Java™ Platform
Standard Ed. 6

javax.script
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
static String ARGV
          Reserved key for a named value that passes an array of positional arguments to a script.
static String ENGINE
          Reserved key for a named value that is the name of the ScriptEngine implementation.
static String ENGINE_VERSION
          Reserved key for a named value that identifies the version of the ScriptEngine implementation.
static String FILENAME
          Reserved key for a named value that is the name of the file being executed.
static String LANGUAGE
          Reserved key for a named value that is the full name of Scripting Language supported by the implementation.
static String LANGUAGE_VERSION
          Reserved key for the named value that identifies the version of the scripting language supported by the implementation.
static String NAME
          Reserved key for a named value that identifies the short name of the scripting language.
 
Method Summary
 Bindings createBindings()
          Returns an uninitialized Bindings.
 Object eval(Reader reader)
          Same as eval(String) except that the source of the script is provided as a Reader
 Object eval(Reader reader, Bindings n)
          Same as eval(String, Bindings) except that the source of the script is provided as a Reader.
 Object eval(Reader reader, ScriptContext context)
          Same as eval(String, ScriptContext) where the source of the script is read from a Reader.
 Object eval(String script)
          Executes the specified script.
 Object eval(String script, Bindings n)
          Executes the script using the Bindings argument as the ENGINE_SCOPE Bindings of the ScriptEngine during the script execution.
 Object eval(String script, ScriptContext context)
          Causes the immediate execution of the script whose source is the String passed as the first argument.
 Object get(String key)
          Retrieves a value set in the state of this engine.
 Bindings getBindings(int scope)
          Returns a scope of named values.
 ScriptContext getContext()
          Returns the default ScriptContext of the ScriptEngine whose Bindings, Reader and Writers are used for script executions when no ScriptContext is specified.
 ScriptEngineFactory getFactory()
          Returns a ScriptEngineFactory for the class to which this ScriptEngine belongs.
 void put(String key, Object value)
          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.
 void setBindings(Bindings bindings, int scope)
          Sets a scope of named values to be used by scripts.
 void setContext(ScriptContext context)
          Sets the default ScriptContext of the ScriptEngine whose Bindings, Reader and Writers are used for script executions when no ScriptContext is specified.
 

Field Detail

ARGV

static final String ARGV
Reserved key for a named value that passes an array of positional arguments to a script.

See Also:
Constant Field Values

FILENAME

static final String FILENAME
Reserved key for a named value that is the name of the file being executed.

See Also:
Constant Field Values

ENGINE

static final String ENGINE
Reserved key for a named value that is the name of the ScriptEngine implementation.

See Also:
Constant Field Values

ENGINE_VERSION

static final String ENGINE_VERSION
Reserved key for a named value that identifies the version of the ScriptEngine implementation.

See Also:
Constant Field Values

NAME

static final String NAME
Reserved key for a named value that identifies the short name of the scripting language. The name is used by the ScriptEngineManager to locate a ScriptEngine with a given name in the getEngineByName method.

See Also:
Constant Field Values

LANGUAGE

static final String LANGUAGE
Reserved key for a named value that is the full name of Scripting Language supported by the implementation.

See Also:
Constant Field Values

LANGUAGE_VERSION

static final String LANGUAGE_VERSION
Reserved key for the named value that identifies the version of the scripting language supported by the implementation.

See Also:
Constant Field Values
Method Detail

eval

Object eval(String script,
            ScriptContext context)
            throws ScriptException
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 - A ScriptContext exposing sets of attributes in different scopes. The meanings of the scopes ScriptContext.GLOBAL_SCOPE, and ScriptContext.ENGINE_SCOPE are defined in the specification.

The ENGINE_SCOPE Bindings of the ScriptContext contains 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 occurrs in script. ScriptEngines should create and throw ScriptException wrappers for checked Exceptions thrown by underlying scripting implementations.
NullPointerException - if either argument is null.

eval

Object eval(Reader reader,
            ScriptContext context)
            throws ScriptException
Same as eval(String, ScriptContext) where the source of the script is read from a Reader.

Parameters:
reader - The source of the script to be executed by the script engine.
context - The ScriptContext passed to the script engine.
Returns:
The value returned from the execution of the script.
Throws:
ScriptException - if an error occurrs in script.
NullPointerException - if either argument is null.

eval

Object eval(String script)
            throws ScriptException
Executes the specified script. The default ScriptContext for the ScriptEngine is used.

