Maven 阴影可执行 uber jar NoClassDefFoundError

Question

我正在使用 maven shade 插件创建一个可执行的 uber jar，它依赖于我想要的本地系统 jar (mobile-dock-support.jar) 中的某些类在打包阶段包含，所以我有像这样配置的阴影插件

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>2.4.2</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <transformers>
                    <transformer
                        implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <mainClass>uk.xxx.mobiledock.PCSyncApplication</mainClass>
                    </transformer>
                </transformers>
            </configuration>
        </execution>
    </executions>
    <dependencies>
        <dependency>
            <groupId>uk.xxx</groupId>
            <artifactId>mobile-dock-support</artifactId>
            <version>0.0.1-SNAPSHOT</version>
            <scope>system</scope>
            <systemPath>${project.build.directory}/../src/main/libs/mobile-dock-support.jar</systemPath>
        </dependency>
    </dependencies>
</plugin>

它似乎很好地打包了罐子，但是当我运行使用 java -jar xxx.jar 罐子时，它给了我以下内容

java.lang.NoClassDefFoundError: uk/xxx/mobiledock/MobileDockException
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
        at java.lang.Class.privateGetMethodRecursive(Unknown Source)
        at java.lang.Class.getMethod0(Unknown Source)
        at java.lang.Class.getMethod(Unknown Source)
        at sun.launcher.LauncherHelper.validateMainClass(Unknown Source)
        at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Caused by: java.lang.ClassNotFoundException: uk.xxx.mobiledock.MobileDockException
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 7 more
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main"

我还设置了 exec maven 插件，运行正在 mvn exec:java -Dexec.mainClass=uk.xxx.mobiledock.PCSyncApplication 运行按预期设置程序。

这里是 exec maven 插件的设置方式

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>exec-maven-plugin</artifactId>
    <version>1.4.0</version>
    <executions>
        <execution>
            <goals>
                <goal>java</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <includePluginDependencies>true</includePluginDependencies>
        <mainClass>uk.xxx.mobiledock.PCSyncApplication</mainClass>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>uk.xxx</groupId>
            <artifactId>mobile-dock-support</artifactId>
            <version>0.0.1-SNAPSHOT</version>
            <scope>system</scope>
            <systemPath>${project.build.directory}/../src/main/libs/mobile-dock-support.jar</systemPath>
        </dependency>
    </dependencies>
</plugin>

Answer 1

好的，看来问题是 shade 插件没有将系统依赖项复制到 uber jar。有几种 'correct' 方法可以解决这个问题

使用 mvn install
使用存储库管理器，例如 Nexus

但是如果你像我一样没有以上两个选项，因为它是一个协作项目，并且没有像 Nexus 这样的选项，那么我就是这样做的

使用 maven 依赖插件将任何系统依赖项复制到相对于打包的 jar 的某个位置，例如。

<plugin>
    <artifactId>maven-dependency-plugin</artifactId>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>copy-dependencies</goal>
            </goals>
            <configuration>
                <outputDirectory>${project.build.directory}/lib</outputDirectory>
                <includeArtifactIds>mobile-dock-support</includeArtifactIds>
            </configuration>
        </execution>
    </executions>
</plugin>

将复制的 jar 作为 class 路径的一部分添加到 uber jar 的清单文件中，例如

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>2.4.2</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <transformers>
                    <transformer
                        implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <manifestEntries>
                            <Main-Class>uk.xxx.mobiledock.PCSyncApplication</Main-Class>
                            <Class-Path>lib/mobile-dock-support-${mobile-dock-support.version}.jar</Class-Path>
                        </manifestEntries>
                    </transformer>
                </transformers>
            </configuration>
        </execution>
    </executions>
</plugin>

Maven 阴影可执行 uber jar NoClassDefFoundError

Maven shade executable uber jar NoClassDefFoundError

java

maven

exec-maven-plugin

maven-shade-plugin