jdk

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/*
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 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 */
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import java.io.*;
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import java.net.URI;
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import java.util.HashMap;
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import java.util.Map;
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import javax.tools.*;
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import static java.util.Collections.unmodifiableMap;
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/**
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 * class for storing source/byte code in memory.
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 */
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public class InMemoryFileManager extends ForwardingJavaFileManager {
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    private final Map<String, InMemoryJavaFile> classes = new HashMap<>();
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    public InMemoryFileManager(JavaFileManager fileManager) {
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        super(fileManager);
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    }
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    @Override
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    public JavaFileObject getJavaFileForOutput(Location location, String className, JavaFileObject.Kind kind, FileObject sibling) throws IOException {
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        InMemoryJavaFile javaFile = new InMemoryJavaFile(className);
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        classes.put(className, javaFile);
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        return javaFile;
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    }
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    @Override
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    public ClassLoader getClassLoader(Location location) {
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        return new ClassLoader(this.getClass().getClassLoader()) {
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            @Override
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            protected Class<?> findClass(String name) throws ClassNotFoundException {
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                InMemoryJavaFile classData = classes.get(name);
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                if (classData == null) throw new ClassNotFoundException(name);
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                byte[] byteCode = classData.bos.toByteArray();
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                return defineClass(name, byteCode, 0, byteCode.length);
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            }
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        };
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    }
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    public Map<String, ? extends JavaFileObject> getClasses() {
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        return unmodifiableMap(classes);
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    }
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    private static class InMemoryJavaFile extends SimpleJavaFileObject {
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        private final ByteArrayOutputStream bos =
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                new ByteArrayOutputStream();
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        protected InMemoryJavaFile(String name) {
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            super(URI.create("mfm:///" + name.replace('.', '/') + Kind.CLASS.extension), Kind.CLASS);
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        }
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        @Override
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        public OutputStream openOutputStream() throws IOException {
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            return bos;
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        }
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        @Override
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        public InputStream openInputStream() throws IOException {
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            return new ByteArrayInputStream(bos.toByteArray());
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        }
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    }
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}
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