Java tutorial
/* * The contents of this file are subject to the terms * of the Common Development and Distribution License * (the License). You may not use this file except in * compliance with the License. * * You can obtain a copy of the License at * https://javaserverfaces.dev.java.net/CDDL.html or * legal/CDDLv1.0.txt. * See the License for the specific language governing * permission and limitations under the License. * * When distributing Covered Code, include this CDDL * Header Notice in each file and include the License file * at legal/CDDLv1.0.txt. * If applicable, add the following below the CDDL Header, * with the fields enclosed by brackets [] replaced by * your own identifying information: * "Portions Copyrighted [year] [name of copyright owner]" * * [Name of File] [ver.__] [Date] * * Copyright 2006 Sun Microsystems Inc. All Rights Reserved */ /* * The Apache Software License, Version 1.1 * * Copyright (c) 1999 The Apache Software Foundation. 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For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package com.sun.faces.el.impl; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.Iterator; import java.util.List; /** * <p>Represents a function call.</p> * * @author Shawn Bayern (in the style of Nathan's other classes) */ public class FunctionInvocation extends Expression { //------------------------------------- // Constants //------------------------------------- private static Log log = LogFactory.getLog(FunctionInvocation.class); //------------------------------------- // Properties //------------------------------------- // property index private String functionName; private List argumentList; public String getFunctionName() { return functionName; } public void setFunctionName(String f) { functionName = f; } public List getArgumentList() { return argumentList; } public void setArgumentList(List l) { argumentList = l; } //------------------------------------- /** * Constructor */ public FunctionInvocation(String functionName, List argumentList) { this.functionName = functionName; this.argumentList = argumentList; } //------------------------------------- // Expression methods //------------------------------------- /** * Returns the expression in the expression language syntax */ public String getExpressionString() { StringBuffer b = new StringBuffer(); b.append(functionName); b.append("("); Iterator i = argumentList.iterator(); while (i.hasNext()) { b.append(((Expression) i.next()).getExpressionString()); if (i.hasNext()) b.append(", "); } b.append(")"); return b.toString(); } //------------------------------------- /** * Evaluates by looking up the name in the VariableResolver */ public Object evaluate(ExpressionInfo exprInfo) throws ElException { FunctionMapper functions = exprInfo.getFunctionMapper(); // if the Map is null, then the function is invalid if (functions == null) { if (log.isErrorEnabled()) { String message = MessageUtil.getMessageWithArgs(Constants.UNKNOWN_FUNCTION, functionName); log.error(message); throw new ElException(message); } } // normalize function name String prefix = null; String localName = null; int index = functionName.indexOf(':'); if (index == -1) { prefix = ""; localName = functionName; } else { prefix = functionName.substring(0, index); localName = functionName.substring(index + 1); } // ensure that the function's name is mapped Method target = (Method) functions.resolve(prefix, localName); if (target == null) { if (log.isErrorEnabled()) { String message = MessageUtil.getMessageWithArgs(Constants.UNKNOWN_FUNCTION, functionName); log.error(message); throw new ElException(message); } } // ensure that the number of arguments matches the number of parameters Class[] params = target.getParameterTypes(); if (params.length != argumentList.size()) { if (log.isErrorEnabled()) { String message = MessageUtil.getMessageWithArgs(Constants.INAPPROPRIATE_FUNCTION_ARG_COUNT, functionName, new Integer(params.length), new Integer(argumentList.size())); log.error(message); throw new ElException(message); } } // now, walk through each parameter, evaluating and casting its argument Object[] arguments = new Object[argumentList.size()]; for (int i = 0; i < params.length; i++) { // evaluate arguments[i] = ((Expression) argumentList.get(i)).evaluate(exprInfo); // coerce arguments[i] = Coercions.coerce(arguments[i], params[i]); } // finally, invoke the target method, which we know to be static try { return (target.invoke(null, arguments)); } catch (InvocationTargetException ex) { if (log.isErrorEnabled()) { String message = MessageUtil.getMessageWithArgs(Constants.FUNCTION_INVOCATION_ERROR, functionName); Throwable t = ex.getTargetException(); log.error(message, t); throw new ElException(message, t); } return null; } catch (Throwable t) { if (log.isErrorEnabled()) { String message = MessageUtil.getMessageWithArgs(Constants.FUNCTION_INVOCATION_ERROR, functionName); log.error(message, t); throw new ElException(message, t); } return null; } } //------------------------------------- }