java安装的环境变量

问题描述

如何在 Windows 中为 Java 设置环境变量(类路径)?

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

推荐答案

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

设置以下用户环境变量(==用户变量类型的环境变量)

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 Files\Java\jdk1.8.0_112
• JDK_HOME : %JAVA_HOME%
• JRE_HOME : %JAVA_HOME%\jre
• CLASSPATH : .;%JAVA_HOME%\lib;%JAVA_HOME%\jre\lib
• PATH : your-unique-entries;%JAVA_HOME%\bin(确保较长的 your-unique-entries包含对另一个 Java 安装文件夹的任何其他引用.

• JAVA_HOME : C:\Program Files\Java\jdk1.8.0_112
• JDK_HOME : %JAVA_HOME%
• JRE_HOME : %JAVA_HOME%\jre
• CLASSPATH : .;%JAVA_HOME%\lib;%JAVA_HOME%\jre\lib
• PATH : your-unique-entries;%JAVA_HOME%\bin (make sure that the longish your-unique-entries does not contain any other references to another Java installation folder.

64 位系统上的 Windows 用户注意事项:

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

请注意，这些环境变量是从root"环境变量 JAVA_HOME 派生而来的.这使得在更新 JDK 时更新环境变量变得容易.只需将 JAVA_HOME 指向全新安装.

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.

有一篇博文解释了所有这些环境变量背后的基本原理.

• 添加一个用户环境变量 JAVA_TOOL_OPTIONS，值为-Dfile.encoding="UTF-8".这可以确保 Java(以及诸如 Maven 之类的工具)将使用 UTF-8 的 Charset.defaultCharset()(而不是默认的Windows-1252).这在处理我自己和其他人的代码时省去了很多麻烦，不幸的是，这些代码经常假设(正常的)默认编码 UTF-8.
• 安装JDK时，它会在系统环境变量 Path中添加一个条目C:\ProgramData\Oracle\Java\javapath;.我偶然注意到该目录中的链接在 JDK 安装更新期间没有更新.所以最好将 C:\ProgramData\Oracle\Java\javapath; 从 Path 系统环境变量中删除，以获得一致的环境.

• 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:\ProgramData\Oracle\Java\javapath;. 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:\ProgramData\Oracle\Java\javapath; from the Path system environment variable in order to have a consistent environment.

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