Maven知识点一览

Maven

介绍和搭建

介绍

Maven是基于项目对象模型(POM),可以通过一小段描述信息来管理项目的构建,报告,和文档的软件项目管理工具。

环境搭建

网址:https://maven.apache.org/download.cgi

windows下载这个包:

配置环境变量:

M2_HOME :

path: %M2_HOME%in;

打开cmd验证:

修改配置文件中本地仓库位置:

打开setting.xml文件:

修改仓库为你自己的文件夹位置:

保存关闭即可。

小案例

Maven约定目录结构

mvn-project

​ src

​ -main

​ -java

​ -package

​ -test

​ -java

​ -package

​ resources

​ target

​ pom.xml

小测试

常用maven命令

mvn -v 查看maven版本

mvn compile 编译

mvn test 测试

mvn package 打包

mvn clean 删除target

mvn install 安装jar包到本地仓库

建立maven-test目录并在其中建立如下目录结构

在main最后目录下建立一个Hallo.java文件，内容如下:

package com.imooc.maven01.model;

public class Hello{
	public String sayHello(){
		return "Hello";
	}
}

在test文件夹最后目录下建立一个TestHello.java文件，内容如下:

package com.imooc.maven01.model;

import org.junit.*;
import org.junit.Assert.*;
public class HelloTest{
	@Test
	public void testSayHello(){
		Assert.assertEquals("Hello",new Hello().sayHello());
	}
}

在maven-test文件夹下建立一个pom.xml文件,内容如下:

<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.imooc.maven01</groupId>
	<artifactId>maven-test</artifactId>
	<version>1.0</version>
	<dependencies>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.10</version>
		</dependency>
	</dependencies>
</project>

在maven-test目录下执行maven命令:

mvn compile

输出如下:

mvn test

输出如下:

mvn package

输出如下:

执行mvn clean,输出如下:

可以看到target文件夹已经不存在了:

执行 mvn install,输出如下:

可以在本地仓库中看到我们的jar包已经存在:

如果输出正确,代表安装及项目创建正确。

注册到仓库并被其他项目依赖

在maven-test目录执行: mvn install

成功后新建一个项目maven-test-2,目录如下:

并且在main最后一个目录下建立一个Speak.java文件,内容如下:

package com.imooc.maven02.util;
import com.imooc.maven01.model.*;

public class Speak{
	public String useSayHallo(){
		return new Hello().sayHello();
	}
}

在test最后一个文件夹下建立一个TestSpeak.java文件,内容如下:

package com.imooc.maven02.util;

import org.junit.*;
import org.junit.Assert.*;
public class SpeakTest{
	@Test
	public void testSayHello(){
		Assert.assertEquals("Hello",new Speak().useSayHallo());
	}
}

pom.xml添加junit和maven-test依赖:

<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.imooc.maven02</groupId>
	<artifactId>maven-test-2</artifactId>
	<version>1.0</version>
	<dependencies>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.10</version>
		</dependency>
		<dependency>
			<groupId>com.imooc.maven01</groupId>
			<artifactId>maven-test</artifactId>
			<version>1.0</version>
		</dependency>
	</dependencies>
</project>

执行maven test

成功,表示依赖相关操作正确。基于此功能方便在其他原有项目上构建更大的项目。

自动生成maven项目骨架

在命令行输入mvn archetype:generate,然后等待下载完相应插件根据提示输入groupId,artifactId,version然后就会自动帮你创建一个对应的maven骨架项目

结果如下:

或者直接设置所有的属性:

mvn archetype:generate -DgroupId=com.imooc.maven04 -DartifactId=maven-test-4 -Dversion1.0

-Dpackage=com.imooc.maven04.demo

然后一路回车即可完成创建

IDEA中配置Maven

当前项目配置:

为新建项目配置默认maven:

最好再更改一下下面的设置:

