Question

我在尝试运行Mapreduce Wordcount示例时遇到了这个问题：

Exception in thread "main" java.lang.ClassNotFoundException: /usr/local/hadoop/input
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at org.apache.hadoop.util.RunJar.run(RunJar.java:214)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:136)

我读到这是因为创建jar文件时我没有选择主文件。

这是我用来创建jar文件的命令供你参考：

javac -classpath /usr/local/hadoop/etc/hadoop:/usr/local/hadoop/share/hadoop/common/lib/* :/usr/local/hadoop/share/hadoop/common/* :/usr/local/hadoop/share/hadoop/hdfs:/usr/local/hadoop/share/hadoop/hdfs/lib/* :/usr/local/hadoop/share/hadoop/hdfs/* :/usr/local/hadoop/share/hadoop/yarn/lib/* :/usr/local/hadoop/share/hadoop/yarn/* :/usr/local/hadoop/share/hadoop/mapreduce/lib/* :/usr/local/hadoop/share/hadoop/mapreduce/* :/contrib/capacity-scheduler/*.jar -d wordcount_classes WordCount.java

基本上，我想我希望命令行等同于这个问题：question。

Answer 1

尝试将清单文件用于主类，并使用以下步骤创建一个jar

在命令提示符中创建jar文件

Start Command Prompt.
Navigate to the folder that holds your class files:

C:\>cd \mywork

Set path to include JDK’s bin.  For example:

C:\mywork> path c:\Program Files\Java\jdk1.7.0_25\bin;%path%

Compile your class(es):

C:\mywork> javac *.java

Create a manifest file and your jar file:

C:\mywork> echo Main-Class: Craps >manifest.txt

C:\mywork> jar cvfm Craps.jar manifest.txt *.class

or

C:\mywork> jar cvfe Craps.jar Craps *.class

Test your jar:

C:\mywork> Craps.jar

or

C:\mywork> java -jar Craps.jar

创建jar时选择主类

1 个答案: