Manually create a maven project yourself. First of all, you must understand the directory structure of the maven project, and secondly, you must be able to configure pom.xml.
Let’s illustrate
Prerequisite: Maven configuration is successful
Single maven project
1 Manually create a directory. You can put the directory there. You can take the file name by yourself. Here I named it backup1, then open the directory, create a directory named src in the directory, and create a pom.xml file
<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>backup</groupId>
<artifactId>backup</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<name/>
<description/>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
The pom.xml file is standard and cannot be dropped.
<groupId>backup</groupId>
<artifactId>backup</artifactId>
These two are required, one for group id and one for project id
<packaging>jar</packaging> This indicates the type of packaging. There are jar, war, ear, pom, the first three are common, and the last one means there are sub-maven directories,
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
</dependency>
This is which package you need, you import which package, you need to know the groupid, artifactid, version of the imported package. What I introduced is servlet, it will find servlet-api in remote library or import it in local warehouse.
Next is the Maven plug-in. Maven is essentially a plug-in framework. Its core does not perform any specific build tasks. All these tasks are completed by the plug-in. For example, compiling the source code is done by the maven-compiler-plugin. , So to compile, you need to configure a <artifactId>maven-compiler-plugin</artifactId>, and a maven-compiler-plugin code. If you want to have fun with maven, here is the entry point, but I only know a little For one thing, it has not been studied in depth.
配置基本上，完成了，在进入src目录，在创建一个main目录，在目录下在创建三个目录，如下，java目录就是写java代码的地方了，resource就是放配置文件的地方了，webapp就是web项目。
好了一个空的maven工程就好了，
在backup目录下执行mvn package ， 执行完毕后，你在src目录下就多了一个target目录，里面就是打包jar,backup-1.0.jar就出来了。
如果你在pom.xml中把<packaging>jar</packaging>,改为<packaging>war</packaging>,打包出来就是一个war包了。
maven项目有多子项目创建
在创建一个目录backup，拷贝上面已经创建好了的项目，在复制一份，改个名字backup2, 在复制一个名为backup3,在backup目录下创建一个pom.xml
<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.backup</groupId>
<artifactId>backup</artifactId>
<version>1.0</version>
<packaging>pom</packaging>
<name/>
<description/>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<modules>
<module>backup1</module>
<module>backup2</module>
<module>backup3</module>
</modules>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
这个pom.xml不同之处有1 packaging 值为pom,2 多了modules组件，这就是可以引入多个maven项目,这里配置了3个maven项目
backup下的3个maven项目pom有变，
<parent>
<groupId>com.backup</groupId>
<artifactId>backup</artifactId>
<version>1.0</version>
</parent>
三个pom都需要加入parent节点 ，这样表明三个maven同在一个组，backup1和backup2设置 <packaging>jar</packaging>
儿backup3 <packaging>war</packaging>同时依赖backup1,backup2
<dependencies>
<dependency>
<groupId>com.backup</groupId>
<artifactId>backup1</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>com.backup</groupId>
<artifactId>backup2</artifactId>
<version>1.0</version>
</dependency>
</dependencies>
这样在backup目录下打包，在backup3/target,就可以看到刚打好的包。在lib中会引入backup1,backup2两个jar包的。
多个maven项目依赖就是这样玩的了。我还玩的不够熟练，只能简单的介绍到这里了。