BAEL-4856 Integrate progress when downloading

libraries-http-2/src/main/java/com/baeldung/okhttp/download/BinaryFileDownloader.java

@@ -7,6 +7,9 @@ import okhttp3.ResponseBody;
 import org.jetbrains.annotations.NotNull;
 
 import java.io.IOException;
+import java.util.Objects;
+
+import static org.springframework.http.HttpHeaders.CONTENT_LENGTH;
 
 public class BinaryFileDownloader implements AutoCloseable {
 
@@ -22,7 +25,8 @@ public class BinaryFileDownloader implements AutoCloseable {
         Request request = createRequest(url);
         Response response = executeRequest(request);
         ResponseBody responseBody = getResponseBodyOrFail(response);
-        return write(responseBody);
+        double length = getResponseLength(response);
+        return write(responseBody, length);
     }
 
     @NotNull
@@ -43,8 +47,12 @@ public class BinaryFileDownloader implements AutoCloseable {
         return responseBody;
     }
 
-    private long write(ResponseBody responseBody) throws IOException {
-        return writer.write(responseBody.byteStream());
+    private double getResponseLength(Response response) {
+        return Double.parseDouble(Objects.requireNonNull(response.header(CONTENT_LENGTH, "1")));
+    }
+
+    private long write(ResponseBody responseBody, double length) throws IOException {
+        return writer.write(responseBody.byteStream(), length);
     }
 
     @Override

libraries-http-2/src/main/java/com/baeldung/okhttp/download/BinaryFileWriter.java

@@ -9,12 +9,14 @@ public class BinaryFileWriter implements AutoCloseable {
 
     private static final int CHUNK_SIZE = 1024;
     private final OutputStream outputStream;
+    private final ProgressCallable progressCallable;
 
-    public BinaryFileWriter(OutputStream outputStream) {
+    public BinaryFileWriter(OutputStream outputStream, ProgressCallable progressCallable) {
         this.outputStream = outputStream;
+        this.progressCallable = progressCallable;
     }
 
-    public long write(InputStream inputStream) throws IOException {
+    public long write(InputStream inputStream, double length) throws IOException {
         try (BufferedInputStream input = new BufferedInputStream(inputStream)) {
             byte[] dataBuffer = new byte[CHUNK_SIZE];
             int readBytes;
@@ -22,6 +24,7 @@ public class BinaryFileWriter implements AutoCloseable {
             while ((readBytes = input.read(dataBuffer)) != -1) {
                 totalBytes += readBytes;
                 outputStream.write(dataBuffer, 0, readBytes);
+                progressCallable.onProgress(totalBytes / length * 100.0);
             }
             return totalBytes;
         }

libraries-http-2/src/main/java/com/baeldung/okhttp/download/ProgressCallable.java

@@ -0,0 +1,7 @@
+package com.baeldung.okhttp.download;
+
+public interface ProgressCallable {
+
+    void onProgress(double progress);
+
+}