1 /* 2 * Copyright (c) 2005, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package javax.script; 27 28 import java.util.List; 29 30 /** 31 * <code>ScriptEngineFactory</code> is used to describe and instantiate 32 * <code>ScriptEngines</code>. 33 * <br><br> 34 * Each class implementing <code>ScriptEngine</code> has a corresponding 35 * factory that exposes metadata describing the engine class. 36 * <br><br>The <code>ScriptEngineManager</code> 37 * uses the service-provider loader mechanism described in the 38 * {@link java.util.ServiceLoader} class to obtain 39 * instances of {@code ScriptEngineFactory} instances. 40 * See {@link ScriptEngineManager#ScriptEngineManager()} and 41 * {@link ScriptEngineManager#ScriptEngineManager(java.lang.ClassLoader)}. 42 * 43 * @since 1.6 44 */ 45 public interface ScriptEngineFactory { 46 /** 47 * Returns the full name of the <code>ScriptEngine</code>. For 48 * instance an implementation based on the Mozilla Rhino Javascript engine 49 * might return <i>Rhino Mozilla Javascript Engine</i>. 50 * @return The name of the engine implementation. 51 */ getEngineName()52 public String getEngineName(); 53 54 /** 55 * Returns the version of the <code>ScriptEngine</code>. 56 * @return The <code>ScriptEngine</code> implementation version. 57 */ getEngineVersion()58 public String getEngineVersion(); 59 60 61 /** 62 * Returns an immutable list of filename extensions, which generally identify scripts 63 * written in the language supported by this <code>ScriptEngine</code>. 64 * The array is used by the <code>ScriptEngineManager</code> to implement its 65 * <code>getEngineByExtension</code> method. 66 * @return The list of extensions. 67 */ getExtensions()68 public List<String> getExtensions(); 69 70 71 /** 72 * Returns an immutable list of mimetypes, associated with scripts that 73 * can be executed by the engine. The list is used by the 74 * <code>ScriptEngineManager</code> class to implement its 75 * <code>getEngineByMimetype</code> method. 76 * @return The list of mime types. 77 */ getMimeTypes()78 public List<String> getMimeTypes(); 79 80 /** 81 * Returns an immutable list of short names for the <code>ScriptEngine</code>, which may be used to 82 * identify the <code>ScriptEngine</code> by the <code>ScriptEngineManager</code>. 83 * For instance, an implementation based on the Mozilla Rhino Javascript engine might 84 * return list containing {"javascript", "rhino"}. 85 * @return an immutable list of short names 86 */ getNames()87 public List<String> getNames(); 88 89 /** 90 * Returns the name of the scripting language supported by this 91 * <code>ScriptEngine</code>. 92 * @return The name of the supported language. 93 */ getLanguageName()94 public String getLanguageName(); 95 96 /** 97 * Returns the version of the scripting language supported by this 98 * <code>ScriptEngine</code>. 99 * @return The version of the supported language. 100 */ getLanguageVersion()101 public String getLanguageVersion(); 102 103 /** 104 * Returns the value of an attribute whose meaning may be implementation-specific. 105 * Keys for which the value is defined in all implementations are: 106 * <ul> 107 * <li>ScriptEngine.ENGINE</li> 108 * <li>ScriptEngine.ENGINE_VERSION</li> 109 * <li>ScriptEngine.LANGUAGE</li> 110 * <li>ScriptEngine.LANGUAGE_VERSION</li> 111 * <li>ScriptEngine.NAME</li> 112 * </ul> 113 * <p> 114 * The values for these keys are the Strings returned by <code>getEngineName</code>, 115 * <code>getEngineVersion</code>, <code>getLanguageName</code>, 116 * <code>getLanguageVersion</code> for the first four keys respectively. For NAME, one of the Strings 117 * returned by <code>getNames</code> is returned.<br><br> 118 * A reserved key, <code><b>THREADING</b></code>, whose value describes the behavior of the engine 119 * with respect to concurrent execution of scripts and maintenance of state is also defined. 120 * These values for the <code><b>THREADING</b></code> key are:<br><br> 121 * <ul> 122 * <li><code>null</code> - The engine implementation is not thread safe, and cannot 123 * be used to execute scripts concurrently on multiple threads. 124 * <li><code>"MULTITHREADED"</code> - The engine implementation is internally 125 * thread-safe and scripts may execute concurrently although effects of script execution 126 * on one thread may be visible to scripts on other threads. 