Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright 2005-2006 Sun Microsystems, Inc.  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.  Sun designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  */

 package javax.tools;

 import java.io.File;

 import java.net.URL;

 import java.net.URLClassLoader;

 import java.net.MalformedURLException;

 import java.util.Locale;

 import java.util.logging.Logger;

 import java.util.logging.Level;

 import static java.util.logging.Level.*;

 /**

  * Provides methods for locating tool providers, for example,

  * providers of compilers.  This class complements the

  * functionality of {@link java.util.ServiceLoader}.

  *

  * @author Peter von der Ahé

  * @since 1.6

  */

 public class ToolProvider {

     private ToolProvider() {}

     private static final String propertyName = "sun.tools.ToolProvider";

     private static final String loggerName   = "javax.tools";

     /*

      * Define the system property "sun.tools.ToolProvider" to enable

      * debugging:

      *

      *     java ... -Dsun.tools.ToolProvider ...

      */

     static <T> T trace(Level level, Object reason) {

         // NOTE: do not make this method private as it affects stack traces

         try {

             if (System.getProperty(propertyName) != null) {

                 StackTraceElement[] st = Thread.currentThread().getStackTrace();

                 String method = "???";

                 String cls = ToolProvider.class.getName();

                 if (st.length > 2) {

                     StackTraceElement frame = st[2];

                     method = String.format((Locale)null, "%s(%s:%s)",

                                            frame.getMethodName(),

                                            frame.getFileName(),

                                            frame.getLineNumber());

                     cls = frame.getClassName();

                 }

                 Logger logger = Logger.getLogger(loggerName);

                 if (reason instanceof Throwable) {

                     logger.logp(level, cls, method,

                                 reason.getClass().getName(), (Throwable)reason);

                 } else {

                     logger.logp(level, cls, method, String.valueOf(reason));

                 }

             }

         } catch (SecurityException ex) {

             System.err.format((Locale)null, "%s: %s; %s%n",

                               ToolProvider.class.getName(),

                               reason,

                               ex.getLocalizedMessage());

         }

         return null;

     }

     /**

      * Gets the Java™ programming language compiler provided

      * with this platform.

      * @return the compiler provided with this platform or

      * {@code null} if no compiler is provided

      */

     public static JavaCompiler getSystemJavaCompiler() {

         if (Lazy.compilerClass == null)

             return trace(WARNING, "Lazy.compilerClass == null");

         try {

             return Lazy.compilerClass.newInstance();

         } catch (Throwable e) {

             return trace(WARNING, e);

         }

     }

     /**

      * Returns the class loader for tools provided with this platform.

      * This does not include user-installed tools.  Use the

      * {@linkplain java.util.ServiceLoader service provider mechanism}

      * for locating user installed tools.

      *

      * @return the class loader for tools provided with this platform

      * or {@code null} if no tools are provided

      */

     public static ClassLoader getSystemToolClassLoader() {

         if (Lazy.compilerClass == null)

             return trace(WARNING, "Lazy.compilerClass == null");

         return Lazy.compilerClass.getClassLoader();

     }

     /**

      * This class will not be initialized until one of the above

      * methods are called.  This ensures that searching for the

      * compiler does not affect platform start up.

      */

     static class Lazy  {

         private static final String defaultJavaCompilerName

             = "com.sun.tools.javac.api.JavacTool";

         private static final String[] defaultToolsLocation

             = { "lib", "tools.jar" };

         static final Class<? extends JavaCompiler> compilerClass;

         static {

             Class<? extends JavaCompiler> c = null;

             try {

                 c = findClass().asSubclass(JavaCompiler.class);

             } catch (Throwable t) {

                 trace(WARNING, t);

             }

             compilerClass = c;

         }

         private static Class<?> findClass()

             throws MalformedURLException, ClassNotFoundException

         {

             try {

                 return enableAsserts(Class.forName(defaultJavaCompilerName, false, null));

             } catch (ClassNotFoundException e) {

                 trace(FINE, e);

             }

             File file = new File(System.getProperty("java.home"));

             if (file.getName().equalsIgnoreCase("jre"))

                 file = file.getParentFile();

             for (String name : defaultToolsLocation)

                 file = new File(file, name);

             URL[] urls = {file.toURI().toURL()};

             trace(FINE, urls[0].toString());

             ClassLoader cl = URLClassLoader.newInstance(urls);

             cl.setPackageAssertionStatus("com.sun.tools.javac", true);

             return Class.forName(defaultJavaCompilerName, false, cl);

         }

         private static Class<?> enableAsserts(Class<?> cls) {

             try {

                 ClassLoader loader = cls.getClassLoader();

                 if (loader != null)

                     loader.setPackageAssertionStatus("com.sun.tools.javac", true);

                 else

                     trace(FINE, "loader == null");

             } catch (SecurityException ex) {

                 trace(FINE, ex);

             }

             return cls;

         }

     }

 }