pom.xml解析

<project>

​	<modelVersion></modelVersion>

​	<groupId>反写公司网址+项目名</groupId>

​	<artifactId>项目名+模块名</artifactId>

​	<!--大版本.分支版本.小版本 snapshot快照,alpha内测,beta公测,Release稳定,GA正式发布-->

​	<version></version>

​	<!--默认是jar可以是war,zip,pom-->

​	<packaging></packaging>

​	<!--项目描述名-->

​	<name></name>

​	<!--项目网址-->

​	<url></url>

​	<!--项目描述-->

​	<description></description>

​	<!--开发者-->	

​	<developers></developers>

​	<licenses></licenses>

​	<organization></organization>

​	<dependencies>	

​			<dependency>

​				<groupId></groupId>

​				<artifactId></artifactId>

​				<version></version>

​				<type></type>

​				<!--依赖使用范围-->	

​				<scope></scope>

​				<!--依赖是否可选默认是false-->	

​				<optional></optional>

​				<!--排除依赖列表-->	

​				<exclusions>

​						<exclusion></exclusion>

​				</exclusions>

​			</dependency>

​	</dependencies>

<!--依赖管理(父模块定义给子模块用)-->	

<dependencyManagement>

​	<dependencies>

​			<dependency></dependency>

​	</dependencies>

​	<build>

​		<!--插件列表-->

​		<plugin>

​				<groupId></groupId>

​				<artifactId></artifactId>

​				<version></version>

​		</plugin>

​	</build>

<!--继承父模块-->

<parent></parent>

<!--聚合多个模块编译-->

<modules></modules>

</dependencyManagement>

</project>

依赖范围

三种类路径

编译,测试,运行

scope

compile:默认范围,编译测试运行都有效

provided:在测试和编译时有效

runtime:只在测试和运行时有效

test：只在测试时有效

system：只在测试和编译时有效,与本地环境关联,可移植性较差

import:导入的范围,只使用在dependencyManagement中,表示从其他的pom中导入dependecy的配置

依赖传递

bige<--nange<--shanji（默认依赖bige可以排除）

hongxing-bige的pom.xml

<?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.hongxing</groupId>
  <artifactId>hongxing-bige</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>hongxing-bige</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.0</version>
    </dependency>
  </dependencies>

</project>

hongxing-nange的pom.xml

<?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.hongxing</groupId>
  <artifactId>hongxing-nange</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>hongxing-nange</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.hongxing</groupId>
      <artifactId>hongxing-bige</artifactId>
      <version>1.0-SNAPSHOT</version>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.5</version>
    </dependency>
  </dependencies>

</project>

hongxing-shanji的pom.xml

<?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.hongxing</groupId>
  <artifactId>hongxing-shanji</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>hongxing-shanji</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.hongxing</groupId>
      <artifactId>hongxing-nange</artifactId>
      <version>1.0-SNAPSHOT</version>
    </dependency>
  </dependencies>

</project>

hongxing-shanji如果不想依赖hongxing-bige可以用下面的方式引入hongxing-nange

<dependency>
      <groupId>com.hongxing</groupId>
      <artifactId>hongxing-nange</artifactId>
      <version>1.0-SNAPSHOT</version>
      <exclusions>
        <exclusion>
          <groupId>com.hongxing</groupId>
          <artifactId>hongxing-bige</artifactId>
        </exclusion>
      </exclusions>
    </dependency>

依赖冲突

短路优先

A-->B-->C-->X(jar)

A-->D-->X(jar)

会优先解析短的路径

上面hongxing-shanji默认的commons-io的版本会是hongxing-nange中的版本

路径长度相同,谁的dependacy先声明,谁先解析

A-->B--X(jar)

A-->D-->X(jar)

如果在A中先声明D就用D中的X.jar版本

聚合

可以建立一个聚合maven项目来管理hongxing-bige,hongxing-nange，hongxing-shanji

建立一个hongxing-allmaven项目,pom.xml如下

<?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.hongxing</groupId>
  <artifactId>hongxing-all</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>pom</packaging>

  <name>hongxing-all</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

    <modules>
      <module>../hongxingbige</module>
      <module>../hongxingnange</module>
      <module>../hongxingshanji</module>
    </modules>
</project>

运行该项目,会将三个module的pom.xml都运行

继承

可以建立一个父maven项目来提供依赖给子项目继承,父类提供详细描述,子类只需填写groupId和artifactId即可引入依赖。

继承后各pom.xml(注意要先将父pom注册到仓库中)

hongxing-parent的pom.xml

<?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.hongxing</groupId>
  <artifactId>hongxing-parent</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>pom</packaging>
  <name>hongxing-parent</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <junit.version>4.11</junit.version>
  </properties>
<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>${junit.version}</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

</project>

hongxing-bige的pom.xml

<?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.hongxing</groupId>
  <artifactId>hongxing-bige</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>hongxing-bige</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>
  <parent>
    <groupId>com.hongxing</groupId>
    <artifactId>hongxing-parent</artifactId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.0</version>
    </dependency>
  </dependencies>

</project>

hongxing-nage的pom.xml

<?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.hongxing</groupId>
  <artifactId>hongxing-nange</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>hongxing-nange</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>
  <parent>
    <groupId>com.hongxing</groupId>
    <artifactId>hongxing-parent</artifactId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
    </dependency>
    <dependency>
      <groupId>com.hongxing</groupId>
      <artifactId>hongxing-bige</artifactId>
      <version>1.0-SNAPSHOT</version>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.5</version>
    </dependency>
  </dependencies>

</project>

hongxing-shanji的pom.xml

<?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.hongxing</groupId>
  <artifactId>hongxing-shanji</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>hongxing-shanji</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>
  <parent>
    <groupId>com.hongxing</groupId>
    <artifactId>hongxing-parent</artifactId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
    </dependency>
    <dependency>
      <groupId>com.hongxing</groupId>
      <artifactId>hongxing-nange</artifactId>
      <version>1.0-SNAPSHOT</version>
      <exclusions>
        <exclusion>
          <groupId>com.hongxing</groupId>
          <artifactId>hongxing-bige</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
  </dependencies>

</project>