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2010-05-31T15:28:28Z

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== Any script have to be compiled into intermediate code. ==

This compilation takes a relatively large amount of CPU cycles.
With the Invocable interface you can save time by storing the compiled intermediate code for reuse.



<source lang="java">
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class InvocableDemo {
public static void main(String[] args) throws Exception {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");
engine.eval("function add (a, b) {c = a + b; return c; }");
Invocable jsInvoke = (Invocable) engine;
Object result1 = jsInvoke.invokeFunction("add", new Object[] { 10, 5 });
System.out.println(result1);
Adder adder = jsInvoke.getInterface(Adder.class);
int result2 = adder.add(10, 5);
System.out.println(result2);
}
}
interface Adder {
int add(int a, int b);
}</source>



== Call a JavaScript function three times ==



<source lang="java">
import javax.script.rupilable;
import javax.script.rupiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class CompileTest {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
engine.put("counter", 0);
if (engine instanceof Compilable) {
Compilable compEngine = (Compilable) engine;
try {
CompiledScript script = compEngine.rupile("function count(){counter=counter+1;return counter;}; count();");
System.out.println(script.eval());
System.out.println(script.eval());
System.out.println(script.eval());
} catch (ScriptException e) {
System.err.println(e);
}
} else {
System.err.println("Engine can"t compile code");
}
}
}
/**/</source>



<pre class=codeResult>1.0
2.0
3.0</pre>

== Catch ScriptException ==



<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 BindingDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");
engine.put("a", 1);
engine.put("b", 5);
Bindings bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);
Object a = bindings.get("a");
Object b = bindings.get("b");
System.out.println("a = " + a);
System.out.println("b = " + b);
Object result;
try {
result = engine.eval("c = aaaa + bbbb;");
System.out.println("a + b = " + result);
} catch (ScriptException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}</source>



<pre class=codeResult>a = 1
b = 5
javax.script.ScriptException: sun.org.mozilla.javascript.internal.EcmaError: ReferenceError: "aaaa" is not defined. (<Unknown source>#1) in <Unknown source> at line number 1
at com.sun.script.javascript.RhinoScriptEngine.eval(RhinoScriptEngine.java:110)
at com.sun.script.javascript.RhinoScriptEngine.eval(RhinoScriptEngine.java:124)
at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:247)
at BindingDemo.main(BindingDemo.java:22)</pre>

== Execute Javascript script in a file ==



<source lang="java">
import java.io.FileReader;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class RunScriptFileDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");
try {
FileReader reader = new FileReader("yourFile.js");
engine.eval(reader);
reader.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
/* File: yourFile.js
*
function add(a, b) {
c = a + b;
return c;
}
result = add (10, 5);
print ("Result = " + result);
*/</source>



== Executing Scripts from Java Programs ==



<source lang="java">
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
import javax.script.ScriptException;

public class ScriptExecutionDemo {
public static void main(String[] args) throws ScriptException {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine jsEngine = manager.getEngineByExtension("js");
jsEngine.eval("println ("Hello! JavaScript executed from a Java program.")");
}
}</source>



== Get a ScriptEngine by MIME type ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class GetEngineByMimeDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
/* Retrieve a ScriptEngine that supports the text/javascript MIME type */
ScriptEngine jsEngine = manager.getEngineByMimeType("text/javascript");
if (!(jsEngine == null)) {
System.out.println("text/javascript MIME type retrieved:" + jsEngine);
}
ScriptEngine jsEngine2 = manager.getEngineByMimeType("text/vbscript");
if (jsEngine2 == null)
System.out.println("\nNo supported script engine found for text/vbscript MIME type.");
}
}</source>



== Get Script engine by extension name ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class GetEngineByExtensionDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
/* Retrieve a ScriptEngine that supports scripts with .js extension */
ScriptEngine jsEngine = manager.getEngineByExtension("js");
System.out.println(jsEngine);
}
}</source>



