Refactor the utility class

ml/src/main/java/com/baeldung/logreg/DataUtilities.java

@@ -1,102 +0,0 @@
-/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available 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.
- *
- * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
-
-package com.baeldung.logreg;
-
-import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
-import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
-import org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream;
-import org.apache.http.HttpEntity;
-import org.apache.http.client.methods.CloseableHttpResponse;
-import org.apache.http.client.methods.HttpGet;
-import org.apache.http.impl.client.CloseableHttpClient;
-import org.apache.http.impl.client.HttpClientBuilder;
-
-import java.io.*;
-
-/**
- * Common data utility functions.
- * 
- * @author fvaleri
- */
-public class DataUtilities {
-
-  /**
-   * Download a remote file if it doesn't exist.
-   * @param remoteUrl URL of the remote file.
-   * @param localPath Where to download the file.
-   * @return True if and only if the file has been downloaded.
-   * @throws Exception IO error.
-   */
-  public static boolean downloadFile(String remoteUrl, String localPath) throws IOException {
-    boolean downloaded = false;
-    if (remoteUrl == null || localPath == null)
-      return downloaded;
-    File file = new File(localPath);
-    if (!file.exists()) {
-      file.getParentFile().mkdirs();
-      HttpClientBuilder builder = HttpClientBuilder.create();
-      CloseableHttpClient client = builder.build();
-      try (CloseableHttpResponse response = client.execute(new HttpGet(remoteUrl))) {
-        HttpEntity entity = response.getEntity();
-        if (entity != null) {
-          try (FileOutputStream outstream = new FileOutputStream(file)) {
-            entity.writeTo(outstream);
-            outstream.flush();
-            outstream.close();
-          }
-        }
-      }
-      downloaded = true;
-    }
-    if (!file.exists())
-      throw new IOException("File doesn't exist: " + localPath);
-    return downloaded;
-  }
-
-  /**
-   * Extract a "tar.gz" file into a local folder.
-   * @param inputPath Input file path.
-   * @param outputPath Output directory path.
-   * @throws IOException IO error.
-   */
-  public static void extractTarGz(String inputPath, String outputPath) throws IOException {
-    if (inputPath == null || outputPath == null)
-      return;
-    final int bufferSize = 4096;
-    if (!outputPath.endsWith("" + File.separatorChar))
-      outputPath = outputPath + File.separatorChar;
-    try (TarArchiveInputStream tais = new TarArchiveInputStream(
-        new GzipCompressorInputStream(new BufferedInputStream(new FileInputStream(inputPath))))) {
-      TarArchiveEntry entry;
-      while ((entry = (TarArchiveEntry) tais.getNextEntry()) != null) {
-        if (entry.isDirectory()) {
-          new File(outputPath + entry.getName()).mkdirs();
-        } else {
-          int count;
-          byte data[] = new byte[bufferSize];
-          FileOutputStream fos = new FileOutputStream(outputPath + entry.getName());
-          BufferedOutputStream dest = new BufferedOutputStream(fos, bufferSize);
-          while ((count = tais.read(data, 0, bufferSize)) != -1) {
-            dest.write(data, 0, count);
-          }
-          dest.close();
-        }
-      }
-    }
-  }
-
-}

ml/src/main/java/com/baeldung/logreg/MnistClassifier.java

@@ -67,18 +67,20 @@ public class MnistClassifier {
 
         final String path = basePath + "mnist_png" + File.separator;
         if (!new File(path).exists()) {
-            logger.debug("Downloading data {}", dataUrl);
+            logger.info("Downloading data {}", dataUrl);
             String localFilePath = basePath + "mnist_png.tar.gz";
-            logger.info("local file: {}", localFilePath);
+            File file = new File(localFilePath);
-            if (DataUtilities.downloadFile(dataUrl, localFilePath)) {
+            if (!file.exists()) {
-                DataUtilities.extractTarGz(localFilePath, basePath);
+                file.getParentFile()
+                    .mkdirs();
+                Utils.downloadAndSave(dataUrl, file);
+                Utils.extractTarArchive(file, basePath);
             }
         } else {
-            logger.info("local file exists {}", path);
+            logger.info("Using the local data from folder {}", path);
-
         }
 
