Java 创建jar时选择main类

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)

我读到这是因为在创建jar文件时，我没有选择主文件

这是我用来创建jar文件供您参考的命令：

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

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基本上，我想我需要与这个问题等价的命令行：。

尝试对主类使用manifest文件，并使用以下步骤创建jar

在命令提示符下创建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

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尝试对主类使用清单文件，并使用以下步骤创建jar

在命令提示符下创建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

见