1 package org.apache.turbine.modules.screens; 2 3 /* 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, 15 * software distributed under the License is distributed on an 16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 17 * KIND, either express or implied. See the License for the 18 * specific language governing permissions and limitations 19 * under the License. 20 */ 21 22 23 // Turbine stuff. 24 25 import org.apache.turbine.modules.Screen; 26 import org.apache.turbine.pipeline.PipelineData; 27 import org.apache.turbine.util.RunData; 28 29 /** 30 * Base class for writing Screens that output binary data. This class 31 * is provided as a helper class for those who want to write Screens 32 * that output raw binary data. For example, it may be extended into 33 * a Screen that outputs a SVG file or a SWF (Flash Player format) 34 * movie. The only thing one has to do is to implement the two 35 * methods <code>getContentType(PipelineData data)</code> and 36 * <code>doOutput(PipelineData data)</code> (see below). 37 * 38 * <p> You might want to take a look at the ImageServer screen class 39 * contained in the TDK.<br> 40 * 41 * @author <a href="mailto:rkoenig@chez.com">Regis Koenig</a> 42 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 43 * @version $Id$ 44 */ 45 public abstract class RawScreen implements Screen 46 { 47 /** 48 * Build the Screen. This method actually makes a call to the 49 * doOutput() method in order to generate the Screen content. 50 * 51 * @param pipelineData Turbine information. 52 * @return A ConcreteElement. 53 * @throws Exception a generic exception. 54 */ 55 @Override 56 public final String doBuild(PipelineData pipelineData) 57 throws Exception 58 { 59 RunData data = pipelineData.getRunData(); 60 data.getResponse().setContentType(getContentType(pipelineData)); 61 data.declareDirectResponse(); 62 doOutput(pipelineData); 63 return null; 64 } 65 66 /** 67 * Set the content type. This method should be overridden to 68 * actually set the real content-type header of the output. 69 * 70 * @param pipelineData Turbine information. 71 * @return A String with the content type. 72 */ 73 protected abstract String getContentType(PipelineData pipelineData); 74 75 /** 76 * Actually output the dynamic content. The OutputStream can be 77 * accessed like this: <pre>OutputStream out = 78 * data.getResponse().getOutputStream();</pre>. 79 * 80 * @param pipelineData Turbine information. 81 * @throws Exception a generic exception. 82 */ 83 protected abstract void doOutput(PipelineData pipelineData) throws Exception; 84 85 /** 86 * The layout must be set to null. 87 * 88 * @param pipelineData Turbine information. 89 * @return A null String. 90 */ 91 @Override 92 public final String getLayout(PipelineData pipelineData) 93 { 94 return null; 95 } 96 }