欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页

JSP + Servlet + JDBC + Mysql 实现增删改查

程序员文章站 2022-06-18 12:55:13
...

Servlet是一个特殊的Java程序,它运行于服务器的JVM中,能够依靠服务器的支持向浏览器提供显示内容。

JSP本质上是Servlet的一种简易形式, JSP会被服务器处理成一个类似于Servlet的Java程序,可以简化页面内容的生成。

 Servlet和JSP最主要的不同点在于,Servlet 的应用逻辑是在Java 文件中,并且完全从表示层中的HTML分离开来。而JSP的情况是Java和HTML可以组合成一个扩展名为.jsp 的文件(有人说,Servlet就是在Java中写HTML,而JSP就是在HTML中写Java代码,当然,这个说法还是很片面的)。

JSP侧重于视图,Servlet更侧重于控制逻辑,在MVC架构模式中,JSP适合充当视图(view)而Servlet适合充当控制器(controller)。

 

JSP + Servlet + JDBC + Mysql 实现增删改查

JSP + Servlet + JDBC + Mysql 实现增删改查                JSP + Servlet + JDBC + Mysql 实现增删改查

1、项目目录结构

JSP + Servlet + JDBC + Mysql 实现增删改查

 

2、项目环境:

    Eclipse Neon.3 Release (4.6.3)

    jdk1.8.0_121

    apache-tomcat-8.5.24

    MYSQL5.7

    Navicat for MySQL 11.1.13

    所需jar包:

JSP + Servlet + JDBC + Mysql 实现增删改查

        数据库连接jar:mysql-connector-java-5.1.39-bin.jar

        jstl标签jar:jstl-1.2.jar

 

3、数据库相关配置

JSP + Servlet + JDBC + Mysql 实现增删改查

 

4、源代码

 

  • 4.1 dao层(直接与数据库进行交互的层)

AdminDao.java

package com.web.tom.dao;

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

import com.web.tom.entity.Admin;

/**
 * 
 * @author tom
 *
 */
public class AdminDao {
	public List<Admin> getAllAdmin() { // 查询所有信息
		List<Admin> list = new ArrayList<Admin>(); // 创建集合
		Connection conn = DbHelper.getConnection();
		String sql = "select * from admin"; // SQL查询语句
		try {
			PreparedStatement pst = conn.prepareStatement(sql);
			ResultSet rst = pst.executeQuery();
			while (rst.next()) {
				Admin admin = new Admin();
				admin.setId(rst.getInt("id")); // 得到ID
				admin.setUsername(rst.getString("username"));
				admin.setUserpwd(rst.getString("userpwd"));
				list.add(admin);
			}
			rst.close(); // 关闭
			pst.close(); // 关闭
		} catch (SQLException e) {
			e.printStackTrace(); // 抛出异常
		}
		return list; // 返回一个集合
	}

	public boolean addAdmin(Admin admin) { // 添加信息
		String sql = "INSERT INTO `admin`(`id`,`username`,`userpwd`) VALUES (?,?,?)"; // 添加的SQL语句
		Connection conn = DbHelper.getConnection();
		try {
			PreparedStatement pst = conn.prepareStatement(sql);
			pst.setInt(1, admin.getId());
			pst.setString(2, admin.getUsername());
			pst.setString(3, admin.getUserpwd());
			int count = pst.executeUpdate();
			pst.close();
			return count > 0 ? true : false; // 是否添加的判断
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return false;
	}

	public boolean updateAdmin(Admin admin) { // 修改
		String sql = "UPDATE `admin` SET `username`=?,`userpwd`=? WHERE `id` = ?"; // 修改的SQL语句,根据ID修改
		Connection conn = DbHelper.getConnection();
		try {
			PreparedStatement pst = conn.prepareStatement(sql);
			pst.setString(1, admin.getUsername());
			pst.setString(2, admin.getUserpwd());
			pst.setInt(3, admin.getId()); // 根据的ID
			int count = pst.executeUpdate();
			pst.close(); // 关闭
			return count > 0 ? true : false; // 是否修改的判断
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return false;
	}

	public boolean deleteAdmin(int id) { // 删除
		String sql = "delete from admin where id = ?"; // 删除的SQL语句,根据ID删除
		Connection conn = DbHelper.getConnection();
		try {
			PreparedStatement pst = conn.prepareStatement(sql);
			pst.setInt(1, id);
			int count = pst.executeUpdate();
			pst.close();
			return count > 0 ? true : false; // 是否删除的判断
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return false;
	}

	public Admin selectAdminById(int id) { // 根据ID进行查询
		Connection conn = DbHelper.getConnection();
		String sql = "select * from admin where id = " + id;
		Admin admin = null;
		try {
			PreparedStatement pst = conn.prepareStatement(sql);
			ResultSet rst = pst.executeQuery();
			while (rst.next()) {
				admin = new Admin();
				admin.setId(rst.getInt("id"));
				admin.setUsername(rst.getString("username"));
				admin.setUserpwd(rst.getString("userpwd"));
			}
			rst.close();
			pst.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return admin; // 返回
	}
}

