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/*
 * Copyright 2002-2018 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
 *
 *      https://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.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import bsh.EvalError;
import bsh.Interpreter;
import bsh.Primitive;
import bsh.XThis;

import org.springframework.core.NestedRuntimeException;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.ReflectionUtils;

/**
 * Utility methods for handling BeanShell-scripted objects.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 2.0
 */
public abstract class BshScriptUtils {

	/**
	 * Create a new BeanShell-scripted object from the given script source.
	 * 

With this {@code createBshObject} variant, the script needs to * declare a full class or return an actual instance of the scripted object. * @param scriptSource the script source text * @return the scripted Java object * @throws EvalError in case of BeanShell parsing failure */ public static Object createBshObject(String scriptSource) throws EvalError { return createBshObject(scriptSource, null, null); } /** * Create a new BeanShell-scripted object from the given script source, * using the default ClassLoader. *

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 scriptSource the script source text * @param scriptInterfaces the interfaces that the scripted Java object is * supposed to implement (may be {@code null} or empty if the script itself * declares a full class or returns an actual instance of the scripted object) * @return the scripted Java object * @throws EvalError in case of BeanShell parsing failure * @see #createBshObject(String, Class[], ClassLoader) */ public static Object createBshObject(String scriptSource, @Nullable Class... scriptInterfaces) throws EvalError { return createBshObject(scriptSource, scriptInterfaces, ClassUtils.getDefaultClassLoader()); } /** * Create a new BeanShell-scripted object from 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 scriptSource the script source text * @param scriptInterfaces the interfaces that the scripted Java object is * supposed to implement (may be {@code null} or empty if the script itself * declares a full class or returns an actual instance of the scripted object) * @param classLoader the ClassLoader to use for evaluating the script * @return the scripted Java object * @throws EvalError in case of BeanShell parsing failure */ public static Object createBshObject(String scriptSource, @Nullable Class[] scriptInterfaces, @Nullable ClassLoader classLoader) throws EvalError { Object result = evaluateBshScript(scriptSource, scriptInterfaces, classLoader); if (result instanceof Class) { Class clazz = (Class) result; try { return ReflectionUtils.accessibleConstructor(clazz).newInstance(); } catch (Throwable ex) { throw new IllegalStateException("Could not instantiate script class: " + clazz.getName(), ex); } } else { return result; } } /** * Evaluate the specified BeanShell script based on the given script source, * returning the Class defined by the script. *

The script may either declare a full class or return an actual instance of * the scripted object (in which case the Class of the object will be returned). * In any other case, the returned Class will be {@code null}. * @param scriptSource the script source text * @param classLoader the ClassLoader to use for evaluating the script * @return the scripted Java class, or {@code null} if none could be determined * @throws EvalError in case of BeanShell parsing failure */ @Nullable static Class determineBshObjectType(String scriptSource, @Nullable ClassLoader classLoader) throws EvalError { Assert.hasText(scriptSource, "Script source must not be empty"); Interpreter interpreter = new Interpreter(); if (classLoader != null) { interpreter.setClassLoader(classLoader); } Object result = interpreter.eval(scriptSource); if (result instanceof Class) { return (Class) result; } else if (result != null) { return result.getClass(); } else { return null; } } /** * Evaluate the specified BeanShell script based on the given script source, * keeping a returned script Class or script Object as-is. *

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 scriptSource the script source text * @param scriptInterfaces the interfaces that the scripted Java object is * supposed to implement (may be {@code null} or empty if the script itself * declares a full class or returns an actual instance of the scripted object) * @param classLoader the ClassLoader to use for evaluating the script * @return the scripted Java class or Java object * @throws EvalError in case of BeanShell parsing failure */ static Object evaluateBshScript( String scriptSource, @Nullable Class[] scriptInterfaces, @Nullable ClassLoader classLoader) throws EvalError { Assert.hasText(scriptSource, "Script source must not be empty"); Interpreter interpreter = new Interpreter(); interpreter.setClassLoader(classLoader); Object result = interpreter.eval(scriptSource); if (result != null) { return result; } else { // Simple BeanShell script: Let's create a proxy for it, implementing the given interfaces. if (ObjectUtils.isEmpty(scriptInterfaces)) { throw new IllegalArgumentException("Given script requires a script proxy: " + "At least one script interface is required.\nScript: " + scriptSource); } XThis xt = (XThis) interpreter.eval("return this"); return Proxy.newProxyInstance(classLoader, scriptInterfaces, new BshObjectInvocationHandler(xt)); } } /** * InvocationHandler that invokes a BeanShell script method. */ private static class BshObjectInvocationHandler implements InvocationHandler { private final XThis xt; public BshObjectInvocationHandler(XThis xt) { this.xt = xt; } @Override @Nullable public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if (ReflectionUtils.isEqualsMethod(method)) { return (isProxyForSameBshObject(args[0])); } else if (ReflectionUtils.isHashCodeMethod(method)) { return this.xt.hashCode(); } else if (ReflectionUtils.isToStringMethod(method)) { return "BeanShell object [" + this.xt + "]"; } try { Object result = this.xt.invokeMethod(method.getName(), args); if (result == Primitive.NULL || result == Primitive.VOID) { return null; } if (result instanceof Primitive) { return ((Primitive) result).getValue(); } return result; } catch (EvalError ex) { throw new BshExecutionException(ex); } } private boolean isProxyForSameBshObject(Object other) { if (!Proxy.isProxyClass(other.getClass())) { return false; } InvocationHandler ih = Proxy.getInvocationHandler(other); return (ih instanceof BshObjectInvocationHandler && this.xt.equals(((BshObjectInvocationHandler) ih).xt)); } } /** * Exception to be thrown on script execution failure. */ @SuppressWarnings("serial") public static final class BshExecutionException extends NestedRuntimeException { private BshExecutionException(EvalError ex) { super("BeanShell script execution failed", ex); } } }





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