Embeds the Java Runtime Environment into a Node.js app
npm install jre
This module will embed the Java Runtime Environment (JRE) into a Node.js app.
It will download the platform specific JRE at installation time.
Afterwards the embedding app can be bundled into a platform specific package.
This package would not require any further JRE installation steps by users.
``bash`
npm install --save node-jre
In this example we will run the a Java class-file at the relative path
java/Hello.class. It's source code java/Hello.java would look like this:
`java`
public class Hello {
public static void main(String[] args) {
System.out.println("Hello, " + args[0] + "!");
}
}
You can compile it with something like this:
`bash`
javac java/Hello.java
By running the following file you should get true as output.
`javascript
var jre = require('node-jre');
var output = jre.spawnSync( // call synchronously
['java'], // add the relative directory 'java' to the class-path
'Hello', // call main routine in class 'Hello'
['World'], // pass 'World' as only parameter
{ encoding: 'utf8' } // encode output as string
).stdout.trim(); // take output from stdout as trimmed String
console.log(output === 'Hello, World!'); // Should print 'true'
`
jre.install([callback]) Downloads and prepares a Java Runtime Engine (JRE). It is automatically called during module installation.callback
- (function(error)). Will be called when installation is finished. In case of any problems, error will be defined and contain a description.
jre.spawn(classpath, classname[, args][, options]) Spawns a new child process by running the main method of a given Java class. This is a wrapper around [child_process.spawn]. Please look there for further documentation.classpath
- (array of strings). Paths to .jar files or directories containing .classfiles.classname
- (string). The Java class to run.args
- (array of strings).options
The command line arguments that are to be passed to the Java class's main method.
Same as in [child_process.spawn].
- (object). Options that are passed to [child_process.spawn].
- Returns an object of the type [child_process.ChildProcess].
[child_process.spawn]: https://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options
[child_process.ChildProcess]: https://nodejs.org/api/child_process.html#child_process_class_childprocess
jre.spawnSync(classpath, classname[, args][, options]) Synchronously spawns a new child process by running the main method of a given Java class. The command will not return until the spawned process ends. This is a wrapper around [child_process.spawnSync]. Please look there for further documentation.classpath
- (array of strings). Paths to .jar files or directories containing .classfiles.classname
- (string). The Java class to run.args
- (array of strings).options` (object). Options that are passed to [child_process.spawnSync].
The command line arguments that are to be passed to the Java class's main method.
Same as in [child_process.spawnSync].
-
- Returns a result object as in [child_process.spawnSync].
[child_process.spawnSync]: https://nodejs.org/api/child_process.html#child_process_child_process_spawnsync_command_args_options
Copyright (c) 2016 schreiben
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