Execute java project with node-jre module

Question

I am developing a node.js application where I need to execute java code.

I am using de node-jre module (https://www.npmjs.com/package/node-jre).

The example in this web (Hello.class) is running correctly with this code and compilling de Hello class by console with javac Hello.java:

    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();

The problem is when I tried to execute my java project (developed with eclipse). The documentation say that in this directory 'java' search inside jar files. So, it was the first thing I tried: to export the proyect to jar, but it does not work.

So, how can I execute a complete project (with only one main class)?, I think it is important to say that the project use external libraries.

The META-INF/MANIFEST.MF inside jar looks like:

Manifest-Version: 1.0
Class-Path: .
Main-Class: com.packagename.example1.ClassName

Name: org/apache/oro
Specification-Title: Jakarta ORO
Implementation-Title: org.apache.oro
Implementation-Version: 2.0.8 2003-12-28 11:00:13
Specification-Version: 2.0.8
Specification-Vendor: Apache Software Foundation
Implementation-Vendor: Apache Software Foundation

So, my code is:

 var output = jre.spawnSync(  // call synchronously 
    ['java'],                // add the relative directory 'java' to the class-path 
    'ClassName',                 // call main routine in class 'Hello' 
    ['World'],               // pass 'World' as only parameter 
    { encoding: 'utf8' }     // encode output as string 
  ).stdout.trim();

And I tried also with:

 var output = jre.spawnSync(  // call synchronously 
        ['java'],                // add the relative directory 'java' to the class-path 
        'com.packagename.example1.ClassName',                 // call main routine in class 'Hello' 
        ['World'],               // pass 'World' as only parameter 
        { encoding: 'utf8' }     // encode output as string 
      ).stdout.trim();

'java' was the folder that I have in node in the same level that server.js

What does your Manifest file look like inside the jar? Is the main class declared? The classpath? — Adonis
– Adonis, Commented Jul 14, 2017 at 11:32
In the Manifiest: Manifest-Version: 1.0 Class-Path: . Main-Class: com.package.example1.ClassName — aitana
– aitana, Commented Jul 14, 2017 at 11:42
You can edit your post if needs be to add details. Also please check how to create a MCVE: stackoverflow.com/help/mcve It will help anyone seeing the post to understand and reproduce your issue — Adonis
– Adonis, Commented Jul 14, 2017 at 11:45

aitana · Accepted Answer · 2017-07-17 07:13:54Z

1

The problem was that I just put the directory where the .jar file is and the correct way was to put the complete path to the jar file: java/Nameofjarfile.jar

 var output = jre.spawnSync(  // call synchronously 
        ['java/Nameofjarfile.jar'],                // add the relative directory 'java' to the class-path 
        'com.packagename.example1.ClassName',                 // call main routine in class 'Hello' 
        ['World'],               // pass 'World' as only parameter 
        { encoding: 'utf8' }     // encode output as string 
      ).stdout.trim();

answered Jul 17, 2017 at 7:13

aitana

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