手搭手入门纯Servlet+JSP+Mybatis+Tomcat9实现Web更删改查-阿里云开发者社区

Servlet对象的生命周期

Servlet对象的生命周期是由Tomcat服务器(中间件)全权负责的。

Tomcat服务器(中间件)有通常被称为WEB容器。

我们自己new的Servlet对象是不受Tomcat管理

WEB容器创建的Servlet对象，这些对象都会被放到一个集合当中HashMap，只有放到HashMap集合当中的Servlet才能够被WEB容器管理

WEB容器底层有HashMap这样的集合

Tomcat启动是会解析web.xml文件，启动的时候Servlet对象并不会被实例化。用户发送请求访问时会创建Servlet对象。

web.xml配置文件：描述请求路径和与Servlet类之间的对应关系。

<!-- <load-on-startup>该标签使对象在web容器启动时，创建Servlet对象

数字表示的是该对象执行的有限循序 0为最高优先级级 -->

<load-on-startup>1</load-on-startup>

Servlect对象被创建出来后，Tomcat服务器马上调用Servlect调用的init方法。

用户发送第二三次请求时，Servlrct对象并没有新建，还是使用原来的Servlet对象。

Servlect对象是单例的

无参构造方法、init方法只在第一次用户发送请求的时候执行。

每发送一次请求Service方法就执行一次。

Tomcat关闭时，则执行destroy()方法。Servlrct并没销毁(即将销毁)，destroy()方法执行结束之后Servlrct对象才会销毁，内存释放。

关于Servlect类中方法的调用次数

构造方法只执行一次

Init方法只执行一次

Service用户每请求一次则执行一次

Destroy只执行一次

Tomcat安装

Linux安装Tomcat （linux-x86-arm-mips）安装Tomcat 9.0-云社区-华为云

Windos配置Tomcat

关于Tomcat服务器的目录

bin: 该目录是Tomcat服务器的命令文件存放的目录，打开关闭Tomcat

conf: 该目录是Tomcat服务器的配置文件存放目录。(Server.xml文件中可以配置端口号,默认Tomcat端口是8080)

lib: 该目录是Tom服务器核心程序目录，因为Tomcat服务器是java语言编写的，这里的jar包里面都是class文件。

logs: Tomcat服务器的日志目录，Tomcat服务器启动等信息都会在这个目录下生成日志文件。

temp: Tomcat服务器的临时目录。存储在临时文件。

webapps: 该目录当中就是用来存放大量的webapp(web application web应用)

work: 该目录

windos启动tomcat

或

浏览器访问

http://localhost:8080/

http://127.0.0.1:8080/

案例

环境：IDEA2022+JDK1.8

技术栈：Servlet+JSP+Mybatis+Tomcat9

Pom.xml配置

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<modelVersion>4.0.0</modelVersion>

<groupId>org.example</groupId>

<artifactId>Servlet-Mybatis2</artifactId>

<version>1.0-SNAPSHOT</version>

<packaging>jar</packaging>

<properties>

<maven.compiler.source>8</maven.compiler.source>

<maven.compiler.target>8</maven.compiler.target>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

</properties>

<dependencies>

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

<version>3.8.1</version>

<scope>test</scope>

</dependency>

<dependency>

<groupId>org.mybatis</groupId>

<artifactId>mybatis</artifactId>

<version>3.5.1</version>

</dependency>

<dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

<version>5.1.9</version>

</dependency>

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

<version>4.13.2</version>

<scope>test</scope>

</dependency>

<dependency>

<groupId>javax.servlet</groupId>

<artifactId>javax.servlet-api</artifactId>

<version>4.0.1</version>

<scope>provided</scope>

</dependency>

<dependency>

<groupId>javax.servlet.jsp</groupId>

<artifactId>javax.servlet.jsp-api</artifactId>

<version>2.2.1</version>

<scope>provided</scope>

</dependency>

</dependencies>

<build>

<resources>

<resource>

<directory>src/main/java</directory>

<includes>

<include>**/*.properties</include>

<include>**/*.xml</include>

</includes>

<filtering>false</filtering>

</resource>

</resources>

</build>

</project>

mybatis-config.xml配置

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE configuration

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"https://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>

