JSP + Servlet + JDBC + Mysql 实现增删改查
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)。
1、项目目录结构
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:
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
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>
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