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IntelliJ IEDA开发servlet

创建普通 Maven 项目，并输入项目信息，这里指定项目名称为 hello-servlet

向 pom.xml 中添加以下内容

<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">

    ....
    
    <packaging>war</packaging>
    <dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <configuration>
                    <webResources>
                        <resource>
                            <directory>${project.basedir}/src/main/resources/</directory>
                        </resource>
                    </webResources>
                    <warName>${project.artifactId}</warName>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project

packaging指定打包方式为war包，servlet-api是开发servlet程序的基础依赖包，scope必须声明为provided，表示运行时依赖由运行环境提供，打包需要借助maven-war-plugin工具进行打包。

在 resources 目录下创建 WEB-INF 目录，并在 WEB-INF 目录下创建 web.xml 文件，名称不能改。

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         version="2.5" xmlns="http://java.sun.com/xml/ns/javaee">
    <servlet>
        <servlet-name>hello</servlet-name>
        <servlet-class>com.demo.service.HelloServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>hello</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>
</web-app>

新建Servlet类

package com.demo.service;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Description:
 * @author: jianfeng.zheng
 * @since: 2020/7/7 21:31 PM
 * @history: 1.2020/7/7 created by jianfeng.zheng
 */
public class HelloServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String name=req.getParameter("username");
        String content="hello "+name;
        resp.getOutputStream().write(content.getBytes("utf-8"));
        resp.getOutputStream().flush();
    }
}

此时的目录结构如下：

.
├── hello-servlet.iml
├── pom.xml
└── src
    └── main
        ├── java
        │   └── com
        │       └── demo
        │           └── service
        │               └── HelloServlet.java
        └── resources
            └── WEB-INF
                └── web.xml