Maven简介

Maven 是一个项目管理工具，可以对 Java 项目进行自动化的构建和依赖管理。

下载maven

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

wget -c https://dlcdn.apache.org/maven/maven-3/3.8.6/binaries/apache-maven-3.8.6-bin.tar.gz

添加国内镜像

阿里云maven镜像库: https://developer.aliyun.com/mvn/guide

• 修改maven目录下的 settings.xml 文件

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

• 修改项目 pom.xml 文件

    <repositories>
        <repository>
            <id>aliyunmaven</id>
            <url>https://maven.aliyun.com/repository/public</url>
            <releases>
                <enabled>true</enabled>
            </releases>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>

创建新项目

mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

• DgroupId: 组织名，公司网址的反写 + 项目名称
• DartifactId: 项目名-模块名
• DarchetypeArtifactId: 指定 ArchetypeId，maven-archetype-quickstart，创建一个简单的 Java 应用
• DinteractiveMode: 是否使用交互模式

报错: java mvn package no main manifest attribute

解决:

• 使用 java -classpath(-cp)命令: java -cp xxx.jar my.packagepath.MainClass
  OR
• pom.xml 添加设置:

<build>
  <plugins>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>3.0.2</version>
        <configuration>
            <archive>
            <manifest>
                <!-- <addClasspath>true</addClasspath> -->
                <!-- <classpathPrefix>lib/</classpathPrefix> -->
                <mainClass>cn.xjfme.encrypt.test.SecurityTestAll</mainClass>
            </manifest>
            </archive>
        </configuration>
    </plugin>
  </plugins>
</build>

OR

<build>
  <plugins>
    <plugin>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-maven-plugin</artifactId>
      <configuration>
        <executable>true</executable>
      </configuration>
    </plugin>
  </plugins>
</build>

打包命令

mvn package

报错:

[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 15 source files to /home/santic/SM2_SM3_SM4Encrypt/target/classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] Source option 5 is no longer supported. Use 7 or later.
[ERROR] Target option 5 is no longer supported. Use 7 or later.
[INFO] 2 errors
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE

在maven的conf下的setting.xml中加上

<profile>
    <id>jdk-1.8</id>
    <activation>
    <jdk>1.8</jdk>
    <activeByDefault>true</activeByDefault>
    </activation>
    <properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
    </properties>
</profile>

将jar依赖包打进jar包

正确示范:

  <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-assembly-plugin</artifactId>
      <executions>
          <execution>
              <phase>package</phase>
              <goals>
                  <goal>single</goal>
              </goals>
              <configuration>
                  <archive>
                  <manifest>
                      <mainClass>my.hangjin.App</mainClass>
                  </manifest>
                  </archive>
                  <descriptorRefs>
                      <descriptorRef>jar-with-dependencies</descriptorRef>
                  </descriptorRefs>
              </configuration>
          </execution>
      </executions>
  </plugin>

网上错误示范:

<build>
    <plugins>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <configuration>
                <archive>
                    <manifest><mainClass>com.wyz.Main</mainClass></manifest>
                </archive>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
        </plugin>
    </plugins>
</build>

引用本地jar包

<dependency>
    <groupId>com.dm</groupId>
    <artifactId>DmJdbcDriver</artifactId>
    <version>1.8.0</version>
    <scope>system</scope>
    <systemPath>${project.basedir}/src/lib/DmJdbcDriver18.jar</systemPath>
</dependency>

<scope>system</scope>，system依赖不是由maven仓库，而是本地的jar包，因此必须配合systemPath标签来指定本地的jar包所在全路径。这类jar包默认会参与编译、测试、运行，但是不会被参与打包阶段。
如果也想打包进去的话，需要在插件里做配置 <includeSystemScope>true</includeSystemScope>

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <configuration>
        <!-- maven打包时会将外部引入的jar包（比如在根目录下或resource文件下新加外部jar包）打包到项目jar -->
        <includeSystemScope>true</includeSystemScope>
    </configuration>
</plugin>

Maven官网: https://maven.apache.org/guides/getting-started/maven-in-five-minutes.html
java -jar xx.jar是如何运行的 https://blog.csdn.net/qq_35785465/article/details/124490253
用Maven管理第三方jar包依赖 https://tianmingxing.com/2020/02/29/%E7%94%A8Maven%E7%AE%A1%E7%90%86%E7%AC%AC%E4%B8%89%E6%96%B9jar%E5%8C%85%E4%BE%9D%E8%B5%96/
maven配置阿里云镜像的两种方式 https://blog.csdn.net/shaoming314/article/details/120357151
Maven打包可执行jar包方法大全（史上最全） https://blog.csdn.net/londa/article/details/115098901