1 package org.apache.turbine.modules; 2 3 4 /* 5 * Licensed to the Apache Software Foundation (ASF) under one 6 * or more contributor license agreements. See the NOTICE file 7 * distributed with this work for additional information 8 * regarding copyright ownership. The ASF licenses this file 9 * to you under the Apache License, Version 2.0 (the 10 * "License"); you may not use this file except in compliance 11 * with the License. You may obtain a copy of the License at 12 * 13 * http://www.apache.org/licenses/LICENSE-2.0 14 * 15 * Unless required by applicable law or agreed to in writing, 16 * software distributed under the License is distributed on an 17 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 18 * KIND, either express or implied. See the License for the 19 * specific language governing permissions and limitations 20 * under the License. 21 */ 22 23 24 import org.apache.turbine.Turbine; 25 import org.apache.turbine.pipeline.PipelineData; 26 27 /** 28 * The purpose of this class is to allow one to load and execute 29 * Screen modules. 30 * 31 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a> 32 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> 33 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 34 * @version $Id$ 35 */ 36 public class ScreenLoader 37 extends GenericLoader<Screen> 38 { 39 /** The single instance of this class. */ 40 private static ScreenLoader instance = new ScreenLoader(); 41 42 /** 43 * These ctor's are private to force clients to use getInstance() 44 * to access this class. 45 */ 46 private ScreenLoader() 47 { 48 super(Screen.class, 49 () -> Turbine.getConfiguration().getInt(Screen.CACHE_SIZE_KEY, 50 Screen.CACHE_SIZE_DEFAULT)); 51 } 52 53 /** 54 * Attempts to load and execute the external Screen. This is used 55 * when you want to execute a Screen which returns its output via 56 * a String instead of out the data.getResponse() value. 57 * This allows you to easily chain the execution of Screen modules 58 * together. 59 * 60 * @param pipelineData Turbine information. 61 * @param name Name of object that will execute the screen. 62 * @return the output of the screen module 63 * @throws Exception a generic exception. 64 */ 65 public String eval(PipelineData pipelineData, String name) 66 throws Exception 67 { 68 // Execute screen 69 return getAssembler(name).build(pipelineData); 70 } 71 72 /** 73 * Attempts to load and execute the Screen. This is used when you 74 * want to execute a Screen which returns its output via the 75 * data.getResponse() object. 76 * 77 * @param pipelineData Turbine information. 78 * @param name Name of object that will execute the screen. 79 * @throws Exception a generic exception. 80 */ 81 @Override 82 public void exec(PipelineData pipelineData, String name) 83 throws Exception 84 { 85 this.eval(pipelineData, name); 86 } 87 88 /** 89 * The method through which this class is accessed. 90 * 91 * @return The single instance of this class. 92 */ 93 public static ScreenLoader getInstance() 94 { 95 return instance; 96 } 97 }