Interface ScriptEngine
- All Known Implementing Classes:
AbstractScriptEngine
public interface ScriptEngine
ScriptEngine is the fundamental interface whose methods must be
fully functional in every implementation of this specification.
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.
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.
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.
- Since:
- 1.6
-
Field Summary
FieldsModifier and TypeFieldDescriptionstatic final StringReserved key for a named value that passes an array of positional arguments to a script.static final StringReserved key for a named value that is the name of theScriptEngineimplementation.static final StringReserved key for a named value that identifies the version of theScriptEngineimplementation.static final StringReserved key for a named value that is the name of the file being executed.static final StringReserved key for a named value that is the full name of Scripting Language supported by the implementation.static final StringReserved key for the named value that identifies the version of the scripting language supported by the implementation.static final StringReserved key for a named value that identifies the short name of the scripting language. -
Method Summary
Modifier and TypeMethodDescriptionReturns an uninitializedBindings.Same aseval(String)except that the source of the script is provided as aReaderSame aseval(String, Bindings)except that the source of the script is provided as aReader.eval(Reader reader, ScriptContext context) Same aseval(String, ScriptContext)where the source of the script is read from aReader.Executes the specified script.Executes the script using theBindingsargument as theENGINE_SCOPEBindingsof theScriptEngineduring the script execution.eval(String script, ScriptContext context) Causes the immediate execution of the script whose source is the String passed as the first argument.Retrieves a value set in the state of this engine.getBindings(int scope) Returns a scope of named values.Returns the defaultScriptContextof theScriptEnginewhose Bindings, Reader and Writers are used for script executions when noScriptContextis specified.Returns aScriptEngineFactoryfor the class to which thisScriptEnginebelongs.voidSets 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.voidsetBindings(Bindings bindings, int scope) Sets a scope of named values to be used by scripts.voidsetContext(ScriptContext context) Sets the defaultScriptContextof theScriptEnginewhose Bindings, Reader and Writers are used for script executions when noScriptContextis specified.
-
Field Details
-
ARGV
Reserved key for a named value that passes an array of positional arguments to a script.- See Also:
-
FILENAME
Reserved key for a named value that is the name of the file being executed.- See Also:
-
ENGINE
Reserved key for a named value that is the name of theScriptEngineimplementation.- See Also:
-
ENGINE_VERSION
Reserved key for a named value that identifies the version of theScriptEngineimplementation.- See Also:
-
NAME
Reserved key for a named value that identifies the short name of the scripting language. The name is used by theScriptEngineManagerto locate aScriptEnginewith a given name in thegetEngineByNamemethod.- See Also:
-
LANGUAGE
Reserved key for a named value that is the full name of Scripting Language supported by the implementation.- See Also:
-
LANGUAGE_VERSION
Reserved key for the named value that identifies the version of the scripting language supported by the implementation.- See Also:
-
-
Method Details
-
eval
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.- Parameters:
script- The script to be executed by the script engine.context- AScriptContextexposing sets of attributes in different scopes. The meanings of the scopesScriptContext.GLOBAL_SCOPE, andScriptContext.ENGINE_SCOPEare defined in the specification.
TheENGINE_SCOPEBindingsof theScriptContextcontains the bindings of scripting variables to application objects to be used during this script execution.- Returns:
- The value returned from the execution of the script.
- Throws:
ScriptException- if an error occurs in script. ScriptEngines should create and throwScriptExceptionwrappers for checked Exceptions thrown by underlying scripting implementations.NullPointerException- if either argument is null.
-
eval
Same aseval(String, ScriptContext)where the source of the script is read from aReader.- Parameters:
reader- The source of the script to be executed by the script engine.context- TheScriptContextpassed to the script engine.- Returns:
- The value returned from the execution of the script.
- Throws:
ScriptException- if an error occurs in script. ScriptEngines should create and throwScriptExceptionwrappers for checked Exceptions thrown by underlying scripting implementations.NullPointerException- if either argument is null.
-
eval
Executes the specified script. The defaultScriptContextfor theScriptEngineis used.- Parameters:
script- The script language source to be executed.- Returns:
- The value returned from the execution of the script.
- Throws:
ScriptException- if an error occurs in script. ScriptEngines should create and throwScriptExceptionwrappers for checked Exceptions thrown by underlying scripting implementations.NullPointerException- if the argument is null.
-
eval
Same aseval(String)except that the source of the script is provided as aReader- Parameters:
reader- The source of the script.- Returns:
- The value returned by the script.
- Throws:
ScriptException- if an error occurs in script. ScriptEngines should create and throwScriptExceptionwrappers for checked Exceptions thrown by underlying scripting implementations.NullPointerException- if the argument is null.
