/*****************************************************************************
* Copyright (C) NanoContainer Organization. All rights reserved. *
* ------------------------------------------------------------------------- *
* The software in this package is published under the terms of the BSD *
* style license a copy of which has been included with this distribution in *
* the LICENSE.txt file. *
* *
* Original code by Leo Simons *
*****************************************************************************/
package org.nanocontainer.script.bsh;
import bsh.EvalError;
import bsh.Interpreter;
import org.picocontainer.Parameter;
import org.picocontainer.PicoContainer;
import org.picocontainer.PicoInitializationException;
import org.picocontainer.PicoIntrospectionException;
import org.picocontainer.defaults.AbstractComponentAdapter;
import org.picocontainer.defaults.UnsatisfiableDependenciesException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.util.Arrays;
import java.util.Collections;
/**
* This adapter relies on <a href="http://beanshell.org/">Bsh</a> for instantiation
* (and possibly also initialisation) of component instances.
* <p/>
* When {@link org.picocontainer.ComponentAdapter#getComponentInstance} is called (by PicoContainer),
* the adapter instance will look for a script with the same name as the component implementation
* class (but with the .bsh extension). This script must reside in the same folder as the class.
* (It's ok to have them both in a jar).
* <p/>
* The bsh script's only contract is that it will have to instantiate a bsh variable called
* "instance".
* <p/>
* The script will have access to the following variables:
* <ul>
* <li>adapter - the adapter calling the script</li>
* <li>picoContainer - the MutablePicoContainer calling the adapter</li>
* <li>componentKey - the component key</li>
* <li>componentImplementation - the component implementation</li>
* <li>parameters - the ComponentParameters (as a List)</li>
* </ul>
*
* @author <a href="mail at leosimons dot com">Leo Simons</a>
* @author Aslak Hellesoy
* @version $Id: BeanShellComponentAdapter.java 1570 2004-08-07 20:04:48Z joehni $
*/
public class BeanShellComponentAdapter extends AbstractComponentAdapter {
private final Parameter[] parameters;
private Object instance = null;
public BeanShellComponentAdapter(Object componentKey, Class componentImplementation, Parameter[] parameters) {
super(componentKey, componentImplementation);
this.parameters = parameters;
}
public Object getComponentInstance(PicoContainer pico)
throws PicoInitializationException, PicoIntrospectionException {
if (instance == null) {
try {
Interpreter i = new Interpreter();
i.set("adapter", this);
i.set("picoContainer", pico);
i.set("componentKey", getComponentKey());
i.set("componentImplementation", getComponentImplementation());
i.set("parameters", parameters != null ? Arrays.asList(parameters) : Collections.EMPTY_LIST);
i.eval("import " + getComponentImplementation().getName() + ";");
String scriptPath = "/" + getComponentImplementation().getName().replace('.', '/') + ".bsh";
// Inside IDEA, this relies on the compilation output path being the same directory as the source path.
// kludge - copy ScriptableDemoBean.bsh to the same location in the test output compile class path.
// the same problem exists for maven, but some custom jelly script will be able to fix that.
URL scriptURL = getComponentImplementation().getResource(scriptPath);
if (scriptURL == null) {
throw new BeanShellScriptInitializationException("Couldn't load script at path " + scriptPath);
}
Reader sourceReader = new InputStreamReader(scriptURL.openStream());
i.eval(sourceReader, i.getNameSpace(), scriptURL.toExternalForm());
instance = i.get("instance");
if (instance == null) {
throw new BeanShellScriptInitializationException("The 'instance' variable was not instantiated");
}
} catch (EvalError e) {
throw new BeanShellScriptInitializationException(e);
} catch (IOException e) {
throw new BeanShellScriptInitializationException(e);
}
}
return instance;
}
public void verify(PicoContainer pico) throws UnsatisfiableDependenciesException {
}
}