content: /*
   * 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
   *
   *     https://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 org.apache.avro.reflect;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  import static org.junit.jupiter.api.Assertions.*;
  
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.math.BigInteger;
  import java.nio.ByteBuffer;
  import java.nio.channels.FileChannel;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Iterator;
  import org.apache.avro.Schema;
  import org.apache.avro.file.DataFileReader;
  import org.apache.avro.file.DataFileWriter;
  import org.apache.avro.file.FileReader;
  import org.apache.avro.file.SeekableByteArrayInput;
  import org.apache.avro.io.DatumWriter;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.api.io.TempDir;
  
  public class TestByteBuffer {
  
    @TempDir
    public File DIR;
  
    static class X {
      String name = "";
      ByteBuffer content;
    }
  
    File content;
  
    @BeforeEach
    public void before() throws IOException {
      content = new File(DIR.getPath(), "test-content");
      try (FileOutputStream out = new FileOutputStream(content)) {
        for (int i = 0; i < 100000; i++) {
          out.write("hello world\n".getBytes(UTF_8));
        }
      }
    }
  
    @Test
    void test() throws Exception {
      Schema schema = ReflectData.get().getSchema(X.class);
      ByteArrayOutputStream bout = new ByteArrayOutputStream();
      writeOneXAsAvro(schema, bout);
      X record = readOneXFromAvro(schema, bout);
  
      String expected = getmd5(content);
      String actual = getmd5(record.content);
      assertEquals(expected, actual, "md5 for result differed from input");
    }
  
    private X readOneXFromAvro(Schema schema, ByteArrayOutputStream bout) throws IOException {
      SeekableByteArrayInput input = new SeekableByteArrayInput(bout.toByteArray());
      ReflectDatumReader<X> datumReader = new ReflectDatumReader<>(schema);
      FileReader<X> reader = DataFileReader.openReader(input, datumReader);
      Iterator<X> it = reader.iterator();
      assertTrue(it.hasNext(), "missing first record");
      X record = it.next();
      assertFalse(it.hasNext(), "should be no more records - only wrote one out");
      return record;
    }
  
    private void writeOneXAsAvro(Schema schema, ByteArrayOutputStream bout) throws IOException, FileNotFoundException {
      DatumWriter<X> datumWriter = new ReflectDatumWriter<>(schema);
      try (DataFileWriter<X> writer = new DataFileWriter<>(datumWriter)) {
        writer.create(schema, bout);
        X x = new X();
        x.name = "xxx";
        try (FileInputStream fis = new FileInputStream(content)) {
          try (FileChannel channel = fis.getChannel()) {
            long contentLength = content.length();
            // set the content to be a file channel.
            ByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, contentLength);
            x.content = buffer;
            writer.append(x);
          }
        }
        writer.flush();
      }
    }
  
    private String getmd5(File content) throws Exception {
      try (FileInputStream fis = new FileInputStream(content)) {
        try (FileChannel channel = fis.getChannel()) {
          long contentLength = content.length();
          ByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, contentLength);
          return getmd5(buffer);
        }
      }
    }
  
    String getmd5(ByteBuffer buffer) throws NoSuchAlgorithmException {
      MessageDigest mdEnc = MessageDigest.getInstance("MD5");
      mdEnc.reset();
      mdEnc.update(buffer);
      return new BigInteger(1, mdEnc.digest()).toString(16);
    }
  }
  