配置单元：虽然使用JDK8，但AppClassLoader不能强制转换为URLClassLoader

Question

安装jdk9后，我一直看到这个问题：

$hive
Java HotSpot(TM) 64-Bit Server VM warning: Ignoring option MaxPermSize; support was removed in 8.0
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/usr/local/Cellar/hive/2.3.1/libexec/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/Cellar/hadoop/2.8.1/libexec/share/hadoop/common/lib/slf4j-log4j12-1.7.10.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Exception in thread "main" java.lang.ClassCastException: java.base/jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to java.base/java.net.URLClassLoader
    at org.apache.hadoop.hive.ql.session.SessionState.<init>(SessionState.java:394)
    at org.apache.hadoop.hive.ql.session.SessionState.<init>(SessionState.java:370)
    at org.apache.hadoop.hive.cli.CliSessionState.<init>(CliSessionState.java:60)
    at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:708)
    at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:686)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.apache.hadoop.util.RunJar.run(RunJar.java:234)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:148)

但我有

$java -version
java version "1.8.0_144"
Java(TM) SE Runtime Environment (build 1.8.0_144-b01)
Java HotSpot(TM) 64-Bit Server VM (build 25.144-b01, mixed mode)

vi $(which hive)

#!/bin/bash
JAVA_HOME="$(/usr/libexec/java_home --version 1.8)" HIVE_HOME="/usr/local/Cellar/hive/2.3.1/libexec" exec "/usr/local/Cellar/hive/2.3.1/libexec/bin/hive" "$@"

$/usr/libexec/java_home --version 1.8
/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home

这是macOS上的配置单元2.3.1

 $hive --version
Hive 2.3.1
Git git://jcamachorodriguez-rMBP.local/Users/jcamachorodriguez/src/workspaces/hive/HIVE-apache/hive -r 7590572d9265e15286628013268b2ce785c6aa08
Compiled by jcamachorodriguez on Thu Oct 19 18:37:58 PDT 2017
From source with checksum 03c91029a6103bd91f25a6ff8a01fbcd

Answer 1

安装jdk8，并在hadoop-env.sh中相应地更改路径，这对我起到了作用。