“NanoHttpd微型服务器”使用及源码阅读

“NanoHttpd微型服务器”使用及源码阅读

NanoHttpd仅有一个Java文件的微型Http服务器实现。其方便嵌入式设备（例如：Android设备）中启动一个本地服务器，接收客户端本地部分请求；应用场景也非常广泛，例如：本地代理方式播放m3u8视频、本地代理方式加载一些加密秘钥等。

这里分三部分学习一个这个NanoHttpd：

  • 了解官方对NanoHttpd描述定义
  • 举例NanoHttpd在Android上的使用（Android本地代理，播放Sdcard中的m3u8视频）
  • 分析源码实现

NanoHttpd GitHub地址：https://github.com/NanoHttpd/nanohttpd

一、NanoHttpd 官方描述

Tiny, easily embeddable HTTP server in Java.
微小的，轻量级适合嵌入式设备的Java Http服务器；
NanoHTTPD is a light-weight HTTP server designed for embedding in other applications, released under a Modified BSD licence.
NanoHTTPD是一个轻量级的、为嵌入式设备应用设计的HTTP服务器，遵循修订后的BSD许可协议。

核心功能描述：

  • Only one Java file, providing HTTP 1.1 support.
    仅一个Java文件，支持Http 1.1
  • No fixed config files, logging, authorization etc. (Implement by yourself if you need them. Errors are passed to java.util.logging, though.)
    没有固定的配置文件、日志系统、授权等等（如果你有需要需自己实现。工程中的日志输出，通过java.util.logging实现的）
  • Support for HTTPS (SSL).
    支持Https
  • Basic support for cookies.
    支持cookies
  • Supports parameter parsing of GET and POST methods.
    支持POST和GET 参数请求
  • Some built-in support for HEAD, POST and DELETE requests. You can easily implement/customize any HTTP method, though.
    内置支持HEAD、POST、DELETE请求，你可以方便的实现或自定义任何HTTP方法请求。
  • Supports file upload. Uses memory for small uploads, temp files for large ones.
    支持文件上传。小文件上传使用内存缓存，大文件使用临时文件缓存。
  • Never caches anything.
    不缓存任何内容
  • Does not limit bandwidth, request time or simultaneous connections by default.
  • 默认不限制带宽、请求时间 和 最大请求量
  • All header names are converted to lower case so they don't vary between browsers/clients.
    所有Header 名都被转换为小写，因此不会因客户端或浏览器的不同而有所差别
  • Persistent connections (Connection "keep-alive") support allowing multiple requests to be served over a single socket connection.
    支持一个socket连接服务多个长连接请求。

二、NanoHttpd在Android上的使用举例

为了学习NanoHttpd，做了一个简单Demo “Android 本地代理方式播放 Sdcard中的m3u8视频”：
Android 本地代理方式播放 Sdcard中的m3u8视频
https://github.com/AndroidAppCodeDemo/Android_LocalM3u8Server

实现效果图：

enter description here

注：

下边来主要来跟踪学习NanoHttpd的源码...

三、NanoHttpd源码跟踪学习

注：基于 NanoHttpd 2.3.1版本
NanoHttpd 2.3.1版本下载
https://github.com/NanoHttpd/nanohttpd/releases/tag/nanohttpd-project-2.3.1

NanoHTTPD大概的处理流程是：

  • 开启一个服务端线程，绑定对应的端口，调用 ServerSocket.accept()方法进入等待状态
  • 每个客户端连接均开启一个线程，执行ClientHandler.run()方法
  • 客户端线程中，创建一个HTTPSession会话。执行HTTPSession.execute()
  • HTTPSession.execute() 中会完成 uri, method, headers, parms, files 的解析，并调用如下方法：
// 自定义服务器时，亦需要重载该方法
// 该方法传入参数中，已解析出客户端请求的所有数据，重载该方法进行相应的业务处理
HTTPSession.serve(String uri, Method method, Map<String, String> headers, Map<String, String> parms, Map<String, String> files)
  • 组织Response数据，并调用ChunkedOutputStream.send(outputStream)返回给客户端

建议：
对于Http request、response 数据组织形式不是很了解的同学，建议自己了解后再阅读NanoHTTPD源码。 也可参考我的另一篇文章：
HTTP 协议详解
https://xiaxl.blog.csdn.net/article/details/104541274

3.1、NanoHTTPD.start

从服务器启动开始学习...

