javaBean封装

                            **为了代码的整洁，所以用javaBean封装，以把java和jsp分离。**

以下是我封装的类

封装类：

DBHelper类：链接数据库，因为Oracle我没有添加触发器，所以在类中写了getNextId函数，使它自增

代码：

package com.zking.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class DBHelper {
    
    private static String user="scott";
    private static String uwpd="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();
        }
    }
    
    public static Connection getCon() {
        Connection con=null;
        try {
            con=DriverManager.getConnection(url, user, uwpd);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return con;
    }
    
    public static void closeDB(Connection con,PreparedStatement ps,ResultSet rs) {
        try {
            if(con!=null) {
                con.close();
            }
            if(ps!=null) {
                ps.close();
            }
            if(rs!=null) {
                rs.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    public static int getNextId(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();
        }finally {
            DBHelper.closeDB(con, ps, rs);
        }
        return id;
        
    }
}

News类： 新闻实体类

package com.zking.entity;

import java.sql.Date;

public class News {

    private int  nid;
    private int tid;
    private String ntitle;
    private String nzz;
    private String ncontent;
    private Date ndate;
    private int nlook;
    private String nzy;
    private String ntp;
    
    
    
    public News(int tid, String ntitle, String nzz, String ncontent, String nzy) {
        super();
        this.tid = tid;
        this.ntitle = ntitle;
        this.nzz = nzz;
        this.ncontent = ncontent;
        this.nzy = nzy;
    }
    public News(int nid, int tid, String ntitle, String nzz, String ncontent, int nlook, String nzy) {
        super();
        this.nid = nid;
        this.tid = tid;
        this.ntitle = ntitle;
        this.nzz = nzz;
        this.ncontent = ncontent;
        this.nlook = nlook;
        this.nzy = nzy;
    }
    public News() {
        super();
    }
    public News(int tid, String ntitle, String nzz, String ncontent, Date ndate, int nlook, String nzy, String ntp) {
        super();
        this.tid = tid;
        this.ntitle = ntitle;
        this.nzz = nzz;
        this.ncontent = ncontent;
        this.ndate = ndate;
        this.nlook = nlook;
        this.nzy = nzy;
        this.ntp = ntp;
    }
    public News(int nid, int tid, String ntitle, String nzz, String ncontent, Date ndate, int nlook, String nzy,
            String ntp) {
        super();
        this.nid = nid;
        this.tid = tid;
        this.ntitle = ntitle;
        this.nzz = nzz;
        this.ncontent = ncontent;
        this.ndate = ndate;
        this.nlook = nlook;
        this.nzy = nzy;
        this.ntp = ntp;
    }
    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 getNcontent() {
        return ncontent;
    }
    public void setNcontent(String ncontent) {
        this.ncontent = ncontent;
    }
    public Date getNdate() {
        return ndate;
    }
    public void setNdate(Date ndate) {
        this.ndate = ndate;
    }
    public int getNlook() {
        return nlook;
    }
    public void setNlook(int nlook) {
        this.nlook = nlook;
    }
    public String getNzy() {
        return nzy;
    }
    public void setNzy(String nzy) {
        this.nzy = nzy;
    }
    public String getNtp() {
        return ntp;
    }
    public void setNtp(String ntp) {
        this.ntp = ntp;
    }
    
    
}

NewsDao类：新闻增删改查等的方法

package com.zking.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;

import com.zking.entity.News;
import com.zking.entity.Ptextt;
import com.zking.util.DBHelper;

public class NewsDao {
    public int addNews(News newst) {
        int i=0;
        Connection con=null;
        PreparedStatement ps=null;
        try {
            con=DBHelper.getCon();
            ps=con.prepareStatement("insert into newst(nid,tid,ntitle,nzz,ncontent,ndate,nlook,nzy)values(?,?,?,?,?,sysdate,0,?)");
            ps.setInt(1, DBHelper.getNextId("newst", "nid"));
            ps.setInt(2, newst.getTid());
            ps.setString(3, newst.getNtitle());
            ps.setString(4, newst.getNzz());
            ps.setString(5, newst.getNcontent());
            ps.setString(6, newst.getNzy());
            i=ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, null);
        }
        return i;
    }
    
    
    public int delNews(int n) {
        int i=0;
        Connection con=null;
        PreparedStatement ps=null;
        try {
            con=DBHelper.getCon();
            ps=con.prepareStatement("delete newst where nid="+n);
            i=ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, null);
        }
        return i;
    }
    
    
    public int updaNewst(int nid,News newst) {
        int i=0;
        Connection con=null;
        PreparedStatement ps=null;
        try {
            con=DBHelper.getCon();
            ps=con.prepareStatement("update newst set tid=?,ntitle=?,nzz=?,ncontent=?,nzy=? where nid="+nid);
            ps.setInt(1, newst.getTid());
            ps.setString(2, newst.getNtitle());
            ps.setString(3, newst.getNzz());
            ps.setString(4, newst.getNcontent());
            ps.setString(5, newst.getNzy());
            i=ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, null);
        }
        return i;
    }
    
