001package org.apache.turbine.modules; 002 003/* 004 * Licensed to the Apache Software Foundation (ASF) under one 005 * or more contributor license agreements. See the NOTICE file 006 * distributed with this work for additional information 007 * regarding copyright ownership. The ASF licenses this file 008 * to you under the Apache License, Version 2.0 (the 009 * "License"); you may not use this file except in compliance 010 * with the License. You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, 015 * software distributed under the License is distributed on an 016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 017 * KIND, either express or implied. See the License for the 018 * specific language governing permissions and limitations 019 * under the License. 020 */ 021 022import org.apache.turbine.Turbine; 023import org.apache.turbine.pipeline.PipelineData; 024 025/** 026 * The purpose of this class is to allow one to load and execute 027 * Navigation modules. 028 * 029 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a> 030 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> 031 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 032 * @version $Id$ 033 */ 034public class NavigationLoader 035 extends GenericLoader<Navigation> 036{ 037 /** The single instance of this class. */ 038 private static NavigationLoader instance = new NavigationLoader(); 039 040 /** 041 * These ctor's are private to force clients to use getInstance() 042 * to access this class. 043 */ 044 private NavigationLoader() 045 { 046 super(Navigation.class, 047 () -> Turbine.getConfiguration().getInt(Navigation.CACHE_SIZE_KEY, 048 Navigation.CACHE_SIZE_DEFAULT)); 049 } 050 051 /** 052 * Attempts to load and execute the external Navigation. This is 053 * used when you want to execute a Navigation which returns its 054 * output via a MultiPartElement instead of out the data.getPage() 055 * value. This allows you to easily chain the execution of 056 * Navigation modules together. 057 * 058 * @param pipelineData Turbine information. 059 * @param name Name of object that will execute the navigation. 060 * @return the navigation module output 061 * @throws Exception a generic exception. 062 */ 063 public String eval(PipelineData pipelineData, String name) 064 throws Exception 065 { 066 // Execute Navigation 067 return getAssembler(name).build(pipelineData); 068 } 069 070 /** 071 * Attempts to load and execute the external Navigation. 072 * 073 * @param pipelineData Turbine information. 074 * @param name Name of object instance. 075 * @throws Exception a generic exception. 076 */ 077 @Override 078 public void exec(PipelineData pipelineData, String name) 079 throws Exception 080 { 081 this.eval(pipelineData, name); 082 } 083 084 /** 085 * The method through which this class is accessed. 086 * 087 * @return The single instance of this class. 088 */ 089 public static NavigationLoader getInstance() 090 { 091 return instance; 092 } 093}