/**
 * Start the server. 启动服务器
 *
 * @param timeout timeout to use for socket connections. 超时时间
 * @param daemon  start the thread daemon or not. 守护线程
 * @throws IOException if the socket is in use.
 */
public void start(final int timeout, boolean daemon) throws IOException {
    // 创建一个ServerSocket
    this.myServerSocket = this.getServerSocketFactory().create();
    this.myServerSocket.setReuseAddress(true);

    // 创建 ServerRunnable
    ServerRunnable serverRunnable = createServerRunnable(timeout);
    // 启动一个线程监听客户端请求
    this.myThread = new Thread(serverRunnable);
    this.myThread.setDaemon(daemon);
    this.myThread.setName("NanoHttpd Main Listener");
    this.myThread.start();
    //
    while (!serverRunnable.hasBinded && serverRunnable.bindException == null) {
        try {
            Thread.sleep(10L);
        } catch (Throwable e) {
            // on android this may not be allowed, that's why we
            // catch throwable the wait should be very short because we are
            // just waiting for the bind of the socket
        }
    }
    if (serverRunnable.bindException != null) {
        throw serverRunnable.bindException;
    }
}

从以上代码中，可以看到：

  • 代码前两行，创建一个ServerSocket
  • 开启一个线程，执行ServerRunnable。这里其实就是服务端启动一个线程，用来监听客户端的请求，具体代码在ServerRunnable中。

3.2、ServerRunnable.run()

@Override
public void run() {
    Log.e(TAG, "---run---");
    try {
        // bind
        myServerSocket.bind(hostname != null ? new InetSocketAddress(hostname, myPort) : new InetSocketAddress(myPort));
        hasBinded = true;
    } catch (IOException e) {
        this.bindException = e;
        return;
    }
    Log.e(TAG, "bind ok");
    do {
        try {
            Log.e(TAG, "before accept");
            // 等待客户端连接
            final Socket finalAccept = NanoHTTPD.this.myServerSocket.accept();
            // 设置超时时间
            if (this.timeout > 0) {
                finalAccept.setSoTimeout(this.timeout);
            }
            // 服务端：输入流
            final InputStream inputStream = finalAccept.getInputStream();
            Log.e(TAG, "asyncRunner.exec");
            // 执行客户端 ClientHandler
            NanoHTTPD.this.asyncRunner.exec(createClientHandler(finalAccept, inputStream));
        } catch (IOException e) {
            NanoHTTPD.LOG.log(Level.FINE, "Communication with the client broken", e);
        }
    } while (!NanoHTTPD.this.myServerSocket.isClosed());
}

ServerRunnable的run()方法：

  • 调用 ServerSocket.bind 方法，绑定对应的端口
  • 调用 ServerSocket.accept() 线程进入阻塞等待状态
  • 客户端连接后，会执行createClientHandler(finalAccept, inputStream)创建一个ClientHandler，并开启一个线程，执行其对应的ClientHandler.run()方法
  • 自定义服务器时，重载Response HTTPSession.serve(uri, method, headers, parms, files)方法，对客户端的请求数据做出处理

3.3、ClientHandler.run()

@Override
public void run() {
    Log.e(TAG, "---run---");
    // 服务端 输出流
    OutputStream outputStream = null;
    try {
        // 服务端的输出流
        outputStream = this.acceptSocket.getOutputStream();
        // 创建临时文件
        TempFileManager tempFileManager = NanoHTTPD.this.tempFileManagerFactory.create();
        // session 会话
        HTTPSession session = new HTTPSession(tempFileManager, this.inputStream, outputStream, this.acceptSocket.getInetAddress());
        // 执行会话
        while (!this.acceptSocket.isClosed()) {
            session.execute();
        }
    } catch (Exception e) {
        // When the socket is closed by the client,
        // we throw our own SocketException
        // to break the "keep alive" loop above. If
        // the exception was anything other
        // than the expected SocketException OR a
        // SocketTimeoutException, print the
        // stacktrace
        if (!(e instanceof SocketException && "NanoHttpd Shutdown".equals(e.getMessage())) && !(e instanceof SocketTimeoutException)) {
            NanoHTTPD.LOG.log(Level.SEVERE, "Communication with the client broken, or an bug in the handler code", e);
        }
    } finally {
        safeClose(outputStream);
        safeClose(this.inputStream);
        safeClose(this.acceptSocket);
        NanoHTTPD.this.asyncRunner.closed(this);
    }
}
  • TempFileManager临时文件是为了缓存客户端Post请求的请求Body数据（如果数据较小，内存缓存；文件较大，缓存到文件中）
  • 创建一个HTTPSession会话，并执行其对应的HTTPSession.execute()方法
  • HTTPSession.execute()中会对客户端的请求进行解析

3.4、HTTPSession.execute()


