1 /* 2 * Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Sun designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Sun in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 22 * CA 95054 USA or visit www.sun.com if you need additional information or 23 * have any questions. 24 */ 25 26 package javax.annotation.processing; 27 28 import javax.tools.JavaFileManager; 29 import javax.tools.*; 30 import javax.lang.model.element.Element; 31 import java.io.IOException; 32 33 /** 34 * This interface supports the creation of new files by an annotation 35 * processor. Files created in this way will be known to the 36 * annotation processing tool implementing this interface, better 37 * enabling the tool to manage them. Source and class files so 38 * created will be considered for processing by the tool after the 39 * {@code close} method has been called on the {@code Writer} or 40 * {@code OutputStream} used to write the contents of the file. 41 * 42 * Three kinds of files are distinguished: source files, class files, 43 * and auxiliary resource files. 44 * 45 * <p> There are two distinguished supported locations (subtrees 46 * within the logical file system) where newly created files are 47 * placed: one for {@linkplain 48 * javax.tools.StandardLocation#SOURCE_OUTPUT new source files}, and 49 * one for {@linkplain javax.tools.StandardLocation#CLASS_OUTPUT new 50 * class files}. (These might be specified on a tool's command line, 51 * for example, using flags such as {@code -s} and {@code -d}.) The 52 * actual locations for new source files and new class files may or 53 * may not be distinct on a particular run of the tool. Resource 54 * files may be created in either location. The methods for reading 55 * and writing resources take a relative name argument. A relative 56 * name is a non-null, non-empty sequence of path segments separated 57 * by {@code '/'}; {@code '.'} and {@code '..'} are invalid path 58 * segments. A valid relative name must match the 59 * "path-rootless" rule of <a 60 * href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986</a>, section 61 * 3.3. 62 * 63 * <p>The file creation methods take a variable number of arguments to 64 * allow the <em>originating elements</em> to be provided as hints to 65 * the tool infrastructure to better manage dependencies. The 66 * originating elements are the types or packages (representing {@code 67 * package-info} files) which caused an annotation processor to 68 * attempt to create a new file. For example, if an annotation 69 * processor tries to create a source file, {@code 70 * GeneratedFromUserSource}, in response to processing 71 * 72 * <blockquote><pre> 73 * @Generate 74 * public class UserSource {} 75 * </pre></blockquote> 76 * 77 * the type element for {@code UserSource} should be passed as part of 78 * the creation method call as in: 79 * 80 * <blockquote><pre> 81 * filer.createSourceFile("GeneratedFromUserSource", 82 * eltUtils.getTypeElement("UserSource")); 83 * </pre></blockquote> 84 * 85 * If there are no originating elements, none need to be passed. This 86 * information may be used in an incremental environment to determine 87 * the need to rerun processors or remove generated files. 88 * Non-incremental environments may ignore the originating element 89 * information. 90 * 91 * <p> During each run of an annotation processing tool, a file with a 92 * given pathname may be created only once. If that file already 93 * exists before the first attempt to create it, the old contents will 94 * be deleted. Any subsequent attempt to create the same file during 95 * a run will throw a {@link FilerException}, as will attempting to 96 * create both a class file and source file for the same type name or 97 * same package name. The {@linkplain Processor initial inputs} to 98 * the tool are considered to be created by the zeroth round; 99 * therefore, attempting to create a source or class file 100 * corresponding to one of those inputs will result in a {@link 101 * FilerException}. 102 * 103 * <p> In general, processors must not knowingly attempt to overwrite 104 * existing files that were not generated by some processor. A {@code 105 * Filer} may reject attempts to open a file corresponding to an 106 * existing type, like {@code java.lang.Object}. Likewise, the 107 * invoker of the annotation processing tool must not knowingly 108 * configure the tool such that the discovered processors will attempt 109 * to overwrite existing files that were not generated. 110 * 111 * <p> Processors can indicate a source or class file is generated by 112 * including an {@link javax.annotation.Generated @Generated} 113 * annotation. 114 * 115 * <p> Note that some of the effect of overwriting a file can be 116 * achieved by using a <i>decorator</i>-style pattern. Instead of 117 * modifying a class directly, the class is designed so that either 118 * its superclass is generated by annotation processing or subclasses 119 * of the class are generated by annotation processing. If the 120 * subclasses are generated, the parent class may be designed to use 121 * factories instead of public constructors so that only subclass 122 * instances would be presented to clients of the parent class. 123 * 124 * @author Joseph D. Darcy 125 * @author Scott Seligman 126 * @author Peter von der Ahé 127 * @since 1.6 128 */ 129 public interface Filer { 130 /** 131 * Creates a new source file and returns an object to allow 132 * writing to it. The file's name and path (relative to the 133 * {@linkplain StandardLocation#SOURCE_OUTPUT root output location 134 * for source files}) are based on the type to be declared in that 135 * file. If more than one type is being declared, the name of the 136 * principal top-level type (the public one, for example) should 137 * be used. A source file can also be created to hold information 138 * about a package, including package annotations. To create a 139 * source file for a named package, have {@code name} be the 140 * package's name followed by {@code ".package-info"}; to create a 141 * source file for an unnamed package, use {@code "package-info"}. 