    
    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();
            String sql = "select * from(select a.*,rownum mid from newst a)b where mid>=? and mid<=?";        
            ps=con.prepareStatement(sql);
            ps.setInt(1, start);
            ps.setInt(2, end);
            
            rs=ps.executeQuery();
            while(rs.next()) {
                News newst=new News(rs.getInt(1), rs.getInt(2), rs.getString(3), rs.getString(4), rs.getString(5), rs.getDate(6), rs.getInt(7), rs.getString(8), rs.getString(9));
                nlist.add(newst);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, rs);
        }
        return nlist;
    }
    
    public ArrayList<News> pageNewsByTid(int pageIndex,int pageSize,int tid){
        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();
            String sql = "select * from(select a.*,rownum mid from newst a where tid="+tid+") b where mid>=? and mid<=?";        
            ps=con.prepareStatement(sql);
            ps.setInt(1, start);
            ps.setInt(2, end);
            
            rs=ps.executeQuery();
            while(rs.next()) {
                News newst=new News(rs.getInt(1), rs.getString(3), rs.getString(4), rs.getString(5), rs.getDate(6), rs.getInt(7), rs.getString(8), rs.getString(9));
                nlist.add(newst);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, rs);
        }
        return nlist;
    }
    
    public int getMaxPage(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 newst where ntitle 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();
        }finally {
            DBHelper.closeDB(con, ps, rs);
        }
        return maxPage;
    }
    
    public int getMaxPageByTid(int pageSize,int tid) {
        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 newst where tid like '%"+tid+"%'");
            rs = ps.executeQuery();
            if(rs.next()) {
                count = rs.getInt(1);
                maxPage = count/pageSize;
                if(count%pageSize!=0) {
                    maxPage++;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, rs);
        }
        return maxPage;
    }
    
    //分页的模糊查询
    public ArrayList<News> pagelikeNews(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();
            String sql = "select * from(select a.*,rownum mid from newst a where ntitle like '%"+str+"%')b where mid>=? and mid<=?";        
            ps=con.prepareStatement(sql);
            ps.setInt(1, start);
            ps.setInt(2, end);
            
            rs=ps.executeQuery();
            while(rs.next()) {
                News newst=new News(rs.getInt(1), rs.getInt(2), rs.getString(3), rs.getString(4), rs.getString(5), rs.getDate(6), rs.getInt(7), rs.getString(8), rs.getString(9));
                nlist.add(newst);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, rs);
        }
        return nlist;
    }
    
    public News p(int n) {
        Connection con = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        News pp=null;
        try {
            con = DBHelper.getCon();
            ps = con.prepareStatement("select * from Newst where nid="+n);
            rs = ps.executeQuery();
            if(rs.next()) {
                pp=new News(rs.getInt(1), rs.getInt(2), rs.getString(3), rs.getString(4), rs.getString(5) , rs.getDate(6), rs.getInt(7), rs.getString(8), rs.getString(9));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            DBHelper.closeDB(con, ps, rs);
        }
        return pp;
    }
    public static void main(String[] args) {
        System.out.println(new NewsDao().delNews(50));
    }
    
}

联合一起来使用

<%@page import="java.util.Date"%>
<%@page import="com.zking.entity.News"%>
<%@page import="com.zking.dao.NewsDao"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%
    request.setCharacterEncoding("utf-8");
    int tid=Integer.valueOf(request.getParameter("ntid"));
    String ntile=request.getParameter("ntitle");
    String nzz=request.getParameter("nauthor");
    String nzy=request.getParameter("nsummary");
    String ncontent=request.getParameter("ncontent");
    
    int i=new NewsDao().addNews(new News(1,tid,ntile,nzz,ncontent,0,nzy));
    
    if(i>0){
        out.print("<script>alert('成功成功！！');location.href='../admin.jsp'</script>");
    }else{
        out.print("<script>alert('添加失败！！');location.href='add_new.jsp'</script>");
    }
%>

其它类似，所以我只举一例

总结：

 **   javaBean封装后，一些冗长重复的代码可以直接拿来调用，省时省力，代码整洁清晰。**