<environments default="myuser">

<environment id="myuser">

<transactionManager type="JDBC"/>

<dataSource type="POOLED">

<property name="driver" value="com.mysql.jdbc.Driver"/>

<property name="url" value="jdbc:mysql://IP:3306/mysql?"/>

<property name="username" value="root"/>

<property name="password" value="111111"/>

</dataSource>

</environment>

</environments>

<mappers>

<mapper resource="com/mybatis/TTT111Dao.xml"/>

</mappers>

</configuration>

MyBatisUtils工具类

package com.mybatis;

import org.apache.ibatis.io.Resources;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;

import java.io.InputStream;

/**

* @author QGS

* @version 1.0.0

* @date 2023年02月25日 21:42:04

* @packageName com.mybatis

* @className MyBatisUtils

* @describe TODO

*/

public class MyBatisUtils {

private static SqlSessionFactory sqlSessionFactory = null;

static {

String config="mybatis-config.xml";

InputStream inputStream = null;

try {

inputStream = Resources.getResourceAsStream(config);

//创建SqlSessionFactory对象

sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

} catch (IOException e) {

throw new RuntimeException(e);

}

//获取sqlSession的方法,非自动提交事务

public static SqlSession getSqlSession(){

SqlSession sqlSession = null;

if (sqlSessionFactory!=null){

sqlSession = sqlSessionFactory.openSession();//非自动提交事务

}

return sqlSession;

}

//获取sqlSession的方法,自动提交事务

public static SqlSession getSqlSessionAuto(){

SqlSession sqlSession = null;

if (sqlSessionFactory!=null){

sqlSession = sqlSessionFactory.openSession(true);//自动提交事务

}

return sqlSession;

}

Dao接口

package com.mybatis;

import com.Object.TTT111;

import org.apache.ibatis.annotations.Param;

import java.util.List;

/**

* @author QGS

* @version 1.0.0

* @date 2023年02月25日 21:15:35

* @packageName com.mybatis

* @className TTT111Dao

* @describe TODO

*/

public interface TTT111Dao {

List<TTT111> selectALL();

TTT111 selectById(int id);

int deleteById(int id);

//通过对象传值

int modify(TTT111 ttt111);

//通过@Param()传值

int save(@Param("id") int id ,@Param("name") String name,@Param("address") String address);

}

mapper文件

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE mapper

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"https://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.mybatis.TTT111Dao">

<select id="selectALL" resultType="com.Object.TTT111">

SELECT id,name,address FROM TTT11

</select>

<select id="selectById" resultType="com.Object.TTT111">

SELECT id,name,address FROM TTT11 Where id=#{id}

</select>

<delete id="deleteById">

delete from TTT11 where id=#{id}

</delete>

<update id="modify">

UPDATE TTT11 SET name=#{name},address=#{address} WHERE id=#{id}

</update>

<insert id="save">

insert into TTT11 values(#{id},#{name},#{address})

</insert>

</mapper>

实现类

get+set+有参无参构造+重写equals and hashCode

Servlet

package com.servlect.service;

import com.Object.TTT111;

import com.mybatis.MyBatisUtils;

import com.mybatis.TTT111Dao;

import org.apache.ibatis.session.SqlSession;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.List;

/**

* @author QGS

* @version 1.0.0

* @date 2023年03月03日 20:26:22

* @packageName com.servlect.service

* @className MouldServlet

* @describe TODO

*/

@WebServlet({"/list/renew","/list/edit","/list","/list/detail","/list/delete","/list/save"})

public class MouldServlet extends HttpServlet {

@Override

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding("UTF-8");

response.setContentType("text/html;charset=UTF-8");

//获取

String servletPath = request.getServletPath();

if ("/list/renew".equals(servletPath)){

renew(request,response);

}else if ("/list/edit".equals(servletPath)){

edit(request,response);

}else if ("/list".equals(servletPath)){

list(request,response);

}else if ("/list/detail".equals(servletPath)){

detail(request,response);

}else if ("/list/delete".equals(servletPath)){

delete(request,response);

}else if ("/list/save".equals(servletPath)) {

save(request, response);

}else {

PrintWriter out = response.getWriter();

out.print("访问路径不存在！");

}

private void save(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String id = request.getParameter("id");

String name = request.getParameter("name");

String address = request.getParameter("address");

//执行数据库insert语句

SqlSession sqlSession = MyBatisUtils.getSqlSessionAuto();

TTT111Dao mapper = sqlSession.getMapper(TTT111Dao.class);

int save = mapper.save(Integer.parseInt(id), name, address);

if (save==1){

//成功

//转发的是一次请求

response.sendRedirect("/ServletWeb/list");

