Java tutorial
/* * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.script; import java.io.Reader; import java.util.Map; import java.util.Set; /** * <code>ScriptEngine</code> is the fundamental interface whose methods must be * fully functional in every implementation of this specification. * <br><br> * These methods provide basic scripting functionality. Applications written to this * simple interface are expected to work with minimal modifications in every implementation. * It includes methods that execute scripts, and ones that set and get values. * <br><br> * The values are key/value pairs of two types. The first type of pairs consists of * those whose keys are reserved and defined in this specification or by individual * implementations. The values in the pairs with reserved keys have specified meanings. * <br><br> * The other type of pairs consists of those that create Java language Bindings, the values are * usually represented in scripts by the corresponding keys or by decorated forms of them. * * @author Mike Grogan * @since 1.6 */ public interface ScriptEngine { /** * Reserved key for a named value that passes * an array of positional arguments to a script. */ public static final String ARGV = "javax.script.argv"; /** * Reserved key for a named value that is * the name of the file being executed. */ public static final String FILENAME = "javax.script.filename"; /** * Reserved key for a named value that is * the name of the <code>ScriptEngine</code> implementation. */ public static final String ENGINE = "javax.script.engine"; /** * Reserved key for a named value that identifies * the version of the <code>ScriptEngine</code> implementation. */ public static final String ENGINE_VERSION = "javax.script.engine_version"; /** * Reserved key for a named value that identifies * the short name of the scripting language. The name is used by the * <code>ScriptEngineManager</code> to locate a <code>ScriptEngine</code> * with a given name in the <code>getEngineByName</code> method. */ public static final String NAME = "javax.script.name"; /** * Reserved key for a named value that is * the full name of Scripting Language supported by the implementation. */ public static final String LANGUAGE = "javax.script.language"; /** * Reserved key for the named value that identifies * the version of the scripting language supported by the implementation. */ public static final String LANGUAGE_VERSION = "javax.script.language_version"; /** * Causes the immediate execution of the script whose source is the String * passed as the first argument. The script may be reparsed or recompiled before * execution. State left in the engine from previous executions, including * variable values and compiled procedures may be visible during this execution. * * @param script The script to be executed by the script engine. * * @param context A <code>ScriptContext</code> exposing sets of attributes in * different scopes. The meanings of the scopes <code>ScriptContext.GLOBAL_SCOPE</code>, * and <code>ScriptContext.ENGINE_SCOPE</code> are defined in the specification. * <br><br> * The <code>ENGINE_SCOPE</code> <code>Bindings</code> of the <code>ScriptContext</code> contains the * bindings of scripting variables to application objects to be used during this * script execution. * * * @return The value returned from the execution of the script. * * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting * implementations. * @throws NullPointerException if either argument is null. */ public Object eval(String script, ScriptContext context) throws ScriptException; /** * Same as <code>eval(String, ScriptContext)</code> where the source of the script * is read from a <code>Reader</code>. * * @param reader The source of the script to be executed by the script engine. * * @param context The <code>ScriptContext</code> passed to the script engine. * * @return The value returned from the execution of the script. * * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting * implementations. * @throws NullPointerException if either argument is null. */ public Object eval(Reader reader, ScriptContext context) throws ScriptException; /** * Executes the specified script. The default <code>ScriptContext</code> for the <code>ScriptEngine</code> * is used. * * @param script The script language source to be executed. * * @return The value returned from the execution of the script. * * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting * implementations. * @throws NullPointerException if the argument is null. */ public Object eval(String script) throws ScriptException; /** * Same as <code>eval(String)</code> except that the source of the script is * provided as a <code>Reader</code> * * @param reader The source of the script. * * @return The value returned by the script. * * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting * implementations. * @throws NullPointerException if the argument is null. */ public Object eval(Reader reader) throws ScriptException; /** * Executes the script using the <code>Bindings</code> argument as the <code>ENGINE_SCOPE</code> * <code>Bindings</code> of the <code>ScriptEngine</code> during the script execution. The * <code>Reader</code>, <code>Writer</code> and non-<code>ENGINE_SCOPE</code> <code>Bindings</code> of the * default <code>ScriptContext</code> are used. The <code>ENGINE_SCOPE</code> * <code>Bindings</code> of the <code>ScriptEngine</code> is not changed, and its * mappings are unaltered by the script execution. * * @param script The source for the script. * * @param n The <code>Bindings</code> of attributes to be used for script execution. * * @return The value returned by the script. * * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting * implementations. * @throws NullPointerException if either argument is null. */ public Object