@Test
public void test_is_well_formed_utf_8() {

    for (int b = 0xA0; b <= 0xBF; b++) {
        for (int b2 = 0; b2 < 0xFF; b2++) {

            final byte[] bytes = new byte[]{'a', 'b', 'c', (byte) 0xED, (byte) b, (byte) b2, 'd', 'e', 'f'};

            final ByteBuf buf = Unpooled.buffer();

            buf.writeShort(bytes.length);
            buf.writeBytes(bytes);

            //checking both original guava method for byte-arrays and the ByteBuf implementation
            assertFalse(Utf8Utils.isWellFormed(buf, bytes.length));
            assertFalse(Utf8.isWellFormed(bytes));

            buf.release();
        }
    }
}
 

@Nullable
private static String getSanitizedId(@Nonnull String id) {
    try {
        if (Utf8.encodedLength(id) > MAX_TR_ID_SIZE) {
            if (CharMatcher.ascii().matchesAllOf(id)) {
                // Most of the time, the string will be of ascii characters, so return a truncated ID based on length
                return id.substring(0, MAX_TR_ID_SIZE - 3) + "...";
            } else {
                // In theory, we could try and split the UTF-16 string and find a string that fits, but that
                // is fraught with peril, not the least of which because one might accidentally split a low
                // surrogate/high surrogate pair.
                return null;
            }
        } else {
            return id;
        }
    } catch (IllegalArgumentException e) {
        return null;
    }
}
 

/**
 * Validate if value can be decoded by given charset.
 *
 * @param value nls string in byte array
 * @param charset charset
 * @throws RuntimeException If the given value cannot be represented in the
 *     given charset
 */
public static void validateCharset(ByteString value, Charset charset) {
  if (charset == StandardCharsets.UTF_8) {
    final byte[] bytes = value.getBytes();
    if (!Utf8.isWellFormed(bytes)) {
      //CHECKSTYLE: IGNORE 1
      final String string = new String(bytes, charset);
      throw RESOURCE.charsetEncoding(string, charset.name()).ex();
    }
  }
}
 

/**
 * Validate if value can be decoded by given charset.
 *
 * @param value nls string in byte array
 * @param charset charset
 * @throws RuntimeException If the given value cannot be represented in the
 *     given charset
 */
public static void validateCharset(ByteString value, Charset charset) {
  if (charset == StandardCharsets.UTF_8) {
    final byte[] bytes = value.getBytes();
    if (!Utf8.isWellFormed(bytes)) {
      //CHECKSTYLE: IGNORE 1
      final String string = new String(bytes, charset);
      throw RESOURCE.charsetEncoding(string, charset.name()).ex();
    }
  }
}
 

/**
 * Decodes and optionally validates a publish payload
 * <p>
 * Results in {@link Mqtt5DisconnectReasonCode#PAYLOAD_FORMAT_INVALID} with DISCONNECT by:
 * <p>
 * - payloadFormatIndicator == UTF-8 AND validatePayloadFormat = true AND payload is not UTF-8 well formed.
 *
 * @param channel                the channel of the mqtt client
 * @param buf                    the encoded ByteBuf of the message
 * @param payloadLength          the length of the payload
 * @param payloadFormatIndicator the nullable {@link Mqtt5PayloadFormatIndicator}
 * @param validatePayloadFormat  the configured boolean for payload validation (default false)
 * @return the payload as a byte[] or {@code null} if this method disconnected.
 */
protected @Nullable byte[] decodePayload(final @NotNull Channel channel,
                                         final @NotNull ByteBuf buf,
                                         final int payloadLength,
                                         final @Nullable Mqtt5PayloadFormatIndicator payloadFormatIndicator,
                                         final boolean validatePayloadFormat) {

    final byte[] payload;
    if (payloadLength > 0) {
        payload = new byte[payloadLength];
        buf.readBytes(payload);

        if (Mqtt5PayloadFormatIndicator.UTF_8 == payloadFormatIndicator) {
            if (validatePayloadFormat) {
                if (!Utf8.isWellFormed(payload)) {
                    disconnector.disconnect(channel,
                            "A client (IP: {}) sent a PUBLISH with an invalid UTF-8 payload. This is not allowed. Disconnecting client.",
                            "Sent a PUBLISH with an invalid UTF-8 payload",
                            Mqtt5DisconnectReasonCode.PAYLOAD_FORMAT_INVALID,
                            ReasonStrings.DISCONNECT_PAYLOAD_FORMAT_INVALID_PUBLISH);
                    return null;
                }
            }
        }
    } else {
        payload = emptyPayload;
    }
    return payload;
}
 

