I find that, when i load a javascript file in java *twice *using this
pattern
ScriptObjectMirror som = scriptEngine.eval("load('c:/temp/test.js');");
it locks the JS file (prevents its deletion). This does NOT happen if i
load the file only once. Furthermore, this happens even if i null out the
resulting ScriptObjectMirrors. My question is: how can I avoid this? I need
to be able to load the file and get the resulting ScriptObjectMirror
multiple times and be able to delete the source file.
Is Nashorn not properly closing a stream? It's odd that it doesn't lock
the file for the first SOM, but does for the second (and subsequent)
SOMs....
Try it with this code. Instructions:
1) Create a file "test.js" and put it where you want. I put it in
c:\temp\test.js
(function(module) {
var exports = module.exports;
exports.test = function() {
return "test ok";
}
return module.exports;})({exports:{}, id:'test'});
2) Create a Temp.java as follows and run it first with *loadSecondSom =
true*. The deletion will fail. Then run it with *loadSecondSom = false*.
The deletion will succeed. (Note: the "pause" is only to make it clearer...)
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import javax.script.ScriptEngine;
import javax.script.ScriptException;
import jdk.nashorn.api.scripting.NashornScriptEngineFactory;
import jdk.nashorn.api.scripting.ScriptObjectMirror;
public class Temp {
private static final NashornScriptEngineFactory nashornFactory = new
NashornScriptEngineFactory();
private static ScriptEngine scriptEngine = nashornFactory.getScriptEngine();
private static void deleteFile(String sPath) throws IOException {
Path p = Paths.get(sPath);
Files.delete(p);
}
private static void pause(int numsecs) {
int x;
try {
for (int i=0;i<numsecs;i++) {
Thread.sleep(1000);
x = i;
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void main(String[] ss) {
boolean loadSecondSom = true;
String sPath = "C:/temp/test.js";
try {
System.out.println("loading and calling som1...");
ScriptObjectMirror som1 = (ScriptObjectMirror)scriptEngine.eval("load('" +
sPath + "');");
System.out.println(som1.callMember("test"));
System.out.println("Sleeping ... ");
pause(2);
if (loadSecondSom) {
System.out.println("loading and calling som2...");
ScriptObjectMirror som2 = (ScriptObjectMirror)scriptEngine.eval("load('" +
sPath + "');");
System.out.println(som2.callMember("test"));
}
System.out.println("Sleeping ... ");
pause(2);
System.out.println("Attempting to delete the file from the fs...");
try {
deleteFile(sPath);
} catch (IOException e) {
System.out.println("Cannot delete the file: "+e);
}
System.out.println("DONE");
} catch (ScriptException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
