利用java编写一个留言板功能

Messages.html 
  
 留言板 
 
 
 
 
姓名：
 
  
 
 
E-mail：
 
  
 
 
主题：
 
  
 
  
留言：
 
  
 
  
 
  
 
 
  
 
   
 
  
 
  查看留言
 
  
 
  
 
?
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.*"%> 
 
 
所有留言
 
  
 <%   
  int message_count=0; 
  Collection  messages=myBean.getAllMessage(); 
  Iterator  it=messages.iterator(); 
  while(it.hasNext()){ MessageData mg=(MessageData)it.next();   
 %> 
   
  <% message_count++; 
 }  
  %> 
 
 
    
留言人:
 
    
<%=mg.getName()%>
 
    
<% out.println( 
  ""+mg.getEmail()+""); 
%>
 
  
 
    
主题:
 
    
<%=mg.getTitle()%>
 
  
 
  
 
    
内容:
 
    
<%=mg.getContent()%>
 
  
 
我要留言
 

?
addMessage.jsp 
<%@ page language="java" contentType="text/html; charset=GBK"
  pageEncoding="GBK"%> 
 
   
 
 
 
<% try { myBean.setMessage(Mdata);  myBean.addMessage(); } 
  catch(Exception e) { e.printStackTrace();} 
%> 
 

?
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 getAllMessage()throws Exception 
  { Collection ret=new ArrayList(); 
  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; 
  } 
}