Question

我收到此错误：

INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ cdt-hive ---
[INFO] Building jar: /Users/alexamil/WebstormProjects/cisco/cdt-hive/target/cdt-hive-1.0-SNAPSHOT.jar
[INFO] 
[INFO] --- exec-maven-plugin:1.6.0:java (default-cli) @ cdt-hive ---
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/Users/alexamil/.m2/repository/org/slf4j/slf4j-log4j12/1.7.5/slf4j-log4j12-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/Users/alexamil/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.4.1/log4j-slf4j-impl-2.4.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
Trying to connect!
[WARNING] 
java.lang.IncompatibleClassChangeError: Implementing class
        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 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 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$1.run(URLClassLoader.java:362)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        at org.eclipse.jetty.server.ServerConnector.<init>(ServerConnector.java:97)
        at spark.embeddedserver.jetty.SocketConnectorFactory.createSocketConnector(SocketConnectorFactory.java:45)
        at spark.embeddedserver.jetty.EmbeddedJettyServer.ignite(EmbeddedJettyServer.java:96)
        at spark.Service.lambda$init$0(Service.java:349)
        at java.lang.Thread.run(Thread.java:745)

我可以确认只有当我用Δ符号包含下面指示的Spark路径注册行时才会出现错误。

以下是我正在运行的代码：

package cdt;
import org.apache.log4j.*;
import java.sql.*;
import static spark.Spark.*;

public class App {

    final static Logger logger = Logger.getLogger(App.class);

    public static void main(String[] args) throws ClassNotFoundException, SQLException {

        BasicConfigurator.configure(); // configure log4j
        Logger.getRootLogger().setLevel(Level.WARN);

        get("/hello", (req, res) -> "Hello World"); // ∆ register Spark route

        Class.forName("org.apache.hive.jdbc.HiveDriver");

        System.out.println("Trying to connect!");
        Connection con = DriverManager.getConnection("jdbc:hive2://hdprd1-edge-lb01:8888",
                "hdpair", "Dat@_Infusi0n_1");
        System.out.println("Connected!");
        Statement stmt = con.createStatement();
        String sql = ("show tables");
        System.out.println("Trying to execute query!");
        ResultSet res = stmt.executeQuery(sql);
        System.out.println("Query executed!");

        if (res.next()) {
            System.out.println(res.getString(1));
        } else {
            System.out.println("Could not connect!");
        }
    }
}

这是我的pom.xml文件：

<project>

    <modelVersion>4.0.0</modelVersion>
    <groupId>cdt</groupId>
    <artifactId>cdt-hive</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>cdt-hive</name>
    <url>http://maven.apache.org</url>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <build>

        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.6.0</version>
                <configuration>
                    <mainClass>cdt.App</mainClass>
                    <arguments>
                        <argument>foo</argument>
                        <argument>bar</argument>
                        <argument>baz</argument>
                    </arguments>
                </configuration>
            </plugin>
        </plugins>
    </build>



    <dependencies>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.5</version>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>2.8.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-jdbc</artifactId>
            <version>2.1.1</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.8.2</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.sparkjava</groupId>
            <artifactId>spark-core</artifactId>
            <version>2.5</version>
        </dependency>
    </dependencies>

</project>

有谁知道这个错误是什么以及Spark代码调用是如何导致它的？如何避免呢？

Answer 1

此错误表示该类无法在运行时加载，因为运行时环境中的某些类与其他类不兼容。乍一看，SLF4j 似乎存在一些问题 - 也许您在运行时类路径中有多个版本的库，但选择了错误的一个。

使用

mvn help:dependency-tree

打印依赖层次结构并仔细检查不同版本的重复项。然后检查您的服务器运行时类路径

Java Spark服务器 - java.lang.IncompatibleClassChangeError：实现类

1 个答案: