Fixing a problem with UTF8 encoded files being read as a stream

Author: Ron Radtke

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilFS.java

@@ -21,9 +21,7 @@
 import com.facebook.react.modules.core.DeviceEventManagerModule;
 
 import java.io.*;
-import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
-import java.nio.charset.CharsetEncoder;
 import java.security.MessageDigest;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -360,20 +358,25 @@ else if (resolved == null) {
                 fs = new FileInputStream(new File(path));
             }
 
-            byte[] buffer = new byte[chunkSize];
             int cursor = 0;
             boolean error = false;
 
             if (encoding.equalsIgnoreCase("utf8")) {
-                CharsetEncoder encoder = Charset.forName("UTF-8").newEncoder();
-                while ((cursor = fs.read(buffer)) != -1) {
-                    encoder.encode(ByteBuffer.wrap(buffer).asCharBuffer());
-                    String chunk = new String(buffer, 0, cursor);
+                InputStreamReader isr = new InputStreamReader(fs, Charset.forName("UTF-8"));
+                BufferedReader reader = new BufferedReader(isr, chunkSize);
+                char[] buffer = new char[chunkSize];
+                // read chunks of the string
+                while (reader.read(buffer, 0, chunkSize) != -1) {
+                    String chunk = new String(buffer);
                     emitStreamEvent(streamId, "data", chunk);
                     if (tick > 0)
                         SystemClock.sleep(tick);
                 }
+
+                reader.close();
+                isr.close();
             } else if (encoding.equalsIgnoreCase("ascii")) {
+                byte[] buffer = new byte[chunkSize];
                 while ((cursor = fs.read(buffer)) != -1) {
                     WritableArray chunk = Arguments.createArray();
                     for (int i = 0; i < cursor; i++) {
@@ -384,6 +387,7 @@ else if (resolved == null) {
                         SystemClock.sleep(tick);
                 }
             } else if (encoding.equalsIgnoreCase("base64")) {
+                byte[] buffer = new byte[chunkSize];
                 while ((cursor = fs.read(buffer)) != -1) {
                     if (cursor < chunkSize) {
                         byte[] copy = new byte[cursor];
@@ -407,7 +411,7 @@ else if (resolved == null) {
             if (!error)
                 emitStreamEvent(streamId, "end", "");
             fs.close();
-            buffer = null;
+
         } catch (FileNotFoundException err) {
             emitStreamEvent(
                     streamId,
@@ -710,8 +714,8 @@ static void exists(String path, Callback callback) {
     /**
      * List content of folder
      *
-     * @param path     Target folder
-     * @param callback JS context callback
+     * @param path    Target folder
+     * @param promise JS context promise
      */
     static void ls(String path, Promise promise) {
         try {