-
eval
Executes the script using theBindingsargument as theENGINE_SCOPEBindingsof theScriptEngineduring the script execution. TheReader,Writerand non-ENGINE_SCOPEBindingsof the defaultScriptContextare used. TheENGINE_SCOPEBindingsof theScriptEngineis not changed, and its mappings are unaltered by the script execution.- Parameters:
script- The source for the script.n- TheBindingsof attributes to be used for script execution.- Returns:
- The value returned by the script.
- Throws:
ScriptException- if an error occurs in script. ScriptEngines should create and throwScriptExceptionwrappers for checked Exceptions thrown by underlying scripting implementations.NullPointerException- if either argument is null.
-
eval
Same aseval(String, Bindings)except that the source of the script is provided as aReader.- Parameters:
reader- The source of the script.n- TheBindingsof attributes.- Returns:
- The value returned by the script.
- Throws:
ScriptException- if an error occurs in script. ScriptEngines should create and throwScriptExceptionwrappers for checked Exceptions thrown by underlying scripting implementations.NullPointerException- if either argument is null.
-
put
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 asgetBindings(ScriptContext.ENGINE_SCOPE).put.- Parameters:
key- The name of named value to addvalue- The value of named value to add.- Throws:
NullPointerException- if key is null.IllegalArgumentException- if key is empty.
-
get
Retrieves a value set in the state of this engine. The value might be one which was set usingsetValueor some other value in the state of theScriptEngine, depending on the implementation. Must have the same effect asgetBindings(ScriptContext.ENGINE_SCOPE).get- Parameters:
key- The key whose value is to be returned- Returns:
- the value for the given key
- Throws:
NullPointerException- if key is null.IllegalArgumentException- if key is empty.
-
getBindings
Returns a scope of named values. The possible scopes are:
ScriptContext.GLOBAL_SCOPE- The set of named values representing global scope. If thisScriptEngineis created by aScriptEngineManager, then the manager sets global scope bindings. This may benullif no global scope is associated with thisScriptEngineScriptContext.ENGINE_SCOPE- The set of named values representing the state of thisScriptEngine. The values are generally visible in scripts using the associated keys as variable names.- Any other value of scope defined in the default
ScriptContextof theScriptEngine.
TheBindingsinstances that are returned must be identical to those returned by thegetBindingsmethod ofScriptContextcalled with corresponding arguments on the defaultScriptContextof theScriptEngine.- Parameters:
scope- EitherScriptContext.ENGINE_SCOPEorScriptContext.GLOBAL_SCOPEwhich specifies theBindingsto return. Implementations ofScriptContextmay define additional scopes. If the defaultScriptContextof theScriptEnginedefines additional scopes, any of them can be passed to get the correspondingBindings.- Returns:
- The
Bindingswith the specified scope. - Throws:
IllegalArgumentException- if specified scope is invalid
-
setBindings
Sets a scope of named values to be used by scripts. The possible scopes are:
ScriptContext.ENGINE_SCOPE- The specifiedBindingsreplaces the engine scope of theScriptEngine.ScriptContext.GLOBAL_SCOPE- The specifiedBindingsmust be visible as theGLOBAL_SCOPE.- Any other value of scope defined in the default
ScriptContextof theScriptEngine.
The method must have the same effect as calling thesetBindingsmethod ofScriptContextwith the corresponding value ofscopeon the defaultScriptContextof theScriptEngine.- Parameters:
bindings- TheBindingsfor the specified scope.scope- The specified scope. EitherScriptContext.ENGINE_SCOPE,ScriptContext.GLOBAL_SCOPE, or any other valid value of scope.- Throws:
IllegalArgumentException- if the scope is invalidNullPointerException- if the bindings is null and the scope isScriptContext.ENGINE_SCOPE
-
createBindings
Bindings createBindings()Returns an uninitializedBindings.- Returns:
- A
Bindingsthat can be used to replace the state of thisScriptEngine.
-
getContext
ScriptContext getContext()Returns the defaultScriptContextof theScriptEnginewhose Bindings, Reader and Writers are used for script executions when noScriptContextis specified.- Returns:
- The default
ScriptContextof theScriptEngine.
-
setContext
Sets the defaultScriptContextof theScriptEnginewhose Bindings, Reader and Writers are used for script executions when noScriptContextis specified.- Parameters:
context- AScriptContextthat will replace the defaultScriptContextin theScriptEngine.- Throws:
NullPointerException- if context is null.
-
getFactory
ScriptEngineFactory getFactory()Returns aScriptEngineFactoryfor the class to which thisScriptEnginebelongs.- Returns:
- The
ScriptEngineFactory
-