== Get the value in JavaScript from Java Code by reference the variable name ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class RunJavaScript {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
try {
engine.put("name", "abcde");
engine.eval("var output = "";for (i = 0; i <= name.length; i++) {"
+ " output = name.charAt(i)+"-" + output" + "}");
String name = (String) engine.get("output");
System.out.println(name);
} catch (ScriptException e) {
System.err.println(e);
}
}
}
//</source>



<pre class=codeResult>-e-d-c-b-a-</pre>

== Invoke an function ==



<source lang="java">
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class InvocableTest {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
try {
engine.eval("function myFunction(name){var output = "";"
+ " for (i = 0; i <= name.length; i++) {output = name.charAt(i)+"-"+ output"
+ " } return output;}");
Invocable invokeEngine = (Invocable) engine;
Object o = invokeEngine.invokeFunction("myFunction", "abcde");
System.out.println(o);
} catch (NoSuchMethodException e) {
System.err.println(e);
} catch (ScriptException e) {
System.err.println(e);
}
}
}</source>



== Java Language Binding with JavaScript ==

The Rhino scripting engine of Java SE 6 allows you to use the Java programming language in scripts.



<source lang="java">
importPackage(javax.swing);
importPackage(java.lang);
importPackage(java.awt.event);
jFrame1 = new JFrame("Greeting");
jLabel1 = new JLabel("Name:");
jTextField1 = JTextField();
jLabel2 = new JLabel();
jButton1 = new JButton("Click");
jFrame1.setSize(400, 400);
listener1 = {
actionPerformed:function(e)
{
jLabel2.setText("Hello "+jTextField1.getText()+ " !");
}
}
alistener = new ActionListener(listener1);
jButton1.addActionListener(alistener);
jFrame1.getContentPane().setLayout(null);
jFrame1.getContentPane().add(jLabel1);
jFrame1.getContentPane().add(jTextField1);
jFrame1.getContentPane().add(jLabel2);
jFrame1.getContentPane().add(jButton1);
jLabel1.setBounds(10, 50, 40, 20);
jTextField1.setBounds(50, 50, 220, 20);
jLabel2.setBounds(10, 100, 220, 20);
jButton1.setBounds(280, 50, 120, 23);
jFrame1.setDefaultCloseOperation(jFrame1.EXIT_ON_CLOSE);
jFrame1.setVisible(true);
for(;;)
{
}</source>



== Listing All Script Engines ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
public class ListEngineFactoryDemo {
public static void main(String[] args) {
// create ScriptEngineManager
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factoryList = manager.getEngineFactories();
for (ScriptEngineFactory factory : factoryList) {
System.out.println(factory.getEngineName());
System.out.println(factory.getLanguageName());
}
}
}</source>



<pre class=codeResult>Mozilla Rhino
ECMAScript</pre>

== List the script engines ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
public class ListEngines {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();
for (ScriptEngineFactory factory : factories) {
System.out.println(factory.getEngineName());
System.out.println(factory.getEngineVersion());
System.out.println(factory.getLanguageName());
System.out.println(factory.getLanguageVersion());
System.out.println(factory.getExtensions());
System.out.println(factory.getMimeTypes());
System.out.println(factory.getNames());
}
}
}
/*
*/</source>



<pre class=codeResult>Mozilla Rhino
1.6 release 2
ECMAScript
1.6
[js]
[application/javascript, application/ecmascript, text/javascript, text/ecmascript]
[js, rhino, JavaScript, javascript, ECMAScript, ecmascript]</pre>

== Pass parameter to JavaScript through Java code ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class RunJavaScript {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
try {
engine.put("name", "abcde");
engine.eval("var output = "";for (i = 0; i <= name.length; i++) {"
+ " output = name.charAt(i)+"-" + output" + "}");
String name = (String) engine.get("output");
System.out.println(name);
} catch (ScriptException e) {
System.err.println(e);
}
}
}
//</source>