eval(String script, Bindings n) throws ScriptException; /** * Same as <code>eval(String, Bindings)</code> except that the source of the script * is provided as a <code>Reader</code>. * * @param reader The source of the script. * @param n The <code>Bindings</code> of attributes. * * @return The value returned by the script. * * @throws ScriptException if an error occurs in script. ScriptEngines should create and throw * <code>ScriptException</code> wrappers for checked Exceptions thrown by underlying scripting * implementations. * @throws NullPointerException if either argument is null. */ public Object eval(Reader reader, Bindings n) throws ScriptException; /** * Sets a key/value pair in the state of the ScriptEngine that may either create * a Java Language Binding to be used in the execution of scripts or be used in some * other way, depending on whether the key is reserved. Must have the same effect as * <code>getBindings(ScriptContext.ENGINE_SCOPE).put</code>. * * @param key The name of named value to add * @param value The value of named value to add. * * @throws NullPointerException if key is null. * @throws IllegalArgumentException if key is empty. */ public void put(String key, Object value); /** * Retrieves a value set in the state of this engine. The value might be one * which was set using <code>setValue</code> or some other value in the state * of the <code>ScriptEngine</code>, depending on the implementation. Must have the same effect * as <code>getBindings(ScriptContext.ENGINE_SCOPE).get</code> * * @param key The key whose value is to be returned * @return the value for the given key * * @throws NullPointerException if key is null. * @throws IllegalArgumentException if key is empty. */ public Object get(String key); /** * Returns a scope of named values. The possible scopes are: * <br><br> * <ul> * <li><code>ScriptContext.GLOBAL_SCOPE</code> - The set of named values representing global * scope. If this <code>ScriptEngine</code> is created by a <code>ScriptEngineManager</code>, * then the manager sets global scope bindings. This may be <code>null</code> if no global * scope is associated with this <code>ScriptEngine</code></li> * <li><code>ScriptContext.ENGINE_SCOPE</code> - The set of named values representing the state of * this <code>ScriptEngine</code>. The values are generally visible in scripts using * the associated keys as variable names.</li> * <li>Any other value of scope defined in the default <code>ScriptContext</code> of the <code>ScriptEngine</code>. * </li> * </ul> * <br><br> * The <code>Bindings</code> instances that are returned must be identical to those returned by the * <code>getBindings</code> method of <code>ScriptContext</code> called with corresponding arguments on * the default <code>ScriptContext</code> of the <code>ScriptEngine</code>. * * @param scope Either <code>ScriptContext.ENGINE_SCOPE</code> or <code>ScriptContext.GLOBAL_SCOPE</code> * which specifies the <code>Bindings</code> to return. Implementations of <code>ScriptContext</code> * may define additional scopes. If the default <code>ScriptContext</code> of the <code>ScriptEngine</code> * defines additional scopes, any of them can be passed to get the corresponding <code>Bindings</code>. * * @return The <code>Bindings</code> with the specified scope. * * @throws IllegalArgumentException if specified scope is invalid * */ public Bindings getBindings(int scope); /** * Sets a scope of named values to be used by scripts. The possible scopes are: *<br><br> * <ul> * <li><code>ScriptContext.ENGINE_SCOPE</code> - The specified <code>Bindings</code> replaces the * engine scope of the <code>ScriptEngine</code>. * </li> * <li><code>ScriptContext.GLOBAL_SCOPE</code> - The specified <code>Bindings</code> must be visible * as the <code>GLOBAL_SCOPE</code>. * </li> * <li>Any other value of scope defined in the default <code>ScriptContext</code> of the <code>ScriptEngine</code>. *</li> * </ul> * <br><br> * The method must have the same effect as calling the <code>setBindings</code> method of * <code>ScriptContext</code> with the corresponding value of <code>scope</code> on the default * <code>ScriptContext</code> of the <code>ScriptEngine</code>. * * @param bindings The <code>Bindings</code> for the specified scope. * @param scope The specified scope. Either <code>ScriptContext.ENGINE_SCOPE</code>, * <code>ScriptContext.GLOBAL_SCOPE</code>, or any other valid value of scope. * * @throws IllegalArgumentException if the scope is invalid * @throws NullPointerException if the bindings is null and the scope is * <code>ScriptContext.ENGINE_SCOPE</code> */ public void setBindings(Bindings bindings, int scope); /** * Returns an uninitialized <code>Bindings</code>. * * @return A <code>Bindings</code> that can be used to replace the state of this <code>ScriptEngine</code>. **/ public Bindings createBindings(); /** * Returns the default <code>ScriptContext</code> of the <code>ScriptEngine</code> whose Bindings, Reader * and Writers are used for script executions when no <code>ScriptContext</code> is specified. * * @return The default <code>ScriptContext</code> of the <code>ScriptEngine</code>. */ public ScriptContext getContext(); /** * Sets the default <code>ScriptContext</code> of the <code>ScriptEngine</code> whose Bindings, Reader * and Writers are used for script executions when no <code>ScriptContext</code> is specified. * * @param context A <code>ScriptContext</code> that will replace the default <code>ScriptContext</code> in * the <code>ScriptEngine</code>. * @throws NullPointerException if context is null. */ public void setContext(ScriptContext context); /** * Returns a <code>ScriptEngineFactory</code> for the class to which this <code>ScriptEngine</code> belongs. * * @return The <code>ScriptEngineFactory</code> */ public ScriptEngineFactory getFactory(); }