这是一个基于MVC+DAO的留言管理系统，包含增删改查，其中查询，有全部查询和按关键字进行模糊查询的功能。文章底部附件是源码程序。大家共同学习，共同进步。具体如下：
NoteDAO.java
package cn.mldn.lxh.note.dao ;
import java.util.* ;
import cn.mldn.lxh.note.vo.* ;
public interface NoteDAO
{
// 增加操作
public void insert(Note note) throws Exception ;
// 修改操作
public void update(Note note) throws Exception ;
// 删除操作
public void delete(int id) throws Exception ;
// 按ID查询，主要为更新使用
public Note queryById(int id) throws Exception ;
// 查询全部
public List queryAll() throws Exception ;
// 模糊查询
public List queryByLike(String cond) throws Exception ;
};
NoteDAOImpl.java
package cn.mldn.lxh.note.dao.impl ;
import java.sql.* ;
import java.util.* ;
import cn.mldn.lxh.note.vo.* ;
import cn.mldn.lxh.note.dao.* ;
import cn.mldn.lxh.note.dbc.* ;
public class NoteDAOImpl implements NoteDAO
{
// 增加操作
public void insert(Note note) throws Exception
{
String sql = "INSERT INTO note(id,title,author,content) VALUES(note_sequ.nextVal,?,?,?)" ;
PreparedStatement pstmt = null ;
DataBaseConnection dbc = null ;
dbc = new DataBaseConnection() ;
try
{
pstmt = dbc.getConnection().prepareStatement(sql) ;
pstmt.setString(1,note.getTitle()) ;
pstmt.setString(2,note.getAuthor()) ;
pstmt.setString(3,note.getContent()) ;
pstmt.executeUpdate() ;
pstmt.close() ;
}
catch (Exception e)
{
// System.out.println(e) ;
throw new Exception("操作中出现错误！！！") ;
}
finally
{
dbc.close() ;
}
}
// 修改操作
public void update(Note note) throws Exception
{
String sql = "UPDATE note SET title=?,author=?,content=? WHERE id=?" ;
PreparedStatement pstmt = null ;
DataBaseConnection dbc = null ;
dbc = new DataBaseConnection() ;
try
{
pstmt = dbc.getConnection().prepareStatement(sql) ;
pstmt.setString(1,note.getTitle()) ;
pstmt.setString(2,note.getAuthor()) ;
pstmt.setString(3,note.getContent()) ;
pstmt.setInt(4,note.getId()) ;
pstmt.executeUpdate() ;
pstmt.close() ;
}
catch (Exception e)
{
throw new Exception("操作中出现错误！！！") ;
}
finally
{
dbc.close() ;
}
}
// 删除操作
public void delete(int id) throws Exception
{
String sql = "DELETE FROM note WHERE id=?" ;
PreparedStatement pstmt = null ;
DataBaseConnection dbc = null ;
dbc = new DataBaseConnection() ;
try
{
pstmt = dbc.getConnection().prepareStatement(sql) ;
pstmt.setInt(1,id) ;
pstmt.executeUpdate() ;
pstmt.close() ;
}
catch (Exception e)
{
throw new Exception("操作中出现错误！！！") ;
}
finally
{
dbc.close() ;
}
}
// 按ID查询，主要为更新使用
public Note queryById(int id) throws Exception
{
Note note = null ;
String sql = "SELECT id,title,author,content FROM note WHERE id=?" ;
PreparedStatement pstmt = null ;
DataBaseConnection dbc = null ;
dbc = new DataBaseConnection() ;
try
{
pstmt = dbc.getConnection().prepareStatement(sql) ;
pstmt.setInt(1,id) ;
ResultSet rs = pstmt.executeQuery() ;
if(rs.next())
{
note = new Note() ;
note.setId(rs.getInt(1)) ;
note.setTitle(rs.getString(2)) ;
note.setAuthor(rs.getString(3)) ;
note.setContent(rs.getString(4)) ;
}
rs.close() ;
pstmt.close() ;
}
catch (Exception e)
{
throw new Exception("操作中出现错误！！！") ;
}
finally
{
dbc.close() ;
}
return note ;
}
// 查询全部
public List queryAll() throws Exception
{
List all = new ArrayList() ;
String sql = "SELECT id,title,author,content FROM note" ;
PreparedStatement pstmt = null ;
