001package org.apache.turbine.modules; 002 003 004/* 005 * Licensed to the Apache Software Foundation (ASF) under one 006 * or more contributor license agreements. See the NOTICE file 007 * distributed with this work for additional information 008 * regarding copyright ownership. The ASF licenses this file 009 * to you under the Apache License, Version 2.0 (the 010 * "License"); you may not use this file except in compliance 011 * with the License. You may obtain a copy of the License at 012 * 013 * http://www.apache.org/licenses/LICENSE-2.0 014 * 015 * Unless required by applicable law or agreed to in writing, 016 * software distributed under the License is distributed on an 017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 018 * KIND, either express or implied. See the License for the 019 * specific language governing permissions and limitations 020 * under the License. 021 */ 022 023 024import org.apache.turbine.Turbine; 025import org.apache.turbine.pipeline.PipelineData; 026 027/** 028 * The purpose of this class is to allow one to load and execute 029 * Screen modules. 030 * 031 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a> 032 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> 033 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 034 * @version $Id: ScreenLoader.java 1773378 2016-12-09 13:19:59Z tv $ 035 */ 036public class ScreenLoader 037 extends GenericLoader<Screen> 038 implements Loader<Screen> 039{ 040 /** The single instance of this class. */ 041 private static ScreenLoader instance = new ScreenLoader(); 042 043 /** 044 * These ctor's are private to force clients to use getInstance() 045 * to access this class. 046 */ 047 private ScreenLoader() 048 { 049 super(); 050 } 051 052 /** 053 * Attempts to load and execute the external Screen. This is used 054 * when you want to execute a Screen which returns its output via 055 * a String instead of out the data.getResponse() value. 056 * This allows you to easily chain the execution of Screen modules 057 * together. 058 * 059 * @param pipelineData Turbine information. 060 * @param name Name of object that will execute the screen. 061 * @return the output of the screen module 062 * @throws Exception a generic exception. 063 */ 064 public String eval(PipelineData pipelineData, String name) 065 throws Exception 066 { 067 // Execute screen 068 return getAssembler(name).build(pipelineData); 069 } 070 071 /** 072 * Attempts to load and execute the Screen. This is used when you 073 * want to execute a Screen which returns its output via the 074 * data.getResponse() object. 075 * 076 * @param pipelineData Turbine information. 077 * @param name Name of object that will execute the screen. 078 * @throws Exception a generic exception. 079 */ 080 @Override 081 public void exec(PipelineData pipelineData, String name) 082 throws Exception 083 { 084 this.eval(pipelineData, name); 085 } 086 087 /** 088 * Pulls out an instance of the object by name. Name is just the 089 * single name of the object. 090 * 091 * @param name Name of object instance. 092 * @return A Screen with the specified name, or null. 093 * @throws Exception a generic exception. 094 */ 095 @Override 096 public Screen getAssembler(String name) 097 throws Exception 098 { 099 return getAssembler(Screen.class, name); 100 } 101 102 /** 103 * @see org.apache.turbine.modules.Loader#getCacheSize() 104 */ 105 @Override 106 public int getCacheSize() 107 { 108 return ScreenLoader.getConfiguredCacheSize(); 109 } 110 111 /** 112 * The method through which this class is accessed. 113 * 114 * @return The single instance of this class. 115 */ 116 public static ScreenLoader getInstance() 117 { 118 return instance; 119 } 120 121 /** 122 * Helper method to get the configured cache size for this module 123 * 124 * @return the configure cache size 125 */ 126 private static int getConfiguredCacheSize() 127 { 128 return Turbine.getConfiguration().getInt(Screen.CACHE_SIZE_KEY, 129 Screen.CACHE_SIZE_DEFAULT); 130 } 131}