java留言管理系统中模糊查询实例分享

本文分享了一个基于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，具体内容如下
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>

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