DataBaseConnection dbc = null ;
dbc = new DataBaseConnection() ;
try
{
pstmt = dbc.getConnection().prepareStatement(sql) ;
ResultSet rs = pstmt.executeQuery() ;
while(rs.next())
{
Note note = new Note() ;
note.setId(rs.getInt(1)) ;
note.setTitle(rs.getString(2)) ;
note.setAuthor(rs.getString(3)) ;
note.setContent(rs.getString(4)) ;
all.add(note) ;
}
rs.close() ;
pstmt.close() ;
}
catch (Exception e)
{
System.out.println(e) ;
throw new Exception("操作中出现错误！！！") ;
}
finally
{
dbc.close() ;
}
return all ;
}
// 模糊查询
public List queryByLike(String cond) throws Exception
{
List all = new ArrayList() ;
String sql = "SELECT id,title,author,content FROM note WHERE title LIKE ? or AUTHOR LIKE ? or CONTENT LIKE ?" ;
PreparedStatement pstmt = null ;
DataBaseConnection dbc = null ;
dbc = new DataBaseConnection() ;
try
{
pstmt = dbc.getConnection().prepareStatement(sql) ;
pstmt.setString(1,"%"+cond+"%") ;
pstmt.setString(2,"%"+cond+"%") ;
pstmt.setString(3,"%"+cond+"%") ;
ResultSet rs = pstmt.executeQuery() ;
while(rs.next())
{
Note note = new Note() ;
note.setId(rs.getInt(1)) ;
note.setTitle(rs.getString(2)) ;
note.setAuthor(rs.getString(3)) ;
note.setContent(rs.getString(4)) ;
all.add(note) ;
}
rs.close() ;
pstmt.close() ;
}
catch (Exception e)
{
System.out.println(e) ;
throw new Exception("操作中出现错误！！！") ;
}
finally
{
dbc.close() ;
}
return all ;
}
};
NoteServlet.java
package cn.mldn.lxh.note.servlet ;
import java.io.* ;
import javax.servlet.* ;
import javax.servlet.http.* ;
import cn.mldn.lxh.note.factory.* ;
import cn.mldn.lxh.note.vo.* ;
public class NoteServlet extends HttpServlet
{
public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException
{
this.doPost(request,response) ;
}
public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException
{
request.setCharacterEncoding("GB2312") ;
String path = "errors.jsp" ;
// 接收要操作的参数值
String status = request.getParameter("status") ;
if(status!=null)
{
// 参数有内容，之后选择合适的方法
// 查询全部操作
if("selectall".equals(status))
{
try
{
request.setAttribute("all",DAOFactory.getNoteDAOInstance().queryAll()) ;
}
catch (Exception e)
{
}
path = "list_notes.jsp" ;
}
// 插入操作
if("insert".equals(status))
{
// 1、接收插入的信息
String title = request.getParameter("title") ;
String author = request.getParameter("author") ;
String content = request.getParameter("content") ;
// 2、实例化VO对象
Note note = new Note() ;
note.setTitle(title) ;
note.setAuthor(author) ;
note.setContent(content) ;
// 3、调用DAO完成数据库的插入操作
boolean flag = false ;
try
{
DAOFactory.getNoteDAOInstance().insert(note) ;
flag = true ;
}
catch (Exception e)
{}
request.setAttribute("flag",new Boolean(flag)) ;
path = "insert_do.jsp" ;
}
// 按ID查询操作，修改之前需要将数据先查询出来
if("selectid".equals(status))
{
// 接收参数
int id = 0 ;
try
{
id = Integer.parseInt(request.getParameter("id")) ;
}
catch(Exception e)
{}
try
{
request.setAttribute("note",DAOFactory.getNoteDAOInstance().queryById(id)) ;
}
catch (Exception e)
{
}
path = "update.jsp" ;
}
// 更新操作
if("update".equals(status))
{
int id = 0 ;
try
{
id = Integer.parseInt(request.getParameter("id")) ;
}
catch(Exception e)
{}
String title = request.getParameter("title") ;
String author = request.getParameter("author") ;
String content = request.getParameter("content") ;
