Android: Allow to provide a different HttpClient implementation

lib/android_build/app/build.gradle

@@ -30,6 +30,10 @@ android {
             version "3.10.2"
         }
     }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
 }
 
 dependencies {

lib/android_build/app/src/test/java/com/microsoft/applications/events/maesdktest/HttpClientRequestTest.java

@@ -0,0 +1,40 @@
+//
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+//
+package com.microsoft.applications.events.maesdktest;
+
+import com.microsoft.applications.events.HttpClientRequest;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.junit.Assert.*;
+
+public class HttpClientRequestTest {
+    @Test
+    public void testHeaders() {
+        byte[] bytes = "key1value1key33key2value2".getBytes(UTF_8);
+        int[] header_lengths = new int[] { 4, 6, 5, 0, 4, 6 };
+
+        HttpClientRequest.Headers headers = new HttpClientRequest.Headers(header_lengths, bytes);
+        ArrayList<String> actual = new ArrayList<>();
+        while (headers.hasNext()) {
+            HttpClientRequest.HeaderEntry entry = headers.next();
+            actual.add(entry.key);
+            actual.add(entry.value);
+        }
+
+        Assert.assertEquals(6, headers.length);
+        Assert.assertArrayEquals(
+                new String[] {"key1", "value1", "key33", "", "key2", "value2"},
+                actual.toArray()
+        );
+    }
+}

lib/android_build/maesdk/src/main/java/com/microsoft/applications/events/HttpClient.java

@@ -23,17 +23,20 @@
 import android.os.Build;
 import android.provider.Settings;
 import android.util.Log;
+
 import androidx.annotation.Keep;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
+
 import java.io.BufferedInputStream;
 import java.io.OutputStream;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.Date;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -86,16 +89,15 @@ public final void onCapabilitiesChanged(
   private boolean m_metered;
 }
 
-class Request implements Runnable {
+class Request implements HttpClientRequest {
 
   Request(
-      HttpClient parent,
-      String url,
-      String method,
-      byte[] body,
-      String request_id,
-      int[] header_length,
-      byte[] header_buffer)
+          @NonNull HttpClient parent,
+          String url,
+          String method,
+          byte[] body,
+          String request_id,
+          @NonNull Headers headers)
       throws java.io.IOException {
     m_parent = parent;
     m_connection = (HttpURLConnection) parent.newUrl(url).openConnection();
@@ -106,13 +108,9 @@ class Request implements Runnable {
       m_connection.setDoOutput(true);
     }
     m_request_id = request_id;
-    int offset = 0;
-    for (int i = 0; i + 1 < header_length.length; i += 2) {
-      String k = new String(header_buffer, offset, header_length[i], UTF_8);
-      offset += header_length[i];
-      String v = new String(header_buffer, offset, header_length[i + 1], UTF_8);
-      offset += header_length[i + 1];
-      m_connection.setRequestProperty(k, v);
+    while (headers.hasNext()) {
+      HeaderEntry header = headers.next();
+      m_connection.setRequestProperty(header.key, header.value);
     }
   }
 
@@ -190,7 +188,7 @@ public class HttpClient {
 
   /** Shim FutureTask: we would like to @Keep the cancel method for JNI */
   static class FutureShim extends FutureTask<Boolean> {
-    FutureShim(Request inner) {
+    FutureShim(HttpClientRequest inner) {
       super(inner, true);
     }
 
@@ -202,7 +200,12 @@ public boolean cancel(boolean mayInterruptIfRunning) {
   }
 
   public HttpClient(Context context) {
+    this(context, new HttpClientRequest.Factory.AndroidUrlConnection());
+  }
+
+  public HttpClient(Context context, HttpClientRequest.Factory requestFactory) {
     m_context = context;
+    m_requestFactory = requestFactory;
     String path = System.getProperty("java.io.tmpdir");
     setCacheFilePath(path);
     setDeviceInfo(calculateID(context), Build.MANUFACTURER, Build.MODEL);
@@ -376,7 +379,8 @@ public FutureTask<Boolean> createTask(
       int[] header_index,
       byte[] header_buffer) {
     try {
-      Request r = new Request(this, url, method, body, request_id, header_index, header_buffer);
+      HttpClientRequest.Headers headers = new HttpClientRequest.Headers(header_index, header_buffer);
+      HttpClientRequest r = m_requestFactory.create(this, url, method, body, request_id, headers);
       return new FutureShim(r);
     } catch (Exception e) {
       return null;
@@ -393,4 +397,5 @@ public void executeTask(FutureTask<Boolean> t) {
   private android.net.ConnectivityManager m_connectivityManager;
   private PowerInfoReceiver m_power_receiver;
   private final Context m_context;
-}
+  private final HttpClientRequest.Factory m_requestFactory;
+}

lib/android_build/maesdk/src/main/java/com/microsoft/applications/events/HttpClientRequest.java

@@ -0,0 +1,72 @@
+//
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+//
+package com.microsoft.applications.events;
+
+import androidx.annotation.NonNull;
+
+import java.io.IOException;
+import java.util.Iterator;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+public interface HttpClientRequest extends Runnable {
+
+    interface Factory {
+        HttpClientRequest create(
+                @NonNull HttpClient parent,
+                String url,
+                String method,
+                byte[] body,
+                String request_id,
+                @NonNull Headers headers
+        ) throws IOException;
+
+        class AndroidUrlConnection implements HttpClientRequest.Factory {
+            @Override
+            public HttpClientRequest create(@NonNull HttpClient parent, String url, String method, byte[] body, String request_id, @NonNull Headers headers) throws IOException {
+                return new Request(parent, url, method, body, request_id, headers);
+            }
+        }
+    }
+
+    final class HeaderEntry {
+        public final String key;
+        public final String value;
+
+        public HeaderEntry(String key, String value) {
+            this.key = key;
+            this.value = value;
+        }
+    }
+
+    final class Headers implements Iterator<HeaderEntry> {
+        public final int length;
+        private final int[] header_lengths;
+        private final byte[] buffer;
+        private int current = 0;
+        private int offset = 0;
+
+        public Headers(int[] header_lengths, byte[] buffer) {
+            this.length = header_lengths.length;
+            this.header_lengths = header_lengths;
+            this.buffer = buffer;
+        }
+
+        @Override
+        public boolean hasNext() {
+            return current + 2 <= length;
+        }
+
+        @Override
+        public HeaderEntry next() {
+            String k = new String(buffer, offset, header_lengths[current], UTF_8);
+            offset += header_lengths[current];
+            String v = new String(buffer, offset, header_lengths[current + 1], UTF_8);
+            offset += header_lengths[current + 1];
+            current += 2;
+            return new HeaderEntry(k,v);
+        }
+    }
+}