java 结合zlmediakit将rtsp流转换为websocket-flv推送给前端浏览器进行播放的代码

以下是Java结合ZLMediaKit将RTSP流转换为WebSocket-FLV推送给前端浏览器进行播放的代码：

import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.alibaba.fastjson.JSONObject;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.util.ReferenceCountUtil;
import org.zeromq.ZMQ;
import org.zeromq.ZMQ.Context;
import org.zeromq.ZMQ.Socket;
import org.zeromq.ZMsg;
import java.io.IOException;

public class RtspToWebSocketHandler extends ChannelInboundHandlerAdapter {
    private static final Logger logger = LoggerFactory.getLogger(RtspToWebSocketHandler.class);
    private ZMQ.Context context;
    private ZMQ.Socket subscriber;
    private ZMQ.Socket publisher;
    private String publisherAddress;
    private String subscriberAddress;
    private String rtspUrl;
    private String roomId;
    private String sdp;
    private String tag;
    private boolean isPushStream;

    public RtspToWebSocketHandler(String publisherAddress, String subscriberAddress, String rtspUrl, String roomId, String sdp, String tag) {
        this.publisherAddress = publisherAddress;
        this.subscriberAddress = subscriberAddress;
        this.rtspUrl = rtspUrl;
        this.roomId = roomId;
        this.sdp = sdp;
        this.tag = tag;
        this.isPushStream = false;
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        if (msg instanceof FullHttpRequest) {
            handleHttpRequest(ctx, (FullHttpRequest) msg);
        } else if (msg instanceof WebSocketFrame) {
            handleWebSocketFrame(ctx, (WebSocketFrame) msg);
        } else {
            ReferenceCountUtil.release(msg);
        }
    }

    private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) throws Exception {
        // Handle a bad request.
        if (!req.decoderResult().isSuccess()) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST));
            return;
        }

        // Allow only GET methods.
        if (req.method() != GET) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN));
            return;
        }

        // Handshake
        WebSocketServerProtocolHandler wsHandler = new WebSocketServerProtocolHandler(WEBSOCKET_PATH, null, true, 65536);
        wsHandler.handshake(ctx.channel(), req);
    }

    private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
        // Check for closing frame
        if (frame instanceof CloseWebSocketFrame) {
            ctx.close();
            return;
        }

        // Check for ping frame
        if (frame instanceof PingWebSocketFrame) {
            ctx.write(new PongWebSocketFrame(frame.content().retain()));
            return;
        }

        // Check for binary frame
        if (!(frame instanceof BinaryWebSocketFrame)) {
            throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass().getName()));
        }

        // Start pushing stream
        if (!isPushStream) {
            logger.info("Start pushing stream. roomId: {}", roomId);
            startPushStream();
            isPushStream = true;
        }

        // Send WebSocket frame to ZLMediaKit
        BinaryWebSocketFrame binaryWebSocketFrame = (BinaryWebSocketFrame) frame;
        byte[] data = binaryWebSocketFrame.content().nioBuffer().array();
        publisher.sendMore(roomId).send(data);
    }

    private void startPushStream() {
        // Create ZMQ context and sockets
        context = ZMQ.context(1);
        subscriber = context.socket(ZMQ.SUB);
        publisher = context.socket(ZMQ.PUB);

        // Connect to subscriber and publisher
        subscriber.connect(subscriberAddress);
        subscriber.subscribe(tag.getBytes());
        publisher.connect(publisherAddress);

        // Send stream info to ZLMediaKit
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("api", "addMediaSource");
        jsonObject.put("url", rtspUrl);
        jsonObject.put("vhost", "default");
        jsonObject.put("enable_rtsp", true);
        jsonObject.put("enable_rtp", true);
        jsonObject.put("enable_tcp", true);
        jsonObject.put("enable_udp", true);
        jsonObject.put("timeout_sec", 30);
        jsonObject.put("merge", true);
        jsonObject.put("hls_enabled", false);
        jsonObject.put("mp4_enabled", false);
        jsonObject.put("record_enabled", false);
        jsonObject.put("broadcast_enabled", true);
        jsonObject.put("room_id", roomId);
        jsonObject.put("sdp", sdp);
        publisher.sendMore(tag).send(jsonObject.toJSONString().getBytes());
        logger.info("Send stream info to ZLMediaKit. roomId: {}, rtspUrl: {}", roomId, rtspUrl);

        // Start receiving stream from ZLMediaKit
        new Thread(() -> {
            while (!Thread.currentThread().isInterrupted()) {
                try {
                    ZMsg zMsg = ZMsg.recvMsg(subscriber);
                    if (zMsg == null) {
                        continue;
                    }
                    byte[] data = zMsg.getLast().getData();
                    BinaryWebSocketFrame binaryWebSocketFrame = new BinaryWebSocketFrame(Unpooled.wrappedBuffer(data));
                    ctx.channel().writeAndFlush(binaryWebSocketFrame);
                    logger.debug("Received stream from ZLMediaKit. roomId: {}, data length: {}", roomId, data.length);
                } catch (IOException e) {
                    logger.error("Error receiving stream from ZLMediaKit. roomId: {}", roomId, e);
                    break;
                }
            }

            // Close sockets
            subscriber.close();
            publisher.close();
            context.term();
        }).start();
    }

    private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) {
        // Generate an error page if response getStatus code is not OK (200).
        if (res.status().code() != 200) {
            ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(), CharsetUtil.UTF_8);
            res.content().writeBytes(buf);
            buf.release();
            HttpHeaderUtil.setContentLength(res, res.content().readableBytes());
        }

        // Send the response and close the connection if necessary.
        ChannelFuture f = ctx.channel().writeAndFlush(res);
        if (!HttpHeaderUtil.isKeepAlive(req) || res.status().code() != 200) {
            f.addListener(ChannelFutureListener.CLOSE);
        }
    }
}

使用方法：

1. 在Netty的ChannelPipeline中加入RtspToWebSocketHandler。
2. 当前端连接WebSocket时，会触发RtspToWebSocketHandler的channelRead方法，此时需要调用WebSocketServerProtocolHandler的handshake方法进行握手。
3. 当前端发送WebSocket帧时，会触发RtspToWebSocketHandler的channelRead方法，此时会将WebSocket帧发送给ZLMediaKit，ZLMediaKit会将转换后的FLV数据发送给RtspToWebSocketHandler，RtspToWebSocketHandler再将FLV数据发送给前端浏览器进行播放。
4. 当前端关闭WebSocket时，会触发RtspToWebSocketHandler的handleWebSocketFrame方法，此时需要关闭ZMQ的subscriber和publisher。

注意事项：

1. 代码中的ZLMediaKit的接口参数可能与实际情况不符，需要根据实际情况进行修改。
2. 代码中的ZMQ版本为4.x，如果使用的是3.x版本需要进行相应修改。
3. 代码中使用了Fastjson和Netty，需要进行相应依赖的引入。