public abstract class TomcatServlet {
 
    public void service(ServletRequest request, ServletResponse response){
        if ("GET".equalsIgnoreCase(request.getMethod())){
            doGet(request, response);
        }else if ("POST".equalsIgnoreCase(request.getMethod())){
            doPost(request, response);
        }else {
            doResponse(response, "暫不支持其它請(qǐng)求方法");
        }
    }
 
    public abstract void doGet(ServletRequest request, ServletResponse response);
    public abstract void doPost(ServletRequest request, ServletResponse response);
 
    public void doResponse(ServletResponse response, String message){
        response.write(message);
    }
}          

@Data
public class ServletRequest {
 
    private ChannelHandlerContext context;
    private HttpRequest httpRequest;
 
    public ServletRequest(){
 
    }
 
    public ServletRequest(ChannelHandlerContext context, HttpRequest httpRequest){
        this.context = context;
        this.httpRequest = httpRequest;
    }
 
    public String getMethod(){
        return httpRequest.method().name();
    }
 
    public HttpHeaders getHeaders(){
        return httpRequest.headers();
    }
 
    public Map<String, List<String>> getParameters(){
        QueryStringDecoder decoder = new QueryStringDecoder(httpRequest.uri());
        return decoder.parameters();
    }
 
    public Map<String,String> getPostFormParameters(){
        Map<String,String> params = new HashMap<>();
 
        HttpPostRequestDecoder decoder = new HttpPostRequestDecoder(httpRequest);
        decoder.getBodyHttpDatas().forEach(item -> {
            if (item.getHttpDataType() == InterfaceHttpData.HttpDataType.Attribute){
                Attribute attribute = (Attribute) item;
 
                try {
                    String key = attribute.getName();
                    String value = attribute.getValue();
 
                    params.put(key, value);
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        });
 
        return params;
    }
 
    public Map<String, Object> getPostBody(){
        ByteBuf content = ((FullHttpRequest)httpRequest).content();
        byte[] bytes = new byte[content.readableBytes()];
        content.readBytes(bytes);
 
        return JSON.parseObject(new String(bytes)).getInnerMap();
    }
}

@Data
public class ServletResponse {
 
    private ChannelHandlerContext context;
    private HttpRequest httpRequest;
 
    public ServletResponse(){
 
    }
 
    public ServletResponse(ChannelHandlerContext context, HttpRequest httpRequest){
        this.context = context;
        this.httpRequest = httpRequest;
    }
 
    public void write(String message){
        FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
        response.headers().set("Content-Type","application/json;charset=utf-8");
        response.content().writeCharSequence(message, StandardCharsets.UTF_8);
 
        context.channel().writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }
}

ublic class CustomServlet extends TomcatServlet{
 
    @Override
    public void doGet(ServletRequest request, ServletResponse response) {
        System.out.println("處理GET請(qǐng)求");
        System.out.println("請(qǐng)求參數(shù)為：");
        request.getParameters().forEach((key,value) -> System.out.println(key + " ==> "+value));
 
        doResponse(response, "GET success");
    }
 
    @Override
    public void doPost(ServletRequest request, ServletResponse response) {
        if (request.getHeaders().get("Content-Type").contains("x-www-form-urlencoded")){
            System.out.println("處理POST Form請(qǐng)求");
            System.out.println("請(qǐng)求參數(shù)為：");
            request.getPostFormParameters().forEach((key,value) -> System.out.println(key + " ==> " + value));
 
            doResponse(response, "POST Form success");
        }else if (request.getHeaders().get("Content-Type").contains("application/json")){
            System.out.println("處理POST json請(qǐng)求");
            System.out.println("請(qǐng)求參數(shù)為：");
            request.getPostBody().forEach((key,value) -> System.out.println(key + " ==> " + value));
 
            doResponse(response, "POST json success");
        }else {
            doResponse(response, "error：暫不支持其它post請(qǐng)求方式");
        }
    }
}

public class ServletMapping {
 
    private static final Map<String,TomcatServlet> urlServletMapping = new HashMap<>();
 
    public static Map<String, TomcatServlet> getUrlServletMapping(){
        return urlServletMapping;
    }
}

servlet.url=/hello
servlet.className=com.example.demo.tomcat.servlet.CustomServlet

public class CustomServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {
 
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, FullHttpRequest request) throws Exception {
        String uri = request.uri();
        String path = uri;
        if (uri.contains("?")){
            path = uri.substring(0,uri.indexOf("?"));
        }
 
        if (ServletMapping.getUrlServletMapping().containsKey(path)){
            ServletRequest servletRequest = new ServletRequest(channelHandlerContext, request);
            ServletResponse servletResponse = new ServletResponse(channelHandlerContext, request);
 
            ServletMapping.getUrlServletMapping().get(path).service(servletRequest, servletResponse);
        }else {
            FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
            response.content().writeCharSequence("404 NOT FOUND："+path+"不存在", StandardCharsets.UTF_8);
 
            channelHandlerContext.channel().writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
        }
    }
}

public class NettyServer {
 
    private static final Properties webProperties = new Properties();
 
    public static void init(){
        try {
            InputStream inputStream = new FileInputStream("./web.properties");
            webProperties.load(inputStream);
 
            for (Object item : webProperties.keySet()){
                String key = (String)item;
                if (key.endsWith(".url")){
                    String servletKey = key.replaceAll("\\.url","\\.className");
                    String servletName = webProperties.getProperty(servletKey);
 
                    TomcatServlet servlet = (TomcatServlet) Class.forName(servletName).newInstance();
                    ServletMapping.getUrlServletMapping().put(webProperties.getProperty(key),servlet);
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }
 
    public static void startServer(int port){
        init();
 
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
 
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 128)
                    .childOption(ChannelOption.SO_KEEPALIVE, true)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
 @Overrideprotected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline channelPipeline = socketChannel.pipeline();
channelPipeline.addLast(new HttpRequestDecoder());
channelPipeline.addLast(new HttpResponseEncoder());
channelPipeline.addLast(new HttpObjectAggregator(65535));
channelPipeline.addLast(new CustomServerHandler());}
                    });
 
            ChannelFuture channelFuture = serverBootstrap.bind(port).sync();
            channelFuture.channel().closeFuture().sync();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
 
    public static void main(String[] args) {
        startServer(8000);
    }
}