import org.apache.hadoop.io.compress.zlib.ZlibCompressor; //导入依赖的package包/类
/**
 * Method for compressor availability check
 */
private static <T extends Compressor, E extends Decompressor> boolean isAvailable(TesterPair<T, E> pair) {
  Compressor compressor = pair.compressor;

  if (compressor.getClass().isAssignableFrom(Lz4Compressor.class)
          && (NativeCodeLoader.isNativeCodeLoaded()))
    return true;

  else if (compressor.getClass().isAssignableFrom(BuiltInZlibDeflater.class)
          && NativeCodeLoader.isNativeCodeLoaded())
    return true;

  else if (compressor.getClass().isAssignableFrom(ZlibCompressor.class)) {
    return ZlibFactory.isNativeZlibLoaded(new Configuration());
  }              
  else if (compressor.getClass().isAssignableFrom(SnappyCompressor.class)
          && isNativeSnappyLoadable())
    return true;
  
  return false;      
}
 

import org.apache.hadoop.io.compress.zlib.ZlibCompressor; //导入依赖的package包/类
private void testGzipCodecWrite(boolean useNative) throws IOException {
  // Create a gzipped file using a compressor from the CodecPool,
  // and try to read it back via the regular GZIPInputStream.

  // Use native libs per the parameter
  Configuration conf = new Configuration();
  if (useNative) {
    assumeTrue(ZlibFactory.isNativeZlibLoaded(conf));
  } else {
    assertFalse("ZlibFactory is using native libs against request",
        ZlibFactory.isNativeZlibLoaded(conf));
  }

  // Ensure that the CodecPool has a BuiltInZlibDeflater in it.
  Compressor zlibCompressor = ZlibFactory.getZlibCompressor(conf);
  assertNotNull("zlibCompressor is null!", zlibCompressor);
  assertTrue("ZlibFactory returned unexpected deflator",
        useNative ? zlibCompressor instanceof ZlibCompressor
                  : zlibCompressor instanceof BuiltInZlibDeflater);

  CodecPool.returnCompressor(zlibCompressor);

  // Create a GZIP text file via the Compressor interface.
  CompressionCodecFactory ccf = new CompressionCodecFactory(conf);
  CompressionCodec codec = ccf.getCodec(new Path("foo.gz"));
  assertTrue("Codec for .gz file is not GzipCodec", 
             codec instanceof GzipCodec);

  final String msg = "This is the message we are going to compress.";
  final String tmpDir = System.getProperty("test.build.data", "/tmp/");
  final String fileName = new Path(new Path(tmpDir),
      "testGzipCodecWrite.txt.gz").toString();

  BufferedWriter w = null;
  Compressor gzipCompressor = CodecPool.getCompressor(codec);
  if (null != gzipCompressor) {
    // If it gives us back a Compressor, we should be able to use this
    // to write files we can then read back with Java's gzip tools.
    OutputStream os = new CompressorStream(new FileOutputStream(fileName),
        gzipCompressor);
    w = new BufferedWriter(new OutputStreamWriter(os));
    w.write(msg);
    w.close();
    CodecPool.returnCompressor(gzipCompressor);

    verifyGzipFile(fileName, msg);
  }

  // Create a gzip text file via codec.getOutputStream().
  w = new BufferedWriter(new OutputStreamWriter(
      codec.createOutputStream(new FileOutputStream(fileName))));
  w.write(msg);
  w.close();

  verifyGzipFile(fileName, msg);
}
 

import org.apache.hadoop.io.compress.zlib.ZlibCompressor; //导入依赖的package包/类
public void testGzipCodecWrite(boolean useNative) throws IOException {
  // Create a gzipped file using a compressor from the CodecPool,
  // and try to read it back via the regular GZIPInputStream.

