Revert "Merge pull request #353 from thinkproductivity/mjmasn-patch-1"

This reverts commit 6bbebd3429, reversing
changes made to 90ce0c401a.

android/src/main/java/com/RNFetchBlob/RNFetchBlobFS.java

 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;
             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);
                     emitStreamEvent(streamId, "data", chunk);
                     if(tick > 0)

android/src/main/java/com/RNFetchBlob/RNFetchBlobReq.java

 import java.net.SocketException;
 import java.net.SocketTimeoutException;
 import java.net.URL;
+import java.nio.ByteBuffer;
+import java.nio.charset.CharacterCodingException;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetEncoder;
 import java.security.KeyStore;
 import java.util.ArrayList;
 import java.util.Arrays;
                         // encoding will somehow break the UTF8 string format, to encode UTF8
                         // string correctly, we should do URL encoding before BASE64.
                         byte[] b = resp.body().bytes();
+                        CharsetEncoder encoder = Charset.forName("UTF-8").newEncoder();
                         if(responseFormat == ResponseFormat.BASE64) {
                             callback.invoke(null, RNFetchBlobConst.RNFB_RESPONSE_BASE64, android.util.Base64.encodeToString(b, Base64.NO_WRAP));
                             return;
                         }
-                        String utf8 = new String(b);
-                        callback.invoke(null, RNFetchBlobConst.RNFB_RESPONSE_UTF8, utf8);
+                        try {
+                            encoder.encode(ByteBuffer.wrap(b).asCharBuffer());
+                            // if the data contains invalid characters the following lines will be
+                            // skipped.
+                            String utf8 = new String(b);
+                            callback.invoke(null, RNFetchBlobConst.RNFB_RESPONSE_UTF8, utf8);
+                        }
+                        // This usually mean the data is contains invalid unicode characters, it's
+                        // binary data
+                        catch(CharacterCodingException ignored) {
+                            if(responseFormat == ResponseFormat.UTF8) {
+                                callback.invoke(null, RNFetchBlobConst.RNFB_RESPONSE_UTF8, "");
+                            }
+                            else {
+                                callback.invoke(null, RNFetchBlobConst.RNFB_RESPONSE_BASE64, android.util.Base64.encodeToString(b, Base64.NO_WRAP));
+                            }
+                        }
                     }
                 } catch (IOException e) {
                     callback.invoke("RNFetchBlob failed to encode response data to BASE64 string.", null);