}else {

//保存失败

response.sendRedirect("/ServletWeb/error");

}

private void renew(HttpServletRequest request, HttpServletResponse response) throws IOException {

String id = request.getParameter("id");

String name = request.getParameter("name");

String address = request.getParameter("address");

//执行数据库selectById语句

SqlSession sqlSession = MyBatisUtils.getSqlSessionAuto();

TTT111Dao mapper = sqlSession.getMapper(TTT111Dao.class);

TTT111 ttt111=new TTT111();

ttt111.setId(Integer.parseInt(id));

ttt111.setName(name);

ttt111.setAddress(address);

int modify = mapper.modify(ttt111);

if (modify==1){

response.sendRedirect("/ServletWeb/list");

}else {

//保存失败

response.sendRedirect("/ServletWeb/error");

}

private void edit(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

String contextPath = request.getContextPath();

String id = request.getParameter("id");

//执行数据库selectById语句

SqlSession sqlSession = MyBatisUtils.getSqlSessionAuto();

TTT111Dao mapper = sqlSession.getMapper(TTT111Dao.class);

TTT111 ttt111 = mapper.selectById(Integer.parseInt(id));

//将集合放入请求域中

request.setAttribute("ttt111",ttt111);

request.getRequestDispatcher("/modify.jsp").forward(request,response);

}

private void list(HttpServletRequest request, HttpServletResponse response)

throws IOException, ServletException {

//获取应用的根路径

String contextPath = request.getContextPath();

System.out.println("根路径:"+contextPath);

SqlSession sqlSession = MyBatisUtils.getSqlSessionAuto();

TTT111Dao dao = sqlSession.getMapper(TTT111Dao.class);

List<TTT111> ttt111s = dao.selectALL();

//将集合放入请求域中

request.setAttribute("ttt111s",ttt111s);

//转发

request.getRequestDispatcher("/list.jsp").forward(request,response);

}

private void detail(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

String id = request.getParameter("id");

SqlSession sqlSession = MyBatisUtils.getSqlSessionAuto();

TTT111Dao dao = sqlSession.getMapper(TTT111Dao.class);

TTT111 ttt111 = dao.selectById(Integer.parseInt(id));

request.setAttribute("ttt111",ttt111);

request.getRequestDispatcher("/detail.jsp").forward(request,response);

}

private void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String id = request.getParameter("id");

int i=0;

try {

SqlSession sqlSession = MyBatisUtils.getSqlSessionAuto();

TTT111Dao dao = sqlSession.getMapper(TTT111Dao.class);

i = dao.deleteById(Integer.parseInt(id));

PrintWriter out = response.getWriter();

out.print("执行成功！影响了"+i+"行");

request.getRequestDispatcher("/list").forward(request,response);

}catch (Exception e){

e.printStackTrace();

}

if (i==1){

response.sendRedirect("/ServletWeb/list");

}else {

//保存失败

response.sendRedirect("/ServletWeb/error");

}

JSP

<%--

Created by IntelliJ IDEA.

User: 13631

Date: 2023/3/4

Time: 19:27

To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<!DOCTYPE html>

<html>

<%--index--%>

<head>

<meta charset="utf-8">

<title>welcome</title>

</head>

<body>

<h1 align="center">OA welcome you</h1>

</br>

<h3 align="center">

<a href="<%=request.getContextPath()%>/list">查看用户列表</a>

</h3>

</body>

</html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<!DOCTYPE html>

<%--add.jsp--%>

<html>

<head>

<meta charset="utf-8">

<title>新增用户信息</title>

</head>

<body>

<h1>新增用户信息</h1>

<hr/>

<form action="<%=request.getContextPath()%>/list/save" method="post">

id<input type="text" name="id"/><br/>

姓名<input type="text" name="name"/><br/>

地址<input type="text" name="address"/><br/>

<input type="submit" value="save"/><br/>

</form>

<br />

<a href="<%=request.getContextPath()%>/index.jsp">返回主页面</a>

</body>

</html>

<!DOCTYPE html>

<html>

<%--delect--%>

<head>

<meta charset="utf-8">

<title>删除用户信息</title>

</head>

<body>

<h1>删除用户信息</h1>

<hr/>

<form action="" method="post">

id<input type="text" name="id"/><br/>

<input type="submit" value="delect"/><br/>

</form>

<a href="<%=request.getContextPath()%>/index.jsp">返回主页面</a>

</body>

</html>

<%@ page import="com.Object.TTT111" %><%--

Created by IntelliJ IDEA.

