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Spark+Neo4j 【请求处理失败；嵌套异常是 java.lang.ClassNotFoundException：

分类：编程问答

如何解决Spark+Neo4j 【请求处理失败；嵌套异常是 java.lang.ClassNotFoundException：

我尝试构建一个使用与 spark 集成的 neo4j 的 Spring Boot 应用程序。但是当我运行它时会发生错误。我不明白这是什么意思。


java.lang.classNotFoundException: org.neo4j.spark.DataSource.DefaultSource
    at org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader.loadClass(TomcatEmbeddedWebappClassLoader.java:72) ~[spring-boot-2.4.0.jar:2.4.0]
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1188) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.spark.sql.execution.datasources.DataSource$$anonfun$20$$anonfun$apply$12.apply(DataSource.scala:652) ~[spark-sql_2.11-2.4.7.jar:2.4.7]
    at org.apache.spark.sql.execution.datasources.DataSource$$anonfun$20$$anonfun$apply$12.apply(DataSource.scala:652) ~[spark-sql_2.11-2.4.7.jar:2.4.7]
    at scala.util.Try$.apply(Try.scala:192) ~[scala-library-2.11.12.jar:na]
    at org.apache.spark.sql.execution.datasources.DataSource$$anonfun$20.apply(DataSource.scala:652) ~[spark-sql_2.11-2.4.7.jar:2.4.7]
    at org.apache.spark.sql.execution.datasources.DataSource$$anonfun$20.apply(DataSource.scala:652) ~[spark-sql_2.11-2.4.7.jar:2.4.7]
    at scala.util.Try.orElse(Try.scala:84) ~[scala-library-2.11.12.jar:na]
    at org.apache.spark.sql.execution.datasources.DataSource$.lookupDataSource(DataSource.scala:652) ~[spark-sql_2.11-2.4.7.jar:2.4.7]
    at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:213) ~[spark-sql_2.11-2.4.7.jar:2.4.7]
    at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:186) ~[spark-sql_2.11-2.4.7.jar:2.4.7]
    at com.etuproject.friendfinddboperations.service.WordCountService.getCount(WordCountService.java:35) ~[classes/:na]
    at com.etuproject.friendfinddboperations.controller.WordCountController.count(WordCountController.java:29) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_241]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_241]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_241]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_241]
    at org.springframework.web.method.support.invocableHandlerMethod.doInvoke(invocableHandlerMethod.java:197) ~[spring-web-5.3.1.jar:5.3.1]
    at org.springframework.web.method.support.invocableHandlerMethod.invokeForRequest(invocableHandlerMethod.java:141) ~[spring-web-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.mvc.method.annotation.ServletinvocableHandlerMethod.invokeAndHandle(ServletinvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:893) ~[spring-webmvc-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:807) ~[spring-webmvc-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.dispatcherServlet.dodispatch(dispatcherServlet.java:1061) ~[spring-webmvc-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.dispatcherServlet.doService(dispatcherServlet.java:961) ~[spring-webmvc-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.1.jar:5.3.1]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.3.1.jar:5.3.1]`

我的控制器类就是这样。它只获取一个字符串并调用服务。

import com.etuproject.friendfinddboperations.service.WordCountService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.Arrays;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping(value = "/api/sss")
public class WordCountController {

    @Autowired
    @Qualifier("WordCountService")
    WordCountService service;

    @RequestMapping(method = RequestMethod.POST,path = "/wordcount")
    public Map<String,Long> count(@RequestParam(required = true) String words) {


        return service.getCount(wordList);
    }
}

我的服务类就是这样

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.SparkSession;

@Service("WordCountService")
public class WordCountService {

    @Autowired
    JavaSparkContext sc;


    public Map<String,Long> getCount(List<String> wordList) {
        SparkSession spark = SparkSession
                .builder()
                .appName("Spark sql Example")
                .config("spark.master","local")
                .getorCreate();
        Dataset<Row> ds = spark.read().format("org.neo4j.spark.DataSource")
                .option("url","bolt://localhost:7687")
                .option("authentication.basic.username","neo4j")
                .option("authentication.basic.password","password")
                .option("labels","Person")
                .load();

        ds.show();
        Map<String,Long> wordCounts=new HashMap<>();

        return wordCounts;
    }

}

我的配置文件是 spark.app.name=Spring Spark 字数统计应用程序 spark.master=local[1]

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaSparkContext;
//import org.apache.spark.sql.SparkSession;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class SparkConfig {

    @Value("${spark.app.name}")
    private String appName;
    @Value("${spark.master}")
    private String masterUri;

    @Bean
    public SparkConf conf() {

        return new SparkConf()
                .setAppName(appName)
                .setMaster(masterUri)
                .set("spark.driver.allowMultipleContexts","true");
    }

    @Bean
    public JavaSparkContext sc() {
        return new JavaSparkContext(conf());
    }

}

最后我的 pom 是

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>FindFriends</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>FindFriends</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.3.1</version>
        </dependency>

        <dependency>
            <groupId>neo4j-contrib</groupId>
            <artifactId>neo4j-connector-apache-spark_2.11</artifactId>
            <version>4.0.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <version>RELEASE</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.jgrapht</groupId>
            <artifactId>jgrapht-core</artifactId>
            <version>LATEST</version>
        </dependency>
        <dependency>
            <groupId>MysqL</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>


        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

        <dependency>
            <groupId>com.thoughtworks.paranamer</groupId>
            <artifactId>paranamer</artifactId>
            <version>2.8</version>
        </dependency>
        <dependency>
            <groupId>org.apache.spark</groupId>
            <artifactId>spark-core_2.11</artifactId>
            <version>2.4.7</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-sql -->
        <dependency>
            <groupId>org.apache.spark</groupId>
            <artifactId>spark-sql_2.11</artifactId>
            <version>2.4.7</version>
        </dependency>


    </dependencies>

    <repositories>
        <!-- list of other repositories -->
        <repository>
            <id>SparkPackagesRepo</id>
            <url>http://dl.bintray.com/spark-packages/maven</url>
        </repository>
    </repositories>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

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