为什么我在 MAC OS X 10.11 上看不到 JAVA_HOME 路径？
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Why I am not able to see the JAVA_HOME path on my MAC OS X 10.11?
提问by Andy
I am trying to run a JAVA application on my MAC OS X 10.11 ( El Capitan).
我正在尝试在我的 MAC OS X 10.11 ( El Capitan ) 上运行 JAVA 应用程序。
I used this linkto set the JAVA_HOME on my MAC OS X 10.11.
我使用此链接在我的 MAC OS X 10.11 上设置 JAVA_HOME。
I am able to run the following commands:
java -version
which java
我能够运行以下命令：
java -version
which java
However when I go to the Terminal app on MAC and type echo $JAVA_HOME, I see nothing. Why is that? Does that mean that my JAVA_HOME is not set properly ?
但是，当我转到 MAC 上的终端应用程序并输入 echo $JAVA_HOME 时，我什么也没看到。这是为什么？这是否意味着我的 JAVA_HOME 设置不正确？
采纳答案by Markus W Mahlberg
Where to define it
在哪里定义
Ok, first of all, we have to make clear whereto set JAVA_HOME.
好的，首先我们要明确在哪里设置JAVA_HOME.
Simplified, you can define it in two files: either ~/.bashrcor ~/bash_profile. By defaultthe former is executed for what is called "interactive non-login shells" while the latter is used for "login shells".
A "login shell" is exactly what you'd expect: a shell which is started after login via command line. An "interactive non-login shell" is a shell which is started from within a GUI for example. So, according to that, we should put our export statement into ~/.bashrc.
简化的，你可以在两个文件中定义它：要么~/.bashrc或~/bash_profile。通过默认情况下前者是后者则用于“登录shell”所谓的“交互式非登录shell”执行。“登录外壳”正是您所期望的：通过命令行登录后启动的外壳。例如，“交互式非登录外壳”是从 GUI 内启动的外壳。因此，据此，我们应该将我们的出口声明放入~/.bashrc.
Side note: While OS X's "Terminal" application reads both files mentioned, this is not the default behavior and therefor should not be treated as such. And thats why I wrote an explanation.
旁注：虽然 OS X 的“终端”应用程序读取提到的两个文件，但这不是默认行为，因此不应如此对待。这就是为什么我写了一个解释。
What do define
定义什么
You need to export JAVA_HOME in the ~/.bashrcfile so that every time a shell is opened, the variable is set.
您需要在~/.bashrc文件中导出 JAVA_HOME，以便每次打开 shell 时都会设置该变量。
On OS X, the Java Development Kits and Runtime Environments are stored under /Library/Java/JavaVirtualMachines/for quite a while now. Have a look there. This is how it looks at my machine:
在 OS X 上，Java 开发工具包和运行时环境已经存储/Library/Java/JavaVirtualMachines/了很长时间。去那里看看。这是它如何看待我的机器：
/Library/Java/JavaVirtualMachines/
├── jdk1.7.0_45.jdk
├── jdk1.8.0_20.jdk
├── jdk1.8.0_25.jdk
└── jdk1.8.0_51.jdk
The subfolders look similar to this
子文件夹看起来与此类似
jdk1.7.0_45.jdk/
└── Contents
├── Home
├── Info.plist
└── MacOS
And there we got it. So if you wanted to point to the JDK 1.7.0_45, you'd put the following statement into your .bashrc
我们得到了它。因此，如果您想指向 JDK 1.7.0_45，请将以下语句放入您的.bashrc
export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/Home"
To make sure that the correct binaries for that Java version are called, you also should add the following somewhere after the above statement:
为了确保调用该 Java 版本的正确二进制文件，您还应该在上述语句后的某处添加以下内容：
export PATH=$JAVA_HOME/bin:$PATH
回答by Willie Z
If you want to use jdk 1.6 for some reason, which Apple has stopped supporting. It will be removed after you updated Mac OS. You can still get jdk 1.6 from this page: https://support.apple.com/kb/DL1572?locale=zh_CN
如果您出于某种原因想使用 jdk 1.6，Apple 已停止支持该版本。更新 Mac OS 后，它将被删除。您仍然可以从此页面获取 jdk 1.6：https: //support.apple.com/kb/DL1572?locale =zh_CN
After you install jdk 1.6 again, remember to confirm exporting the correct directory for system variable $JAVA_HOME in ~/.bash_profile, etc. For me, it is "/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home".
再次安装jdk 1.6后，记得在~/.bash_profile等中确认导出系统变量$JAVA_HOME的正确目录，对我来说是“/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home” .
回答by SDen
export JAVA_HOME=$(/usr/libexec/java_home -v 1.8)
that is for Java 8 .... original link where I found it is here Installing Java on Mac OS X 10.10 Yosemite and 10.11 El Capitan
那是针对 Java 8 .... 我找到的原始链接在这里在 Mac OS X 10.10 Yosemite 和 10.11 El Capitan 上安装 Java
But the accepted answer works too. Just need to pay attention to path changes after updates.
但接受的答案也有效。只需要注意更新后的路径变化。
回答by chw1k
You will find many answers on how to set JAVA_HOME in OSX but it is hard to find an answer to the question if setting JAVA_HOME is necessary at all.
您会找到许多关于如何在 OSX 中设置 JAVA_HOME 的答案，但是如果根本需要设置 JAVA_HOME，则很难找到问题的答案。
Why is that? Does that mean that my JAVA_HOME is not set properly?
这是为什么？这是否意味着我的 JAVA_HOME 设置不正确？
On OSX, setting the JAVA_HOME environment variable is optional. The JRE and JDK installers do not provide for JAVA_HOME being set; so JAVA_HOME not being set is perfectly fine.
在 OSX 上，设置 JAVA_HOME 环境变量是可选的。JRE 和 JDK 安装程序不提供 JAVA_HOME 设置；所以 JAVA_HOME 没有被设置是完全没问题的。
