org.springframework.scripting.bsh.BshScriptFactory Maven / Gradle / Ivy
/*
* Copyright 2002-2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.scripting.bsh;
import java.io.IOException;
import bsh.EvalError;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.scripting.ScriptCompilationException;
import org.springframework.scripting.ScriptFactory;
import org.springframework.scripting.ScriptSource;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* {@link org.springframework.scripting.ScriptFactory} implementation
* for a BeanShell script.
*
* Typically used in combination with a
* {@link org.springframework.scripting.support.ScriptFactoryPostProcessor};
* see the latter's javadoc for a configuration example.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @since 2.0
* @see BshScriptUtils
* @see org.springframework.scripting.support.ScriptFactoryPostProcessor
*/
public class BshScriptFactory implements ScriptFactory, BeanClassLoaderAware {
private final String scriptSourceLocator;
private final Class[] scriptInterfaces;
private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
private Class scriptClass;
private final Object scriptClassMonitor = new Object();
private boolean wasModifiedForTypeCheck = false;
/**
* Create a new BshScriptFactory for the given script source.
*
With this {@code BshScriptFactory} variant, the script needs to
* declare a full class or return an actual instance of the scripted object.
* @param scriptSourceLocator a locator that points to the source of the script.
* Interpreted by the post-processor that actually creates the script.
*/
public BshScriptFactory(String scriptSourceLocator) {
Assert.hasText(scriptSourceLocator, "'scriptSourceLocator' must not be empty");
this.scriptSourceLocator = scriptSourceLocator;
this.scriptInterfaces = null;
}
/**
* Create a new BshScriptFactory for the given script source.
*
The script may either be a simple script that needs a corresponding proxy
* generated (implementing the specified interfaces), or declare a full class
* or return an actual instance of the scripted object (in which case the
* specified interfaces, if any, need to be implemented by that class/instance).
* @param scriptSourceLocator a locator that points to the source of the script.
* Interpreted by the post-processor that actually creates the script.
* @param scriptInterfaces the Java interfaces that the scripted object
* is supposed to implement (may be {@code null})
*/
public BshScriptFactory(String scriptSourceLocator, Class... scriptInterfaces) {
Assert.hasText(scriptSourceLocator, "'scriptSourceLocator' must not be empty");
this.scriptSourceLocator = scriptSourceLocator;
this.scriptInterfaces = scriptInterfaces;
}
@Override
public void setBeanClassLoader(ClassLoader classLoader) {
this.beanClassLoader = classLoader;
}
@Override
public String getScriptSourceLocator() {
return this.scriptSourceLocator;
}
@Override
public Class[] getScriptInterfaces() {
return this.scriptInterfaces;
}
/**
* BeanShell scripts do require a config interface.
*/
@Override
public boolean requiresConfigInterface() {
return true;
}
/**
* Load and parse the BeanShell script via {@link BshScriptUtils}.
* @see BshScriptUtils#createBshObject(String, Class[], ClassLoader)
*/
@Override
public Object getScriptedObject(ScriptSource scriptSource, Class... actualInterfaces)
throws IOException, ScriptCompilationException {
Class clazz;
try {
synchronized (this.scriptClassMonitor) {
boolean requiresScriptEvaluation = (this.wasModifiedForTypeCheck && this.scriptClass == null);
this.wasModifiedForTypeCheck = false;
if (scriptSource.isModified() || requiresScriptEvaluation) {
// New script content: Let's check whether it evaluates to a Class.
Object result = BshScriptUtils.evaluateBshScript(
scriptSource.getScriptAsString(), actualInterfaces, this.beanClassLoader);
if (result instanceof Class) {
// A Class: We'll cache the Class here and create an instance
// outside of the synchronized block.
this.scriptClass = (Class) result;
}
else {
// Not a Class: OK, we'll simply create BeanShell objects
// through evaluating the script for every call later on.
// For this first-time check, let's simply return the
// already evaluated object.
return result;
}
}
clazz = this.scriptClass;
}
}
catch (EvalError ex) {
this.scriptClass = null;
throw new ScriptCompilationException(scriptSource, ex);
}
if (clazz != null) {
// A Class: We need to create an instance for every call.
try {
return clazz.newInstance();
}
catch (Throwable ex) {
throw new ScriptCompilationException(
scriptSource, "Could not instantiate script class: " + clazz.getName(), ex);
}
}
else {
// Not a Class: We need to evaluate the script for every call.
try {
return BshScriptUtils.createBshObject(
scriptSource.getScriptAsString(), actualInterfaces, this.beanClassLoader);
}
catch (EvalError ex) {
throw new ScriptCompilationException(scriptSource, ex);
}
}
}
@Override
public Class getScriptedObjectType(ScriptSource scriptSource)
throws IOException, ScriptCompilationException {
synchronized (this.scriptClassMonitor) {
try {
if (scriptSource.isModified()) {
// New script content: Let's check whether it evaluates to a Class.
this.wasModifiedForTypeCheck = true;
this.scriptClass = BshScriptUtils.determineBshObjectType(
scriptSource.getScriptAsString(), this.beanClassLoader);
}
return this.scriptClass;
}
catch (EvalError ex) {
this.scriptClass = null;
throw new ScriptCompilationException(scriptSource, ex);
}
}
}
@Override
public boolean requiresScriptedObjectRefresh(ScriptSource scriptSource) {
synchronized (this.scriptClassMonitor) {
return (scriptSource.isModified() || this.wasModifiedForTypeCheck);
}
}
@Override
public String toString() {
return "BshScriptFactory: script source locator [" + this.scriptSourceLocator + "]";
}
}