Parameters:
script - The script language source to be executed.
Returns:
The value returned from the execution of the script.
Throws:
ScriptException - if error occurrs in script.
NullPointerException - if the argument is null.

eval

Object eval(Reader reader)
            throws ScriptException
Same as eval(String) except that the source of the script is provided as a Reader

Parameters:
reader - The source of the script.
Returns:
The value returned by the script.
Throws:
ScriptException - if an error occurrs in script.
NullPointerException - if the argument is null.

eval

Object eval(String script,
            Bindings n)
            throws ScriptException
Executes the script using the Bindings argument as the ENGINE_SCOPE Bindings of the ScriptEngine during the script execution. The Reader, Writer and non-ENGINE_SCOPE Bindings of the default ScriptContext are used. The ENGINE_SCOPE Bindings of the ScriptEngine is not changed, and its mappings are unaltered by the script execution.

Parameters:
script - The source for the script.
n - The Bindings of attributes to be used for script execution.
Returns:
The value returned by the script.
Throws:
ScriptException - if an error occurrs in script.
NullPointerException - if either argument is null.

eval

Object eval(Reader reader,
            Bindings n)
            throws ScriptException
Same as eval(String, Bindings) except that the source of the script is provided as a Reader.

Parameters:
reader - The source of the script.
n - The Bindings of attributes.
Returns:
The value returned by the script.
Throws:
ScriptException - if an error occurrs.
NullPointerException - if either argument is null.

put

void put(String key,
         Object value)
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 as getBindings(ScriptContext.ENGINE_SCOPE).put.

Parameters:
key - The name of named value to add
value - The value of named value to add.
Throws:
NullPointerException - if key is null.
IllegalArgumentException - if key is empty.

get

Object get(String key)
Retrieves a value set in the state of this engine. The value might be one which was set using setValue or some other value in the state of the ScriptEngine, depending on the implementation. Must have the same effect as getBindings(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

Bindings getBindings(int scope)
Returns a scope of named values. The possible scopes are:



The Bindings instances that are returned must be identical to those returned by the getBindings method of ScriptContext called with corresponding arguments on the default ScriptContext of the ScriptEngine.

Parameters:
scope - Either ScriptContext.ENGINE_SCOPE or ScriptContext.GLOBAL_SCOPE which specifies the Bindings to return. Implementations of ScriptContext may define additional scopes. If the default ScriptContext of the ScriptEngine defines additional scopes, any of them can be passed to get the corresponding Bindings.
Returns:
The Bindings with the specified scope.
Throws:
IllegalArgumentException - if specified scope is invalid

setBindings

void setBindings(Bindings bindings,
                 int scope)
Sets a scope of named values to be used by scripts. The possible scopes are:



The method must have the same effect as calling the setBindings method of ScriptContext with the corresponding value of scope on the default ScriptContext of the ScriptEngine.

Parameters:
bindings - The Bindings for the specified scope.
scope - The specified scope. Either ScriptContext.ENGINE_SCOPE, ScriptContext.GLOBAL_SCOPE, or any other valid value of scope.
Throws:
IllegalArgumentException - if the scope is invalid
NullPointerException - if the bindings is null and the scope is ScriptContext.ENGINE_SCOPE

createBindings

Bindings createBindings()
Returns an uninitialized Bindings.

Returns:
A Bindings that can be used to replace the state of this ScriptEngine.

getContext

ScriptContext getContext()
Returns the default ScriptContext of the ScriptEngine whose Bindings, Reader and Writers are used for script executions when no ScriptContext is specified.

Returns:
The default ScriptContext of the ScriptEngine.

setContext

void setContext(ScriptContext context)
Sets the default ScriptContext of the ScriptEngine whose Bindings, Reader and Writers are used for script executions when no ScriptContext is specified.

Parameters:
context - A ScriptContext that will replace the default ScriptContext in the ScriptEngine.
Throws:
NullPointerException - if context is null.

getFactory

ScriptEngineFactory getFactory()
Returns a ScriptEngineFactory for the class to which this ScriptEngine belongs.

Returns:
The ScriptEngineFactory

Java™ Platform
Standard Ed. 6

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