Attachment 29707 Details for Bug 54239 – ELInterpreterFactory

ELInterpreterFactory

ELInterpreterFactory.java (text/plain), 4.18 KB, created by Sheldon Shao on 2012-12-06 06:02:32 UTC

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Creator: Sheldon Shao

Created: 2012-12-06 06:02:32 UTC

Size: 4.18 KB

patch

obsolete

>/*
> * Licensed to the Apache Software Foundation (ASF) under one or more
> * contributor license agreements.  See the NOTICE file distributed with
> * this work for additional information regarding copyright ownership.
> * The ASF licenses this file to You 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.apache.jasper.compiler;
>
>import javax.servlet.ServletContext;
>
>import org.apache.jasper.JspCompilationContext;
>
>/**
> * ELInterpreter Factory
> * 
> * Supports how to get a right ELInterpreter from ServletContext.
> * 
> * 1. It supports get ELInterpreter instance from ServletContext, so that Web Application can provide its own ELInterpreter.
> * 2. Customized ELInterpreter can be passed-in by setting "org.apache.jasper.compiler.ELInterpreter=xxx" in ServletContext's initialization parameters.
> * 3. If there is no any ELInterpreter, the DefaultELInterpreter will be used
> * 
> * @author Sheldon Shao (XShao@ebay.com)
> */
>public class ELInterpreterFactory {
>
>    private ELInterpreterFactory() {
>    }
>
>    public static final String EL_INTERPRETER_CLASS_NAME = ELInterpreter.class.getName();
>    
>    /**
>     * Default Instance
>     */
>    private static final ELInterpreter DEFAULT_INSTANCE = new DefaultELInterpreter();
>    
>    public static class DefaultELInterpreter implements ELInterpreter {
>
>        /**
>         * Produces a String representing a call to the EL interpreter.
>         *
>         * @param context JspCompilationContext
>         * @param expression
>         *            a String containing zero or more "${}" expressions
>         * @param expectedType
>         *            the expected type of the interpreted result
>         * @param fnmapvar
>         *            Variable pointing to a function map.
>         * @param XmlEscape
>         *            True if the result should do XML escaping
>         * @return a String representing a call to the EL interpreter.
>         */
>        @Override
>        public String interpreterCall(JspCompilationContext context,
>                boolean isTagFile, String expression,
>                Class<?> expectedType, String fnmapvar, boolean xmlEscape) {
>            return JspUtil.interpreterCall(isTagFile, expression, expectedType, fnmapvar, xmlEscape);
>        }
>    }
>
>    /**
>     * Retrieve ELInterpreter implementation from ServletContext
>     * 
>     * @param context ServletContext
>     */
>    public static ELInterpreter getELInterpreter(ServletContext context) throws Exception {
>        ELInterpreter interpreter = null;
>        //Check ELInterpreter in 
>        Object conf = context.getAttribute(EL_INTERPRETER_CLASS_NAME);
>        if (conf == null) {
>            String className = context.getInitParameter(EL_INTERPRETER_CLASS_NAME);
>            if (className != null) {
>                interpreter = toInterpreter(context, className);
>            }
>            else {
>                interpreter =  DEFAULT_INSTANCE;
>            }
>        }
>        else if (conf instanceof ELInterpreter) {
>            interpreter = (ELInterpreter)conf;
>            return interpreter;
>        }
>        else if (conf instanceof String) {
>            interpreter = toInterpreter(context, (String)conf);
>        }
>        context.setAttribute(EL_INTERPRETER_CLASS_NAME, interpreter);
>        return interpreter;
>    }
>    
>    /**
>     * Create ELInterpreter by given class name
>     * 
>     * @param context ServletContext
>     * @param className Class Name
>     * @return
>     */
>    private static ELInterpreter toInterpreter(ServletContext context, String className) throws Exception {
>        return (ELInterpreter)context.getClassLoader().loadClass(className).newInstance();
>    }
>}

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