好吧，学过的东西很快就忘记了，并且这都是一些基本的东西。这怎么能行呢，为了加深印象，自己好好在学习总结一下。JSP+JavaBean技术在我以前做过的一个留言板中用到，那是一次较为完整的开发，所以就拿这个学习吧！在这一次的实习作品中可能会用到，所以想起来复习一下了。
+================================================================================================+
JSP+JavaBean的留言板技术
下面附上源代码以方便学习：
Messages.html <HTML><HEAD> <TITLE> message board </TITLE></HEAD> <BODY> <center>留言板</center> <FORM action="addMessage.jsp" > <TABLE border=1 align="center"> <TR><TD>姓名：</TD><TD><input type="text" name="name" size=25> </TD></TR> <TR><TD>E-mail：</TD> <TD><input type="text" name="email" size=25></TD></TR> <TR><TD>主题：</TD> <TD><input type="text" name="title" size=25></TD></TR> <TR><TD>留言：</TD> <TD><textarea name="content" rows=7 cols=25></textarea> </TD></TR> <TR><TD colspan=3> <TABLE align="center" width="100%" cellspacing="0" cellpadding="0" > <TR> <TD align="center"><input type="submit" value="提交留言"></TD> <TD align="center"> <a href="viewMessages.jsp"><font size=2>查看留言</font></a></TD> <TD align="center"><input type="reset" value="重新填写"></TD> </TR></TABLE></TD> </TR></TABLE></FORM></BODY></HTML>
MessageData.java
package message;
public class MessageData
{ private String name,email,title,content;
//setter或者getter方法
public void setName(String name){this.name=name;}
public void setEmail(String email){ this.email=email;}
public void setTitle(String title){ this.title=title;}
public void setContent(String content){this.content=content;}
public String getName(){ return this.name;}
public String getContent(){ return this.content;}
public String getTitle(){ return this.title;}
public String getEmail(){ return this.email;}}
viewMessages.jsp
<%@ page contentType="text/html; charset=GBK" import="message.MessageData" %>
<%@ page import="java.util.*"%>
<jsp:useBean id="myBean" class="message.MessageBean" scope="page"/>
<HTML><HEAD><TITLE> show the message in the table </TITLE></HEAD>
<BODY><p align="center">所有留言</p>
<TABLE align="center" width="80%" border=1 >
<%
int message_count=0;
Collection <MessageData> messages=myBean.getAllMessage();
Iterator <MessageData> it=messages.iterator();
while(it.hasNext()){ MessageData mg=(MessageData)it.next();
%>
<tr>
<td width="20%">留言人:</td>
<td width="23%"><%=mg.getName()%></td>
<td width="58%" align="center"><% out.println(
"<a href=mailto:"+mg.getEmail()+">"+mg.getEmail()+"</a>");
%></td></tr>
<tr>
<td width="20%">主题:</td>
<td colspan="3"><%=mg.getTitle()%></td>
</tr>
<tr>
<td width="20%">内容:</td>
<td colspan="3"><%=mg.getContent()%></td>
</tr>
<% message_count++;
}
%>
</Table>
<p align="center"><a href="Messages.html">我要留言</a></p>
</body></html>
addMessage.jsp
<%@ page language="java" contentType="text/html; charset=GBK"
pageEncoding="GBK"%>
<jsp:useBean id="Mdata" class="message.MessageData" scope="page">
<jsp:setProperty name="Mdata" property="*"/></jsp:useBean>
<jsp:useBean id="myBean" class="message.MessageBean" scope="page"/>
<HTML><HEAD><TITLE> message into table </TITLE></HEAD>
<BODY>
<% try { myBean.setMessage(Mdata); myBean.addMessage(); }
catch(Exception e) { e.printStackTrace();}
%>
<jsp:forward page="viewMessages.jsp" />
</body></html>
MessageData.java
package message;
public class MessageData
{ private String name,email,title,content;
//setter或者getter方法
public void setName(String name){this.name=name;}
public void setEmail(String email){ this.email=email;}
public void setTitle(String title){ this.title=title;}
public void setContent(String content){this.content=content;}
public String getName(){ return this.name;}
public String getContent(){ return this.content;}
public String getTitle(){ return this.title;}
public String getEmail(){ return this.email;}}
MessageBean.java
package message;
import java.sql.*; //引入java.sql包
import java.util.*;
public class MessageBean {
private Connection con; MessageData msg;
public MessageBean()
{ String JDriver="com.mysql.jdbc.Driver"; //定义驱动程序对象
String userName="root"; //定义数据库用户名
String userPasswd=""; //定义数据库存取密码
String dbName="message"; //定义数据库名
String conURL="jdbc:mysql://localhost:3306/"+dbName;
try{Class.forName(JDriver).newInstance(); //加载JDBC驱动程序
con=DriverManager.getConnection(conURL,userName,userPasswd);
//连接数据库
}
catch(Exception e){System.err.println(e.getMessage());}
}
public void setMessage(MessageData msg) {this.msg=msg;}
// 添加一条留言消息
public void addMessage()throws Exception
{ try{ byte b1[]=msg.getTitle().getBytes("ISO-8859-1");
String ti=new String(b1);
byte b2[]=msg.getName().getBytes("ISO-8859-1");
String na=new String(b2);
byte b3[]=msg.getEmail().getBytes("ISO-8859-1");
String em=new String(b3);
byte b4[]=msg.getContent().getBytes("ISO-8859-1");
String c=new String(b4);
PreparedStatement stm=con.prepareStatement(
"insert into messagetable values(?,?,?,?)");
stm.setString(1,ti); stm.setString(2,na);
if((msg.getEmail()).length()==0)stm.setString(3,"");
else stm.setString(3,em);
stm.setString(4,c);
try {stm.execute(); stm.close(); }
catch(Exception e) { }
con.close(); //关闭数据库连接
}
catch(Exception e){ e.printStackTrace(); throw e;}
}
// 获得所有留言消息，并返回结果到JSP页面
public Collection<MessageData> getAllMessage()throws Exception
{ Collection<MessageData> ret=new ArrayList<MessageData>();
try{ Statement stm=con.createStatement();
ResultSet result=stm.executeQuery(
"select count(*) from messagetable");
int message_count=0;
if(result.next()){ message_count=result.getInt(1);
result.close(); }
if(message_count>0)
{ result=stm.executeQuery("select * from messagetable ");
while(result.next())
{ String title=result.getString("title");
String name=result.getString("name");
String email=result.getString("email");
String content=result.getString("content");
MessageData message=new MessageData();
message.setTitle(title); message.setName(name);
message.setEmail(email); message.setContent(content);
ret.add(message);
}
result.close(); stm.close();
}
con.close();
}
catch(Exception e)
{ e.printStackTrace(); throw e; }
return ret;
}
}
功能简单的留言板，但是清楚的说明了JSP+JavaBean技术的运用，相信这一个例子可以帮助我们更清楚地掌握该技术的原理。