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 mechanism described in the <i>Jar File Specification</i> to obtain 38 * instances of all <code>ScriptEngineFactories</code> available in 39 * the current ClassLoader. 40 * 41 * @since 1.6 42 */ 43 public interface ScriptEngineFactory { 44 /** 45 * Returns the full name of the <code>ScriptEngine</code>. For 46 * instance an implementation based on the Mozilla Rhino Javascript engine 47 * might return <i>Rhino Mozilla Javascript Engine</i>. 48 * @return The name of the engine implementation. 49 */ 50 public String getEngineName(); 51 52 /** 53 * Returns the version of the <code>ScriptEngine</code>. 54 * @return The <code>ScriptEngine</code> implementation version. 55 */ 56 public String getEngineVersion(); 57 58 59 /** 60 * Returns an immutable list of filename extensions, which generally identify scripts 61 * written in the language supported by this <code>ScriptEngine</code>. 62 * The array is used by the <code>ScriptEngineManager</code> to implement its 63 * <code>getEngineByExtension</code> method. 64 * @return The list of extensions. 65 */ 66 public List<String> getExtensions(); 67 68 69 /** 70 * Returns an immutable list of mimetypes, associated with scripts that 71 * can be executed by the engine. The list is used by the 72 * <code>ScriptEngineManager</code> class to implement its 73 * <code>getEngineByMimetype</code> method. 74 * @return The list of mime types. 75 */ 76 public List<String> getMimeTypes(); 77 78 /** 79 * Returns an immutable list of short names for the <code>ScriptEngine</code>, which may be used to 80 * identify the <code>ScriptEngine</code> by the <code>ScriptEngineManager</code>. 81 * For instance, an implementation based on the Mozilla Rhino Javascript engine might 82 * return list containing {"javascript", "rhino"}. 83 * @return an immutable list of short names 84 */ 85 public List<String> getNames(); 86 87 /** 88 * Returns the name of the scripting langauge supported by this 89 * <code>ScriptEngine</code>. 90 * @return The name of the supported language. 91 */ 92 public String getLanguageName(); 93 94 /** 95 * Returns the version of the scripting language supported by this 96 * <code>ScriptEngine</code>. 97 * @return The version of the supported language. 98 */ 99 public String getLanguageVersion(); 100 101 /** 102 * Returns the value of an attribute whose meaning may be implementation-specific. 103 * Keys for which the value is defined in all implementations are: 104 * <ul> 105 * <li>ScriptEngine.ENGINE</li> 106 * <li>ScriptEngine.ENGINE_VERSION</li> 107 * <li>ScriptEngine.NAME</li> 108 * <li>ScriptEngine.LANGUAGE</li> 109 * <li>ScriptEngine.LANGUAGE_VERSION</li> 110 * </ul> 111 * <p> 112 * The values for these keys are the Strings returned by <code>getEngineName</code>, 113 * <code>getEngineVersion</code>, <code>getName</code>, <code>getLanguageName</code> and 114 * <code>getLanguageVersion</code> respectively.<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 */ 141 public Object getParameter(String key); 142 143 /** 144 * Returns a String which can be used to invoke a method of a Java object using the syntax 145 * of the supported scripting language. For instance, an implementation for a Javascript 146 * engine might be; 147 * 148 * <pre>{@code 149 * public String getMethodCallSyntax(String obj, 150 * String m, String... args) { 151 * String ret = obj; 152 * ret += "." + m + "("; 153 * for (int i = 0; i < args.length; i++) { 154 * ret += args[i]; 155 * if (i < args.length - 1) { 156 * ret += ","; 157 * } 158 * } 159 * ret += ")"; 160 * return ret; 161 * } 162 * } </pre> 163 * 164 * @param obj The name representing the object whose method is to be invoked. The 165 * name is the one used to create bindings using the <code>put</code> method of 166 * <code>ScriptEngine</code>, the <code>put</code> method of an <code>ENGINE_SCOPE</code> 167 * <code>Bindings</code>,or the <code>setAttribute</code> method 168 * of <code>ScriptContext</code>. The identifier used in scripts may be a decorated form of the 169 * specified one. 170 * 171 * @param m The name of the method to invoke. 172 * @param args names of the arguments in the method call. 173 * 174 * @return The String used to invoke the method in the syntax of the scripting language. 175 */ 176 public String getMethodCallSyntax(String obj, String m, String... args); 177 178 /** 179 * Returns a String that can be used as a statement to display the specified String using 180 * the syntax of the supported scripting language. For instance, the implementation for a Perl 181 * engine might be; 182 * 183 * <pre><code> 184 * public String getOutputStatement(String toDisplay) { 185 * return "print(" + toDisplay + ")"; 186 * } 187 * </code></pre> 188 * 189 * @param toDisplay The String to be displayed by the returned statement. 190 * @return The string used to display the String in the syntax of the scripting language. 191 * 192 * 193 */ 194 public String getOutputStatement(String toDisplay); 195 196 197 /** 198 * Returns a valid scripting language executable program with given statements. 199 * For instance an implementation for a PHP engine might be: 200 * 201 * <pre>{@code 202 * public String getProgram(String... statements) { 203 * String retval = "<?\n"; 204 * int len = statements.length; 205 * for (int i = 0; i < len; i++) { 206 * retval += statements[i] + ";\n"; 207 * } 208 * return retval += "?>"; 209 * } 210 * }</pre> 211 * 212 * @param statements The statements to be executed. May be return values of 213 * calls to the <code>getMethodCallSyntax</code> and <code>getOutputStatement</code> methods. 214 * @return The Program 215 */ 216 217 public String getProgram(String... statements); 218 219 /** 220 * Returns an instance of the <code>ScriptEngine</code> associated with this 221 * <code>ScriptEngineFactory</code>. A new ScriptEngine is generally 222 * returned, but implementations may pool, share or reuse engines. 223 * 224 * @return A new <code>ScriptEngine</code> instance. 225 */ 226 public ScriptEngine getScriptEngine(); 227 }