Revert read/write file to previous implementation

packages/platforms/react-native/android/src/main/java/com/bugsnag/android/performance/NativeBugsnagPerformanceImpl.java

@@ -153,28 +153,24 @@ void mkdir(String path, Promise promise) {
 
   void readFile(String path, String encoding, Promise promise) {
     Log.w(TAG, "readfile start " + path);
+    File file = new File(path);
+    StringBuilder fileContent = new StringBuilder((int) file.length());
     try(
-      FileInputStream fin = new FileInputStream(new File(path));
-      ByteArrayOutputStream result = new ByteArrayOutputStream();
+      FileInputStream fin = new FileInputStream(file);
+      InputStreamReader isr = new InputStreamReader(fin, encoding);
     ) {
-      byte[] buffer = new byte[4096];
+      char[] buffer = new char[4096];
       int charsRead = 0;
-      while ((charsRead = fin.read(buffer)) != -1) {
-        result.write(buffer, 0, charsRead);
+      while ((charsRead = isr.read(buffer)) != -1) {
+        fileContent.append(buffer, 0, charsRead);
       }
+      String content = fileContent.toString();
+      Log.w(TAG, "readfile content " + content);
 
-      String fileContent = "";
-      if (encoding == "utf8") {
-        fileContent = result.toString();
-      } else if (encoding == "base64") {
-        fileContent = Base64.encodeToString(result.toByteArray(), Base64.DEFAULT);
-      }
-
-      Log.w(TAG, "readfile content " + fileContent);
-      promise.resolve(fileContent);
+      promise.resolve(content);
     } catch (Exception e) {
-      Log.w(TAG, "readfile exception " + e.toString());
       promise.reject(e);
+      Log.w(TAG, "readfile exception " + e.toString());
     }
   }
 
@@ -199,22 +195,15 @@ void writeFile(String path, String data, String encoding, Promise promise){
     Log.w(TAG, "writeFile start " + path);
     try(
       FileOutputStream fout = new FileOutputStream(path);
+      Writer w = new OutputStreamWriter(fout, encoding);
     ) {
-      byte[] buffer = null;
-      if (encoding == "utf8") {
-        buffer = data.getBytes();
-      } else if (encoding == "base64") {
-        buffer = Base64.decode(data, Base64.DEFAULT);
-      }
-
-      if (buffer != null) {
-        fout.write(buffer, 0, data.length());
-      }
+      w.write(data);
 
+      Log.w(TAG, "writeFile end " + path);
       promise.resolve(null);
     } catch (Exception e) {
-      Log.w(TAG, "writeFile exception " + e.toString());
       promise.reject(e);
+      Log.w(TAG, "writeFile exception " + e.toString());
     }
   }