Jweb 简化代码（封装）
赫连越
前面我们写了一整个新闻项目，里面有 用户登录，用户注册及新闻数据的维护（增，删，改查），我们所写的这个项目核心的文件的后缀名为 jsp，里面包含了很多代码，看着呢蛮复杂。
用形象的话来比喻说：我们有同一个衣柜，里面放了衣服，裤子，鞋子，袜子，围巾，帽子等等，很多，也比较杂乱，找起来也特别不方便，而现在呢，我们决定分类简化（封装），把衣服，裤子放在一个大的抽屉里，为衣裤间，围巾和帽子放在另一个中间的抽屉，为戴饰间，等 ，合理分配。
在这个项目里，我们也来了一波简化（封装），在JavaResources的src 下有三个包，分别为：entity:实体类：对象
util:帮助类：连接数据库的一套操作
dao:方法体：写方法 ！！！
admin.jsp :运行的界面。
我们就以新闻admin界面的模糊查询举例：
admin.jsp模糊查询
1.DBHelper( util包 帮助类)
package util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import oracle.jdbc.driver.OracleDriver;
public class DBHelper {
private static String user="scott";
private static String upwd="tiger";
private static String cname="oracle.jdbc.driver.OracleDriver";
private static String url="jdbc:oracle:thin:@localhost:1521:orcl";
static {
try {
Class.forName(cname);
}catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
}
public static Connection getCon() {
Connection con=null;
try {
con=DriverManager.getConnection(url,user,upwd);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return con;
}
public static void closeDb(Connection con,PreparedStatement ps,ResultSet rs) {
try {
if(con!=null) {
con.close();
}
if(ps!=null) {
con.close();
}
if(rs!=null) {
con.close();
}
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
}
public static int getNext(String tablename,String col) {
int id=1;
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("select max("+col+") from +tablename");
rs=ps.executeQuery();
if(rs.next()) {
id=rs.getInt(1)+1;
}
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return id;
}
}
2.News(entity包)新闻实体类
package entity;
import java.sql.Date;
public class News {
private int nid;
private int tid;
private String ntitle;
private String nzz;
private String ncr;
private String look;
private String nzy;
private String npic;
private Date ndate;
public News(int nid, int tid, String ntitle, String nzz, String ncr, String look, String nzy, String npic) {
super();
this.nid = nid;
this.tid = tid;
this.ntitle = ntitle;
this.nzz = nzz;
this.ncr = ncr;
this.look = look;
this.nzy = nzy;
this.npic = npic;
}
public int getNid() {
return nid;
}
public void setNid(int nid) {
this.nid = nid;
}
public int getTid() {
return tid;
}
public void setTid(int tid) {
this.tid = tid;
}
public String getNtitle() {
return ntitle;
}
public void setNtitle(String ntitle) {
this.ntitle = ntitle;
}
public String getNzz() {
return nzz;
}
public void setNzz(String nzz) {
this.nzz = nzz;
}
public String getNcr() {
return ncr;
}
public void setNcr(String ncr) {
this.ncr = ncr;
}
public Date getNdate() {
return ndate;
}
public void setNdate(Date ndate) {
this.ndate = ndate;
}
public String getLook() {
return look;
}
public void setLook(String look) {
this.look = look;
}
public String getNzy() {
return nzy;
}
public void setNzy(String nzy) {
this.nzy = nzy;
}
public String getNpic() {
return npic;
}
public void setNpic(String npic) {
this.npic = npic;
}
public News(int nid, int tid, String ntitle, String nzz, String ncr, Date ndate, String look, String nzy,
String npic) {
super();
this.nid = nid;
this.tid = tid;
this.ntitle = ntitle;
this.nzz = nzz;
this.ncr = ncr;
this.ndate = ndate;
this.look = look;
this.nzy = nzy;
this.npic = npic;
}
public News() {
super();
}
public News(int tid, String ntitle, String nzz, String ncr, Date ndate, String look, String nzy, String npic) {
super();
this.tid = tid;
this.ntitle = ntitle;
this.nzz = nzz;
this.ncr = ncr;
this.ndate = ndate;
this.look = look;
this.nzy = nzy;
this.npic = npic;
}
@Override
public String toString() {
return "News [nid=" + nid + ", tid=" + tid + ", ntitle=" + ntitle + ", nzz=" + nzz + ", ncr=" + ncr + ", ndate="
