org.apache.commons.jexl

Class ScriptFactory

java.lang.Object

org.apache.commons.jexl.ScriptFactory

public class ScriptFactory
extends java.lang.Object

Creates Scripts. To create a JEXL Script, pass valid JEXL syntax to the static createScript() method:

 String jexl = "y = x * 12 + 44; y = y * 4;";
 Script script = ScriptFactory.createScript( jexl );
 

When an Script is created, the JEXL syntax is parsed and verified.

Since:

1.1

Version:

$Id: ScriptFactory.java 429175 2006-08-06 19:05:23Z rahul $

Field Summary

Fields

Modifier and Type	Field and Description
protected static ScriptFactory	factory ScriptFactory is a singleton and this is the private instance fufilling that pattern.
protected static org.apache.commons.logging.Log	log The Log to which all ScriptFactory messages will be logged.
protected static Parser	parser The singleton ScriptFactory also holds a single instance of Parser.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	ScriptFactory() Private constructor, the single instance is always obtained with a call to getInstance().

Method Summary

Modifier and Type	Method and Description
private java.lang.String	cleanScript(java.lang.String script)
protected Script	createNewScript(java.lang.String scriptText) Creates a new Script based on the string.
static Script	createScript(java.io.File scriptFile) Creates a Script from a File containing valid JEXL syntax.
static Script	createScript(java.lang.String scriptText) Creates a Script from a String containing valid JEXL syntax.
static Script	createScript(java.net.URL scriptUrl) Creates a Script from a URL containing valid JEXL syntax.
protected static ScriptFactory	getInstance() Returns the single instance of ScriptFactory.
private static java.lang.String	readerToString(java.io.BufferedReader reader) Read a buffered reader into a StringBuffer and return a String with the contents of the reader.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

protected static org.apache.commons.logging.Log log

The Log to which all ScriptFactory messages will be logged.

parser

protected static Parser parser

The singleton ScriptFactory also holds a single instance of Parser. When parsing expressions, ScriptFactory synchronizes on Parser.

factory

protected static ScriptFactory factory

ScriptFactory is a singleton and this is the private instance fufilling that pattern.

Constructor Detail

ScriptFactory

private ScriptFactory()

Private constructor, the single instance is always obtained with a call to getInstance().

Method Detail

getInstance

protected static ScriptFactory getInstance()

Returns the single instance of ScriptFactory.

Returns:

the instance of ScriptFactory.

createScript

public static Script createScript(java.lang.String scriptText)
                           throws java.lang.Exception

Creates a Script from a String containing valid JEXL syntax. This method parses the script which validates the syntax.

Parameters:

scriptText - A String containing valid JEXL syntax

Returns:

A Script which can be executed with a JexlContext.

Throws:

java.lang.Exception - An exception can be thrown if there is a problem parsing the script.

createScript

public static Script createScript(java.io.File scriptFile)
                           throws java.lang.Exception

Creates a Script from a File containing valid JEXL syntax. This method parses the script and validates the syntax.

Parameters:

scriptFile - A File containing valid JEXL syntax. Must not be null. Must be a readable file.

Returns:

A Script which can be executed with a JexlContext.

Throws:

java.lang.Exception - An exception can be thrown if there is a problem parsing the script.

createScript

public static Script createScript(java.net.URL scriptUrl)
                           throws java.lang.Exception

Creates a Script from a URL containing valid JEXL syntax. This method parses the script and validates the syntax.

Parameters:

scriptUrl - A URL containing valid JEXL syntax. Must not be null. Must be a readable file.

Returns:

A Script which can be executed with a JexlContext.

Throws:

java.lang.Exception - An exception can be thrown if there is a problem parsing the script.

createNewScript

protected Script createNewScript(java.lang.String scriptText)
                          throws java.lang.Exception

Creates a new Script based on the string.

Parameters:

scriptText - valid Jexl script

Returns:

Script a new script

Throws:

java.lang.Exception - for a variety of reasons - mostly malformed scripts

cleanScript

private java.lang.String cleanScript(java.lang.String script)

Parameters:

script - to clean

Returns:

trimmed expression ending in a semi-colon

readerToString

private static java.lang.String readerToString(java.io.BufferedReader reader)
                                        throws java.io.IOException

Read a buffered reader into a StringBuffer and return a String with the contents of the reader.

Parameters:

reader - to be read.

Returns:

the contents of the reader as a String.

Throws:

java.io.IOException - on any error reading the reader.