copy Completely(URI input, URI output) : Copy « File « Java Tutorial

1. Java Tutorial
2. File
3. Copy

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;
import java.nio.channels.FileChannel;

/*
 * 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.    
 */

public class Main {


  public static void copyCompletely(URI input, URI output)
      throws IOException
  {
      try
      {
          InputStream in = null;
          try
          {
              File f = new File(input);
              if (f.exists())
                  in = new FileInputStream(f);
          }
          catch (Exception notAFile)
          {}
          
          File out = new File(output);
          File dir = out.getParentFile();
          dir.mkdirs();
          
          if (in == null)
              in = input.toURL().openStream();
              
          copyCompletely(in, new FileOutputStream(out));
      }
      catch (IllegalArgumentException e)
      {
          throw new IOException("Cannot copy to " + output);
      }
  }
  public static void copyCompletely(InputStream input, OutputStream output) throws IOException {
    // if both are file streams, use channel IO
    if ((output instanceof FileOutputStream) && (input instanceof FileInputStream)) {
      try {
        FileChannel target = ((FileOutputStream) output).getChannel();
        FileChannel source = ((FileInputStream) input).getChannel();

        source.transferTo(0, Integer.MAX_VALUE, target);

        source.close();
        target.close();

        return;
      } catch (Exception e) { /* failover to byte stream version */
      }
    }

    byte[] buf = new byte[8192];
    while (true) {
      int length = input.read(buf);
      if (length < 0)
        break;
      output.write(buf, 0, length);
    }

    try {
      input.close();
    } catch (IOException ignore) {
    }
    try {
      output.close();
    } catch (IOException ignore) {
    }
  }
}