Maven 入门

一、Maven是什么

1. 优秀的构建工具

我们能快速的从源码库构件出最终产品，只需一写配置，能让Maven帮你清理、编译、测试、打包、部署，然后得到最终产品。

2. 不重复发明轮子

Maven已经有庞大的插件，全世界通用，自己不用谢代码

3. 项目管理工具

项目开发过程中需要调用多种jar包，不同的项目可能用相同的jar包，为统一管理项目jar包，实现多个项目中共享JARs。

二、Maven下载和环境变量配置

1. 官网下载

[apache-maven-3.5.2-bin.zip]
(http://mirror.bit.edu.cn/apache/maven/maven-3/3.5.2/binaries/apache-maven-3.5.2-bin.zip)

2. 解压到指定目录

指定目录：C:AppDateapache-maven-3.5.2

3. 配置本机环境变量

环境变量路径：
新建M2_HOME，值：C:AppDateapache-maven-3.5.2
在Path中添加 C:AppDateapache-maven-3.5.2in

2. 解压到指定目录

指定目录：C:AppDateapache-maven-3.5.2

3. 配置本机环境变量

环境变量路径：
新建M2_HOME，值：C:AppDateapache-maven-3.5.2
在Path中添加 C:AppDateapache-maven-3.5.2in

4. CMD验证

打开cmd命令窗口
命令：mvn -v

安装Maven前要配置Java环境

C:Windowssystem32>mvn -v
Apache Maven 3.5.2 (138edd61fd100ec658bfa2d307c43b76940a5d7d; 2017-10-18T15:58:13+08:00)
Maven home: C:AppDateapache-maven-3.5.2in..
Java version: 1.8.0_151, vendor: Oracle Corporation
Java home: C:Program FilesJavajdk1.8.0_151jre
Default locale: zh_CN, platform encoding: GBK
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

三、Maven使用入门

（一）、Maven约定目录结构及内容

• **约定优与配置 **

Maven约定的Java项目结构，以hello-word为例：
CMD 命令：tree /f

E:Class16_MavenDemohello-word> tree /f
│  pom.xml
│
└─src
    ├─main
    │  └─java
    │          HelloWord.java
    │
    └─test
        └─java
                HelloWordTest.java

1.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.xusan</groupId>
  <artifactId>hello-word</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>hello-word</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.7</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

2.主代码

package com.xusan.helloword;

public class HelloWord {
	public String sayHello() {
		return "Hello Maven";
	}
	public static void main(String[] args) {
		System.out.println(new HelloWord().sayHello());
	}
}

3.测试代码

package com.xusan.helloword;
import static org.junit.Assert.assertEquals;
import org.junit.Test;

public class HelloWordTest {
	@Test
	public void testSayHello() {
		HelloWord helloword = new HelloWord();
		String result = helloword.sayHello();
		assertEquals("Hello Maven",result);
	}
}

(二) Maven常用指令

1. mvn -v 或者 mvn -version：验证环境变量
2. mvn help:system ：打印所有系统属性和环境变量
3. mvn compile：编译主源码，但不编译test目录，产生target 文件
4. mvn test：运行单元测试
5. mvn test-compile：编译测试代码，生成targer在test-classes下
6. mvn clean： 删除target 文件夹
7. mvn package ：打包
8. mvn install：安装

1、测试mvn compile

E:Class16_MavenDemohello-word> mvn compile
[INFO] Scanning for projects...

[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ hello-word ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to E:Class16_MavenDemohello-word	argetclasses
[INFO] -----------------------------------------------------------------------
[INFO] BUILD SUCCESS

2、测试mvn compile

 E:Class16_MavenDemohello-word> mvn test-compile
[INFO] Scanning for projects...
(省略...)
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to E:Class16_MavenDemohello-word	arget	est-classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS

3、查看最新目录target

  E:Class16_MavenDemohello-word> tree /f
E:.
│  pom.xml
│
├─src
│  ├─main
│  │  └─java
│  │          HelloWord.java
│  │
│  └─test
│      └─java
│              HelloWordTest.java
│
└─target
    ├─classes
    │  └─com
    │      └─xusan
    │          └─helloword
    │                  HelloWord.class
    │
    ├─maven-status
    │  └─maven-compiler-plugin
    │      ├─compile
    │      │  └─default-compile
    │      │          createdFiles.lst
    │      │          inputFiles.lst
    │      │
    │      └─testCompile
    │          └─default-testCompile
    │                  createdFiles.lst
    │                  inputFiles.lst
    │
    └─test-classes
        └─com
            └─xusan
                └─helloword
                        HelloWordTest.class

4、打包和运行

E:Class16_MavenDemohello-word> mvn clean package
[INFO] Scanning for projects...

（省略...）
[INFO] Building jar: E:Class16_MavenDemohello-word	argethello-word-1.0-SNAPSHOT.jar
[INFO] 
[INFO] BUILD SUCCESS

target下产生一个jar：targethello-word-1.0-SNAPSHOT.jar

5、安装到本地仓库

E:Class16_MavenDemohello-word> mvn install
[INFO] Scanning for projects...
---省略...---
Results :
Tests run: 0, Failures: 0, Errors: 0, Skipped: 0
[INFO] Building jar: E:Class16_MavenDemohello-word	argethello-word-1.0-SNAPSHOT.jar
[INFO] Installing E:Class16_MavenDemohello-word	argethello-word-1.0-SNAPSHOT.jar to C:AppDatemaven
epositorycomxusanhello-word1.0-SNAPSHOThello-word-1.0-SNAPSHOT.jar
---我的本地仓库是：C:AppDatemaven
epository，后面会讲修改本地仓库---
[INFO] Installing E:Class16_MavenDemohello-wordpom.xml to C:AppDatemaven
epositorycomxusanhello-word1.0-SNAPSHOThello-word-1.0-SNAPSHOT.pom
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------