Note note = new Note() ;
note.setId(id) ;
note.setTitle(title) ;
note.setAuthor(author) ;
note.setContent(content) ;
boolean flag = false ;
try
{
DAOFactory.getNoteDAOInstance().update(note) ;
flag = true ;
}
catch (Exception e)
{}
request.setAttribute("flag",new Boolean(flag)) ;
path = "update_do.jsp" ;
}
// 模糊查询
if("selectbylike".equals(status))
{
String keyword = request.getParameter("keyword") ;
try
{
request.setAttribute("all",DAOFactory.getNoteDAOInstance().queryByLike(keyword)) ;
}
catch (Exception e)
{
}
path = "list_notes.jsp" ;
}
// 删除操作
if("delete".equals(status))
{
// 接收参数
int id = 0 ;
try
{
id = Integer.parseInt(request.getParameter("id")) ;
}
catch(Exception e)
{}
boolean flag = false ;
try
{
DAOFactory.getNoteDAOInstance().delete(id) ;
flag = true ;
}
catch (Exception e)
{}
request.setAttribute("flag",new Boolean(flag)) ;
path = "delete_do.jsp" ;
}
}
else
{
// 则表示无参数，非法的客户请求
}
request.getRequestDispatcher(path).forward(request,response) ;
}
};
/*
<servlet>
<servlet-name>note</servlet-name>
<servlet-class>cn.mldn.lxh.note.servlet.NoteServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>note</servlet-name>
<url-pattern>/note/note_mvc/Note</url-pattern>
</servlet-mapping>
*/
list_notes.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.util.*"%>
<%@ page import="cn.mldn.lxh.note.vo.*"%>
<html>
<head>
<title>MVC+DAO 留言管理程序——登陆</title>
</head>
<body>
<center>
<h1>留言管理范例 —— MVC + DAO实现</h1>
<hr>
<br>
<%
// 编码转换
request.setCharacterEncoding("GB2312") ;
if(session.getAttribute("uname")!=null)
{
// 用户已登陆
%>
<%
// 如果有内容，则修改变量i，如果没有，则根据i的值进行无内容提示
int i = 0 ;
String keyword = request.getParameter("keyword") ;
List all = null ;
all = (List)request.getAttribute("all") ;
%>
<form action="Note" method="POST">
请输入查询内容：<input type="text" name="keyword">
<input type="hidden" name="status" value="selectbylike">
<input type="submit" value="查询">
</form>
</h3><a href="insert.jsp">添加新留言</a></h3>
<table width="80%" border="1">
<tr>
<td>留言ID</td>
<td>标题</td>
<td>作者</td>
<td>内容</td>
<td>删除</td>
</tr>
<%
Iterator iter = all.iterator() ;
while(iter.hasNext())
{
Note note = (Note)iter.next() ;
i++ ;
// 进行循环打印，打印出所有的内容，以表格形式
// 从数据库中取出内容
int id = note.getId() ;
String title = note.getTitle() ;
String author = note.getAuthor() ;
String content = note.getContent() ;
// 因为要关键字返红，所以此处需要接收查询关键字
// String keyword = request.getParameter("keyword") ;
if(keyword!=null)
{
// 需要将数据返红
title = title.replaceAll(keyword,"<font color=\"red\">"+keyword+"</font>")
;
author = author.replaceAll(keyword,"<font color=\"red\">"+keyword
+"</font>") ;
content = content.replaceAll(keyword,"<font color=\"red\">"+keyword
+"</font>") ;
}
%>
<tr>
<td><%=id%></td>
<td><a href="Note?id=<%=id%>&status=selectid"><%=title%></a></td>
<td><%=author%></td>
<td><%=content%></td>
<td><a href="Note?id=<%=id%>&status=delete">删除</a></td>
</tr>
<%
}
// 判断i的值是否改变，如果改变，则表示有内容，反之，无内容
if(i==0)
{
// 进行提示
%>
<tr>
<td colspan="5">没有任何内容！！！</td>
</tr>
<%
}
%>
</table>
<%
}
else
{
// 用户未登陆，提示用户登陆，并跳转
response.setHeader("refresh","2;URL=login.jsp") ;
%>
您还未登陆，请先登陆！！！<br>
两秒后自动跳转到登陆窗口！！！<br>
如果没有跳转，请按<a href="login.jsp">这里</a>！！！<br>
<%
}
%>
</center>
</body>
</html>