package、install、deploy区别

后者都比前者多一步。

mvn clean package依次执行了clean、resources、compile、testResources、testCompile、test、jar(打包)等７个阶段。
mvn clean install依次执行了clean、resources、compile、testResources、testCompile、test、jar(打包)、install等8个阶段。
mvn clean deploy依次执行了clean、resources、compile、testResources、testCompile、test、jar(打包)、install、deploy等９个阶段。

package target目录输出打好的Jar包
install target目录输出打好的Jar包，布署到本地maven仓库
deploy target目录输出打好的Jar包，布署到本地maven仓库和远程maven私服仓库

Clean

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-clean-plugin</artifactId>
  <version>3.1.0</version>
  <configuration>
    <filesets>
      <fileset>
        <directory>${basedir}/plugins</directory>
      </fileset>
      <fileset>
        <directory>${basedir}/sqlplugins</directory>
      </fileset>
    </filesets>
  </configuration>
</plugin>

compiler

maven-compiler-plugin
指定版本，要不会默认成Java1.5，编译不通过。

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>3.8.1</version>
      <configuration>
        <source>1.8</source>
        <target>1.8</target>
      </configuration>
    </plugin>
  </plugins>
</build>

打包

maven-jar-plugin和maven-dependency-plugin

用于生成META-INF/MANIFEST.MF文件的部分内容，com.xxg.Main指定MANIFEST.MF中的Main-Class，true会在MANIFEST.MF加上Class-Path项并配置依赖包，lib/指定依赖包所在目录。
只是生成MANIFEST.MF文件还不够，maven-dependency-plugin插件用于将依赖包拷贝到${project.build.directory}/lib指定的位置，即lib目录下。

<plugin>  
  <groupId>org.apache.maven.plugins</groupId>  
  <artifactId>maven-jar-plugin</artifactId>  
  <version>2.6</version>  
  <configuration>  
    <archive>  
      <manifest>  
        <addClasspath>true</addClasspath>  
        <classpathPrefix>lib/</classpathPrefix>  
        <mainClass>com.xxg.Main</mainClass>  
      </manifest>  
    </archive>  
  </configuration>  
</plugin>  
<plugin>  
  <groupId>org.apache.maven.plugins</groupId>  
  <artifactId>maven-dependency-plugin</artifactId>  
  <version>2.10</version>  
  <executions>  
    <execution>  
      <id>copy-dependencies</id>  
      <phase>package</phase>  
      <goals>  
        <goal>copy-dependencies</goal>  
      </goals>  
      <configuration>  
        <outputDirectory>${project.build.directory}/lib</outputDirectory>  
      </configuration>  
    </execution>  
  </executions>  
</plugin>

maven-assembly-plugin

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-assembly-plugin</artifactId>
  <version>2.4.1</version>
  <configuration>
    <descriptorRefs>
      <descriptorRef>jar-with-dependencies</descriptorRef>
    </descriptorRefs>
    <archive>
      <manifest>
        <mainClass>org.gumiho.rest.App</mainClass>
      </manifest>
    </archive>
  </configuration>
  <executions>
    <execution>
      <id>make-assembly</id>
      <phase>package</phase>
      <goals>
        <goal>single</goal>
      </goals>
    </execution>
  </executions>
</plugin>

maven-shade-plugin

<plugin>  
  <groupId>org.apache.maven.plugins</groupId>  
  <artifactId>maven-shade-plugin</artifactId>  
  <version>2.4.1</version>  
  <executions>  
    <execution>  
      <phase>package</phase>  
      <goals>  
        <goal>shade</goal>  
      </goals>  
      <configuration>  
        <transformers>  
          <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">  
            <mainClass>com.xxg.Main</mainClass>  
          </transformer>  
          <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
            <resource>META-INF/spring.handlers</resource>  
          </transformer>  
          <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
            <resource>META-INF/spring.schemas</resource>  
          </transformer>  
        </transformers>  
      </configuration>  
    </execution>  
  </executions>  
</plugin>

Jar

/META-INF/MANIFEST.MF
运行Jar时JVM会读这个文件，如果里面有Main-Class，就不用命令行指定主类了。
jar包还可以包含其它jar包，这个时候，就需要在MANIFEST.MF文件里配置classpath了。

Class-Path: lib/commons-logging-1.2.jar lib/commons-io-2.4.jar  
Main-Class: com.xxg.Main

frontend-maven-plugin

https://www.jianshu.com/p/b378dfad09f6

Test

https://stackoverflow.com/questions/12828416/generate-test-jar-along-with-jar-file-in-test-package

https://maven.apache.org/guides/mini/guide-attached-tests.html
跳过测试失败

mvn clean test -Dmaven.test.failure.ignore=true

传递依赖的规则

依赖调节（Dependency mediation）

就近原则

如下图，甲间接依赖丁。根据就近原则会依赖最靠近自己的、层级最低的丁1.0版本。

    <mirror>
     <id>aliyunmaven</id>
     <mirrorOf>!apache snapshots</mirrorOf>
     <name>阿里云公共仓库</name>
     <url>https://maven.aliyun.com/repository/central</url>
    </mirror>
    <mirror>
      <id>aliyunmaven</id>
      <mirrorOf>apache snapshots</mirrorOf>
      <name>阿里云阿帕奇仓库</name>
      <url>https://maven.aliyun.com/repository/apache-snapshots</url>
    </mirror>

https://developer.aliyun.com/mvn/guide?spm=a2c6h.13651104.0.0.435836a4HkFEEU

-P 在PowerShell有问题

https://stackoverflow.com/questions/16792499/how-do-i-invoke-two-different-profiles-in-one-maven-command

某模块失败继续

--fail-at-end

Maven shaded 不能反序列化问题 maven shade deserialize error
Invalid lambda deserialization
https://issues.apache.org/jira/browse/MSHADE-260