 

DbHelper.java

package com.web.tom.dao;

import java.sql.Connection;
import java.sql.DriverManager;

/**
 * 连接数据库
 * 
 * @author tom
 *
 */
public class DbHelper {
	private static String url = "jdbc:mysql://localhost:3306/JspServlet"; // 数据库地址
	private static String userName = "root"; // 数据库用户名
	private static String passWord = "tanghh"; // 数据库密码
	private static Connection conn = null;

	private DbHelper() {

	}

	public static Connection getConnection() {
		if (null == conn) {
			try {
				Class.forName("com.mysql.jdbc.Driver");
				conn = DriverManager.getConnection(url, userName, passWord);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return conn;
	}

	public static void main(String[] args) { // 测试数据库是否连通
		System.err.println(getConnection());
	}
}

 

 

  • 4.2 entity层(实体类映射层)

Admin.java

package com.web.tom.entity;

import java.io.Serializable;

public class Admin implements Serializable { // 数据封装类

	private static final long serialVersionUID = 1L;

	private int id;
	private String username;
	private String userpwd;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getUserpwd() {
		return userpwd;
	}

	public void setUserpwd(String userpwd) {
		this.userpwd = userpwd;
	}

}

 

 

  • 4.3 servlet层(请求控制层)

AddServlet.java

package com.web.tom.servlet;

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.web.tom.dao.AdminDao;
import com.web.tom.entity.Admin;

public class AddServlet extends HttpServlet { // 添加数据
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		this.doPost(req, resp);
	}

	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String username = req.getParameter("username");
		String userpwd = req.getParameter("userpwd");
		Admin admin = new Admin();
		admin.setUsername(new String(username.getBytes("ISO-8859-1"), "UTF-8")); // 转值,中文需要转换为utf-8
		admin.setUserpwd(new String(userpwd.getBytes("ISO-8859-1"), "UTF-8"));
		AdminDao dao = new AdminDao();
		dao.addAdmin(admin);
		req.getRequestDispatcher("ShowServlet").forward(req, resp);
	}
}

 

DeleteServlet.java

package com.web.tom.servlet;

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.web.tom.dao.AdminDao;

public class DeleteServlet extends HttpServlet { // 删除数据

	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		this.doPost(req, resp);
	}

	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String idStr = req.getParameter("id"); // 删除数据的ID,根据ID删除
		if (idStr != null && !idStr.equals("")) {
			int id = Integer.valueOf(idStr);
			AdminDao dao = new AdminDao();
			dao.deleteAdmin(id);
		}
		req.getRequestDispatcher("ShowServlet").forward(req, resp);
	}

}

ShowServlet.java

package com.web.tom.servlet;

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.web.tom.dao.AdminDao;
import com.web.tom.entity.Admin;

public class ShowServlet extends HttpServlet { // 显示全部数据

	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		this.doPost(req, resp);
	}

	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		AdminDao dao = new AdminDao();
		List<Admin> list = dao.getAllAdmin();
		req.setAttribute("list", list);
		req.getRequestDispatcher("index.jsp").forward(req, resp);
	}
}

 

UpdateServlet.java

 

package com.web.tom.servlet;

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.web.tom.dao.AdminDao;
import com.web.tom.entity.Admin;

public class UpdateServlet extends HttpServlet{  //修改

    private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 查询到选中ID的值所对应的数据
		String idStr = req.getParameter("id");
		if (idStr != null && !idStr.equals("")) {
			int id = Integer.valueOf(idStr);
			AdminDao dao = new AdminDao();
			Admin admin = dao.selectAdminById(id);
			req.setAttribute("admin", admin);
		}
		req.getRequestDispatcher("update.jsp").forward(req, resp);