+ ndate + ", look=" + look + ", nzy=" + nzy + ", npic=" + npic + "]";
}
}
里面的内容就不用过多解释了哈
3.NewsDao(dao包）功能：
package dao;
import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import entity.News;
import entity.Subject;
import util.DBHelper;
public class NewsDao {
//添加方法
public static int add(News news ) {
News n=null;
int i=0;
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("insert into newb(newsid,newstid,newstitle,newszz,newcontent,newsdate,newslook) values(?,?,?,?,?,sysdate,?)");
ps.setInt(1, DBHelper.getNext("newsid","newsb"));
ps.setInt(2,news.getTid());
ps.setString(3, news.getNtitle());
ps.setString(4, news.getNzz());
ps.setString(5, news.getNcr());
ps.setDate(6,news.getNdate());
ps.setString(7, news.getLook());
i=ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return i;
}
//删除
public static int del(int id ) {
int i=0;
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("delete from newsb where newsid="+id);
i=ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return i;
}
//修改
public static int upd(int id,News news ) {
News n=null;
int i=0;
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("update newsb set newstid=?, newstitle=?,newszz=?,newszy=? newscontent=? where newsid="+id);
ps.setInt(1, news.getTid());
ps.setString(2, news.getNtitle());
ps.setString(3, news.getNzz());
ps.setString(4, news.getNzy());
ps.setString(5,news.getNcr());
i=ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return i;
}
//分页查询
public ArrayList<News> pageNews(int pageIndex,int pageSize){
ArrayList<News> nlist=new ArrayList<>();
int start=(pageIndex-1)*pageSize+1;
int end=pageIndex*pageSize;
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("select * from(select a.*,rownum mid from newsb a)b where mid>=? and mid<=?");
ps.setInt(1, start);
ps.setInt(2, end);
rs=ps.executeQuery();
while(rs.next()) {
int nid=rs.getInt(1);
int tid=rs.getInt(2);
String tit=rs.getString(3);
String tit1=rs.getString(4);
String tit2=rs.getString(5);
String tit3=rs.getString(6);
String tit4=rs.getString(7);
String tit6=rs.getString(8);
News ne=new News(nid, tid, tit, tit1, tit2, tit3, tit4, tit6);
nlist.add(ne);
}
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return nlist;
}
//获得最大页码
public static int getMaxpage(int pageSize) {
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
int maxPage=0;
int count=0;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("select count(*) from newsb");
rs=ps.executeQuery();
if(rs.next()) {
count=rs.getInt(1);
maxPage=count/pageSize;
if(count%pageSize!=0) {
maxPage++;
}
}
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return maxPage;
}
//分页模糊查询
public ArrayList<News> pageNewsLike(int pageIndex,int pageSize,String str){
ArrayList<News> nlist=new ArrayList<>();
int start=(pageIndex-1)*pageSize+1;
int end=pageIndex*pageSize;
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("select * from(select a.*,rownum mid from newsb a where newstitle like '%"+str+"%')b where mid>=? and mid<=?");
ps.setInt(1, start);
ps.setInt(2, end);
rs=ps.executeQuery();
while(rs.next()) {
int nid=rs.getInt(1);
int tid=rs.getInt(2);
String tit=rs.getString(3);
String tit1=rs.getString(4);
String tit2=rs.getString(5);
String tit3=rs.getString(6);
String tit4=rs.getString(7);
String tit6=rs.getString(8);
News ne=new News(nid, tid, tit, tit1, tit2, tit3, tit4, tit6);
nlist.add(ne);
}
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return nlist;
}
//获得分页模糊查询的最大气页码
public static int getMaxpageLike(int pageSize,String str) {
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
int maxPage=0;
