hadoop java中的类路径问题

Question

javac -classpath "/installs/hadoop-0.20.2/*.jar;/installs/hadoop-0.20.2/lib/*.jar" appClientModule/grid/comp/tools/CleanTmp.java
appClientModule/grid/comp/tools/CleanTmp.java:2: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:3: package org.apache.hadoop.mapred does not exist
import org.apache.hadoop.mapred.JobConf;
                               ^
appClientModule/grid/comp/tools/CleanTmp.java:4: package org.apache.commons.logging does not exist
import org.apache.commons.logging.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:5: package org.apache.commons.logging.impl does not exist
import org.apache.commons.logging.impl.Log4JLogger;
                                      ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
    ^
appClientModule/grid/comp/tools/CleanTmp.java:9: cannot find symbol
symbol  : class JobConf
location: class grid.comp.tools.CleanTmp
    JobConf jconf;
    ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
                       ^
7 errors
tools $ javac -classpath "/installs/hadoop-0.20.2/*.jar;/installs/hadoop-0.20.2/lib/*.jar" appClientModule/grid/comp/tools/CleanTmp.java
jabir:CompareHdfs jabir.ahmed$ javac -classpath "/installs/hadoop-0.20.2/*.jar;/installs/hadoop-0.20.2/lib/*.jar" appClientModule/grid/comp/tools/CleanTmp.java
appClientModule/grid/comp/tools/CleanTmp.java:2: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:3: package org.apache.hadoop.mapred does not exist
import org.apache.hadoop.mapred.JobConf;
                               ^
appClientModule/grid/comp/tools/CleanTmp.java:4: package org.apache.commons.logging does not exist
import org.apache.commons.logging.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:5: package org.apache.commons.logging.impl does not exist
import org.apache.commons.logging.impl.Log4JLogger;
                                      ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
    ^
appClientModule/grid/comp/tools/CleanTmp.java:9: cannot find symbol
symbol  : class JobConf
location: class grid.comp.tools.CleanTmp
    JobConf jconf;
    ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
                       ^
7 errors
tools $ ls /installs/hadoop-0.20.2/lib/*.jar
/installs/hadoop-0.20.2/lib/ant-contrib-1.0b3.jar           /installs/hadoop-0.20.2/lib/jasper-runtime-5.5.12.jar
/installs/hadoop-0.20.2/lib/aspectjrt-1.6.5.jar             /installs/hadoop-0.20.2/lib/jets3t-0.6.1.jar
/installs/hadoop-0.20.2/lib/aspectjtools-1.6.5.jar          /installs/hadoop-0.20.2/lib/jetty-6.1.26.cloudera.1.jar
/installs/hadoop-0.20.2/lib/commons-cli-1.2.jar             /installs/hadoop-0.20.2/lib/jetty-servlet-tester-6.1.26.cloudera.1.jar
/installs/hadoop-0.20.2/lib/commons-codec-1.4.jar           /installs/hadoop-0.20.2/lib/jetty-util-6.1.26.cloudera.1.jar
/installs/hadoop-0.20.2/lib/commons-daemon-1.0.1.jar            /installs/hadoop-0.20.2/lib/jsch-0.1.42.jar
/installs/hadoop-0.20.2/lib/commons-el-1.0.jar              /installs/hadoop-0.20.2/lib/junit-4.5.jar
/installs/hadoop-0.20.2/lib/commons-httpclient-3.1.jar          /installs/hadoop-0.20.2/lib/kfs-0.2.2.jar
/installs/hadoop-0.20.2/lib/commons-logging-1.0.4.jar           /installs/hadoop-0.20.2/lib/log4j-1.2.15.jar
/installs/hadoop-0.20.2/lib/commons-logging-api-1.0.4.jar       /installs/hadoop-0.20.2/lib/mockito-all-1.8.2.jar
/installs/hadoop-0.20.2/lib/commons-net-1.4.1.jar           /installs/hadoop-0.20.2/lib/oro-2.0.8.jar
/installs/hadoop-0.20.2/lib/core-3.1.1.jar              /installs/hadoop-0.20.2/lib/servlet-api-2.5-20081211.jar
/installs/hadoop-0.20.2/lib/hadoop-fairscheduler-0.20.2-cdh3u2.jar  /installs/hadoop-0.20.2/lib/servlet-api-2.5-6.1.14.jar
/installs/hadoop-0.20.2/lib/hsqldb-1.8.0.10.jar             /installs/hadoop-0.20.2/lib/slf4j-api-1.4.3.jar
/installs/hadoop-0.20.2/lib/jackson-core-asl-1.5.2.jar          /installs/hadoop-0.20.2/lib/slf4j-log4j12-1.4.3.jar
/installs/hadoop-0.20.2/lib/jackson-mapper-asl-1.5.2.jar        /installs/hadoop-0.20.2/lib/xmlenc-0.52.jar
/installs/hadoop-0.20.2/lib/jasper-compiler-5.5.12.jar## Heading ##

那么如何设置类路径

我也尝试通过 env 变量进行设置

$ echo $CLASSPATH /installs/hadoop/lib/.jar:/installs/hadoop/.jar:/installs/hadoop-0.20.2/.jar:/installs/hadoop-0.20.2/lib /.jar

还是失败了

$ javac -version javac 1.6.0_29

Answer 1

寻找更清晰的类路径，例如：

javac -classpath $HADOOP_HOME/hadoop-core-0.20.204.0.jar:$HADOOP_HOME/lib/commons-cli-1.2.jar -d inception src/Inception.java

（在这种情况下，Inception 是您的 java 程序。不知道为什么我提到了这一点，但最好更明确一点！）

如果您使用工具界面，大多数时候您将需要 hadoop-core-(yourversion) 和 commons-cli。

Answer 2

如果你设置了 CLASSPATH 变量，那么你不需要在 javac 命令中指定 -classpath 标志，因为它会从环境变量 CLASSPATH 中获取类路径值

classpath的值需要指向实际的jar文件而不是.jar 例如，

set CLASSPATH=/myapp/mylib.jar

根据您所在的平台，您可以使用 : 或 ;作为不同路径之间的分隔符。对于 Windows，请使用 ;而 UNIX 通常使用：

在 UNIX 中：

set CLASSPATH=/myapp/myclasses1.jar:/myapp/myclasses2.jar

但在 Windows 中，您需要使用分号作为路径之间的分隔符

set CLASSPATH=/myapp/myclasses1.jar;/myapp/myclasses2.jar

Answer 3

inquire 的解决方案帮助了我。这是我在 HDInsight 2.1 版上使用的语法：

C:\apps\dist\java\bin\javac -classpath %HADOOP_HOME%\hadoop-core-1.2.0.1.3.0.1-0302.jar;%HADOOP_HOME%\lib\commons-cli-1.2.jar WordCount.java

Answer 4

无需指定单个库，只需添加“-classpath yarn classpath”。这使得命令非常简单。