对于不包含MANIFEST.MF，或jar包中的MANIFEST.MF未指定MainClass的jar，可以通过java命令行选项-classpath指定classpath。但是如果是包含MainClass的jar，例如：
Manifest-Version: 1.0
Bundle-License: http://www.apache.org/licenses/LICENSE-2.0.txt
Bundle-SymbolicName: org.mybatis.generator.mybatis-generator-core
Archiver-Version: Plexus Archiver
Built-By: zjhua
Bnd-LastModified: 1559632976998
Specification-Title: MyBatis Generator Core
Implementation-Vendor-Id: org.mybatis.generator
Bundle-DocURL: http://www.mybatis.org/mybatis-generator/mybatis-genera
tor-core/
Include-Resource: org/mybatis/generator/config/xml/ibator-config_1_0.d
td=src/main/resources/org/mybatis/generator/config/xml/ibator-config_
1_0.dtd,org/mybatis/generator/config/xml/mybatis-generator-config_1_0
.dtd=src/main/resources/org/mybatis/generator/config/xml/mybatis-gene
rator-config_1_0.dtd,org/mybatis/generator/internal/util/messages/mes
sages.properties=src/main/resources/org/mybatis/generator/internal/ut
il/messages/messages.properties
Import-Package: com.mysql.jdbc,javax.xml.parsers,org.apache.commons.la
ng3,org.apache.log4j,org.apache.tools.ant,org.apache.tools.ant.types,
org.w3c.dom,org.xml.sax
Require-Capability: osgi.ee;filter:="(&(osgi.ee=JavaSE)(version=1.6))"
Main-Class: org.mybatis.generator.api.ShellRunner
Implementation-Build-Date: 2019-06-04 07:22:46+0000
其classpath可以通过maven打包插件指定，如下：
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>com.xxx.uploadFile</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
这样和jar文件在同一目录的lib/下的所有jar就都是能够访问到了。
然后我们通过maven-dependency-plugin插件将特定的包拷贝到lib目录，如下：
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>3.0.1</version>
<executions>
<execution>
<id>copy</id>
<phase>package</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<artifactItems>
<artifactItem>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<outputDirectory>${project.build.directory}/lib/lib1</outputDirectory>
</artifactItem>
<artifactItem>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.7</version>
<outputDirectory>${project.build.directory}/lib/lib1</outputDirectory>
</artifactItem>
</artifactItems>
</configuration>
</execution>
</executions>
</plugin>
也可以拷贝所有依赖，如下：
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
实际情况是我们通常希望基础三方库打到包中，应用jar拷贝到lib目录，同时兼顾易升级和管理复杂性，所以最终是这样的。
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<layout>ZIP</layout>
<mainClass>org.abc.ConsumerStarter</mainClass>
<excludes>
<exclude>
<groupId>abc.org</groupId>
<artifactId>biz-service</artifactId>
</exclude>
</excludes>
<includeSystemScope>true</includeSystemScope>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>3.1.1</version>
<executions>
<execution>
<id>copy</id>
<phase>package</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<artifactItems>
<artifactItem>
<groupId>abc.org</groupId>
<artifactId>biz-service</artifactId>
<version>1.1.0</version>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
</artifactItem>
</artifactItems>
</configuration>
</execution>
</executions>
</plugin>
这样打出来的jar就不包含biz-service，在单独的lib目录中。结合layout ZIP特性，就可以完美实现增量升级。
原文地址：https://www.cnblogs.com/zhjh256/p/10987038.html