001 /* ImageInputStreamSpi.java -- Service provider for image input streams. 002 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package javax.imageio.spi; 040 041 import java.io.File; 042 import java.io.IOException; 043 044 import javax.imageio.stream.ImageInputStream; 045 046 /** 047 * An abstract superclass for service providers that create 048 * {@linkplain javax.imageio.stream.ImageInputStream image input 049 * streams} for a file, URL, byte array or any other source. 050 * 051 * @since 1.4 052 * 053 * @author Sascha Brawer (brawer@dandelis.ch) 054 */ 055 public abstract class ImageInputStreamSpi 056 extends IIOServiceProvider 057 { 058 /** 059 * Indicates which kind of input is processable by the streams 060 * created by {@link #createInputStreamInstance(Object)}. 061 */ 062 protected Class<?> inputClass; 063 064 065 /** 066 * Constructs a service provider for image input streams, given no 067 * parameters. It is up to the sub-class to set {@link #vendorName}, 068 * {@link #version} and {@link #inputClass} to non-null values. 069 */ 070 protected ImageInputStreamSpi() 071 { 072 } 073 074 075 /** 076 * Constructs a service provider for image input streams, given the 077 * vendor name and a version string. 078 * 079 * @throws IllegalArgumentException if <code>vendorName</code> 080 * or <code>version</code> is <code>null</code>. 081 */ 082 public ImageInputStreamSpi(String vendorName, String version, 083 Class<?> inputClass) 084 { 085 super(vendorName, version); 086 this.inputClass = inputClass; 087 } 088 089 090 /** 091 * Determines which kind of input is processable by the streams 092 * created by {@link #createInputStreamInstance(Object)}. 093 */ 094 public Class<?> getInputClass() 095 { 096 return inputClass; 097 } 098 099 100 /** 101 * Determines whether <code>ImageInputStreams</code> created 102 * by this service provider benefit from using a cache file. 103 * 104 * <p>The default behavior is to return <code>false</code>. 105 * 106 * @return <code>true</code> if the created streams are faster or 107 * need less memory when a cache file is being used; 108 * <code>false</code> if no positive effect results from the cache 109 * file. 110 */ 111 public boolean canUseCacheFile() 112 { 113 return false; 114 } 115 116 117 /** 118 * Determines whether <code>ImageInputStreams</code> created 119 * by this service provider require the use of a cache file. 120 * 121 * <p>The default behavior is to return <code>false</code>. 122 * 123 * @return <code>true</code> if the created streams can only work 124 * when a cache file is being used; <code>false</code> if no cache 125 * file is needed. 126 */ 127 public boolean needsCacheFile() 128 { 129 return false; 130 } 131 132 133 public abstract ImageInputStream createInputStreamInstance(Object input, 134 boolean useCache, 135 File cacheDir) 136 throws IOException; 137 138 139 public ImageInputStream createInputStreamInstance(Object input) 140 throws IOException 141 { 142 return createInputStreamInstance(input, canUseCacheFile(), null); 143 } 144 }