<pre class=codeResult>-e-d-c-b-a-</pre>

== Read and execute a script source file ==



<source lang="java">
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class ScriptExecutionReaderDemo {
public static void main(String[] args) throws Exception {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine jsEengine = manager.getEngineByExtension("js");
Reader reader = new InputStreamReader(new FileInputStream("yourJavaScript.js"));
jsEengine.eval(reader);
}
}
//File yourJavaScript.js
/*
importPackage(java.lang);
function getName(name)
{
if ((name != "")&&(name !=null))
{
System.out.println("Hello "+name+"!")
}
else
{
System.out.println("Hello!")
}
}
getName("TOM");
*/</source>



== Retrieving Script Engines by Name ==

A script engine registers alias names with the scripting framework.
For example, the built-in Rhino scripting registers the following names with the scripting framework:
<OL><LI>js</LI><LI>rhino</LI><LI>JavaScript</LI><LI>javascript</LI><LI>ECMAScript</LI><LI>ecmascript</LI></OL>



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class GetEngineByName {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
/* Retrieve a ScriptEngine registered with the rhino name */
ScriptEngine jsEngine = manager.getEngineByName("rhino");
if (!(jsEngine == null)) {
System.out.println(jsEngine);
} else {
System.out.println("\nNo supported script engine foundregistered as Rhino.");
}
}
}</source>



== Retrieving the Metadata of Script Engines ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
public class MetadataDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();
for (ScriptEngineFactory factory : factories) {
System.out.println("Full name = " + factory.getEngineName());
System.out.println("\nVersion = " + factory.getEngineVersion());
System.out.println("\nSupported language version = " + factory.getLanguageVersion());
}
}
}
/*
*/</source>



<pre class=codeResult>Full name = Mozilla Rhino
Version = 1.6 release 2
Supported language version = 1.6</pre>

== Retrieving the Registered Name of a Scripting Engine ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
public class RegisteredNameDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();
for (ScriptEngineFactory factory : factories) {
List<String> regNames = factory.getNames();
for (int i = 0; i < regNames.size(); i++) {
System.out.printf("Registered name " + i + " " + (String) regNames.get(i) + "\n");
}
}
}
}</source>



== Retrieving the Supported File Extensions of a Scripting Engine ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;

public class FileExtensionsDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();
for (ScriptEngineFactory factory : factories) {
List<String> ext = factory.getExtensions();
for (int i = 0; i < ext.size(); i++) {
System.out.printf("Supported file extension: " + (String) ext.get(i) + "\n");
}
}
}
}</source>



== Retrieving the Supported Mime Types of a Scripting Engine ==



<source lang="java">
import java.util.List;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
public class MimeTypesDemo {
public static void main(String[] args) {
ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();
for (ScriptEngineFactory factory : factories) {
List<String> mimeTypes = factory.getMimeTypes();
for (int i = 0; i < mimeTypes.size(); i++) {
System.out.printf("Supported MIME type " + i + " " + (String) mimeTypes.get(i) + "\n");
}
}
}
}</source>



== Run JavaScript and get the result by using Java ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class RunJavaScript {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
try {
Double hour = (Double) engine.eval("var date = new Date();" + "date.getHours();");
String msg;
if (hour < 10) {
msg = "Good morning";
} else if (hour < 16) {
msg = "Good afternoon";
} else if (hour < 20) {
msg = "Good evening";
} else {
msg = "Good night";
}
System.out.println(hour);
System.out.println(msg);
} catch (ScriptException e) {
System.err.println(e);
}
}
}
/*
*/</source>



<pre class=codeResult>10.0
Good afternoon</pre>

== Running Scripts with Java Script Engine ==



<source lang="java">
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class RunScriptDemo {
public static void main (String[] args) {
ScriptEngineManager manager = new ScriptEngineManager ();
ScriptEngine engine = manager.getEngineByName ("js");
String script = "print ("www.jexp.ru")";
try {
engine.eval (script);
} catch (ScriptException e) {
e.printStackTrace();
}
}
}
//</source>



