Java tutorial
/* * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.tools; import java.io.Writer; import java.nio.charset.Charset; import java.util.Locale; import java.util.concurrent.Callable; import javax.annotation.processing.Processor; /** * Interface to invoke Java™ programming language compilers from * programs. * * <p>The compiler might generate diagnostics during compilation (for * example, error messages). If a diagnostic listener is provided, * the diagnostics will be supplied to the listener. If no listener * is provided, the diagnostics will be formatted in an unspecified * format and written to the default output, which is {@code * System.err} unless otherwise specified. Even if a diagnostic * listener is supplied, some diagnostics might not fit in a {@code * Diagnostic} and will be written to the default output. * * <p>A compiler tool has an associated standard file manager, which * is the file manager that is native to the tool (or built-in). The * standard file manager can be obtained by calling {@linkplain * #getStandardFileManager getStandardFileManager}. * * <p>A compiler tool must function with any file manager as long as * any additional requirements as detailed in the methods below are * met. If no file manager is provided, the compiler tool will use a * standard file manager such as the one returned by {@linkplain * #getStandardFileManager getStandardFileManager}. * * <p>An instance implementing this interface must conform to * <cite>The Java™ Language Specification</cite> * and generate class files conforming to * <cite>The Java™ Virtual Machine Specification</cite>. * The versions of these * specifications are defined in the {@linkplain Tool} interface. * * Additionally, an instance of this interface supporting {@link * javax.lang.model.SourceVersion#RELEASE_6 SourceVersion.RELEASE_6} * or higher must also support {@linkplain javax.annotation.processing * annotation processing}. * * <p>The compiler relies on two services: {@linkplain * DiagnosticListener diagnostic listener} and {@linkplain * JavaFileManager file manager}. Although most classes and * interfaces in this package defines an API for compilers (and * tools in general) the interfaces {@linkplain DiagnosticListener}, * {@linkplain JavaFileManager}, {@linkplain FileObject}, and * {@linkplain JavaFileObject} are not intended to be used in * applications. Instead these interfaces are intended to be * implemented and used to provide customized services for a * compiler and thus defines an SPI for compilers. * * <p>There are a number of classes and interfaces in this package * which are designed to ease the implementation of the SPI to * customize the behavior of a compiler: * * <dl> * <dt>{@link StandardJavaFileManager}</dt> * <dd> * * Every compiler which implements this interface provides a * standard file manager for operating on regular {@linkplain * java.io.File files}. The StandardJavaFileManager interface * defines additional methods for creating file objects from * regular files. * * <p>The standard file manager serves two purposes: * * <ul> * <li>basic building block for customizing how a compiler reads * and writes files</li> * <li>sharing between multiple compilation tasks</li> * </ul> * * <p>Reusing a file manager can potentially reduce overhead of * scanning the file system and reading jar files. Although there * might be no reduction in overhead, a standard file manager must * work with multiple sequential compilations making the following * example a recommended coding pattern: * * <pre> * File[] files1 = ... ; // input for first compilation task * File[] files2 = ... ; // input for second compilation task * * JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); * StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null); * * {@code Iterable<? extends JavaFileObject>} compilationUnits1 = * fileManager.getJavaFileObjectsFromFiles({@linkplain java.util.Arrays#asList Arrays.asList}(files1)); * compiler.getTask(null, fileManager, null, null, null, compilationUnits1).call(); * * {@code Iterable<? extends JavaFileObject>} compilationUnits2 = * fileManager.getJavaFileObjects(files2); // use alternative method * // reuse the same file manager to allow caching of jar files * compiler.getTask(null, fileManager, null, null, null, compilationUnits2).call(); * * fileManager.close();</pre> * * </dd> * * <dt>{@link DiagnosticCollector}</dt> * <dd> * Used to collect diagnostics in a list, for example: * <pre> * {@code Iterable<? extends JavaFileObject>} compilationUnits = ...; * JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); * {@code DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();} * StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null); * compiler.getTask(null, fileManager, diagnostics, null, null, compilationUnits).call(); * * for ({@code Diagnostic<? extends JavaFileObject>} diagnostic : diagnostics.getDiagnostics()) * System.out.format("Error on line %d in %s%n", * diagnostic.getLineNumber(), * diagnostic.getSource().toUri()); * * fileManager.close();</pre> * </dd> * * <dt> * {@link ForwardingJavaFileManager}, {@link ForwardingFileObject}, and * {@link ForwardingJavaFileObject} * </dt> * <dd> * * Subclassing is not available for overriding the behavior of a * standard file manager as it is created by calling a method on a * compiler, not by invoking a constructor. Instead forwarding * (or delegation) should be used. These classes makes it easy to * forward most calls to a given file manager or file object while * allowing customizing behavior. For example, consider how to * log all calls to {@linkplain JavaFileManager#flush}: * * <pre> * final Logger logger = ...; * {@code Iterable<? extends JavaFileObject>} compilationUnits = ...; * JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); * StandardJavaFileManager stdFileManager = compiler.getStandardFileManager(null, null, null); * JavaFileManager fileManager = new ForwardingJavaFileManager(stdFileManager) { * public void flush() throws IOException { * logger.entering(StandardJavaFileManager.class.getName(), "flush"); * super.flush(); * logger.exiting(StandardJavaFileManager.class.getName(), "flush"); * } * }; * compiler.getTask(null, fileManager, null, null, null, compilationUnits).call();</pre> * </dd> * * <dt>{@link SimpleJavaFileObject}</dt> * <dd> * * This class provides a basic file object implementation which * can be used as building block for creating file objects. For * example, here is how to define a file object which represent * source code stored in a string: * * <pre> * /** * * A file object used to represent source coming from a string. * {@code *}/ * public class JavaSourceFromString extends SimpleJavaFileObject { * /** * * The source code of this "file". * {@code *}/ * final String code; * * /** * * Constructs a new JavaSourceFromString. * * {@code @}param name the name of the compilation unit represented by this file object * * {@code @}param code the source code for the compilation unit represented by this file object * {@code *}/ * JavaSourceFromString(String name, String code) { * super({@linkplain java.net.URI#create URI.create}("string:///" + name.replace('.','/') + Kind.SOURCE.extension), * Kind.SOURCE); * this.code = code; * } * * {@code @}Override * public CharSequence getCharContent(boolean ignoreEncodingErrors) { * return code; * } * }</pre> * </dd> * </dl> * * @author Peter von der Ahé * @author Jonathan Gibbons * @see DiagnosticListener * @see Diagnostic * @see JavaFileManager * @since 1.6 */ public interface JavaCompiler extends Tool, OptionChecker { /** * Creates a future for a compilation task with the given * components and arguments. The compilation might not have * completed as described in the CompilationTask interface. * * <p>If a file manager is provided, it must be able to handle all * locations defined in {@link StandardLocation}. * * <p>Note that annotation processing can process both the * compilation units of source code to be compiled, passed with * the {@code compilationUnits} parameter, as well as class * files, whose names are passed with the {@code classes} * parameter. * * @param out a Writer for additional output from the compiler; * use {@code System.err} if {@code null} * @param fileManager a file manager; if {@code null} use the * compiler's standard filemanager * @param diagnosticListener a diagnostic listener; if {@code * null} use the compiler's default method for reporting * diagnostics * @param options compiler options, {@code null} means no options * @param classes names of classes to be processed by annotation * processing, {@code null} means no class names * @param compilationUnits the compilation units to compile, {@code * null} means no compilation units * @return an object representing the compilation * @throws RuntimeException if an unrecoverable error * occurred in a user supplied component. The * {@linkplain Throwable#getCause() cause} will be the error in * user code. * @throws IllegalArgumentException if any of the options are invalid, * or if any of the given compilation units are of other kind than * {@linkplain JavaFileObject.Kind#SOURCE source} */ CompilationTask getTask(Writer out, JavaFileManager fileManager, DiagnosticListener<? super JavaFileObject> diagnosticListener, Iterable<String> options, Iterable<String> classes, Iterable<? extends JavaFileObject> compilationUnits); /** * Returns a new instance of the standard file manager implementation * for this tool. The file manager will use the given diagnostic * listener for producing any non-fatal diagnostics. Fatal errors * will be signaled with the appropriate exceptions. * * <p>The standard file manager will be automatically reopened if * it is accessed after calls to {@code flush} or {@code close}. * The standard file manager must be usable with other tools. * * @param diagnosticListener a diagnostic listener for non-fatal * diagnostics; if {@code null} use the compiler's default method * for reporting diagnostics * @param locale the locale to apply when formatting diagnostics; * {@code null} means the {@linkplain Locale#getDefault() default locale}. * @param charset the character set used for decoding bytes; if * {@code null} use the platform default * @return the standard file manager */ StandardJavaFileManager getStandardFileManager(DiagnosticListener<? super JavaFileObject> diagnosticListener, Locale locale, Charset charset); /** * Interface representing a future for a compilation task. The * compilation task has not yet started. To start the task, call * the {@linkplain #call call} method. * * <p>Before calling the call method, additional aspects of the * task can be configured, for example, by calling the * {@linkplain #setProcessors setProcessors} method. */ interface CompilationTask extends Callable<Boolean> { /** * Adds root modules to be taken into account during module * resolution. * Invalid module names may cause either * {@code IllegalArgumentException} to be thrown, * or diagnostics to be reported when the task is started. * @param moduleNames the names of the root modules * @throws IllegalArgumentException may be thrown for some * invalid module names * @throws IllegalStateException if the task has started * @since 9 */ void addModules(Iterable<String> moduleNames); /** * Sets processors (for annotation processing). This will * bypass the normal discovery mechanism. * * @param processors processors (for annotation processing) * @throws IllegalStateException if the task has started */ void setProcessors(Iterable<? extends Processor> processors); /** * Sets the locale to be applied when formatting diagnostics and * other localized data. * * @param locale the locale to apply; {@code null} means apply no * locale * @throws IllegalStateException if the task has started */ void setLocale(Locale locale); /** * Performs this compilation task. The compilation may only * be performed once. Subsequent calls to this method throw * IllegalStateException. * * @return true if and only all the files compiled without errors; * false otherwise * * @throws RuntimeException if an unrecoverable error occurred * in a user-supplied component. The * {@linkplain Throwable#getCause() cause} will be the error * in user code. * @throws IllegalStateException if called more than once */ @Override Boolean call(); } }