<mirrors>
    <mirror>
      <id>aliyunmaven</id>
      <mirrorOf>*</mirrorOf>
      <name>阿里云公共仓库</name>
      <url>https://maven.aliyun.com/repository/public</url>
    </mirror>
</mirrors>

.
├── pom.xml
├── src               # source
│   └── main
│       ├── java      # 业务代码
│       ├── resources # 资源文件
│       └── webapp
│           ├── WEB-INF
│           │   └── web.xml
│           └── index.jsp
└── target            # 目标文件 

<mirror>
    <id>alimaven</id>
    <mirrorOf>central</mirrorOf>
    <name>aliyun maven</name>
    <url>https://maven.aliyun.com/repository/public</url>
</mirror>

<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">  
<!-- 1、项目基本信息配置 -->
<!-- 2、项目构建环境配置 -->
<!-- 3、项目仓库管理配置 -->
<!-- 4、项目依赖管理配置 -->
<!-- 5、项目报表信息配置 -->
<!-- 6、项目部分分发配置 -->
</project>

$ tree
.
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   │   └── com
    │   │       └── demo
    │   │           └── Hello.java
    │   └── resources
    └── test
        ├── java
        │   └── com
        │       └── demo
        └── resources

<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>com.demo</groupId>
  <artifactId>hello</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>
</project>

package com.demo;
public class Hello{
    public static void main(String[] args){
        System.out.println("Hello");
    }
}

# 清理
$ mvn clean
# 编译
$ mvn compile
# 运行
$ mvn exec:java -Dexec.mainClass="com.demo.Hello"

-DgroupID=""
-DartifactID=""
-DpackageName=""
-DarchetypeArtifactId="maven-archetype-quickstart/maven-archetype-webapp"
-DinteractiveMode=false

$ mvn archetype:generate \
-DgroupId=com.demo \
-DartifactId=java-demo \
-DpackageName=com.demo \
-DarchetypeArtifactId=maven-archetype-quickstart

软件的依赖：
  - G: groupID
  - A: artifactID  
  - V: Version
  - Scope
    - compile  编译、运行、测试、打包（默认）
    - provided 编译、运行 eg: servlet
    - runtime  运行、打包 eg: mysql
    - test     测试
    - system   编译、运行

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-dependency-plugin</artifactId>
    <version>3.1.2</version>
</plugin>

<groupId>com.demo</groupId>
<artifactId>maven-demo</artifactId>
<!-- 快照版 -->
<version>1.0-SNAPSHOT</version>
<!-- 正式版  -->
<version>1.0-RELEASE</version>
<!--配置发布仓库地址-->
<distributionManagement>
    <repository>
        <id>my-release</id>
        <name>My Release</name>
        <url>http://localhost:8081/repository/my-release/</url>
    </repository>
    <snapshotRepository>
        <id>my-snapshot</id>
        <name>My Snapshot</name>
        <url>http://localhost:8081/repository/my-snapshot/</url>
    </snapshotRepository>
</distributionManagement>

<servers>
    <server>
        <id>my-snapshot</id>
        <username>admin</username>
        <password>123456</password>
    </server>
    <server>
        <id>my-release</id>
        <username>admin</username>
        <password>123456</password>
    </server>
</servers>

.
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   │   └── com
    │   │       └── demo
    │   │           └── HelloWorld.java
    │   └── resources
    └── test
        └── java

.
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   │   └── com
    │   │       └── demo
    │   │           └── HelloServlet.java
    │   ├── resources
    │   └── webapp
    │       ├── WEB-INF
    │       │   └── web.xml
    │       └── index.jsp
    └── test
        └── java

<?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>com.demo</groupId>
    <artifactId>java-web-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!-- 修改打包方式 -->
    <packaging>war</packaging>
    <dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <!--编译和运行时生效-->
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <!--命令行启动：$ mvn tomcat7:run-->
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
            </plugin>
        </plugins>
    </build>
</project>

<?xml version="1.0" encoding="UTF8"?>
<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_3_1.xsd"
         version="3.1"
         metadata-complete="false">
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>Demo</title>
</head>
<body>
    <h2>我的web项目</h2>
</body>
</html>

package com.demo;
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;
/**
 * 使用 WebServlet 需要配置 web.xml
 * version > 3.0
 * metadata-complete=false
 *
 * 参考：https://www.cnblogs.com/iCheny/p/10976735.html
 */
@WebServlet(value = "/hello")
public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().println("Hello World.");
    }
}

<dependency>
  <groupId>commons-beanutils</groupId>
  <artifactId>commons-beanutils</artifactId>
  <version>1.9.4</version>
</dependency>
<!-- 优先排除低版本的依赖，一般情况下高版本会兼容低版本 -->
<dependency>
  <groupId>org.apache.poi</groupId>
  <artifactId>poi</artifactId>
  <version>3.5-FINAL</version>
  <exclusions>
    <exclusion>
      <artifactId>commons-logging</artifactId>
      <groupId>commons-logging</groupId>
    </exclusion>
  </exclusions>
</dependency>