java模糊查询案例（附源码）

   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>