	}

    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {  //根据此ID对数据的值进行修改
        String username = req.getParameter("username");
        String userpwd = req.getParameter("userpwd");
        String idStr = req.getParameter("id");
        Admin admin = new Admin();
        admin.setId(Integer.valueOf(idStr));
        admin.setUsername(new String(username.getBytes("ISO-8859-1"),"UTF-8"));
        admin.setUserpwd(new String(userpwd.getBytes("ISO-8859-1"),"UTF-8"));
        AdminDao dao = new AdminDao();
        dao.updateAdmin(admin);
        req.getRequestDispatcher("ShowServlet").forward(req, resp);
    }
    
    

}

 

 

 

  • 4.4 web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://xmlns.jcp.org/xml/ns/javaee"
	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
	id="WebApp_ID" version="3.1">
	<display-name>WebBasic</display-name>
	<welcome-file-list>
		<welcome-file>index.html</welcome-file>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
	
	<servlet>
		<servlet-name>AddServlet</servlet-name>
		<servlet-class>com.web.tom.servlet.AddServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>AddServlet</servlet-name>
		<url-pattern>/AddServlet</url-pattern>
	</servlet-mapping>
	
	<servlet>
		<servlet-name>DeleteServlet</servlet-name>
		<servlet-class>com.web.tom.servlet.DeleteServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>DeleteServlet</servlet-name>
		<url-pattern>/DeleteServlet</url-pattern>
	</servlet-mapping>
	
	<servlet>
		<servlet-name>UpdateServlet</servlet-name>
		<servlet-class>com.web.tom.servlet.UpdateServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>UpdateServlet</servlet-name>
		<url-pattern>/UpdateServlet</url-pattern>
	</servlet-mapping>
	
	<servlet>
		<servlet-name>ShowServlet</servlet-name>
		<servlet-class>com.web.tom.servlet.ShowServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>ShowServlet</servlet-name>
		<url-pattern>/ShowServlet</url-pattern>
	</servlet-mapping>
</web-app>

 

5、jsp页面

 

  • 5.1 add.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>    
    <title>添加</title>
    <link rel="stylesheet" href="css/index.css" type="text/css" />
  </head>

  <body>
  <form action="AddServlet" method="post">
    <table border="1" class="t1">
        <tr>
            <td colspan="2"><h1>添加管理员</h1></td>
        </tr>
        <tr>
            <td>管理员帐号:</td>
            <td><input  type="text" name="username"/></td>
        </tr>
        <tr>
            <td>管理员密码:</td>
            <td><input  type="password" name="userpwd"/></td>
        </tr>
        <tr>
            <td colspan="2">
                <input  type="submit" value="提交"/>
                <input  type="reset" value="清空"/>
            </td>
        </tr>
    </table>
   </form>
  </body>
</html>
  • 5.2 index.jsp
<%@ 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>
    <style type="text/css">
            table {
                border: 1px solid pink;
                margin: 0 auto;
            }
            
            td{
                width: 150px;
                border: 1px solid pink;
                text-align: center;
            }
    </style>
</head>
<body>
    <table>
        <tr>
            <td>编号</td>
            <td>帐号</td>
            <td>密码</td>
            <td>操作</td>
        </tr>
        <c:forEach items="${list}" var="item">
            <tr>
                <td>${item.id }</td>
                <td>${item.username }</td>
                <td>${item.userpwd }</td>
                <td><a href="DeleteServlet?id=${item.id }">删除</a>|<a href="UpdateServlet?id=${item.id }">修改</a></td>
            </tr>
        </c:forEach>
        <tr>
            <td colspan="6" style="text-align: left;"><a href="add.jsp">添加管理员</a></td>
        </tr>
    </table>
</body>
</html>
  • 5.3 update.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>    
    <title>修改</title>
    <link rel="stylesheet" href="css/index.css" type="text/css" />
  </head>
  
  <body>
    <form action="UpdateServlet" method="post">
    <table border="1" class="t1">
        <tr>
            <td colspan="2"><h1>修改管理员信息</h1></td>
        </tr>
        <tr>
            <td>编号:</td>
            <td><input  type="text" name="id" value="${admin.id}" readonly="readonly"/></td>
        </tr>
        
        <tr>
            <td>管理员帐号:</td>
            <td><input  type="text" name="username" value="${admin.username}"/></td>
        </tr>
        <tr>
            <td>管理员密码:</td>
            <td><input  type="text" name="userpwd" value="${admin.userpwd}"/></td>
        </tr>
        <tr>
            <td colspan="2">
                <input  type="submit" value="提交"/>
                <input  type="button" value="返回" onclick="history.go(-1)"/>
            </td>
        </tr>
    </table>
   </form>
  </body>
</html>