CODEWITHSUNDEEP
grails
John Little
John Little

Reputation: 12343

How to read a file in src/main/resources in grails

This has been asked before, and I have tried each proposed solution, but all fail.

I have put a javascript file (hl.js) in myapp/src/main/resources

I have tried to read it with the following code taken from the "solutions":

1 - getRsourcesAsStream. returns null inputstream.

 InputStream is = this.class.classLoader.getResourceAsStream("hl.js")

2 - getResource - returns null

 File myFile = grailsApplication.mainContext.getResource("hl.js").file

3 - getResourceAsStream with classloader - returns null.

 ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); 
 InputStream is = classLoader.getResourceAsStream("hl.js");

Interestingly, if I do the following:

 String fileNameAndPath = this.class.classLoader.getResource("hl.js").getFile()
 System.out.println(fileNameAndPath);
 File file = new File(fileNameAndPath)
 InputStream is = file.newInputStream();

This prints out:

/Users/me/dev/grails_projects/myapp/src/main/resources/hl.js

But "is" is always null.

I an trying to get an input stream so I can evaluate the javascript via nashorn:

ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
engine.eval(is)

Grails 3.3.8

Any ideas?

Upvotes: 2

Views: 989

Answers (2)

Rajat Malhotra
Rajat Malhotra

Reputation: 19

Get the resource and open a stream on it.

    def resource = this.class.classLoader.getResource('conf.json')
    def path = resource.file // absolute file path
    return resource.openStream() // input stream for the file

Source: https://www.damirscorner.com/blog/posts/20160313-AccessingApplicationFilesFromCodeInGrails.html

Upvotes: 1

John Little
John Little

Reputation: 12343

Well, I dont know why the solutions 1, 2 and 3 do not work, but I found a more long winded way which does work. The main issue is that there are lots of different implementations of eval(), and netbeans "go to declaration" has never worked (presumably some configuration issue in netbeans).

It turns out that the eval() version i happen to be using is expecting a Reader, where as the default documentation shows it needs in InputStream. Also, reader is not the same as InputStreamReader.

This is the solution I found:

import javax.script.ScriptEngine
import javax.script.ScriptEngineManager
import org.grails.core.io.ResourceLocator

ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
String fileNameAndPath = this.class.classLoader.getResource("hl.js").getFile()
System.out.println(fileNameAndPath);
File file = new File(fileNameAndPath)
System.out.println("exists: " + file.exists())
Reader reader = file.newReader();
engine.eval(reader)

Upvotes: 0

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