Java tutorial
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For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.apache.commons.el; import java.util.List; import java.util.Iterator; import java.lang.reflect.*; import javax.servlet.jsp.el.ELException; import javax.servlet.jsp.el.VariableResolver; import javax.servlet.jsp.el.FunctionMapper; /** * * <p> * Represents a function call. * </p> * * @author Shawn Bayern (in the style of Nathan's other classes) **/ public class FunctionInvocation extends Expression { // ------------------------------------- // 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(VariableResolver pResolver, FunctionMapper functions, Logger pLogger) throws ELException { // if the Map is null, then the function is invalid if (functions == null) pLogger.logError(Constants.UNKNOWN_FUNCTION, functionName); // 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.resolveFunction(prefix, localName); if (target == null) pLogger.logError(Constants.UNKNOWN_FUNCTION, functionName); /* * :shig date:2013-4-10 explain:el?javaobject???, sum(int... lst)java?:sum(int[] lst) */ // ensure that the number of arguments matches the number of parameters boolean bCallBackFunction = false; Class[] params = target.getParameterTypes(); if (params.length == 5) { if (params[0].equals(this.getClass()) && params[1].equals(List.class) && params[2].equals(VariableResolver.class) && params[3].equals(FunctionMapper.class) && params[4].equals(Logger.class)) { bCallBackFunction = true; } } Object[] arguments = null; if (bCallBackFunction) { arguments = new Object[params.length]; arguments[0] = this; arguments[1] = argumentList; arguments[2] = pResolver; arguments[3] = functions; arguments[4] = pLogger; } else { boolean bLastParamIsObjectArray = params.length > 0 && params[params.length - 1].equals(Object[].class); if (params.length != argumentList.size() && !bLastParamIsObjectArray) { pLogger.logError(Constants.INAPPROPRIATE_FUNCTION_ARG_COUNT, functionName, new Integer(params.length), new Integer(argumentList.size())); } arguments = new Object[params.length]; // now, walk through each parameter, evaluating and casting its // argument for (int i = 0; i < params.length; i++) { if (bLastParamIsObjectArray && (i >= (params.length - 1))) { // ??objectel?? Object[] subArguments = new Object[argumentList.size() - i]; for (int j = 0; j < argumentList.size() - i; j++) { // evaluate subArguments[j] = ((Expression) argumentList.get(j + i)).evaluate(pResolver, functions, pLogger); // coerce subArguments[j] = Coercions.coerce(subArguments[j], Object.class, pLogger); } arguments[i] = subArguments; break; } else { // evaluate arguments[i] = ((Expression) argumentList.get(i)).evaluate(pResolver, functions, pLogger); // coerce arguments[i] = Coercions.coerce(arguments[i], params[i], pLogger); } } } // finally, invoke the target method, which we know to be static try { return (target.invoke(functions, arguments)); } catch (InvocationTargetException ex) { pLogger.logError(Constants.FUNCTION_INVOCATION_ERROR, ex.getTargetException(), functionName); return null; } catch (Exception ex) { pLogger.logError(Constants.FUNCTION_INVOCATION_ERROR, ex, functionName); return null; } } /* * :shig date:2013-4-10 explain:el?? sum(int... lst)java?:sum(int[] lst) */ public Object evaluate(VariableResolver pResolver, FunctionMapper functions, Logger pLogger, Expression expression) throws ELException { Object ret = null; ret = expression.evaluate(pResolver, functions, pLogger); return ret; } }