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.pluginsgroupId> <artifactId>maven-jar-pluginartifactId> <configuration> <archive> <manifest> <addClasspath>trueaddClasspath> <classpathPrefix>lib/classpathPrefix> <mainClass>com.xxx.uploadFilemainClass> 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.pluginsgroupId> <artifactId>maven-dependency-pluginartifactId> <version>3.0.1version> <executions> <execution> <id>copyid> <phase>packagephase> <goals> <goal>copygoal> goals> <configuration> <artifactItems> <artifactItem> <groupId>junitgroupId> <artifactId>junitartifactId> <version>4.11version> <outputDirectory>${project.build.directory}/lib/lib1outputDirectory> artifactItem> <artifactItem> <groupId>org.slf4jgroupId> <artifactId>slf4j-log4j12artifactId> <version>1.7.7version> <outputDirectory>${project.build.directory}/lib/lib1outputDirectory> artifactItem> artifactItems> configuration> execution> executions> plugin>
也可以拷贝所有依赖，如下：
<plugin> <groupId>org.apache.maven.pluginsgroupId> <artifactId>maven-dependency-pluginartifactId> <executions> <execution> <id>copy-dependenciesid> <phase>prepare-packagephase> <goals> <goal>copy-dependenciesgoal> goals> <configuration> <outputDirectory>${project.build.directory}/liboutputDirectory> <overWriteReleases>falseoverWriteReleases> <overWriteSnapshots>falseoverWriteSnapshots> <overWriteIfNewer>trueoverWriteIfNewer> configuration> execution> executions> plugin>
实际情况是我们通常希望基础三方库打到包中，应用jar拷贝到lib目录，同时兼顾易升级和管理复杂性，所以最终是这样的。
<plugin> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-maven-pluginartifactId> <configuration> <layout>ZIPlayout> <mainClass>org.abc.ConsumerStartermainClass> <excludes> <exclude> <groupId>abc.orggroupId> <artifactId>biz-serviceartifactId> exclude> excludes> <includeSystemScope>trueincludeSystemScope> configuration> <executions> <execution> <goals> <goal>repackagegoal> goals> execution> executions> plugin> <plugin> <groupId>org.apache.maven.pluginsgroupId> <artifactId>maven-dependency-pluginartifactId> <version>3.1.1version> <executions> <execution> <id>copyid> <phase>packagephase> <goals> <goal>copygoal> goals> <configuration> <artifactItems> <artifactItem> <groupId>abc.orggroupId> <artifactId>biz-serviceartifactId> <version>1.1.0version> <outputDirectory>${project.build.directory}/liboutputDirectory> 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。