实习总结（十五）---JSP+JavaBean实现留言板
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。
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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.javapackage 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.javapackage 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.javapackage 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。