1 /* 2 * Copyright (c) 2005, 2013, 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 factory 35 * that exposes metadata describing the engine class. 36 * <br><br>The <code>ScriptEngineManager</code> 37 * uses the service-provider loader mechanism described in the {@link java.util.ServiceLoader} class to obtain 38 * instances of all <code>ScriptEngineFactories</code>. 39 * 40 * @since 1.6 41 */ 42 public interface ScriptEngineFactory { 43 /** 44 * Returns the full name of the <code>ScriptEngine</code>. For 45 * instance an implementation based on the Mozilla Rhino Javascript engine 46 * might return <i>Rhino Mozilla Javascript Engine</i>. 47 * @return The name of the engine implementation. 48 */ 49 public String getEngineName(); 50 51 /** 52 * Returns the version of the <code>ScriptEngine</code>. 53 * @return The <code>ScriptEngine</code> implementation version. 54 */ 55 public String getEngineVersion(); 56 57 58 /** 59 * Returns an immutable list of filename extensions, which generally identify scripts 60 * written in the language supported by this <code>ScriptEngine</code>. 61 * The array is used by the <code>ScriptEngineManager</code> to implement its 62 * <code>getEngineByExtension</code> method. 63 * @return The list of extensions. 64 */ 65 public List<String> getExtensions(); 66 67 68 /** 69 * Returns an immutable list of mimetypes, associated with scripts that 70 * can be executed by the engine. The list is used by the 71 * <code>ScriptEngineManager</code> class to implement its 72 * <code>getEngineByMimetype</code> method. 73 * @return The list of mime types. 74 */ 75 public List<String> getMimeTypes(); 76 77 /** 78 * Returns an immutable list of short names for the <code>ScriptEngine</code>, which may be used to 79 * identify the <code>ScriptEngine</code> by the <code>ScriptEngineManager</code>. 80 * For instance, an implementation based on the Mozilla Rhino Javascript engine might 81 * return list containing {"javascript", "rhino"}. 82 * @return an immutable list of short names 83 */ 84 public List<String> getNames(); 85 86 /** 87 * Returns the name of the scripting language supported by this 88 * <code>ScriptEngine</code>. 89 * @return The name of the supported language. 90 */ 91 public String getLanguageName(); 92 93 /** 94 * Returns the version of the scripting language supported by this 95 * <code>ScriptEngine</code>. 96 * @return The version of the supported language. 97 */ 98 public String getLanguageVersion(); 99 100 /** 101 * Returns the value of an attribute whose meaning may be implementation-specific. 102 * Keys for which the value is defined in all implementations are: 103 * <ul> 104 * <li>ScriptEngine.ENGINE</li> 105 * <li>ScriptEngine.ENGINE_VERSION</li> 106 * <li>ScriptEngine.LANGUAGE</li> 107 * <li>ScriptEngine.LANGUAGE_VERSION</li> 108 * <li>ScriptEngine.NAME</li> 109 * </ul> 110 * <p> 111 * The values for these keys are the Strings returned by <code>getEngineName</code>, 112 * <code>getEngineVersion</code>, <code>getLanguageName</code>, 113 * <code>getLanguageVersion</code> for the first four keys respectively. For NAME, one of the Strings 114 * returned by <code>getNames</code> is returned.<br><br> 115 * A reserved key, <code><b>THREADING</b></code>, whose value describes the behavior of the engine 116 * with respect to concurrent execution of scripts and maintenance of state is also defined. 117 * These values for the <code><b>THREADING</b></code> key are:<br><br> 118 * <ul> 119 * <li><code>null</code> - The engine implementation is not thread safe, and cannot 120 * be used to execute scripts concurrently on multiple threads. 121 * <li><code>"MULTITHREADED"</code> - The engine implementation is internally 122 * thread-safe and scripts may execute concurrently although effects of script execution 123 * on one thread may be visible to scripts on other threads. 