问题描述
鉴于Java 9即将问世，我们最终可以使用jshell创建Java REPL，我希望有一种方法可以在脚本中添加shebang并让jshell对其进行解释.
Given that Java 9 is upon us and we can finally have a java REPL with jshell I was hoping there was a way to add a shebang to a script and have jshell interpret it.
我尝试创建test.jsh:
#!/usr/bin/env jshell -s
System.out.println("Hello World")
/exit
但是这给出了:
⚡ ./test.jsh
| Error:
| illegal character: '#'
| #!/usr/bin/env jshell -s
| ^
| Error:
| illegal start of expression
| #!/usr/bin/env jshell -s
| ^
Hello World
事实证明，OpenJDK https://bugs中对此有增强要求. openjdk.java.net/browse/JDK-8167440 .
It turns out there is an enhancement request for this in OpenJDK https://bugs.openjdk.java.net/browse/JDK-8167440.
还有其他方法吗?
推荐答案
使用
//usr/bin/env jshell --show-version --execution local "$0" "$@"; exit $?
作为test.jsh的第一行. test.jsh脚本可能类似于:
as the first line of test.jsh. The test.jsh script could look like:
//usr/bin/env jshell --show-version "$0" "$@"; exit $?
System.out.println("Hello World")
/exit
当然，命令行选项--show-version是可选的，但会立即反馈该工具正在运行.
The command line option --show-version is optional, of course, but gives immediate feedback that the tool is running.
extra 命令行选项--execution local可防止jshell生成另一个VM.这样可以加快启动时间，并且如果脚本代码引发异常，则本地VM将退出.
The extra command line option --execution local prevents jshell to spawn another VM. This speeds up launch time and if an exception is thrown by your script code, the local VM will exit.
请咨询jshell --help和jshell --help-extra的输出以获取更多选项.
Consult the output of jshell --help and jshell --help-extra for more options.
更新
还要查看 https://github.com/maxandersen/jbang 可以使用Java脚本，它提供了一个简洁的包装器，可用于从命令行运行.java文件.
Also take a look at https://github.com/maxandersen/jbang Having fun with Java scripting, which offers a neat wrapper around running .java files from the command line.
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