com.king.platform.net.http.netty.sse.ServerEventDecoder.java Source code

Introduction

Here is the source code for com.king.platform.net.http.netty.sse.ServerEventDecoder.java

Source

// Copyright (C) king.com Ltd 2016
// https://github.com/king/king-http-client
// Author: Magnus Gustafsson
// License: Apache 2.0, https://raw.github.com/king/king-http-client/LICENSE-APACHE

package com.king.platform.net.http.netty.sse;

import com.king.platform.net.http.KingHttpException;
import com.king.platform.net.http.SseClientCallback;
import io.netty.buffer.ByteBuf;

import java.nio.charset.StandardCharsets;

public class ServerEventDecoder {
    private final SseClientCallback sseClientCallback;

    private StringBuilder buffer = new StringBuilder();
    private StringBuilder data = new StringBuilder();

    private String lastEventId;
    private String eventName;

    public ServerEventDecoder(SseClientCallback sseClientCallback) {
        this.sseClientCallback = sseClientCallback;

    }

    public void reset() {
        buffer.setLength(0);
        data.setLength(0);
        lastEventId = null;
        eventName = null;
    }

    public void onReceivedContentPart(ByteBuf content) throws KingHttpException {
        String contentString = content.toString(StandardCharsets.UTF_8);
        try {
            char[] chars = contentString.toCharArray();
            for (int i = 0; i < chars.length; i++) {
                char c = chars[i];

                if (isCRLF(i, chars)) {
                    continue;
                }

                if (isNewLine(c)) {
                    String line = buffer.toString();
                    buffer.setLength(0);
                    parseLine(line);
                } else {
                    buffer.append(c);
                }

            }
        } catch (Exception e) {
            throw new KingHttpException("Failed to parse incoming content in SSE stream", e);
        }
    }

    private boolean isCRLF(int index, char[] buffer) {
        if (buffer[index] != '\r') {
            return false;
        }

        if (index + 1 >= buffer.length) {
            return false;
        }

        return buffer[index + 1] == '\n';
    }

    private boolean isNewLine(char c) {
        return c == '\r' || c == '\n';
    }

    private void parseLine(String line) {
        line = line.trim();

        if (line.isEmpty()) {
            dispatchEvent();
            return;
        }

        if (line.startsWith(":")) {
            return;
        }

        int colonIndex;

        if ((colonIndex = line.indexOf(":")) != -1) {
            String field = line.substring(0, colonIndex);
            String value;
            if (line.charAt(colonIndex + 1) == ' ') {
                value = line.substring(colonIndex + 2);
            } else {
                value = line.substring(colonIndex + 1);
            }
            processField(field, value);
        } else {
            processField(line.trim(), "");
        }

    }

    private void dispatchEvent() {
        final String thisEventName = eventName;
        eventName = null;

        if (data.length() == 0) {
            return;
        }

        if (isNewLine(data.charAt(data.length() - 1))) {
            data.setLength(data.length() - 1);
        }

        final String dataString = data.toString();
        data.setLength(0);

        sseClientCallback.onEvent(lastEventId, thisEventName, dataString);
    }

    private void processField(String field, String value) {
        switch (field.charAt(0)) {
        case 'd': {
            data.append(value).append("\n");
            break;
        }

        case 'i': {
            lastEventId = value;
            break;
        }

        case 'e': {
            eventName = value;
            break;
        }

        case 'r': { //handle retry values from the server
            break;
        }
        }
    }

}