<pre class=codeResult>www.jexp.ru</pre>

== Save the compiled JavaScript to CompiledScript object ==



<source lang="java">
import javax.script.rupilable;
import javax.script.rupiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class CompileTest {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
engine.put("counter", 0);
if (engine instanceof Compilable) {
Compilable compEngine = (Compilable) engine;
try {
CompiledScript script = compEngine.rupile("function count(){counter=counter+1;return counter;}; count();");
System.out.println(script.eval());
System.out.println(script.eval());
System.out.println(script.eval());
} catch (ScriptException e) {
System.err.println(e);
}
} else {
System.err.println("Engine can"t compile code");
}
}
}</source>



== Use jrunscript to execute JavaScript scripts ==

You can use jrunscript in interactive or batch mode to execute scripts.
In interactive mode, you can type and execute scripts from the jrunscript prompt.
In batch mode, you can load and execute script files using jrunscript.
By default, jrunscript executes scripts developed using the JavaScript scripting language.
To specify a different language, you can use the �l option while executing jrunscript.
jrunscript [options]
OptionDescription-classpath pathSpecifies the path to the Java class files.-l languageSpecifies the scripting language.-e scriptEvaluates the given script.-encoding encodingSpecifies the character encoding used while reading script files.-f script-fileEvaluates a script file.-fReads and evaluates a script from the console. This is called interactive mode.-qLists all available script engines.
<pre class=codeResult>jrunscript -e "print("hello world")"</pre>

== Using Java Objects in JavaScript ==



<source lang="java">
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
import javax.script.ScriptException;

public class JavaObjectDemo
{
public static void main(String[] args) throws Exception
{
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine jsEngine;
jsEngine = manager.getEngineByExtension("js");
jsEngine.eval("importPackage(javax.swing);var optionPane =JOptionPane.showMessageDialog(null, "Hello!);");
}
}</source>



== Using thread to run JavaScript by Java ==



<source lang="java">
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class InterfaceTest {
public static void main(String args[]) throws Exception{
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
engine.eval("function run() {print("www.jexp.ru");}");
Invocable invokeEngine = (Invocable) engine;
Runnable runner = invokeEngine.getInterface(Runnable.class);
Thread t = new Thread(runner);
t.start();
t.join();
}
}</source>



== Variables bound through ScriptEngine ==



<source lang="java">
import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class BindingDemo {
public static void main(String[] args) throws Exception {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");
engine.put("a", 1);
engine.put("b", 5);
Bindings bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);
Object a = bindings.get("a");
Object b = bindings.get("b");
System.out.println("a = " + a);
System.out.println("b = " + b);
Object result = engine.eval("c = a + b;");
System.out.println("a + b = " + result);
}
}</source>



== With Compilable interface you store the intermediate code of an entire script ==



<source lang="java">
import javax.script.rupilable;
import javax.script.rupiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class CompilableDemo {
public static void main(String[] args) throws Exception {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");
Compilable jsCompile = (Compilable) engine;
CompiledScript script = jsCompile.rupile("function hi () {print ("www.jexp.ru !"); }; hi ();");
for (int i = 0; i < 5; i++) {
script.eval();
}
}
}
//</source>



<pre class=codeResult>www.jexp.ru !www.jexp.ru !www.jexp.ru !www.jexp.ru !www.jexp.ru !</pre>

== Working with Compilable Scripts ==



<source lang="java">
import javax.script.rupilable;
import javax.script.rupiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class CompileTest {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
engine.put("counter", 0);
if (engine instanceof Compilable) {
Compilable compEngine = (Compilable) engine;
try {
CompiledScript script = compEngine.rupile("function count(){counter=counter+1;return counter;}; count();");
System.out.println(script.eval());
System.out.println(script.eval());
System.out.println(script.eval());
} catch (ScriptException e) {
System.err.println(e);
}
} else {
System.err.println("Engine can"t compile code");
}
}
}
/**/</source>



<pre class=codeResult>1.0
2.0
3.0</pre>

Java Tutorial/Development/Script Engines - История изменений

в 17:44, 31 мая 2010

Admin: 1 версия

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