How can I start a second Java process?

问题

How can I start a second Java process platform independent? Ideally it should be the same Java version that currently running. Are there any helpful system properties?

回答1:

It is not possible, in general.

The recipe provided in @khachik's answer will not necessarily work for a non Sun implementation of Java.

The java executable is not necessarily called java and doesn't necessarily live in the bin subdirectory. Even with Sun Java, on Windows there are two executables; java and javaw.
The command options for the command that starts a JVM are different for different Java implementations. So the ProcessBuilder step may involve non-portable arguments.

While most JVMs have adopted the primary Sun java command options, there are numerous differences. For example:

IBM J9 uses j9 and j9w as the executable names.
BEA / Oracle JRockit has different -X and -XX options.
Jikes RVM uses rvm as the executable name, and only supports a subset of Sun's java options.
IKVM uses ikvm as the executable name.

(Note: these are just examples that stand out in a cursory reading of the respective online documentation.)

回答2:

You can use java.home system property to find the current JVM:

String jvm = new java.io.File(new java.io.File(System.getProperty("java.home"),
                                               "bin"),
                              "java").getAbsolutePath();

and then run it using ProcessBuilder (or Runtime.exec).

Note that for JDK java.home points to the JRE directory included in JDK.

回答3:

Have you tried using the Apache Commons libs? If you haven't give the launcher project a try. It was quite useful for me some time ago.

Here's the project description from their site:

The Launcher Component is designed to be a cross platform Java application launcher.

The original Java classes come from the Tomcat 4.0 project.

Commons-launcher eliminates the need for a batch or shell script to launch a Java class. Some situations where elimination of a batch or shell script may be desirable are:

You want to avoid having to determining where certain application paths are e.g. your application's home directory, etc. Determining this dynamically in a Windows batch scripts is very tricky on some versions of Windows or when softlinks are used on Unix platforms.

You want to avoid having to handle native file and path separators or native path quoting issues.

You need to enforce certain system properties e.g. java.endorsed.dirs when running with JDK 1.4.

You want to allow users to pass in custom JVM arguments or system properties without having to parse and reorder arguments in your script. This can be tricky and/or messy in batch and shell scripts. You want to bootstrap system properties from a configuration file instead hard-coding them in your batch and shell scripts.

You want to provide localized error messages which is very tricky to do in batch and shell scripts.

来源：https://stackoverflow.com/questions/4421658/how-can-i-start-a-second-java-process

标签

java

process

runtime.exec