java-local/src/main/java/openwhisk/java/local/MemoryFileManager.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package openwhisk.java.local;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.HashMap;
import java.util.Map;

import javax.tools.FileObject;
import javax.tools.ForwardingJavaFileManager;
import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import javax.tools.SimpleJavaFileObject;

/**
 * Keeps compiled class in memory
 *
 */
public class MemoryFileManager extends ForwardingJavaFileManager<JavaFileManager> {
  private final Map<String, ByteArrayOutputStream> compiledClasses = new HashMap<>();

  public MemoryFileManager(ClassLoader classLoader, JavaFileManager fileManager) {
    super(fileManager);
  }

  @Override
  public JavaFileObject getJavaFileForOutput(Location location, final String className,
                                             JavaFileObject.Kind kind, FileObject sibling) throws IOException {
    try {
      return new SimpleJavaFileObject(new URI(""), kind) {
        public OutputStream openOutputStream() throws IOException {
          ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
          compiledClasses.put(className, outputStream);
          return outputStream;
        }
      };
    } catch (URISyntaxException e) {
      throw new RuntimeException(e);
    }
  }

  public byte[] getCompiledClass(String name) {
    ByteArrayOutputStream bytes = compiledClasses.get(name);
    if (bytes == null) {
      return null;
    }
    return bytes.toByteArray();
  }
}