Maven 阴影插件找不到“mainClass”异常？答案

【问题标题】：Maven shade plugin can not find 'mainClass' exception?Maven 阴影插件找不到“mainClass”异常？
【发布时间】：2016-07-18 00:15:21
【问题描述】：

在一个标准的 maven 项目中有一个非常奇怪的构建与 maven-shade-plugin:2.4.3。执行 maven package 命令时总是抛出找不到mainClass 异常。我只是模拟了一个 maven-shade-plugin 的例子，见下文：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mkyong.core.utils</groupId>
    <artifactId>dateUtils</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>dateUtils</name>
    <url>http://maven.apache.org</url>

    <properties>
        <jdk.version>1.7</jdk.version>
        <jodatime.version>2.5</jodatime.version>
        <junit.version>4.11</junit.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>joda-time</groupId>
            <artifactId>joda-time</artifactId>
            <version>${jodatime.version}</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>dateutils</finalName>

        <resources>
            <resource>
                <directory>src/main/resources</directory>
            </resource>
        </resources>
        <plugins>

            <!-- download source code in Eclipse, best practice -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-eclipse-plugin</artifactId>
                <version>2.9</version>
                <configuration>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>false</downloadJavadocs>
                </configuration>
            </plugin>

            <!-- Set a compiler level -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>${jdk.version}</source>
                    <target>${jdk.version}</target>
                </configuration>
            </plugin>

            <!-- Maven Shade Plugin -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.3</version>
                <executions>
                    <!-- Run shade goal on package phase -->
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
          </execution>
                </executions>
        <configuration>
            <shadedArtifactAttached>true</shadedArtifactAttached>
            <shadedClassifierName>jar-with-dependencies</shadedClassifierName>
            <filters>
                <filter>
                    <artifact>*:*</artifact>
                    <excludes>
                        <exclude>META-INF/*.SF</exclude>
                        <exclude>META-INF/*.DSA</exclude>
                        <exclude>META-INF/*.RSA</exclude>
                    </excludes>
                </filter>
            </filters>
            <transformers>
              <transformer
                      implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                  <mainClass>com.mkyong.core.utils.App</mainClass>
              </transformer>
          </transformers>
        </configuration>

            </plugin>

        </plugins>
    </build>

</project>

这个可以运行成功。然后只需更改主类名称，其他类似这样：

<plugin>
     <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
                <configuration>
                    <transformers>
                        <transformer
                                implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                            <mainClass>xxxxxxx</mainClass>
                        </transformer>
                    </transformers>
                </configuration>
            </plugin>

关于插件行的父 pom.xml 文件：

<pluginManagement>
    <plugins>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>2.4.3</version>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <shadedArtifactAttached>true</shadedArtifactAttached>
                <shadedClassifierName>jar-with-dependencies</shadedClassifierName>
                <filters>
                    <filter>
                        <artifact>*:*</artifact>
                        <excludes>
                            <exclude>META-INF/*.SF</exclude>
                            <exclude>META-INF/*.DSA</exclude>
                            <exclude>META-INF/*.RSA</exclude>
                        </excludes>
                    </filter>
                </filters>
            </configuration>
        </plugin>
    </plugins>

</pluginManagement>

所以modules会继承parent，但是打包的时候会抛出异常，说：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-shade-plugin:2.4.3:shade (default) on project analytics-sdk-storm-local: Unable to parse configuration of mojo org.apache.maven.plugins:maven-shade-plugin:2.4.3:shade for parameter mainClass: Cannot find 'mainClass' in class org.apache.maven.plugins.shade.resource.AppendingTransformer -> [Help 1]

但是为什么会这样。有maven依赖树显示：

[INFO] --- maven-dependency-plugin:2.10:tree (default-cli) @ xxxxx ---
[INFO] local:jar:1.0.1-SNAPSHOT
[INFO] +- org.apache.kafka:kafka_2.10:jar:0.8.1.1:compile
[INFO] |  +- com.yammer.metrics:metrics-core:jar:2.2.0:compile
[INFO] |  +- org.xerial.snappy:snappy-java:jar:1.1.2:compile
[INFO] |  +- net.sf.jopt-simple:jopt-simple:jar:3.2:compile
[INFO] |  +- org.scala-lang:scala-library:jar:2.10.1:compile
[INFO] |  \- com.101tec:zkclient:jar:0.3:compile
[INFO] +- org.apache.storm:storm-core:jar:0.9.3:provided
[INFO] |  +- org.clojure:clojure:jar:1.5.1:provided
[INFO] |  +- clj-time:clj-time:jar:0.4.1:provided
[INFO] |  +- joda-time:joda-time:jar:2.8.2:provided
[INFO] |  +- compojure:compojure:jar:1.1.3:provided
[INFO] |  +- org.clojure:core.incubator:jar:0.1.0:provided
[INFO] |  +- org.clojure:tools.macro:jar:0.1.0:provided
[INFO] |  +- clout:clout:jar:1.0.1:provided
[INFO] |  +- ring:ring-core:jar:1.1.5:provided
[INFO] |  +- commons-fileupload:commons-fileupload:jar:1.3.1:provided
[INFO] |  +- javax.servlet:servlet-api:jar:2.5:provided
[INFO] |  +- hiccup:hiccup:jar:0.3.6:provided
[INFO] |  +- ring:ring-devel:jar:0.3.11:provided
[INFO] |  +- clj-stacktrace:clj-stacktrace:jar:0.2.2:provided
[INFO] |  +- ring:ring-jetty-adapter:jar:0.3.11:provided
[INFO] |  +- ring:ring-servlet:jar:0.3.11:provided
[INFO] |  +- org.mortbay.jetty:jetty:jar:6.1.26:provided
[INFO] |  +- org.mortbay.jetty:jetty-util:jar:6.1.26:provided
[INFO] |  +- org.clojure:tools.logging:jar:0.2.3:provided
[INFO] |  +- org.clojure:math.numeric-tower:jar:0.0.1:provided
[INFO] |  +- org.clojure:tools.cli:jar:0.2.4:provided
[INFO] |  +- commons-io:commons-io:jar:2.4:provided
[INFO] |  +- org.apache.commons:commons-exec:jar:1.1:provided
[INFO] |  +- commons-lang:commons-lang:jar:2.5:provided
[INFO] |  +- com.googlecode.json-simple:json-simple:jar:1.1.1:provided
[INFO] |  |  \- junit:junit:jar:4.12:provided
[INFO] |  |     \- org.hamcrest:hamcrest-core:jar:1.3:provided
[INFO] |  +- com.twitter:carbonite:jar:1.4.0:provided
[INFO] |  +- com.esotericsoftware.kryo:kryo:jar:2.21:provided
[INFO] |  +- com.esotericsoftware.reflectasm:reflectasm:jar:shaded:1.07:provided
[INFO] |  +- org.ow2.asm:asm:jar:4.0:compile
[INFO] |  +- com.esotericsoftware.minlog:minlog:jar:1.2:provided
[INFO] |  +- org.objenesis:objenesis:jar:1.2:compile
[INFO] |  +- com.twitter:chill-java:jar:0.3.5:provided
[INFO] |  +- org.yaml:snakeyaml:jar:1.16:provided
[INFO] |  +- commons-logging:commons-logging:jar:1.1.3:provided
[INFO] |  +- commons-codec:commons-codec:jar:1.9:provided
[INFO] |  +- com.googlecode.disruptor:disruptor:jar:2.10.1:provided
[INFO] |  +- org.jgrapht:jgrapht-core:jar:0.9.0:provided
[INFO] |  +- ch.qos.logback:logback-classic:jar:1.1.5:provided
[INFO] |  +- ch.qos.logback:logback-core:jar:1.0.13:provided
[INFO] |  +- org.slf4j:slf4j-api:jar:1.7.12:compile
[INFO] |  +- org.slf4j:log4j-over-slf4j:jar:1.7.16:provided
[INFO] |  \- jline:jline:jar:2.11:compile
[INFO] +- org.apache.storm:storm-kafka:jar:0.9.3:compile
[INFO] |  \- org.apache.curator:curator-framework:jar:2.5.0:compile
[INFO] |     +- org.apache.curator:curator-client:jar:2.5.0:compile
[INFO] |     +- org.apache.zookeeper:zookeeper:jar:3.4.6:compile
[INFO] |     |  \- io.netty:netty:jar:3.7.0.Final:compile
[INFO] |     \- com.google.guava:guava:jar:19.0:compile
[INFO] +- so.sao.analytics:analytics-sdk-common:jar:1.0.1-SNAPSHOT:compile
[INFO] |  +- com.esotericsoftware:kryo:jar:3.0.3:compile
[INFO] |  |  +- com.esotericsoftware:reflectasm:jar:1.10.1:compile
[INFO] |  |  \- com.esotericsoftware:minlog:jar:1.3.0:compile
[INFO] |  \- org.mapdb:mapdb:jar:2.0-beta12:compile
[INFO] \- so.sao.analytics:analytics-sdk-storm-common:jar:1.0.1-SNAPSHOT:compile

我真的不知道为什么它失败了。现在只需注释代码。你见过这个吗，给我看看，谢谢。

【问题讨论】：

请stackoverflow.com/a/29461997/596555

标签： java maven maven-shade-plugin

【解决方案1】：

我也有同样的问题。原来这是由 Spring Boot 引入的一些配置引起的。我使用 spring-boot-starter-parent 作为我的父 pom。

我通过设置 start-class 属性并从我的 pom.xml 中的 shade 插件中删除 ManifestResourceTransformer 配置解决了这个问题。

<properties>
  <start-class>package.Main</start-class>
</properties>

我通过搜索ManifestResourceTransformer 的有效pom 找到了这个属性。

【讨论】：

【解决方案2】：

根据您发布的内容，您已从插件配置中删除了很多内容。在<executions> 部分，您需要指定目标。

修改你的 pom.xml 如下

<project>
    ...
    <build>
        <plugins>
            ...
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.3</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <transformers>
                        <transformer
                            implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                            <mainClass>your.Main</mainClass>
                        </transformer>
                    </transformers>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

执行mvn package 将在./target 中创建阴影Jar。在日志中您应该会看到类似的内容

[INFO] Replacing ../target/..-SNAPSHOT.jar with ../target/..-SNAPSHOT-shaded.jar

由于您没有显示您的 pom.xml，请查看以下差异。

在发布的pom.xmlsn-p 中你有作为实现类

org.apache.maven.plugins.shade.resource.ManifestResourceTransformer

但异常抱怨

org.apache.maven.plugins.shade.resource.AppendingTransformer

【讨论】：

是的，我的父模块pom.xml 文件中有相同的配置。也有参考官方用法maven-shade-plugin/examples/resource-transformers。但还是失败了。在我的另一个项目中，这些设置运行良好。太奇怪了。
@elkan1788 看看我更新的答案。也许在您实际使用的pom.xml 中有某种错字。
谢谢，我pom.xml文件中的核心和demo一样，你可以看我的升级问题。我也觉得和你一样奇怪，为什么它会抛出 AppendingTransformer 异常。也许我的项目中还有其他一些错误设置？