基本原因：java.lang.ClassNotFoundException：com.mysql.jdbc.Driver使用--verbose获取详细的堆栈跟踪。

时间：2018-05-24 03:56:48

标签： mysql hadoop hive centos6.8

我尝试使用VMware Fusion在 macOS 上的 CentOS6.8 上构建spark环境。

我之前安装了 jdk-10.0.1 ， hadoop-2.4.1.tar.gz 和 MySQL 。他们成功地工作了。

但是，当我尝试格式化matadata存储库时，

schematool -dbType mysql -initSchema

发生了以下错误：

    which: no hbase in (/opt/hive/bin:/usr/local/hive/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/java/latest/bin:/usr/local/hadoop/sbin:/usr/local/hadoop/bin:/usr/local/hive/bin:/root/bin:/usr/java/latest/bin:/usr/local/hadoop/sbin:/usr/local/hadoop/bin:/opt/hive/bin)
     ^HMetastore connection URL:     jdbc:mysql://hbase01:3306/myhive?createDatabaseIfNotExist=true
    Metastore Connection Driver :    com.mysql.jdbc.Driver
    Metastore connection User:       myhive
    org.apache.hadoop.hive.metastore.HiveMetaException: Failed to load driver
    Underlying cause: java.lang.ClassNotFoundException : com.mysql.jdbc.Driver
    Use --verbose for detailed stacktrace.
    *** schemaTool failed ***

我忽略它并输入“$ HIVE_HOME / bin / hive”，发生以下错误：

which: no hbase in (/opt/hive/bin:/usr/local/hive/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/java/latest/bin:/usr/local/hadoop/sbin:/usr/local/hadoop/bin:/usr/local/hive/bin:/root/bin:/usr/java/latest/bin:/usr/local/hadoop/sbin:/usr/local/hadoop/bin:/opt/hive/bin)
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:387)
        at org.apache.hadoop.hive.ql.session.SessionState.<init>(SessionState.java:363)
        at org.apache.hadoop.hive.cli.CliSessionState.<init>(CliSessionState.java:60)
        at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:663)
        at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:641)
        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.main(RunJar.java:212)

我确信我已将mysql-connector-java放入hive的lib文件夹中。但仍有问题。

感谢任何帮助。非常感谢！

1 个答案:

答案 0 :(得分：0)

Underlying cause: java.lang.ClassNotFoundException : com.mysql.jdbc.Driver

以上错误显示您必须缺少mysql.jdbc.driver jar。

下载mysql JDBC Connector以从Metastore Service访问MySQL数据库。

将连接器jar放到$ HIVE_HOME / lib目录中，使其在类路径中可用。

 wget http://www.java2s.com/Code/JarDownload/mysql/mysql-connector-java-commercial-5.1.7-bin.jar.zip
 unzip mysql-connector-java-commercial-5.1.7-bin.jar.zip
 cp mysql-connector-java-commercial-5.1.7-bin.jar  $HIVE_HOME/lib/

使用适当的访问权限创建数据库和用户

安装了MySQL。运行以下命令以访问mysql提示符。

sudo mysql

现在在mysql提示符下执行以下命令，在MySQL中配置hive用户和Metastore架构。

create database hive DEFAULT CHARACTER SET utf8; mysql> grant all PRIVILEGES on *.* TO 'hive'@'localhost' IDENTIFIED BY 'password_for_hive' WITH GRANT OPTION;

在上面的命令中，您可以使用IP地址或Metastore Server的主机名代替localhost。

配置Hive以使用MySQL 

gedit $HIVE_HOME/conf/hive-site.xml

将以下配置添加到该行的末尾。

 <property>
    <name>javax.jdo.option.ConnectionURL</name>
    <value>jdbc:mysql://localhost:3306/hive</value>
    <description>JDBC connection string used by Hive Metastore</description>
  </property>

  <property>
    <name>javax.jdo.option.ConnectionDriverName</name>
    <value>com.mysql.jdbc.Driver</value>
    <description>JDBC Driver class</description>
  </property>

  <property>
      <name>javax.jdo.option.ConnectionUserName</name>
      <value>hive</value>
      <description>Metastore database user name</description>
  </property>

  <property>
      <name>javax.jdo.option.ConnectionPassword</name>
      <value>password_hive</value>
      <description>Metastore database password</description>
  </property>

  <property>
      <name>hive.metastore.uris</name>
      <value>thrift://localhost:9084</value>
      <description>Thrift server hostname and port</description>
  </property>

##保存文件并关闭它

在上述配置中，您可以使用相关的IP地址或主机名代替localhost。

更改hive-site.xml

的属性值 
<property>
    <name>hive.exec.scratchdir</name>
    <value>/home/path/to/apache-hive-2.3.2-bin/iotmp</value>
    <description>HDFS root scratch dir for Hive jobs which gets created with write all (733) permission. For each connecting user, an HDFS scratch dir: ${hive.exec.scratchdir}/&lt;username&gt; is created, with ${hive.scratch.dir.permission}.</description>
  </property>
<name>hive.exec.local.scratchdir</name>
    <value>/home/path/to/apache-hive-2.3.2-bin/iotmp</value>
    <description>Local scratch space for Hive jobs</description>
  </property>

  <property>
    <name>hive.downloaded.resources.dir</name>
    <value>/home/path/to/apache-hive-2.3.2-bin/iotmp</value>
    <description>Temporary local directory for added resources in the remote file system.</description>
  </property>

编辑hive-env.sh文件并添加以下内容

export METASTORE_PORT=9084

启动Hive Metastore Server

初始化Hive Metastore数据库架构：

 HIVE_HOME/bin/schematool -initSchema -dbType $databaseType $ hive
--service metastore &

启动hive 

 hive
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