User: 13631

Date: 2023/3/4

Time: 22:58

To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<!DOCTYPE html>

<html>

<%--detail--%>

<head>

<meta charset='utf-8'>

<title>用户详情</title>

</head>

<body>

<h1 align='center'>用户详情</h1>

<hr/>

<table border='1px' align='center' width='50%'>

<tr>

<th>序号</th>

<th>名称</th>

<th>地址</th>

</tr>

<%

TTT111 ttt111 = (TTT111)request.getAttribute("ttt111");

%>

<tr>

<td><%=ttt111.getId()%></td>

<td><%=ttt111.getName()%></td>

<td><%=ttt111.getAddress()%></td>

<td>

<a href="<%=request.getContextPath()%>/index.jsp">返回主页面</a>

</td>

</tr>

</table>

</body>

</html>

<!DOCTYPE html>

<html lang="en">

<%--error--%>

<head>

<meta charset="UTF-8">

<title>error</title>

</head>

<body>

<h1> 操作失败<a href="javascript:void(0)" onclick="window.history.back()">返回</a> </h1>

</body>

</html>

<%@ page import="java.util.List" %>

<%@ page import="com.Object.TTT111" %>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<!DOCTYPE html>

<html>

<%--list--%>

<head>

<meta charset="utf-8">

<title>用户列表</title>

<script type="text/javascript">

function delect(id){

if(window.confirm("删除不可恢复哟！")){

document.location.href ="<%=request.getContextPath()%>/list/delete?id="+ id;

}

</script>

</head>

<body>

<h1 align="center">用户列表</h1>

<hr/>

<table border="1px" align="center" width="50%">

<tr>

<th>序号</th>

<th>名称</th>

<th>地址</th>

<th>操作</th>

</tr>

<%

//从request域当中取出集合

List<TTT111> ttt111s =(List<TTT111>)request.getAttribute("ttt111s");

for (TTT111 ttt111 : ttt111s) {

%>

<tr>

<td><%=ttt111.getId()%></td>

<td><%=ttt111.getName()%></td>

<td><%=ttt111.getAddress()%></td>

<td>

<a href="javascript:void(0)" onclick="delect(<%=ttt111.getId()%>)">删除</a>

<a href="<%=request.getContextPath()%>/list/edit?id=<%=ttt111.getId()%>">修改</a>

<a href="<%=request.getContextPath()%>/list/detail?id=<%=ttt111.getId()%>">详情</a>

<a href="<%=request.getContextPath()%>/index.jsp">返回主页面</a>

</td>

</tr>

<%

}

%>

</table>

<a href="add.jsp">新增</a>

</body>

</html>

<%@ page import="com.Object.TTT111" %><%--

Created by IntelliJ IDEA.

User: 13631

Date: 2023/3/4

Time: 23:06

To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<!DOCTYPE html>

<html>

<%--modify--%>

<head>

<meta charset="utf-8">

<title>修改用户信息</title>

</head>

<body>

<h1 align="center">修改用户信息</h1>

<hr/>

<%

TTT111 ttt111 =(TTT111) request.getAttribute("ttt111");

%>

<center>

<form action=<%=request.getContextPath()%>/list/renew" method="post" >

i d: <input type="text" name="id" value="<%=ttt111.getId()%>"readonly /><br/>

姓名: <input type="text" name="name" value="<%=ttt111.getName()%>" /><br/>

地址: <input type="text" name="address" value="<%=ttt111.getAddress()%>" /><br/>

<input type="submit" value="提交"/><br/>

</form><br/>

<a href="<%=request.getContextPath()%>/index.jsp">返回主页面</a>

</center>

</body>

</html>

效果

如有错误请指正,谢谢

手搭手入门纯Servlet+JSP+Mybatis+Tomcat9实现Web更删改查

Servlet对象的生命周期

Tomcat安装

案例

Pom.xml配置

mybatis-config.xml配置

MyBatisUtils工具类

Dao接口

mapper文件

Servlet

JSP

效果

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插件

手搭手入门纯Servlet+JSP+Mybatis+Tomcat9实现Web更删改查

Servlet对象的生命周期

Tomcat安装

案例

Pom.xml配置

mybatis-config.xml配置

MyBatisUtils工具类

Dao接口

mapper文件

Servlet

JSP

效果

热门文章

最新文章

相关课程

相关电子书

相关实验场景