6、执行jar

命令：java -jar

E:Class16_MavenDemohello-word> cd .	arget
PS E:Class16_MavenDemohello-word	arget> java -jar .hello-word-1.0-SNAPSHOT.jar
.hello-word-1.0-SNAPSHOT.jar中没有主清单属性

• 原因：
  HelloWord类有main方法，默认打包成jar无法直接运行，带有main方法类信息无法添加到manifest中运行（打开jar文件中的META-INF/MANIFEST.MF文件，无法看到Main-Class一行）
• 解决办法：
  Maven插件————”Apache Maven Shade Plugin“中的“ManifestResourceTransformer”可以解决问题, 参考——四、POM插件配置

7、mvn install

E:Class16_MavenDemohello-word> mvn install
E:Class16_MavenDemohello-word> cd .	arget
E:Class16_MavenDemohello-word	arget> java -jar .hello-word-1.0-SNAPSHOT.jar
Hello Maven

输出Hello Maven 代表成功编译。

（三）Archetype生成项目骨架

1. mvn archetype:generate

2000多个骨架供选择，直接回车，默认

2043: remote -> us.fatehi:schemacrawler-archetype-plugin-dbconnector (-)
2044: remote -> us.fatehi:schemacrawler-archetype-plugin-lint (-)
2045: remote -> xyz.luan.generator:xyz-generator (-)
Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): 1108:
Choose org.apache.maven.archetypes:maven-archetype-quickstart version:
1: 1.0-alpha-1
2: 1.0-alpha-2
3: 1.0-alpha-3
4: 1.0-alpha-4
5: 1.0
6: 1.1
Choose a number: 6: archetype:generatearchetype:generate

Choose org.apache.maven.archetypes:maven-archetype-quickstart version:
1: 1.0-alpha-1
2: 1.0-alpha-2
3: 1.0-alpha-3
4: 1.0-alpha-4
5: 1.0
6: 1.1
Choose a number: 6:
Define value for property 'groupId': com.xusan
Define value for property 'artifactId': helloword
[INFO] Using property: version = 1.0-SNAPSHOT
Define value for property 'package' com.xusan: : com.xusan
Confirm properties configuration:
groupId: com.xusan
artifactId: helloword
version: 1.0-SNAPSHOT
package: com.xusan
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-quickstart:1.1
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: basedir, Value: E:Class16_MavenDemoArchetype
[INFO] Parameter: package, Value: com.xusan
[INFO] Parameter: groupId, Value: com.xusan
[INFO] Parameter: artifactId, Value: helloword
[INFO] Parameter: packageName, Value: com.xusan
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] project created from Old (1.x) Archetype in dir: E:Class16_MavenDemoArchetypehelloword

生成一个新的helloword骨架

E:Class16_MavenDemoArchetype> tree /f
E:.
└─helloword
    │  pom.xml
    │
    └─src
        ├─main
        │  └─java
        │      └─com
        │          └─xusan
        │                  App.java
        │
        └─test
            └─java
                └─com
                    └─xusan
                            AppTest.java

1.生成的main/./App

package com.xusan;

/**
 * Hello world!
 *
 */
public class App 
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
    }
}

2.生成的test/./AAppTest

package com.xusan;

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
 * Unit test for simple App.
 */
public class AppTest 
    extends TestCase
{
    /**
     * Create the test case
     *
     * @param testName name of the test case
     */
    public AppTest( String testName )
    {
        super( testName );
    }

    /**
     * @return the suite of tests being tested
     */
    public static Test suite()
    {
        return new TestSuite( AppTest.class );
    }

    /**
     * Rigourous Test :-)
     */
    public void testApp()
    {
        assertTrue( true );
    }
}

3.生成的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.xusan</groupId>
  <artifactId>helloword</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>helloword</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

2.直接编辑命令包含3要素

命令：mvn archetype:generate "-DgroupId=com.xusan.maven01" "-DartifactId=demo-maven01" "-Dversion=1.0-SNAPSHOT" "-Dpackage=com.xusan.maven01"

四、Maven项目核心POM .xml

pom定义了项目的基本信息，描述了项目的构建、依赖

1、Maven项目的基本坐标：

<!-- 项目包名: 公司地址名称反写+项目名称-->
  <groupId>com.xusan</groupId>
<!--项目模块名称：一般为 项目名-模块名 -->
  <artifactId>hello-word</artifactId>
<!-- 指定当前pom 的版本-->
  <version>1.0-SNAPSHOT</version>

2.POM插件配置

(1).查看官方配置文档

官网ManifestResourceTransformer配置

(2).配置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.xusan</groupId>
  <artifactId>hello-word</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>hello-word</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.7</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  
  <build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-shade-plugin</artifactId>
				<version>3.1.0</version>
				<executions>
					<execution>
						<goals>
							<goal>shade</goal>
						</goals>
						<configuration>
							<transformers>
								<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
								<manifestEntries>
								<Main-Class>com.xusan.helloword.HelloWord</Main-Class>										
								</manifestEntries>
								</transformer>
							</transformers>
						</configuration>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>	
  
</project>

只要修改包名即可

<manifestEntries>
	<!--改成包名-->
	<Main-Class>com.xusan.helloword.HelloWord</Main-Class>
</manifestEntries>