127 * <li><code>"THREAD-ISOLATED"</code> - The implementation satisfies the requirements 128 * of "MULTITHREADED", and also, the engine maintains independent values 129 * for symbols in scripts executing on different threads. 130 * <li><code>"STATELESS"</code> - The implementation satisfies the requirements of 131 * <code>"THREAD-ISOLATED"</code>. In addition, script executions do not alter the 132 * mappings in the <code>Bindings</code> which is the engine scope of the 133 * <code>ScriptEngine</code>. In particular, the keys in the <code>Bindings</code> 134 * and their associated values are the same before and after the execution of the script. 135 * </ul> 136 * <br><br> 137 * Implementations may define implementation-specific keys. 138 * 139 * @param key The name of the parameter 140 * @return The value for the given parameter. Returns <code>null</code> if no 141 * value is assigned to the key. 142 * 143 * @throws NullPointerException if the key is null. 144 */ getParameter(String key)145 public Object getParameter(String key); 146 147 /** 148 * Returns a String which can be used to invoke a method of a Java object using the syntax 149 * of the supported scripting language. For instance, an implementation for a Javascript 150 * engine might be; 151 * 152 * <pre>{@code 153 * public String getMethodCallSyntax(String obj, 154 * String m, String... args) { 155 * String ret = obj; 156 * ret += "." + m + "("; 157 * for (int i = 0; i < args.length; i++) { 158 * ret += args[i]; 159 * if (i < args.length - 1) { 160 * ret += ","; 161 * } 162 * } 163 * ret += ")"; 164 * return ret; 165 * } 166 * } </pre> 167 * 168 * @param obj The name representing the object whose method is to be invoked. The 169 * name is the one used to create bindings using the <code>put</code> method of 170 * <code>ScriptEngine</code>, the <code>put</code> method of an <code>ENGINE_SCOPE</code> 171 * <code>Bindings</code>,or the <code>setAttribute</code> method 172 * of <code>ScriptContext</code>. The identifier used in scripts may be a decorated form of the 173 * specified one. 174 * 175 * @param m The name of the method to invoke. 176 * @param args names of the arguments in the method call. 177 * 178 * @return The String used to invoke the method in the syntax of the scripting language. 179 * 180 * @throws NullPointerException if obj or m or args or any of the elements of args is null. 181 */ getMethodCallSyntax(String obj, String m, String... args)182 public String getMethodCallSyntax(String obj, String m, String... args); 183 184 /** 185 * Returns a String that can be used as a statement to display the specified String using 186 * the syntax of the supported scripting language. For instance, the implementation for a Perl 187 * engine might be; 188 * 189 * <pre><code> 190 * public String getOutputStatement(String toDisplay) { 191 * return "print(" + toDisplay + ")"; 192 * } 193 * </code></pre> 194 * 195 * @param toDisplay The String to be displayed by the returned statement. 196 * @return The string used to display the String in the syntax of the scripting language. 197 * 198 * 199 */ getOutputStatement(String toDisplay)200 public String getOutputStatement(String toDisplay); 201 202 203 /** 204 * Returns a valid scripting language executable program with given statements. 205 * For instance an implementation for a PHP engine might be: 206 * 207 * <pre>{@code 208 * public String getProgram(String... statements) { 209 * String retval = "<?\n"; 210 * int len = statements.length; 211 * for (int i = 0; i < len; i++) { 212 * retval += statements[i] + ";\n"; 213 * } 214 * return retval += "?>"; 215 * } 216 * }</pre> 217 * 218 * @param statements The statements to be executed. May be return values of 219 * calls to the <code>getMethodCallSyntax</code> and <code>getOutputStatement</code> methods. 220 * @return The Program 221 * 222 * @throws NullPointerException if the <code>statements</code> array or any of its elements is null 223 */ getProgram(String... statements)224 public String getProgram(String... statements); 225 226 /** 227 * Returns an instance of the <code>ScriptEngine</code> associated with this 228 * <code>ScriptEngineFactory</code>. A new ScriptEngine is generally 229 * returned, but implementations may pool, share or reuse engines. 230 * 231 * @return A new <code>ScriptEngine</code> instance. 232 */ getScriptEngine()233 public ScriptEngine getScriptEngine(); 234 } 235