javax.script package: How to import JavaScript files? - javax.script

Question

I'm using javax.script package for running external JavaScript files within Java application.
How can I import one JavaScript file into another JavaScript file, without using Java code?

Answer 1

When you say without using java code, I am not completely sure what you mean, but this is a pure javascript that works (although it is calling java):
importPackage(java.io);
function loadJs(name, user) {
println("Loading " + name);
var f = new File(name);
var br = new BufferedReader(new FileReader(f));
var line = null;
var script = "";
while((line = br.readLine())!=null) {
script += line;
}
println(script);
eval(script);
hello(user);
}
...proivided, of course, that I have the file named (say c:/temp/hellouser.js) with something like:
function hello(name) { print('Hello, ' + name); }
I tested the script using a groovy script:
import javax.script.*;
sem = new ScriptEngineManager();
engine = sem.getEngineByExtension("js");
script1 = """
importPackage(java.io);
function loadJs(name, user) {
println("Loading " + name);
var f = new File(name);
var br = new BufferedReader(new FileReader(f));
var line = null;
var script = "";
while((line = br.readLine())!=null) {
script += line;
}
println(script);
eval(script);
hello(user);
}
""";
engine.eval(script1);
Object obj = engine.get("obj");
Invocable inv = (Invocable) engine;
inv.invokeFunction("loadJs", "c:/temp/hellouser.js", "Nicholas");
and the output was:
Loading c:/temp/hellouser.js
function hello(name) { print('Hello, ' + name); }
Hello, Nicholas
I hope this is approximately what you were looking for....
=========================== UPDATE ===========================
Here's a cleaned up version that extends the Rhino script engine factory (because the engine itself is final):
import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptException;
import com.sun.script.javascript.RhinoScriptEngineFactory;
/**
* <p>Title: LoadEnabledRhinoEngineFactory</p>
* <p>Description: Adding a loadJs function to the standard JS engine</p>
* <p>Company: Helios Development Group LLC</p>
* #author Whitehead (nwhitehead AT heliosdev DOT org)
* <p><code>org.helios.apmrouter.js.LoadEnabledRhinoEngineFactory</code></p>
*/
public class LoadEnabledRhinoEngineFactory extends RhinoScriptEngineFactory {
/** The load script source */
public static final String LOAD_JS =
"importPackage(java.io); " +
"var script = ''; " +
"var ctx = null; " +
"function loadScript(name) { " +
"var f = new File(name); " +
"var br = new BufferedReader(new FileReader(f)); " +
"var line = null; " +
"while((line = br.readLine())!=null) { " +
" script += line; " +
"} " +
"_e_ngine.eval(script);" +
"} ";
/**
* {#inheritDoc}
* #see com.sun.script.javascript.RhinoScriptEngineFactory#getScriptEngine()
*/
#Override
public ScriptEngine getScriptEngine() {
ScriptEngine se = super.getScriptEngine();
Bindings b = se.createBindings();
b.put("_e_ngine", se);
se.setBindings(b, ScriptContext.GLOBAL_SCOPE);
try {
se.eval(LOAD_JS);
} catch (ScriptException e) {
throw new RuntimeException(e);
}
return se;
}
Now, loadScript(fileName) is part of the engine and you can cleanly call it with JS like:
loadScript('c:/temp/hellouser.js');
hello('Nicholas');"
or as I tested in Java:
ScriptEngine se = new LoadEnabledRhinoEngineFactory().getScriptEngine();
try {
se.eval("loadScript('c:/temp/hellouser.js'); hello('Nicholas');");
} catch (Exception e) {
e.printStackTrace(System.err);
}
Cheers.