我正在测试中启动MiniDfsCluster(我的依赖项是2.0.0-cdh4.5.0).我使用一个简单的例程来启动它：

File baseDir = new File("./target/hdfs/" + RunWithHadoopCluster.class.getSimpleName()).getAbsoluteFile();
FileUtil.fullyDelete(baseDir);
Configuration conf = new Configuration();
conf.set(MiniDFSCluster.HDFS_MINIDFS_BASEDIR, baseDir.getAbsolutePath());
MiniDFSCluster.Builder builder = new MiniDFSCluster.Builder(conf);
MiniDFSCluster hdfsCluster = builder.build();
String hdfsURI = "hdfs://localhost:"+ hdfsCluster.getNameNodePort() + "/";

并不断收到以下错误.

12:02:15.994 [main] WARN  o.a.h.metrics2.impl.MetricsConfig - Cannot locate configuration: tried hadoop-metrics2-namenode.properties,hadoop-metrics2.properties
12:02:16.047 [main] INFO  o.a.h.m.impl.MetricsSystemImpl - Scheduled snapshot period at 10 second(s).
12:02:16.047 [main] INFO  o.a.h.m.impl.MetricsSystemImpl - NameNode metrics system started

java.lang.IncompatibleClassChangeError: Implementing class
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at org.apache.hadoop.metrics2.source.JvmMetrics.getEventCounters(JvmMetrics.java:162)
    at org.apache.hadoop.metrics2.source.JvmMetrics.getMetrics(JvmMetrics.java:96)
    at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.getMetrics(MetricsSourceAdapter.java:194)
    at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.updateJmxCache(MetricsSourceAdapter.java:171)
    at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.getMBeanInfo(MetricsSourceAdapter.java:150)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getNewMBeanClassName(DefaultMBeanServerInterceptor.java:333)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:319)
    at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:522)
    at org.apache.hadoop.metrics2.util.MBeans.register(MBeans.java:57)
    at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.startMBeans(MetricsSourceAdapter.java:220)
    at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.start(MetricsSourceAdapter.java:95)
    at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.registerSource(MetricsSystemImpl.java:244)
    at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.register(MetricsSystemImpl.java:222)
    at org.apache.hadoop.metrics2.source.JvmMetrics.create(JvmMetrics.java:80)
    at org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics.create(NameNodeMetrics.java:94)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.initMetrics(NameNode.java:278)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:436)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:613)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:598)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1169)
    at org.apache.hadoop.hdfs.MiniDFSCluster.createNameNode(MiniDFSCluster.java:879)
    at org.apache.hadoop.hdfs.MiniDFSCluster.createNameNodesAndSetConf(MiniDFSCluster.java:770)
    at org.apache.hadoop.hdfs.MiniDFSCluster.initMiniDFSCluster(MiniDFSCluster.java:628)
    at org.apache.hadoop.hdfs.MiniDFSCluster.<init>(MiniDFSCluster.java:323)
    at org.apache.hadoop.hdfs.MiniDFSCluster.<init>(MiniDFSCluster.java:113)
    at org.apache.hadoop.hdfs.MiniDFSCluster$Builder.build(MiniDFSCluster.java:305)

这可能是什么原因？

解决方法:

仔细检查您的依赖项.此错误表明类路径上的日志jar版本不兼容.我遇到了类似的问题,不得不排除由另一个第三方库引入的log4j-over-slf4j依赖性.