Spark Maven项目打包后找不到主类

项目配置：IDEA + Maven + spark2.2 + scala 2.11.4 + java8

问题：使用IDEA，Maven创建java和scala项目，写完代码本地运行没有问题，打包后，java程序没有问题，scala程序总是找不到主类

java.lang.ClassNotFoundException: cn.spark.sql.SparkSQLDemo
        at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:348)
        at org.apache.spark.util.Utils$.classForName(Utils.scala:225)
        at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:686)
        at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:185)
        at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:210)
        at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:124)
        at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)

问题原因：Maven缺少插件scala-maven-plugin
问题解决：加入插件

<build>
        <plugins>
            <plugin>
                <groupId>net.alchim31.mavengroupId>
                <artifactId>scala-maven-pluginartifactId>
                <version>3.2.2version>
                <executions>
                    <execution>
                        <id>compile-scalaid>
                        <phase>compilephase>
                        <goals>
                            <goal>add-sourcegoal>
                            <goal>compilegoal>
                        goals>
                    execution>
                    <execution>
                        <id>test-compile-scalaid>
                        <phase>test-compilephase>
                        <goals>
                            <goal>add-sourcegoal>
                            <goal>testCompilegoal>
                        goals>
                    execution>
                executions>
                <configuration>
                    <scalaVersion>2.11.4scalaVersion>
                configuration>
            plugin>

            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
                <version>3.2version>
                <configuration>
                    <source>1.8source>
                    <target>1.8target>
                configuration>
            plugin>

            <plugin>
                <artifactId>maven-assembly-pluginartifactId>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependenciesdescriptorRef>
                    descriptorRefs>
                    <archive>
                        <manifest>
                            <mainClass>mainClass>
                        manifest>
                    archive>
                configuration>
                <executions>
                    <execution>
                        <id>make-assemblyid>
                        <phase>packagephase>
                        <goals>
                            <goal>singlegoal>
                        goals>
                    execution>
                executions>
            plugin>

            <plugin>
                <groupId>org.codehaus.mojogroupId>
                <artifactId>exec-maven-pluginartifactId>
                <version>1.6.0version>
                <executions>
                    <execution>
                        <goals>
                            <goal>execgoal>
                        goals>
                    execution>
                executions>
                <configuration>
                    <executable>javaexecutable>
                    <includeProjectDependencies>trueincludeProjectDependencies>
                    <includePluginDependencies>falseincludePluginDependencies>
                    <classpathScope>compileclasspathScope>
                    <mainClass>cn.spark.study.AppmainClass>
                configuration>
            plugin>
        plugins>
    build>