142 * 143 * <p> Note that to use a particular {@linkplain 144 * java.nio.charset.Charset charset} to encode the contents of the 145 * file, an {@code OutputStreamWriter} with the chosen charset can 146 * be created from the {@code OutputStream} from the returned 147 * object. If the {@code Writer} from the returned object is 148 * directly used for writing, its charset is determined by the 149 * implementation. An annotation processing tool may have an 150 * {@code -encoding} flag or analogous option for specifying this; 151 * otherwise, it will typically be the platform's default 152 * encoding. 153 * 154 * <p>To avoid subsequent errors, the contents of the source file 155 * should be compatible with the {@linkplain 156 * ProcessingEnvironment#getSourceVersion source version} being used 157 * for this run. 158 * 159 * @param name canonical (fully qualified) name of the principal type 160 * being declared in this file or a package name followed by 161 * {@code ".package-info"} for a package information file 162 * @param originatingElements type or package elements causally 163 * associated with the creation of this file, may be elided or 164 * {@code null} 165 * @return a {@code JavaFileObject} to write the new source file 166 * @throws FilerException if the same pathname has already been 167 * created, the same type has already been created, or the name is 168 * not valid for a type 169 * @throws IOException if the file cannot be created 170 */ 171 JavaFileObject createSourceFile(CharSequence name, 172 Element... originatingElements) throws IOException; 173 174 /** 175 * Creates a new class file, and returns an object to allow 176 * writing to it. The file's name and path (relative to the 177 * {@linkplain StandardLocation#CLASS_OUTPUT root output location 178 * for class files}) are based on the name of the type being 179 * written. A class file can also be created to hold information 180 * about a package, including package annotations. To create a 181 * class file for a named package, have {@code name} be the 182 * package's name followed by {@code ".package-info"}; creating a 183 * class file for an unnamed package is not supported. 184 * 185 * <p>To avoid subsequent errors, the contents of the class file 186 * should be compatible with the {@linkplain 187 * ProcessingEnvironment#getSourceVersion source version} being used 188 * for this run. 189 * 190 * @param name binary name of the type being written or a package name followed by 191 * {@code ".package-info"} for a package information file 192 * @param originatingElements type or package elements causally 193 * associated with the creation of this file, may be elided or 194 * {@code null} 195 * @return a {@code JavaFileObject} to write the new class file 196 * @throws FilerException if the same pathname has already been 197 * created, the same type has already been created, or the name is 198 * not valid for a type 199 * @throws IOException if the file cannot be created 200 */ 201 JavaFileObject createClassFile(CharSequence name, 202 Element... originatingElements) throws IOException; 203 204 /** 205 * Creates a new auxiliary resource file for writing and returns a 206 * file object for it. The file may be located along with the 207 * newly created source files, newly created binary files, or 208 * other supported location. The locations {@link 209 * StandardLocation#CLASS_OUTPUT CLASS_OUTPUT} and {@link 210 * StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must be 211 * supported. The resource may be named relative to some package 212 * (as are source and class files), and from there by a relative 213 * pathname. In a loose sense, the full pathname of the new file 214 * will be the concatenation of {@code location}, {@code pkg}, and 215 * {@code relativeName}. 216 * 217 * <p>Files created via this method are not registered for 218 * annotation processing, even if the full pathname of the file 219 * would correspond to the full pathname of a new source file 220 * or new class file. 221 * 222 * @param location location of the new file 223 * @param pkg package relative to which the file should be named, 224 * or the empty string if none 225 * @param relativeName final pathname components of the file 226 * @param originatingElements type or package elements causally 227 * associated with the creation of this file, may be elided or 228 * {@code null} 229 * @return a {@code FileObject} to write the new resource 230 * @throws IOException if the file cannot be created 231 * @throws FilerException if the same pathname has already been 232 * created 233 * @throws IllegalArgumentException for an unsupported location 234 * @throws IllegalArgumentException if {@code relativeName} is not relative 235 */ 236 FileObject createResource(JavaFileManager.Location location, 237 CharSequence pkg, 238 CharSequence relativeName, 239 Element... originatingElements) throws IOException; 240 241 /** 242 * Returns an object for reading an existing resource. The 243 * locations {@link StandardLocation#CLASS_OUTPUT CLASS_OUTPUT} 244 * and {@link StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must 245 * be supported. 246 * 247 * @param location location of the file 248 * @param pkg package relative to which the file should be searched, 249 * or the empty string if none 250 * @param relativeName final pathname components of the file 251 * @return an object to read the file 252 * @throws FilerException if the same pathname has already been 253 * opened for writing 254 * @throws IOException if the file cannot be opened 255 * @throws IllegalArgumentException for an unsupported location 256 * @throws IllegalArgumentException if {@code relativeName} is not relative 257 */ 258 FileObject getResource(JavaFileManager.Location location, 259 CharSequence pkg, 260 CharSequence relativeName) throws IOException; 261 }