-        logger.info("Vectorizing data...");
+        logger.info("Vectorizing the data from folder {}", path);
         // vectorization of train data
         File trainData = new File(path + "training");
         FileSplit trainSplit = new FileSplit(trainData, NativeImageLoader.ALLOWED_FORMATS, randNumGen);

ml/src/main/java/com/baeldung/logreg/MnistPrediction.java

@@ -36,18 +36,22 @@ public class MnistPrediction {
     }
 
     public static void main(String[] args) throws IOException {
-        String path = fileChose().toString();
+        if (!modelPath.exists()) {
+            logger.info("The model not found. Have you trained it?");
+            return;
+        }
         MultiLayerNetwork model = ModelSerializer.restoreMultiLayerNetwork(modelPath);
+        String path = fileChose();
         File file = new File(path);
 
         INDArray image = new NativeImageLoader(height, width, channels).asMatrix(file);
         new ImagePreProcessingScaler(0, 1).transform(image);
-        
+
         // Pass through to neural Net
         INDArray output = model.output(image);
 
         logger.info("File: {}", path);
-        logger.info(output.toString());
+        logger.info("Probabilities: {}", output);
     }
 
 }

ml/src/main/java/com/baeldung/logreg/Utils.java

@@ -0,0 +1,103 @@
+package com.baeldung.logreg;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.commons.compress.archivers.ArchiveEntry;
+import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
+import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
+import org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream;
+import org.apache.http.HttpEntity;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClientBuilder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Utility class for digit classifier.
+ * 
+ */
+public class Utils {
+
+    private static final Logger logger = LoggerFactory.getLogger(Utils.class);
+
+    private Utils() {
+    }
+
+    /**
+     * Download the content of the given url and save it into a file.
+     * @param url
+     * @param file
+     */
+    public static void downloadAndSave(String url, File file) throws IOException {
+        CloseableHttpClient client = HttpClientBuilder.create()
+            .build();
+        logger.info("Connecting to {}", url);
+        try (CloseableHttpResponse response = client.execute(new HttpGet(url))) {
+            HttpEntity entity = response.getEntity();
+            if (entity != null) {
+                logger.info("Downloaded {} bytes", entity.getContentLength());
+                try (FileOutputStream outstream = new FileOutputStream(file)) {
+                    logger.info("Saving to the local file");
+                    entity.writeTo(outstream);
+                    outstream.flush();
+                    logger.info("Local file saved");
+                }
+            }
+        }
+    }
+
+    /**
+     * Extract a "tar.gz" file into a given folder.
+     * @param file
+     * @param folder 
+     */
+    public static void extractTarArchive(File file, String folder) throws IOException {
+        logger.info("Extracting archive {} into folder {}", file.getName(), folder);
+        // @formatter:off
+        try (FileInputStream fis = new FileInputStream(file);
+            BufferedInputStream bis = new BufferedInputStream(fis);
+            GzipCompressorInputStream gzip = new GzipCompressorInputStream(bis); 
+            TarArchiveInputStream tar = new TarArchiveInputStream(gzip)) {
+       // @formatter:on
+            TarArchiveEntry entry;
+            while ((entry = (TarArchiveEntry) tar.getNextEntry()) != null) {
+                extractEntry(entry, tar, folder);
+            }
+        }
+      logger.info("Archive extracted"); 
+    }
+
+    /**
+     * Extract an entry of the input stream into a given folder
+     * @param entry
+     * @param tar
+     * @param folder
+     * @throws IOException
+     */
+    public static void extractEntry(ArchiveEntry entry, InputStream tar, String folder) throws IOException {
+        final int bufferSize = 4096;
+        final String path = folder + entry.getName();
+        if (entry.isDirectory()) {
+            new File(path).mkdirs();
+        } else {
+            int count;
+            byte[] data = new byte[bufferSize];
+            // @formatter:off
+            try (FileOutputStream os = new FileOutputStream(path); 
+                BufferedOutputStream dest = new BufferedOutputStream(os, bufferSize)) {
+           // @formatter:off
+                while ((count = tar.read(data, 0, bufferSize)) != -1) {
+                    dest.write(data, 0, count);
+                }
+            }
+        }
+    }
+}