）-->
</div></td></tr>
</table>
</body>
</html>

<html>
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.util.*, java.lang.*,java.sql.*,javax.sql.*,org.dnxh.CommentItem"%>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>显示文章</title>
</head>
<body>
<%
<!—代码（2）-->
Connection conn=null;
String con_user = "example1";
String con_password = "example1";
String con_dburl = "jdbc:oracle:thin:@localhost:iasdb";
String con_driver = "oracle.jdbc.driver.OracleDriver";
PreparedStatement pstmt=null;
ResultSet rsComment=null;
Vector vectorComment = new Vector();
String selectSQL= "SELECT content, time\n" +
"FROM article ORDER BY time DESC";
try
{
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
Class.forName(con_driver);
conn = DriverManager.getConnection(con_dburl,con_user,con_password);
pstmt=conn.prepareStatement(selectSQL);
rsComment=pstmt.executeQuery();
while(rsComment.next())
{
CommentItem commentItem = new CommentItem();
commentItem.setContent(rsComment.getString(1));
commentItem.setTime(rsComment.getDate(2));
vectorComment.add(commentItem);
}
vectorComment.trimToSize();
}
catch (Exception e){}
%>
<table border="0" width="100%">
<tr>
<td>发表时间</td>
<td>文章内容</td>
</tr>
<%
if (vectorComment!=null && vectorComment.size()>0)
{
int counter=vectorComment.size();
CommentItem commentlist = null;
for (int i=0;i<counter;i++)
{
commentlist=null;
commentlist=(CommentItem)(vectorComment.get(i));
%>
<tr>
<td><%=commentlist.getCmTime()%></td>
<td><%=commentlist.getCmContent()%></td>
</tr>
<%
}
}
%>
</table>
</body>
</html>

package org.dnxh;
import java.util.Date;
public class CommentItem
{
private String cmContent; //评论内容
private java.sql.Date cmTime; //评论时间
public CommentItem() {
this.content="";
this.time=null;
}
/**
* 设置评论内容
*/
public void setContent(String content)
{this.content = content;};
/**
* 取得评论内容
*/
public String getContent()
{return content;};
/**
* 设置评论时间
*/
public void setTime(java.sql.Date time)
{this.time=ctime;};
/**
* 取得评论时间
*/
public java.sql.Date getTime()
{return time;};
}

二 传统的设计方法及其弊端

二　传统的设计方法及其弊端