@Override
public void execute() throws IOException {
    Log.e(TAG, "---execute---");
    Response r = null;
    try {
        // Read the first 8192 bytes.
        // The full header should fit in here.
        // Apache's default header limit is 8KB.
        // Do NOT assume that a single read will get the entire header
        // at once!
        // Apache默认header限制8k
        byte[] buf = new byte[HTTPSession.BUFSIZE];
        this.splitbyte = 0;
        this.rlen = 0;
        // 客户端输入流
        int read = -1;
        this.inputStream.mark(HTTPSession.BUFSIZE);
        // 读取8k的数据
        try {
            read = this.inputStream.read(buf, 0, HTTPSession.BUFSIZE);
        } catch (SSLException e) {
            throw e;
        } catch (IOException e) {
            safeClose(this.inputStream);
            safeClose(this.outputStream);
            throw new SocketException("NanoHttpd Shutdown");
        }
        if (read == -1) {
            // socket was been closed
            safeClose(this.inputStream);
            safeClose(this.outputStream);
            throw new SocketException("NanoHttpd Shutdown");
        }
        // 分割header数据
        while (read > 0) {
            this.rlen += read;
            // header
            this.splitbyte = findHeaderEnd(buf, this.rlen);
            // 找到header
            if (this.splitbyte > 0) {
                break;
            }
            // 8k中剩余数据
            read = this.inputStream.read(buf, this.rlen, HTTPSession.BUFSIZE - this.rlen);
        }
        // header数据不足8k，跳过header数据
        if (this.splitbyte < this.rlen) {
            this.inputStream.reset();
            this.inputStream.skip(this.splitbyte);
        }
        //
        this.parms = new HashMap<String, List<String>>();
        // 清空header列表
        if (null == this.headers) {
            this.headers = new HashMap<String, String>();
        } else {
            this.headers.clear();
        }
        // 解析 客户端请求
        // Create a BufferedReader for parsing the header.
        BufferedReader hin = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(buf, 0, this.rlen)));
        // Decode the header into parms and header java properties
        Map<String, String> pre = new HashMap<String, String>();
        decodeHeader(hin, pre, this.parms, this.headers);
        //
        if (null != this.remoteIp) {
            this.headers.put("remote-addr", this.remoteIp);
            this.headers.put("http-client-ip", this.remoteIp);
        }
        Log.e(TAG, "headers: " + headers);

        this.method = Method.lookup(pre.get("method"));
        if (this.method == null) {
            throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Syntax error. HTTP verb " + pre.get("method") + " unhandled.");
        }
        Log.e(TAG, "method: " + method);

        this.uri = pre.get("uri");
        Log.e(TAG, "uri: " + uri);

        this.cookies = new CookieHandler(this.headers);
        Log.e(TAG, "cookies: " + this.cookies.cookies);

        String connection = this.headers.get("connection");
        Log.e(TAG, "connection: " + connection);
        boolean keepAlive = "HTTP/1.1".equals(protocolVersion) && (connection == null || !connection.matches("(?i).*close.*"));
        Log.e(TAG, "keepAlive: " + keepAlive);
        // Ok, now do the serve()

        // TODO: long body_size = getBodySize();
        // TODO: long pos_before_serve = this.inputStream.totalRead()
        // (requires implementation for totalRead())
        // 构造一个response
        r = serve(HTTPSession.this);
        // TODO: this.inputStream.skip(body_size -
        // (this.inputStream.totalRead() - pos_before_serve))

        if (r == null) {
            throw new ResponseException(Response.Status.INTERNAL_ERROR, "SERVER INTERNAL ERROR: Serve() returned a null response.");
        } else {
            String acceptEncoding = this.headers.get("accept-encoding");
            this.cookies.unloadQueue(r);
            // method
            r.setRequestMethod(this.method);
            r.setGzipEncoding(useGzipWhenAccepted(r) && acceptEncoding != null && acceptEncoding.contains("gzip"));
            r.setKeepAlive(keepAlive);

            // 发送response
            r.send(this.outputStream);
        }
        if (!keepAlive || r.isCloseConnection()) {
            throw new SocketException("NanoHttpd Shutdown");
        }
    } catch (SocketException e) {
        // throw it out to close socket object (finalAccept)
        throw e;
    } catch (SocketTimeoutException ste) {
        // treat socket timeouts the same way we treat socket exceptions
        // i.e. close the stream & finalAccept object by throwing the
        // exception up the call stack.
        throw ste;
    } catch (SSLException ssle) {
        Response resp = newFixedLengthResponse(Response.Status.INTERNAL_ERROR, NanoHTTPD.MIME_PLAINTEXT, "SSL PROTOCOL FAILURE: " + ssle.getMessage());
        resp.send(this.outputStream);
        safeClose(this.outputStream);
    } catch (IOException ioe) {
        Response resp = newFixedLengthResponse(Response.Status.INTERNAL_ERROR, NanoHTTPD.MIME_PLAINTEXT, "SERVER INTERNAL ERROR: IOException: " + ioe.getMessage());
        resp.send(this.outputStream);
        safeClose(this.outputStream);
    } catch (ResponseException re) {
        Response resp = newFixedLengthResponse(re.getStatus(), NanoHTTPD.MIME_PLAINTEXT, re.getMessage());
        resp.send(this.outputStream);
        safeClose(this.outputStream);
    } finally {
        safeClose(r);
        this.tempFileManager.clear();
    }
}
  • HTTPSession.execute() 完成了 uri, method, headers, parms, files 的解析
  • 完成解析后，调用Response serve(IHTTPSession session)方法，创建了一个Response
  • 完成Response数据组织后，这里会调用ChunkedOutputStream.send(outputStream)方法将数据发出去。

到这里，主要流程结束，其他细节需大家自己去用心研读源码了。我的Demo中增加了很多中文注释，可以帮助大家省下一部分力气，就这样了

相关参考

NanoHttpd GitHub
https://github.com/NanoHttpd/nanohttpd

NanoHttpd源码分析
https://www.iteye.com/blog/shensy-1880381

========== THE END ==========

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原文地址：https://www.cnblogs.com/xiaxveliang/p/12395936.html