124 * <li><code>"THREAD-ISOLATED"</code> - The implementation satisfies the requirements 125 * of "MULTITHREADED", and also, the engine maintains independent values 126 * for symbols in scripts executing on different threads. 127 * <li><code>"STATELESS"</code> - The implementation satisfies the requirements of 128 * <li><code>"THREAD-ISOLATED"</code>. In addition, script executions do not alter the 129 * mappings in the <code>Bindings</code> which is the engine scope of the 130 * <code>ScriptEngine</code>. In particular, the keys in the <code>Bindings</code> 131 * and their associated values are the same before and after the execution of the script. 132 * </ul> 133 * <br><br> 134 * Implementations may define implementation-specific keys. 135 * 136 * @param key The name of the parameter 137 * @return The value for the given parameter. Returns <code>null</code> if no 138 * value is assigned to the key. 139 * 140 * @throws NullPointerException if the key is null. 141 */ 142 public Object getParameter(String key); 143 144 /** 145 * Returns a String which can be used to invoke a method of a Java object using the syntax 146 * of the supported scripting language. For instance, an implementation for a Javascript 147 * engine might be; 148 * 149 * <pre>{@code 150 * public String getMethodCallSyntax(String obj, 151 * String m, String... args) { 152 * String ret = obj; 153 * ret += "." + m + "("; 154 * for (int i = 0; i < args.length; i++) { 155 * ret += args[i]; 156 * if (i < args.length - 1) { 157 * ret += ","; 158 * } 159 * } 160 * ret += ")"; 161 * return ret; 162 * } 163 * } </pre> 164 * 165 * @param obj The name representing the object whose method is to be invoked. The 166 * name is the one used to create bindings using the <code>put</code> method of 167 * <code>ScriptEngine</code>, the <code>put</code> method of an <code>ENGINE_SCOPE</code> 168 * <code>Bindings</code>,or the <code>setAttribute</code> method 169 * of <code>ScriptContext</code>. The identifier used in scripts may be a decorated form of the 170 * specified one. 171 * 172 * @param m The name of the method to invoke. 173 * @param args names of the arguments in the method call. 174 * 175 * @return The String used to invoke the method in the syntax of the scripting language. 176 */ 177 public String getMethodCallSyntax(String obj, String m, String... args); 178 179 /** 180 * Returns a String that can be used as a statement to display the specified String using 181 * the syntax of the supported scripting language. For instance, the implementation for a Perl 182 * engine might be; 183 * 184 * <pre><code> 185 * public String getOutputStatement(String toDisplay) { 186 * return "print(" + toDisplay + ")"; 187 * } 188 * </code></pre> 189 * 190 * @param toDisplay The String to be displayed by the returned statement. 191 * @return The string used to display the String in the syntax of the scripting language. 192 * 193 * 194 */ 195 public String getOutputStatement(String toDisplay); 196 197 198 /** 199 * Returns a valid scripting language executable program with given statements. 200 * For instance an implementation for a PHP engine might be: 201 * 202 * <pre>{@code 203 * public String getProgram(String... statements) { 204 * String retval = "<?\n"; 205 * int len = statements.length; 206 * for (int i = 0; i < len; i++) { 207 * retval += statements[i] + ";\n"; 208 * } 209 * return retval += "?>"; 210 * } 211 * }</pre> 212 * 213 * @param statements The statements to be executed. May be return values of 214 * calls to the <code>getMethodCallSyntax</code> and <code>getOutputStatement</code> methods. 215 * @return The Program 216 */ 217 218 public String getProgram(String... statements); 219 220 /** 221 * Returns an instance of the <code>ScriptEngine</code> associated with this 222 * <code>ScriptEngineFactory</code>. A new ScriptEngine is generally 223 * returned, but implementations may pool, share or reuse engines. 224 * 225 * @return A new <code>ScriptEngine</code> instance. 226 */ 227 public ScriptEngine getScriptEngine(); 228 }