java安装环境变量

How to set the environment variables for Java in Windows (the classpath)?

解决方案

Java SE Development Kit 8u112 on a 64-bit Windows 7 or Windows 8

Set the following user environment variables (== environment variables of type user variables)

• JAVA_HOME : C:Program FilesJavajdk1.8.0_112
• JDK_HOME : %JAVA_HOME%
• JRE_HOME : %JAVA_HOME%jre
• CLASSPATH : .;%JAVA_HOME%lib;%JAVA_HOME%jrelib
• PATH : your-unique-entries;%JAVA_HOME%in (make sure that the longish your-unique-entries does not contain any other references to another Java installation folder.

Note for Windows users on 64-bit systems:

Progra~1 = 'Program Files'
Progra~2 = 'Program Files(x86)'

Notice that these environment variables are derived from the "root" environment variable JAVA_HOME. This makes it easy to update your environment variables when updating the JDK. Just point JAVA_HOME to the fresh installation.

There is a blogpost explaining the rationale behind all these environment variables.

Optional recommendations

• Add an user environment variable JAVA_TOOL_OPTIONS with value -Dfile.encoding="UTF-8". This ensures that Java (and tools such as Maven) will run with a Charset.defaultCharset() of UTF-8 (instead of the default Windows-1252). This has saved a lot of headaches when wirking with my own code and that of others, which unfortunately often assume the (sane) default encoding UTF-8.
• When JDK is installed, it adds to the system environment variable Path an entry C:ProgramDataOracleJavajavapath;. I anecdotally noticed that the links in that directory didn't get updated during an JDK installation update. So it's best to remove C:ProgramDataOracleJavajavapath; from the Path system environment variable in order to have a consistent environment.