int count=0;
try {
con=DBHelper.getCon();
ps=con.prepareStatement("select count(*) from newsb where newstitle like '%"+str+"%' ");
rs=ps.executeQuery();
if(rs.next()) {
count=rs.getInt(1);
maxPage=count/pageSize;
if(count%pageSize!=0) {
maxPage++;
}
}
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return maxPage;
}
}
4.admin.jsp界面
<%@page import="entity.users"%> <%@page import="dao.NewsDao"%> <%@page import="entity.News"%> <%@page import="java.util.ArrayList"%> <%@page import="java.sql.ResultSet"%> <%@page import="java.sql.DriverManager"%> <%@page import="java.sql.Connection"%> <%@page import="java.sql.PreparedStatement"%> <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>管理员后台</title> <link href="CSS/admin.css" rel="stylesheet" type="text/css" /> </head> <body> <% /*Object ob=session.getAttribute("u"); if(ob==null){ out.print("<script>alert('您还未登录,请您登录');location.href='login.jsp'</script>"); }*/ %> <div id="header"> <div id="welcome">欢迎使用新闻管理系统！</div> <div id="nav"> <div id="logo"><img src="images/logo.jpg" alt="新闻中国" /></div> <div id="a_b01"><img src="images/a_b01.gif" alt="" /></div> </div> </div> <div id="admin_bar"> <div id="status">管理员：      <a href="login.jsp">login out</a></div> <div id="channel"> </div> </div> <div id="main"> <div id="opt_list"> <ul> <li><a href="add_news.jsp">添加新闻</a></li> <li><a href="upd_news.jsp">编辑新闻</a></li> <li><a href="add_sub.jsp">添加主题</a></li> <li><a href="upd_sub.jsp">编辑主题</a></li> </ul> </div> <div id="opt_area"> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <script language="javascript"> function clickdel(){ return confirm("删除请点击确认"); } </script> <form action="admin.jsp" align="center"> <input type="text" name="str"> <input type="submit" value="查询"> </form> <ul class="classlist"> <% String str=request.getParameter("str"); if(str==null){ str=""; } int pageIndex = 1; int pageSize = 5; String index = request.getParameter("pageIndex"); if(index!=null){//如果接收到页面，就给页面pageIndex赋值 pageIndex = Integer.valueOf(index); } int maxPage=new NewsDao().getMaxpageLike(pageSize, str); ArrayList<News> nlist=new NewsDao().pageNewsLike(pageIndex, pageSize,str); for(News s:nlist){ %> <li> <a href="read_news.jsp?nid=<%=s.getNid()%>"> <%=s.getNtitle() %> </a> <span> 作者： <%=s.getNzz() %>      <a href='upd_news.jsp?nid=<%=s.getNid()%>'>修改</a>      <a href='dodel.jsp?nid=<%=s.getNid() %>' onclick='return clickdel()'>删除</a> </span> </li> <li class='space'></li> <%} %> <p align="right"> <a href="admin.jsp">首页</a> <a href="admin.jsp?pageIndex=<%=pageIndex>1?pageIndex-1:1%><% if(str!=null){ out.print("&str="+str); } %>">上一页</a> 当前页数:[<%=pageIndex %>/<%=maxPage %>] <a href="admin.jsp?pageIndex=<%=pageIndex<maxPage?pageIndex+1:maxPage%><% if(str!=null){ out.print("&str="+str); }%>">下一页</a> <a href="admin.jsp?pageIndex=<%=maxPage%>">末页</a> </p> </ul> </div> </div> <div id="site_link"> <a href="#">关于我们</a><span>|</span> <a href="#">Aboue Us</a><span>|</span> <a href="#">联系我们</a><span>|</span> <a href="#">广告服务</a><span>|</span> <a href="#">供稿服务</a><span>|</span> <a href="#">法律声明</a><span>|</span> <a href="#">招聘信息</a><span>|</span> <a href="#">网站地图</a><span>|</span> <a href="#">留言反馈</a> </div> <div id="footer"> <p class="">24小时客户服务热线：010-68988888      <a href="#">常见问题解答</a>      新闻热线：010-627488888<br /> 文明办网文明上网举报电话：010-627488888      举报邮箱：<a href="#">jubao@jb-aptech.com.cn</a></p> <p class="copyright">Copyright © 1999-2009 News China gov, All Right Reserver<br /> 新闻中国 版权所有</p> </div> </body> </body> </html>
是不是封装起来代码整齐且简单呢？？老有味道了！！！
可以直接用的，数据库的内容设置好就ok呢。
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