我已经成功安装了hadoop。但是，当我运行hadoop命令时，它会提示以下错误：

C:\>hadoop version
'JAVA_HOME' is not recognized as an internal or external command,
 operable program or batch file.
 Hadoop 2.7.3
 Subversion https://git-wip-us.apache.org/repos/asf/hadoop.git -r 
 baa91f7c6bc9cb92be5982de4719c1c8af91ccff Compiled by root on 2016- 
 0818T01:41ZCompiled with protoc 2.5.0 From source with checksum 
 2e4ce5f957ea4db193bce3734ff29ff4 This command was run using /C:/hadoop- 
 2.7.3/share/hadoop/common/hadoop-common-2.7.3.jar

我检查并修复了jave\u home和path的环境变量。我没有发现路径问题，但在运行hadoop命令或连接到hdfs时，上述错误仍然存在。下面是我运行javac命令时的输出。

C:\>javac
Usage: javac <options> <source files>
where possible options include:
-g                         Generate all debugging info
-g:none                    Generate no debugging info
-g:{lines,vars,source}     Generate only some debugging info
-nowarn                    Generate no warnings
-verbose                   Output messages about what the compiler is doing
-deprecation               Output source locations where deprecated APIs are

我怎样才能解决这个问题？