基本的CRUD操作

导入包---实体类------数据库连接----数据库操作----service层数据操作----网页对service层可视化实现

model

package com.ij34.model;

public class article {
   private int id;
   private String title;
   private String content;
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getTitle() {
    return title;
}
public void setTitle(String title) {
    this.title = title;
}
public String getContent() {
    return content;
}
public void setContent(String content) {
    this.content = content;
}
   
}

View Code

dao

package com.ij34.dao;

import java.sql.DriverManager;

import com.mysql.jdbc.Connection;



public class DbConn {
    private static String username="root";
    private static String password="123456";
    private static String url="jdbc:mysql://localhost:3306/articles?useUnicode=true&characterEncoding=UTF-8";
    private static Connection conn=null;
    
    public static Connection getConnection(){
        if(conn==null){
            try {
                Class.forName("com.mysql.jdbc.Driver");
                conn=(Connection) DriverManager.getConnection(url, username, password);
            } catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
            }
        }
        return conn;
    }
     
    //test connection
    public static void main(String[] args) {
        DbConn db=new DbConn();
        System.out.println(db.toString());
    }
}

View Code

package com.ij34.dao;

import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.ij34.model.article;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;

public class ArticleDao {
   
    public List<article> getfindAll(){  //查All，返回list
        List<article> list=new ArrayList<article>();
        String sql="select * from article";
        Connection conn=DbConn.getConnection();
        try {
            PreparedStatement pstm=(PreparedStatement) conn.prepareStatement(sql);
            ResultSet rs=pstm.executeQuery();
            while(rs.next()){
                article art=new article();
                art.setId(rs.getInt("id"));
                art.setTitle(rs.getString("title"));
                art.setContent(rs.getString("content"));
                list.add(art);
            }
            rs.close();
            pstm.close();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return list;
        
    }
    
    public boolean addArticle(article art){ //增
        String sql="insert into article(title,content)values(?,?)";
        Connection conn=DbConn.getConnection();
        try {
            PreparedStatement pstm=(PreparedStatement) conn.prepareStatement(sql);
            pstm.setString(1, art.getTitle());
            pstm.setString(2, art.getContent());
            int count=pstm.executeUpdate();
            pstm.close();
            if(count>0) return true;
            else return false;
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return false;
        
    }
    
    public boolean updateArticle(article art){ //修改
        String sql="update article set title=?,content=? where id=?";
        Connection conn=DbConn.getConnection();
        try {
            PreparedStatement pstm=(PreparedStatement) conn.prepareStatement(sql);
            pstm.setString(1, art.getTitle());
            pstm.setString(2, art.getContent());
            pstm.setInt(3, art.getId());
            int count=pstm.executeUpdate();
            pstm.close();
            if(count>0) return true;
            else return false;
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return false;
        
    }
    
    public boolean deleteArticle(int id){  //删除，根据id
        String sql="delete from article where id=?";
        //String sql="delete from article where id='"+id+"'";
        Connection conn=DbConn.getConnection();
        try {
            PreparedStatement pstm=(PreparedStatement) conn.prepareStatement(sql);
            pstm.setInt(1, id);  
            int count=pstm.executeUpdate();
            pstm.close();
            if(count>0) return true;
            else return false;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
        
    }
    
    public article selectById(int id){//根据id查找
        String sql="select * from article where id="+id;
        Connection conn=DbConn.getConnection();
        article art=null;
        try {
            PreparedStatement pstm=(PreparedStatement) conn.prepareStatement(sql);
            ResultSet rs=pstm.executeQuery();
            while(rs.next()){
                art=new article();
                art.setId(rs.getInt("id"));
                art.setTitle(rs.getString("title"));
                art.setContent(rs.getString("content"));
            }
            rs.close();
            pstm.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return art;
    }
}

View Code

service

add

package com.ij34.service;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ij34.dao.ArticleDao;
import com.ij34.model.article;

public class addArticle extends HttpServlet{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        article art=new article();
        String title=req.getParameter("title");
        String content=req.getParameter("content");
        art.setTitle(new String(title.getBytes("ISO-8859-1"),"UTF-8"));
        art.setContent(new String(content.getBytes("ISO-8859-1"),"UTF-8"));
        ArticleDao ad=new ArticleDao();
        ad.addArticle(art);
        req.getRequestDispatcher("showArticle").forward(req, resp);
    }
   
}

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del

package com.ij34.service;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ij34.dao.ArticleDao;

public class deleteArticle extends HttpServlet{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        String idStr=req.getParameter("id");
        if(idStr!=null&&!idStr.equals("")){
            int id=Integer.valueOf(idStr);
            ArticleDao ad=new ArticleDao();
            ad.deleteArticle(id);
        }
        req.getRequestDispatcher("showArticle").forward(req, resp);
    }

