java留言管理系统中模糊查询实例分享

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 ; }; 

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 ;   } }; 

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> */ 

<%@ 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>