/**
 * Checks whether the given UTF-8 encoded byte array contains characters a UTF-8 encoded String must not according
 * to the MQTT 5 specification.
 * <p>
 * These characters are the null character U+0000 and UTF-16 surrogates.
 *
 * @param binary the UTF-8 encoded byte array.
 * @return whether the binary data contains characters a UTF-8 encoded String must not.
 */
public static boolean containsMustNotCharacters(@NotNull final byte[] binary) {
    if (!Utf8.isWellFormed(binary)) {
        return true;
    }
    for (final byte b : binary) {
        if (b == 0) {
            return true;
        }
    }
    return false;
}
 

/**
 * 计算字符串被UTF8编码后的字节数 via guava
 * 
 * @see Utf8#encodedLength(CharSequence)
 */
public static int utf8EncodedLength(@Nullable CharSequence sequence) {
	if (StringUtils.isEmpty(sequence)) {
		return 0;
	}
	return Utf8.encodedLength(sequence);
}
 

/**
 * 计算字符串被UTF8编码后的字节数 via guava
 * 
 * @see Utf8#encodedLength(CharSequence)
 */
public static int utf8EncodedLength(@Nullable CharSequence sequence) {
	if (StringUtils.isEmpty(sequence)) {
		return 0;
	}
	return Utf8.encodedLength(sequence);
}
 

/**
 * 计算字符串被UTF8编码后的字节数 via guava
 * 
 * @see Utf8#encodedLength(CharSequence)
 */
public static int utf8EncodedLength(@Nullable CharSequence sequence) {
	if (StringUtils.isEmpty(sequence)) {
		return 0;
	}
	return Utf8.encodedLength(sequence);
}
 

public static void sendMessageSplitLarge(PlayerContext ctx, Text text) {
    String json = TextSerializers.JSON.serialize(text);
    int size = Utf8.encodedLength(json);
    if (size > 32767) {
        List<Text> lines = ctx.utils().splitLines(text, ctx.width);
        ctx.getPlayer().sendMessages(lines);
    } else {
        ctx.getPlayer().sendMessage(text);
    }
}
 

/**
 * Item to show on chat message under this text.
 *
 * @param item {@link ItemStack}
 * @return instance of same {@link UltimateFancy}.
 */
public UltimateFancy hoverShowItem(ItemStack item) {
    JSONObject jItem = parseHoverItem(item);
    if (Utf8.encodedLength(jItem.toJSONString()) > 32767)
        pendentElements.add(new ExtraElement("hoverEvent", parseHoverItem(new ItemStack(item.getType()))));

    pendentElements.add(new ExtraElement("hoverEvent", jItem));
    return this;
}
 

private JSONObject parseHoverItem(ItemStack item) {
    JSONObject obj = new JSONObject();
    obj.put("action", "show_item");
    String jItem = convertItemStackToJson(item);
    if (Utf8.encodedLength(jItem) > 32767)
        obj.put("value", convertItemStackToJson(new ItemStack(item.getType())));

    obj.put("value", jItem);
    return obj;
}
 

@Test
public void sanity(){
    String s = "Hello, World!";
    Doc doc = createDoc("testField", s);
    Map<String, Object> origMap = new HashMap<>(doc.getSource());

    DocSizeProcessor sizeProcessor = createProcessor(DocSizeProcessor.class);
    ProcessResult processResult = sizeProcessor.process(doc);

    assertThat(processResult.isSucceeded()).isTrue();
    assertThat(doc.hasField("docSize")).isTrue();
    assertThat((int) doc.getField("docSize")).isEqualTo(Utf8.encodedLength(JsonUtils.toJsonString(origMap)));
}
 

@Test
public void differentLangTest(){
    String s = "こんにちは世界!";
    Doc doc = createDoc("testField", s);
    Map<String, Object> origMap = new HashMap<>(doc.getSource());

