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2010-05-31T17:44:27Z

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== Bindings And Scopes ==



<source lang="java">
import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class GetToKnowBindingsAndScopes {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
manager.put("global", "global bindings");
dumpBindings(manager.getBindings());
ScriptEngine engine = manager.getEngineByExtension("js");
engine.put("engine", "engine bindings");
dumpBindings(engine.getBindings(ScriptContext.GLOBAL_SCOPE));
dumpBindings(engine.getBindings(ScriptContext.ENGINE_SCOPE));
try {
Bindings bindings = engine.createBindings();
bindings.put("engine", "overridden engine bindings");
bindings.put("app", new GetToKnowBindingsAndScopes());
bindings.put("bindings", bindings);
engine.eval("app.dumpBindings (bindings);", bindings);
} catch (ScriptException se) {
System.err.println(se.getMessage());
}
ScriptEngine engine2 = manager.getEngineByExtension("js");
engine2.put("engine2", "engine2 bindings");
dumpBindings(engine2.getBindings(ScriptContext.GLOBAL_SCOPE));
dumpBindings(engine2.getBindings(ScriptContext.ENGINE_SCOPE));
dumpBindings(engine.getBindings(ScriptContext.ENGINE_SCOPE));
}
public static void dumpBindings(Bindings bindings) {
if (bindings == null)
System.out.println(" No bindings");
else
for (String key : bindings.keySet())
System.out.println(" " + key + ": " + bindings.get(key));
System.out.println();
}
}</source>



== Enumerate ScriptEngines ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
public class EnumerateScriptEngines {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();
for (ScriptEngineFactory factory : factories) {
System.out.println("Engine name (full): " + factory.getEngineName());
System.out.println("Engine version: " + factory.getEngineVersion());
System.out.println("Supported extensions:");
List<String> extensions = factory.getExtensions();
for (String extension : extensions)
System.out.println(" " + extension);
System.out.println("Language name: " + factory.getLanguageName());
System.out.println("Language version: " + factory.getLanguageVersion());
System.out.println("Supported MIME types:");
List<String> mimetypes = factory.getMimeTypes();
for (String mimetype : mimetypes)
System.out.println(" " + mimetype);
System.out.println("Supported short names:");
List<String> shortnames = factory.getNames();
for (String shortname : shortnames)
System.out.println(" " + shortname);
System.out.println();
}
}
}</source>



== Function Evaluator ==



<source lang="java">
import java.io.FileReader;
import java.io.IOException;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class FuncEvaluator {
public static void main(String[] args) {
if (args.length != 2) {
System.err
.println("usage: java FuncEvaluator scriptfile " + "script-exp");
return;
}
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("rhino");
try {
System.out.println(engine.eval(new FileReader(args[0])));
System.out.println(engine.eval(args[1]));
} catch (ScriptException se) {
System.err.println(se.getMessage());
} catch (IOException ioe) {
System.err.println(ioe.getMessage());
}
}
}
//////////////
function combinations (n, r)
{
return fact (n)/(fact (r)*fact (n-r))
}
function fact (n)
{
if (n == 0)
return 1;
else
return n*fact (n-1);
}</source>



== Obtain ScriptEngine ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class ObtainScriptEngine {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine1 = manager.getEngineByExtension("js");
System.out.println(engine1);
ScriptEngine engine2 = manager
.getEngineByMimeType("application/javascript");
System.out.println(engine2);
ScriptEngine engine3 = manager.getEngineByName("rhino");
System.out.println(engine3);
}
}</source>



== Pass value and get return value from script ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class MonthlyPayment {
public static void main(String[] args) throws Exception {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByExtension("js");
String calcMonthlyPaymentScript = "intrate = intrate/1200.0;"
+ "payment = principal*intrate*(Math.pow (1+intrate, months)/"
+ " (Math.pow (1+intrate,months)-1));";
engine.put("principal", 20000.0);
System.out.println("Principal = " + engine.get("principal"));
engine.put("intrate", 6.0);
System.out.println("Interest Rate = " + engine.get("intrate") + "%");
engine.put("months", 360);
System.out.println("Months = " + engine.get("months"));
engine.eval(calcMonthlyPaymentScript);
System.out.printf("Monthly Payment = %.2f\n", engine.get("payment"));
}
}</source>



== Temperature Conversion with script ==



<source lang="java">
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class TemperatureConversion {
public static void main(String[] args) throws ScriptException {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("rhino");
String script = "function c2f(degrees){return degrees*9.0/5.0+32;}";
+ "function f2c(degrees){return (degrees-32)*5.0/9.0;}" + " "
+ "function convertTemperature (degrees, toCelsius){"
+ " if (toCelsius)" + "return f2c (degrees);elsereturn c2f (degrees);}";
engine.eval(script);
Invocable invocable = (Invocable) engine;
TempConversion tc = invocable.getInterface(TempConversion.class);
if (tc == null)
System.err.println("Unable to obtain TempConversion interface");
else {
System.out.println("212 degrees Fahrenheit = "
+ tc.convertTemperature(212.0, true) + " degrees Celsius");
}
}
}
interface TempConversion {
double convertTemperature(double degrees, boolean toCelsius);
}</source>



== Test Compilation Speed ==



<source lang="java">
import javax.script.rupilable;
import javax.script.rupiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class TestCompilationSpeed {
final static int MAX_ITERATIONS = 10000;
public static void main(String[] args) throws Exception {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("JavaScript");
String fact = "function fact (n){if (n == 0)return 1; else return n*fact (n-1);};";
long time = System.currentTimeMillis();
for (int i = 0; i < MAX_ITERATIONS; i++)
engine.eval(fact);
System.out.println(System.currentTimeMillis() - time);
Compilable compilable = null;
if (engine instanceof Compilable) {
compilable = (Compilable) engine;
CompiledScript script = compilable.rupile(fact);
time = System.currentTimeMillis();
for (int i = 0; i < MAX_ITERATIONS; i++)
script.eval();
System.out.println(System.currentTimeMillis() - time);
}
}
}</source>



== Threading Behavior ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
public class ThreadingBehavior {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();
for (ScriptEngineFactory factory : factories)
System.out.println("Threading behavior: "
+ factory.getParameter("THREADING"));
}
}</source>

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