idea找不到或無法載入主類

浪費了我好長時間查詢錯誤源頭，百度終無果，最終解決辦法：

1.Mark Directory as 給予scala一個Source root（變成藍色的） 2.修改pom.xml配置檔案

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.etc</groupId>
    <artifactId>spark-sql</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <scala.version>2.10.6</scala.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- 匯入scala的依賴 -->
        <dependency>
          <groupId>org.scala-lang</groupId>
          <artifactId>scala-library</artifactId>
          <version>${scala.version}</version>
      </dependency>

      <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>3.8.1</version>
          <scope>test</scope>
      </dependency>

      <dependency>
          <groupId>org.apache.spark</groupId>
          <artifactId>spark-core_2.10</artifactId>
          <version>1.5.1</version>
      </dependency>
      <dependency>
          <groupId>org.apache.spark</groupId>
          <artifactId>spark-sql_2.10</artifactId>
          <version>1.5.1</version>
      </dependency>
      <dependency>
          <groupId>org.apache.spark</groupId>
          <artifactId>spark-hive_2.10</artifactId>
          <version>1.5.1</version>
      </dependency>
      <dependency>
          <groupId>org.apache.spark</groupId>
          <artifactId>spark-streaming_2.10</artifactId>
          <version>1.5.1</version>
      </dependency>
      <dependency>
          <groupId>org.apache.hadoop</groupId>
          <artifactId>hadoop-client</artifactId>
          <version>2.4.1</version>
      </dependency>
      <dependency>
          <groupId>org.apache.spark</groupId>
          <artifactId>spark-streaming-kafka_2.10</artifactId>
          <version>1.5.1</version>
      </dependency>
      <dependency>
          <groupId>org.apache.spark</groupId>
          <artifactId>spark-streaming-flume_2.10</artifactId>
          <version>1.5.1</version>
      </dependency>
      <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>8.0.11</version>
      </dependency>
      <dependency>
          <groupId>org.apache.hive</groupId>
          <artifactId>hive-jdbc</artifactId>
          <version>0.13.0</version>
      </dependency>
      <dependency>
          <groupId>org.apache.httpcomponents</groupId>
          <artifactId>httpclient</artifactId>
          <version>4.4.1</version>
      </dependency>
      <dependency>
          <groupId>org.apache.httpcomponents</groupId>
          <artifactId>httpcore</artifactId>
          <version>4.4.1</version>
      </dependency>
    </dependencies>

    <build>
      <sourceDirectory>src/main/java</sourceDirectory>
      <testSourceDirectory>src/main/</testSourceDirectory>

      <plugins>
        <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <configuration>
            <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
            </descriptorRefs>
            <archive>
                <manifest>
                    <mainClass></mainClass>
                </manifest>
            </archive>
        </configuration>
        <executions>
            <execution>
                <id>make-assembly</id>
                <phase>package</phase>
                <goals>
                    <goal>single</goal>
                </goals>
            </execution>
        </executions>
    </plugin>

    <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>1.2.1</version>
        <executions>
            <execution>
                <goals>
                    <goal>exec</goal>
                </goals>
            </execution>
        </executions>
        <configuration>
            <executable>java</executable>
            <includeProjectDependencies>true</includeProjectDependencies>
            <includePluginDependencies>false</includePluginDependencies>
            <classpathScope>compile</classpathScope>
            <mainClass>cn.spark.study.App</mainClass>
        </configuration>
    </plugin>

    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
            <source>1.6</source>
            <target>1.6</target>
        </configuration>
    </plugin>


    <!--scala外掛-->
        <plugin>
          <groupId>net.alchim31.maven</groupId>
          <artifactId>scala-maven-plugin</artifactId>
          <version>3.2.2</version>
          <executions>
              <execution>
                  <goals>
                      <goal>compile</goal>
                      <goal>testCompile</goal>
                  </goals>
                  <configuration>
                      <args>                                <!--<arg>-make:transitive</arg>--><!--scala2.11 netbean不支援這個引數-->
                          <arg>-dependencyfile</arg>
                          <arg>${project.build.directory}/.scala_dependencies</arg>
                      </args>
                  </configuration>
                </execution>
            </executions>
        </plugin>


        <!--manven打包外掛-->
        <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>
              <configuration>
                  <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.AppendingTransformer">
                          <resource>reference.conf</resource>
                      </transformer>
                      <transformer
                              implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                          <mainClass>cn.itcast.rpc.Master</mainClass> <!--main方法-->
                      </transformer>
                  </transformers>
              </configuration>
           /execution>
            </executions>
        </plugin>


        </plugins>
    </build>
</project>
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