}

View Code

find

package com.ij34.service;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ij34.dao.ArticleDao;
import com.ij34.model.article;

public class showArticle extends HttpServlet{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        ArticleDao ad=new ArticleDao();
        List<article> list=ad.getfindAll();
        req.setAttribute("list", list);
        req.getRequestDispatcher("show.jsp").forward(req, resp);
    }
   
}

View Code

update

package com.ij34.service;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ij34.dao.ArticleDao;
import com.ij34.model.article;

public class updateArticle extends HttpServlet{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        String idStr=req.getParameter("id");
        if(idStr!=null&&!idStr.equals("")){
            ArticleDao ad=new ArticleDao();
            int id=Integer.valueOf(idStr);
           article art=ad.selectById(id);
           req.setAttribute("article", art);
        }
          req.getRequestDispatcher("update.jsp").forward(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        article art=new article();
        String idStr=req.getParameter("id");
        String title=req.getParameter("title");
        String content=req.getParameter("content");
        art.setId(Integer.valueOf(idStr));
        art.setTitle(new String(title.getBytes("ISO-8859-1"),"UTF-8"));
        art.setContent(new String(content.getBytes("ISO-8859-1"),"UTF-8"));
        ArticleDao ad=new ArticleDao();
        ad.updateArticle(art);
        req.getRequestDispatcher("showArticle").forward(req, resp);
    }
    
}

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web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>Articles</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>addArticle</servlet-name>
    <servlet-class>com.ij34.service.addArticle</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>addArticle</servlet-name>
    <url-pattern>/addArticle</url-pattern>
  </servlet-mapping>
  
    <servlet>
    <servlet-name>deleteArticle</servlet-name>
    <servlet-class>com.ij34.service.deleteArticle</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>deleteArticle</servlet-name>
    <url-pattern>/deleteArticle</url-pattern>
  </servlet-mapping>
  
    <servlet>
    <servlet-name>showArticle</servlet-name>
    <servlet-class>com.ij34.service.showArticle</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>showArticle</servlet-name>
    <url-pattern>/showArticle</url-pattern>
  </servlet-mapping>
  
    <servlet>
    <servlet-name>updateArticle</servlet-name>
    <servlet-class>com.ij34.service.updateArticle</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>updateArticle</servlet-name>
    <url-pattern>/updateArticle</url-pattern>
  </servlet-mapping>
</web-app>

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网页

index

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<jsp:forward page="showArticle"/>  //要写doget

View Code

add

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>添 加</title>
</head>
<body>
<form action="addArticle" method="post">
  <table align="center">
        <tr>
           <td colspan="2"><center><h4>添加</h4></center></td> 
        </tr>
        <tr>
           <td>标 题：</td><td><input type="text" name="title"/></td>
        </tr>
                <tr>
           <td>内 容：</td><td><input type="text" name="content"/></td>
        </tr>
        <tr>
          <td><input type="submit" value="提  交"/></td><td><input type="reset" value="重 置"/></td>
        </tr>
  </table>
</form>
</body>
</html>

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update

<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>修 改</title>
</head>
<body>
<form action="updateArticle" method="post">
  <table align="center">
        <tr>
           <td colspan="2"><center><h4>修 改</h4></center></td> 
        </tr>
                <tr>
           <td>编 号：</td><td><input type="text" name="id" value="${article.id }" readonly="readonly"/></td>
        </tr>
        <tr>
           <td>标 题：</td><td><input type="text" name="title" value="${article.title }"/></td>
        </tr>
                <tr>
           <td>内 容：</td><td><input type="text" name="content" value="${article.content }"></td>
        </tr>
        <tr>
          <td><input type="submit" value="提  交"/></td><td><input type="button" value="返回" onclick="history.go(-1)"/></td>
        </tr>
  </table>
</form>
</body>
</html>

View Code

show

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>显示</title>
</head>
<body>
<form action="showArticle" method="post">
  <table align="center">
   <tr>
   <th>编  号 </th>
   <th>标  题 </th>
   <th>   内               容       </th>
   <th> 操     作 </th>
   </tr>

   <c:forEach var="li" items="${list}">
   <tr>
   <td>${li.id} </td>
   <td> ${li.title} </td>
   <td> ${li.content} </td>
   <td><a href="deleteArticle?id=${li.id}">删除</a>|<a href="updateArticle?id=${li.id}">修改</a></td>
   </tr> 
   </c:forEach>

   <tr>
   <td align="center"><a href="add.jsp"> 添  加 </a></td>
   </tr>
  </table>
</form>
</body>
</html>

View Code

结果

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原文地址：https://www.cnblogs.com/tk55/p/8148209.html