用intellij运行java spark

Question

我是Spark 的新手。我创建了一个maven 项目并获取了一些WordCount 来运行它。我收到此错误消息：

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/spark/api/java/function/FlatMapFunction
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2615)
    at java.lang.Class.getMethod0(Class.java:2856)
    at java.lang.Class.getMethod(Class.java:1668)
    at sun.launcher.LauncherHelper.getMainMethod(LauncherHelper.java:494)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:486)
Caused by: java.lang.ClassNotFoundException: org.apache.spark.api.java.function.FlatMapFunction
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
Disconnected from the target VM, address: '127.0.0.1:52170', transport: 'socket'
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)

maven 文件

<?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>org.spark.test</groupId>
    <artifactId>spark-test</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
           <groupId>org.apache.spark</groupId>
            <artifactId>spark-core_2.10</artifactId>
            <version>1.4.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <properties>
        <java.version>1.7</java.version>
    </properties>
    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.1</version>
                    <configuration>
                        <source>${java.version}</source>
                        <target>${java.version}</target>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

此错误在运行时出现。我该如何处理？我听说过SPARK_CLASSPATH，但我不知道如何设置。

Answer 1

provided 范围意味着 JAR 不会在构建时与您的应用程序一起打包 - jar 将由目标环境提供。删除该行：

 <scope>provided</scope>

使用默认的“编译”范围。您的应用服务器可能不提供 jar，因此需要后者。