Question

我正在尝试在Apache Flink中创建一个Kafka Consumer。我一直在关注Apache Flink文档中的设置和指南。但我得到一个 java.lang.NoClassDefFoundError：org / apache / flink / streaming / api / checkpoint / CheckpointedRestoring 错误。

错误是

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/flink/streaming/api/checkpoint/CheckpointedRestoring
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at com.agt.examples.KafkaConsumer.main(KafkaConsumer.java:34)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.lang.ClassNotFoundException: org.apache.flink.streaming.api.checkpoint.CheckpointedRestoring
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 30 more

KafkaConsumer.class是

public static void main(String[] args) throws Exception{
    StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

    // For Apache Kafka Consumer
    Properties properties = new Properties();
    properties.setProperty("bootstrap.servers", "localhost:9092");

    DataStream<String> stream = env.addSource(new FlinkKafkaConsumer08<String>("my-flink-topic", new SimpleStringSchema(), properties));

    stream.map(new MapFunction<String, String>() {
        private static final long serialVersionUID = -6867736771747690202L;

        @Override
        public String map(String value) throws Exception {
            return value;
        }
    }).print();
    env.execute();

pom.xml是

    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-java</artifactId>
        <version>${flink.version}</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-streaming-java_${scala.binary.version}</artifactId>
        <version>${flink.version}</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-clients_2.10</artifactId>
        <version>1.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-core</artifactId>
        <version>${flink.version}</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.7</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-connector-kafka-0.8_2.10</artifactId>
        <version>1.2.1</version>
    </dependency>

Flink版本是1.4.2，java版本是1.8，我正在使用intellij IDEA。我认为它必须是与依赖关系不相关的东西，但我无法理解这里可能存在的问题。我检查了上面提到的类，但它不在我的库中的流/ api /检查点，当我在网上检查时，它似乎是一个弃用的类。我尝试了mvn clean install，Invalidated caches和Restart，Generate sources和update folders，但仍然出现相同的错误。我按照apache flink设置页面https://ci.apache.org/projects/flink/flink-docs-release-1.2/quickstart/java_api_quickstart.html中的说明创建了项目，但是在我从不同来源进行开发时添加了一些其他依赖项。它是否与其中一个依赖项的版本相关？我完全不在这里。

非常感谢帮助:)

Answer 1

您似乎有flink-clients_2.10和flink-connector-kafka-0.8_2.10依赖项的不一致版本。请尝试在以下部分中使用${flink.version}代替1.2.1：

<dependency>
    <groupId>org.apache.flink</groupId>
    <artifactId>flink-clients_2.10</artifactId>
    <version>1.2.1</version>
</dependency>
<dependency>
    <groupId>org.apache.flink</groupId>
    <artifactId>flink-connector-kafka-0.8_2.10</artifactId>
    <version>1.2.1</version>
</dependency>

尝试在Flink中创建Kafka使用者时出现java.lang.NoClassDefFoundError（CheckpointedRestoring）

1 个答案: