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 {
+    private double getResponseLength(Response response) {
-        return writer.write(responseBody.byteStream());
+        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);
+
+}

libraries-http-2/src/test/java/com/baeldung/okhttp/download/BinaryFileDownloaderIntegrationTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.okhttp.download;
+
+import okhttp3.OkHttpClient;
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+import org.junit.Rule;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class BinaryFileDownloaderIntegrationTest {
+
+    @Rule
+    public MockWebServer server = new MockWebServer();
+
+    @Test
+    public void givenATextFile_whenDownload_thenExpectFileDownloaded() throws IOException {
+        String body = "Hello Baeldung Readers!";
+        server.enqueue(new MockResponse().setBody(body));
+        String fileName = "download.txt";
+        BinaryFileWriter writer = new BinaryFileWriter(new FileOutputStream(fileName), progress -> assertEquals(100.0, progress, .0));
+        BinaryFileDownloader tested = new BinaryFileDownloader(new OkHttpClient(), writer);
+
+        long downloaded = tested.download(server.url("/greetings").toString());
+
+        assertEquals(body.length(), downloaded);
+        File downloadedFile = new File(fileName);
+        assertTrue(downloadedFile.isFile());
+        assertTrue(downloadedFile.delete());
+    }
+
+}

libraries-http-2/src/test/java/com/baeldung/okhttp/download/BinaryFileDownloaderUnitTest.java

@@ -19,6 +19,7 @@ import java.io.InputStream;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyDouble;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -42,12 +43,12 @@ public class BinaryFileDownloaderUnitTest {
         ResponseBody body = ResponseBody.create("BODY", MediaType.get("application/text"));
         Response response = createResponse(url, body);
         when(call.execute()).thenReturn(response);
-        when(writer.write(any())).thenReturn(1L);
+        when(writer.write(any(), anyDouble())).thenReturn(1L);
 
         try (BinaryFileDownloader tested = new BinaryFileDownloader(client, writer)) {
             long size = tested.download(url);
             assertEquals(1L, size);
-            verify(writer).write(any(InputStream.class));
+            verify(writer).write(any(InputStream.class), anyDouble());
         }
         verify(writer).close();
     }
@@ -62,7 +63,7 @@ public class BinaryFileDownloaderUnitTest {
 
         assertThrows(IllegalStateException.class, () -> tested.download(url));
 
-        verify(writer, times(0)).write(any(InputStream.class));
+        verify(writer, times(0)).write(any(InputStream.class), anyDouble());
     }
 
     @NotNull

libraries-http-2/src/test/java/com/baeldung/okhttp/download/BinaryFileWriterUnitTest.java

@@ -28,8 +28,8 @@ public class BinaryFileWriterUnitTest {
         InputStream inputStream = mock(InputStream.class);
         when(inputStream.read(any(), anyInt(), anyInt())).thenReturn(10, -1);
 
-        try (BinaryFileWriter tested = new BinaryFileWriter(outputStream)) {
+        try (BinaryFileWriter tested = new BinaryFileWriter(outputStream, progress -> assertEquals(100.0, progress))) {
-            long result = tested.write(inputStream);
+            long result = tested.write(inputStream, 10);
 
             assertEquals(10, result);
             verify(outputStream).write(any(), eq(0), eq(10));
@@ -42,8 +42,8 @@ public class BinaryFileWriterUnitTest {
     public void givenInputStreamEmpty_whenWrite_thenExpectNotWritten() throws Exception {
         InputStream inputStream = mock(InputStream.class);
 
-        try (BinaryFileWriter tested = new BinaryFileWriter(outputStream)) {
+        try (BinaryFileWriter tested = new BinaryFileWriter(outputStream, progress -> assertEquals(100.0, progress))) {
-            long result = tested.write(inputStream);
+            long result = tested.write(inputStream, 1);
 
             assertEquals(0, result);
             verify(outputStream, times(0)).write(any(), anyInt(), anyInt());