点击开始菜单，输入cmd
在cmd窗口中输入java，如果提示下面的内容，表面jdk,jre已经安装了
如果提示
‘java’ 不是内部或外部命令，也不是可运行的程序或批处理文件。
表明jdk没有安装
打开左下角任务栏中的开始按钮，输入“cmd”点回车在dos面板中输入“java”点击回车，
出现如下界面：
C:\Documents and Settings\xxx>java -ver
Unrecognized option: -ver
Could not create the Java virtual machine.
C:\Documents and Settings\zyx>java -version
java version "1.6.0_07"
Java(TM) SE Runtime Environment (build 1.6.0_07-b06)
Java HotSpot(TM) Client VM (build 10.0-b23, mixed mode, sharing)
C:\Documents and Settings\zyx>java
Usage: java [-options] class [args...]
(to execute a class)
or java [-options] -jar jarfile [args...]
(to execute a jar file)
where options include:
-client to select the "client" VM
-server to select the "server" VM
-hotspot is a synonym for the "client" VM [deprecated]
The default VM is client.
-cp <class search path of directories and zip/jar files>
-classpath <class search path of directories and zip/jar files>
A separated list of directories, JAR archives,
and ZIP archives to search for class files.
-D<name>=<value>
set a system property
-verbose[:class|gc|jni]
enable verbose output
-version print product version and exit
-version:<value>
require the specified version to run
-showversion print product version and continue
-jre-restrict-search | -jre-no-restrict-search
include/exclude user private JREs in the version search
-? -help print this help message
-Xprint help on non-standard options
-ea[:<packagename>...|:<classname>]
-enableassertions[:<packagename>...|:<classname>]
enable assertions
-da[:<packagename>...|:<classname>]
-disableassertions[:<packagename>...|:<classname>]
disable assertions
-esa | -enablesystemassertions
enable system assertions
-dsa | -disablesystemassertions
disable system assertions
-agentlib:<libname>[=<options>]
load native agent library <libname>, e.g. -agentlib:hprof
see also, -agentlib:jdwp=help and -agentlib:hprof=help
-agentpath:<pathname>[=<options>]
load native agent library by full pathname
-javaagent:<jarpath>[=<options>]
load Java programming language agent, see java.lang.instrument
-splash:<imagepath>
show splash screen with specified image
C:\Documents and Settings\xxx>
然后dos面板中输入“javac”
出现java文件说明
最后在dos面板中输入 “java -version”
出现java版本号，完成以上步骤就说明JAVA变量环境已经在电脑上安装好了
C:\Documents and Settings\xxx>java -version
java version "1.6.0_07"
Java(TM) SE Runtime Environment (build 1.6.0_07-b06)
Java HotSpot(TM) Client VM (build 10.0-b23, mixed mode, sharing)