    DocSizeProcessor sizeProcessor = createProcessor(DocSizeProcessor.class);
    ProcessResult processResult = sizeProcessor.process(doc);

    assertThat(processResult.isSucceeded()).isTrue();
    assertThat(doc.hasField("docSize")).isTrue();
    assertThat((int) doc.getField("docSize")).isEqualTo(Utf8.encodedLength(JsonUtils.toJsonString(origMap)));
}
 

/**
 * Item to show on chat message under this text.
 *
 * @param item {@link ItemStack}
 * @return instance of same {@link UltimateFancy}.
 */
public UltimateFancy hoverShowItem(ItemStack item) {
    JSONObject jItem = parseHoverItem(item);
    if (Utf8.encodedLength(jItem.toJSONString()) > 32767)
        pendentElements.add(new ExtraElement("hoverEvent", parseHoverItem(new ItemStack(item.getType()))));

    pendentElements.add(new ExtraElement("hoverEvent", jItem));
    return this;
}
 

private JSONObject parseHoverItem(ItemStack item) {
    JSONObject obj = new JSONObject();
    obj.put("action", "show_item");
    String jItem = convertItemStackToJson(item);
    if (Utf8.encodedLength(jItem) > 32767)
        obj.put("value", convertItemStackToJson(new ItemStack(item.getType())));

    obj.put("value", jItem);
    return obj;
}
 

/**
 * Validate if value can be decoded by given charset.
 *
 * @param value nls string in byte array
 * @param charset charset
 * @throws RuntimeException If the given value cannot be represented in the
 *     given charset
 */
public static void validateCharset(ByteString value, Charset charset) {
  if (charset == StandardCharsets.UTF_8) {
    final byte[] bytes = value.getBytes();
    if (!Utf8.isWellFormed(bytes)) {
      //CHECKSTYLE: IGNORE 1
      final String string = new String(bytes, charset);
      throw RESOURCE.charsetEncoding(string, charset.name()).ex();
    }
  }
}
 

public static int shortLengthStringSize(@Nullable final String string) {
    return Short.BYTES + ((string == null) ? 0 : Utf8.encodedLength(string));
}
 

@Override
public void read(
    final AsnObjectSerializationContext context,
    final AsnCharStringBasedObjectCodec instance,
    final InputStream inputStream
) throws IOException {

  Objects.requireNonNull(context);
  Objects.requireNonNull(instance);
  Objects.requireNonNull(inputStream);

  // WARNING: This length can be maliciously specified by the packet creator, so be careful not to use it for unsafe
  // operations, such as creating a new array of initial size `length`. This usage is safe because it merely caps the
  // InputStream to the specified packet-length, whereas the InputStream is authoritative for when it actually ends,
  // and this limit may be well smaller than `length`.
  int lengthToRead;
  final AsnSizeConstraint sizeConstraint = instance.getSizeConstraint();
  if (sizeConstraint.isFixedSize()) {
    lengthToRead = sizeConstraint.getMax();
  } else {
    // Read the lengthToRead of the encoded OctetString...
    lengthToRead = OerLengthSerializer.readLength(inputStream);
  }

  final String result;
  /* beware the 0-lengthToRead string */
  if (lengthToRead == 0) {
    result = "";
  } else {
    // Use a limited input stream so we don't read too many bytes.
    final InputStream limitedInputStream = ByteStreams.limit(inputStream, lengthToRead);
    // WARNING: Don't close the InputStreamReader so that the underlying inputStream is not closed.
    result = CharStreams.toString(new InputStreamReader(limitedInputStream, instance.getCharacterSet().name()));

    // For UTF-8 characters, result.length() will report the viewable length (e.g., 3) but for certain encoded
    // characters, the actual byte-length will be larger (e.g., the String 元元元 is 3 viewable bytes, but 9 encoded
    // UTF-8 bytes). Thus, when we write the length-prefix, the code will write 9, so when we read, we need to
    // validate that 9 bytes were read, and not 3 (in this example).
    if (Utf8.encodedLength(result) != lengthToRead) {
      throw new IOException(
          format("Unable to properly decode %s bytes (could only read %s bytes)", lengthToRead, result.length())
      );
    }
  }

  instance.setCharString(result);
}
 

@Override
public ProcessResult process(Doc doc) {
    String sourceAsJsonString = JsonUtils.toJsonString(doc.getSource());
    doc.addField(targetField, Utf8.encodedLength(sourceAsJsonString));
    return ProcessResult.success();
}