问题
I have a Java application which requires certain software (one of them being Perl) before it can be run. What I used to do to detect for Perl is:
Runtime.getRuntime().exec("perl Test.pl");
and if there was an IOException declare that there was no Perl.
However, one of my users complained that the app kept failing because he had not placed Perl in his path varible. So this is why I'm asking: Is there any cross-operating system way to detect whether Perl (or any other software) is installed on the user's system and the path to the program?
回答1:
I don't know your target audience (users), but upon failure you could prompt the user to enter the path (a FileChooserDialog) and then store this path for future usage (if the exception is not thrown again). I did that some time ago, luckily I had users that were SysAdmins, so it was OK for them to provide that info when the error happened the first time (I also documented how to update or change these values in a properties file).
Other option as mentioned by Don, is to install the required software as relative to your installation, that's a more common option.
回答2:
These kind of questions seem to be popping out every now and then and the answer (almost) always is no. Most general reason for the negative answer is that Java is run in a homogenous Virtual Machine environment which is by design the same on all platforms; Those operations you can't abstract away/do reliably on at least the most supported platforms just can't be done easily. Detecting external events in the OS in general such as which non-Java applications are also run/installed falls into that "not easy to do" category.
Certainly there could be need/market for JNI libraries for the purpose but those steer heavily from the cross-platform requirement these questions always seem to want to and that's why the short answer is "no". As far as I can see, what you're doing currently is the cleanest way to detect Perl unless you're willing to include perljvm or similar in your project.
回答3:
If the user is not willing to either
- Install perl in an agreed upon location
- Indicate where perl has been installed by storing it's location in an environment variable, config file, windows registry, etc.
then it seems you're only option is to search the entire disk for an executable named 'Perl'. Obviously this could take a very long time, but if you store the location somewhere, at least you should only need to search for it once
回答4:
Getting windows native information using java SDK is not possible without support of external APIs. Instead of using external APIs (which is mostly LGPL licensed and not completely open), we can use the shell commands to get the same.
Step 1 - Checking if (perl) an application is installed
For checking if an application is installed, use ProcessBuilder or Runtime.exec to run one of the following PowerShell command,
Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall* | Select-Object DisplayName | where {$_.DisplayName -match "perl"}
Replace "perl" with your choice of software and stream the output of these and process it.
If PERL (for above question), follow below 2 steps to set path and run perl script from java
Step 2 - If available, set it to Environment Path using java code.
Step 3 - Run your perl script.
来源：https://stackoverflow.com/questions/1354186/detect-if-certain-software-is-installed-on-a-users-machine-in-java