  // Use native libs per the parameter
  Configuration conf = new Configuration();
  conf.setBoolean(CommonConfigurationKeys.IO_NATIVE_LIB_AVAILABLE_KEY, useNative);
  if (useNative) {
    if (!ZlibFactory.isNativeZlibLoaded(conf)) {
      LOG.warn("testGzipCodecWrite skipped: native libs not loaded");
      return;
    }
  } else {
    assertFalse("ZlibFactory is using native libs against request",
        ZlibFactory.isNativeZlibLoaded(conf));
  }

  // Ensure that the CodecPool has a BuiltInZlibDeflater in it.
  Compressor zlibCompressor = ZlibFactory.getZlibCompressor(conf);
  assertNotNull("zlibCompressor is null!", zlibCompressor);
  assertTrue("ZlibFactory returned unexpected deflator",
        useNative ? zlibCompressor instanceof ZlibCompressor
                  : zlibCompressor instanceof BuiltInZlibDeflater);

  CodecPool.returnCompressor(zlibCompressor);

  // Create a GZIP text file via the Compressor interface.
  CompressionCodecFactory ccf = new CompressionCodecFactory(conf);
  CompressionCodec codec = ccf.getCodec(new Path("foo.gz"));
  assertTrue("Codec for .gz file is not GzipCodec", 
             codec instanceof GzipCodec);

  final String msg = "This is the message we are going to compress.";
  final String tmpDir = System.getProperty("test.build.data", "/tmp/");
  final String fileName = new Path(new Path(tmpDir),
      "testGzipCodecWrite.txt.gz").toString();

  BufferedWriter w = null;
  Compressor gzipCompressor = CodecPool.getCompressor(codec);
  if (null != gzipCompressor) {
    // If it gives us back a Compressor, we should be able to use this
    // to write files we can then read back with Java's gzip tools.
    OutputStream os = new CompressorStream(new FileOutputStream(fileName),
        gzipCompressor);
    w = new BufferedWriter(new OutputStreamWriter(os));
    w.write(msg);
    w.close();
    CodecPool.returnCompressor(gzipCompressor);

    verifyGzipFile(fileName, msg);
  }

  // Create a gzip text file via codec.getOutputStream().
  w = new BufferedWriter(new OutputStreamWriter(
      codec.createOutputStream(new FileOutputStream(fileName))));
  w.write(msg);
  w.close();

  verifyGzipFile(fileName, msg);
}
 

import org.apache.hadoop.io.compress.zlib.ZlibCompressor; //导入依赖的package包/类
private void testGzipCodecWrite(boolean useNative) throws IOException {
  // Create a gzipped file using a compressor from the CodecPool,
  // and try to read it back via the regular GZIPInputStream.

  // Use native libs per the parameter
  Configuration conf = new Configuration();
  conf.setBoolean(CommonConfigurationKeys.IO_NATIVE_LIB_AVAILABLE_KEY, useNative);
  if (useNative) {
    if (!ZlibFactory.isNativeZlibLoaded(conf)) {
      LOG.warn("testGzipCodecWrite skipped: native libs not loaded");
      return;
    }
  } else {
    assertFalse("ZlibFactory is using native libs against request",
        ZlibFactory.isNativeZlibLoaded(conf));
  }

  // Ensure that the CodecPool has a BuiltInZlibDeflater in it.
  Compressor zlibCompressor = ZlibFactory.getZlibCompressor(conf);
  assertNotNull("zlibCompressor is null!", zlibCompressor);
  assertTrue("ZlibFactory returned unexpected deflator",
        useNative ? zlibCompressor instanceof ZlibCompressor
                  : zlibCompressor instanceof BuiltInZlibDeflater);

  CodecPool.returnCompressor(zlibCompressor);

  // Create a GZIP text file via the Compressor interface.
  CompressionCodecFactory ccf = new CompressionCodecFactory(conf);
  CompressionCodec codec = ccf.getCodec(new Path("foo.gz"));
  assertTrue("Codec for .gz file is not GzipCodec", 
             codec instanceof GzipCodec);

  final String msg = "This is the message we are going to compress.";
  final String fileName = new Path(GenericTestUtils.getTempPath(
      "testGzipCodecWrite.txt.gz")).toString();

  BufferedWriter w = null;
  Compressor gzipCompressor = CodecPool.getCompressor(codec);
  if (null != gzipCompressor) {
    // If it gives us back a Compressor, we should be able to use this
    // to write files we can then read back with Java's gzip tools.
    OutputStream os = new CompressorStream(new FileOutputStream(fileName),
        gzipCompressor);
    w = new BufferedWriter(new OutputStreamWriter(os));
    w.write(msg);
    w.close();
    CodecPool.returnCompressor(gzipCompressor);

    verifyGzipFile(fileName, msg);
  }

  // Create a gzip text file via codec.getOutputStream().
  w = new BufferedWriter(new OutputStreamWriter(
      codec.createOutputStream(new FileOutputStream(fileName))));
  w.write(msg);
  w.close();

  verifyGzipFile(fileName, msg);
}