day93- javaweb-servlet学习

javaweb的Servlet

1.下载maven，tomcat

试了10版本的tomcat，好像不兼容，果断放弃

安装了tomcat9，就成功了，真是神奇，高了我半天

查了各种攻略，tomcat10确实是bug一堆

2.从maven中导入依赖，搜索依赖等等

3.了解部署web程序的步骤

第一个web程序：

配置pom文件

<?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>javaweb_01_maven_02</artifactId>
     <version>1.0-SNAPSHOT</version>
 
     <properties>
         <maven.compiler.source>8</maven.compiler.source>
         <maven.compiler.target>8</maven.compiler.target>
     </properties>
 
 </project>

创建空的maven项目，引入Servlet，jsp依赖

<?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>javaweb_02_Servlet</artifactId>
     <packaging>pom</packaging>
     <version>1.0-SNAPSHOT</version>
     <modules>
         <module>Servlet_01</module>
     </modules>
 
     <properties>
         <maven.compiler.source>8</maven.compiler.source>
         <maven.compiler.target>8</maven.compiler.target>
     </properties>
     <dependencies>
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>javax.servlet-api</artifactId>
             <version>4.0.1</version>
         </dependency>
 
         <!-- https://mvnrepository.com/artifact/javax.servlet.jsp/jsp-api -->
         <dependency>
             <groupId>javax.servlet.jsp</groupId>
             <artifactId>jsp-api</artifactId>
             <version>2.2</version>
         </dependency>
 
 
 
     </dependencies>
 
 </project>

创建子项目，继承父项目，可以用父项目的所有依赖

子项目

helloServlet

重写doget，dopost方法

 package com.gu.Servlet;
 
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.io.PrintWriter;
 
 public class HelloServlet extends HttpServlet {
     @Override
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         PrintWriter writer = resp.getWriter();
         writer.print("helloServlet");
     }
 
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         super.doPost(req, resp);
     }
 }

在web.xml中注册servlet并产生映射

<?xml version="1.0" encoding="UTF-8"?>
 <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                          http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
          version="4.0"
          metadata-complete="true">
 <!--    注册servlet-->
     <servlet>
         <servlet-name>hello</servlet-name>
         <servlet-class>com.gu.Servlet.HelloServlet</servlet-class>
     </servlet>
     <servlet-mapping>
         <servlet-name>hello</servlet-name>
         <url-pattern>/hello</url-pattern>
     </servlet-mapping>
 </web-app>