ScriptEngineFactory (Java SE 15 & JDK 15) (original) (raw)

public interface ScriptEngineFactory

ScriptEngineFactory is used to describe and instantiateScriptEngines.

Each class implementing ScriptEngine has a corresponding factory that exposes metadata describing the engine class.

The ScriptEngineManager uses the service-provider loader mechanism described in theServiceLoader class to obtain instances of ScriptEngineFactory instances. See ScriptEngineManager() andScriptEngineManager(java.lang.ClassLoader).

Since:

1.6

• Method Summary

• Method Details

  • getEngineName

  Returns the full name of the ScriptEngine. For instance an implementation based on the Mozilla Rhino Javascript engine might return Rhino Mozilla Javascript Engine.
  Returns:
  The name of the engine implementation.

  • getEngineVersion

  String getEngineVersion()
  Returns the version of the ScriptEngine.
  Returns:
  The ScriptEngine implementation version.

  • getExtensions

  Returns an immutable list of filename extensions, which generally identify scripts written in the language supported by this ScriptEngine. The array is used by the ScriptEngineManager to implement itsgetEngineByExtension method.
  Returns:
  The list of extensions.

  • getMimeTypes

  Returns an immutable list of mimetypes, associated with scripts that can be executed by the engine. The list is used by theScriptEngineManager class to implement itsgetEngineByMimetype method.
  Returns:
  The list of mime types.

  • getNames

  Returns an immutable list of short names for the ScriptEngine, which may be used to identify the ScriptEngine by the ScriptEngineManager. For instance, an implementation based on the Mozilla Rhino Javascript engine might return list containing {"javascript", "rhino"}.
  Returns:
  an immutable list of short names

  • getLanguageName

  Returns the name of the scripting language supported by thisScriptEngine.
  Returns:
  The name of the supported language.

  • getLanguageVersion

  String getLanguageVersion()
  Returns the version of the scripting language supported by thisScriptEngine.
  Returns:
  The version of the supported language.

  • getParameter

  Returns the value of an attribute whose meaning may be implementation-specific. Keys for which the value is defined in all implementations are:
  * ScriptEngine.ENGINE
  * ScriptEngine.ENGINE_VERSION
  * ScriptEngine.LANGUAGE
  * ScriptEngine.LANGUAGE_VERSION
  * ScriptEngine.NAME
  The values for these keys are the Strings returned by getEngineName,getEngineVersion, getLanguageName,getLanguageVersion for the first four keys respectively. For NAME, one of the Strings returned by getNames is returned.
  A reserved key, **THREADING**, whose value describes the behavior of the engine with respect to concurrent execution of scripts and maintenance of state is also defined. These values for the **THREADING** key are:
  * null - The engine implementation is not thread safe, and cannot be used to execute scripts concurrently on multiple threads.
  * "MULTITHREADED" - The engine implementation is internally thread-safe and scripts may execute concurrently although effects of script execution on one thread may be visible to scripts on other threads.
  * "THREAD-ISOLATED" - The implementation satisfies the requirements of "MULTITHREADED", and also, the engine maintains independent values for symbols in scripts executing on different threads.
  * "STATELESS" - The implementation satisfies the requirements of"THREAD-ISOLATED". In addition, script executions do not alter the mappings in the Bindings which is the engine scope of theScriptEngine. In particular, the keys in the Bindings and their associated values are the same before and after the execution of the script.
  Implementations may define implementation-specific keys.
  Parameters:
  key - The name of the parameter
  Returns:
  The value for the given parameter. Returns null if no value is assigned to the key.
  Throws:
  [NullPointerException](../../../java.base/java/lang/NullPointerException.html "class in java.lang") - if the key is null.

  • getMethodCallSyntax

  Returns a String which can be used to invoke a method of a Java object using the syntax of the supported scripting language. For instance, an implementation for a Javascript engine might be;
  public String getMethodCallSyntax(String obj, String m, String... args) { String ret = obj; ret += "." + m + "("; for (int i = 0; i < args.length; i++) { ret += args[i]; if (i < args.length - 1) { ret += ","; } } ret += ")"; return ret; }
  Parameters:
  obj - The name representing the object whose method is to be invoked. The name is the one used to create bindings using the put method ofScriptEngine, the put method of an ENGINE_SCOPE Bindings,or the setAttribute method of ScriptContext. The identifier used in scripts may be a decorated form of the specified one.
  m - The name of the method to invoke.
  args - names of the arguments in the method call.
  Returns:
  The String used to invoke the method in the syntax of the scripting language.
  Throws:
  [NullPointerException](../../../java.base/java/lang/NullPointerException.html "class in java.lang") - if obj or m or args or any of the elements of args is null.

  • getOutputStatement

  Returns a String that can be used as a statement to display the specified String using the syntax of the supported scripting language. For instance, the implementation for a Perl engine might be;

   public String getOutputStatement(String toDisplay) {  
        return "print(" + toDisplay + ")";  
   }  
       

  Parameters:
  toDisplay - The String to be displayed by the returned statement.
  Returns:
  The string used to display the String in the syntax of the scripting language.

  • getProgram

  Returns a valid scripting language executable program with given statements. For instance an implementation for a PHP engine might be:

   public String getProgram(String... statements) {  
        String retval = "<?\n";  
        int len = statements.length;  
        for (int i = 0; i < len; i++) {  
            retval += statements[i] + ";\n";  
        }  
        return retval += "?>";  
   }  
       

  Parameters:
  statements - The statements to be executed. May be return values of calls to the getMethodCallSyntax and getOutputStatement methods.
  Returns:
  The Program
  Throws:
  [NullPointerException](../../../java.base/java/lang/NullPointerException.html "class in java.lang") - if the statements array or any of its elements is null

  • getScriptEngine

  Returns an instance of the ScriptEngine associated with thisScriptEngineFactory. A new ScriptEngine is generally returned, but implementations may pool, share or reuse engines.
  Returns:
  A new ScriptEngine instance.