谁能帮我解释一下下面这段代码

唯一 发布于 2012/10/23 00:59
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public void await() {
        // Negative values - don't wait on port - tomcat is embedded or we just don't like ports
        if( port == -2 ) {
            // undocumented yet - for embedding apps that are around, alive.
            return;
        }
        if( port==-1 ) {
            try {
                awaitThread = Thread.currentThread();
                while(!stopAwait) {
                    try {
                        Thread.sleep( 10000 );
                    } catch( InterruptedException ex ) {
                        // continue and check the flag
                    }
                }
            } finally {
                awaitThread = null;
            }
            return;
        }

        // Set up a server socket to wait on
        try {
            awaitSocket =
                new ServerSocket(port, 1,
                                 InetAddress.getByName("localhost"));
        } catch (IOException e) {
            log.error("StandardServer.await: create[" + port
                               + "]: ", e);
            return;
        }

        try {
            awaitThread = Thread.currentThread();

            // Loop waiting for a connection and a valid command
            while (!stopAwait) {
                ServerSocket serverSocket = awaitSocket;
                if (serverSocket == null) {
                    break;
                }
    
                // Wait for the next connection
                Socket socket = null;
                StringBuilder command = new StringBuilder();
                try {
                    InputStream stream = null;
                    try {
                        socket = serverSocket.accept();
                        socket.setSoTimeout(10 * 1000);  // Ten seconds
                        stream = socket.getInputStream();
                    } catch (AccessControlException ace) {
                        log.warn("StandardServer.accept security exception: "
                                           + ace.getMessage(), ace);
                        continue;
                    } catch (IOException e) {
                        if (stopAwait) {
                            // Wait was aborted with socket.close()
                            break;
                        }
                        log.error("StandardServer.await: accept: ", e);
                        break;
                    }

                    // Read a set of characters from the socket
                    int expected = 1024; // Cut off to avoid DoS attack
                    while (expected < shutdown.length()) {
                        if (random == null)
                            random = new Random();
                        expected += (random.nextInt() % 1024);
                    }
                    while (expected > 0) {
                        int ch = -1;
                        try {
                            ch = stream.read();
                        } catch (IOException e) {
                            log.warn("StandardServer.await: read: ", e);
                            ch = -1;
                        }
                        if (ch < 32)  // Control character or EOF terminates loop
                            break;
                        command.append((char) ch);
                        expected--;
                    }
                } finally {
                    // Close the socket now that we are done with it
                    try {
                        if (socket != null) {
                            socket.close();
                        }
                    } catch (IOException e) {
                        // Ignore
                    }
                }

                // Match against our command string
                boolean match = command.toString().equals(shutdown);
                if (match) {
                    break;
                } else
                    log.warn("StandardServer.await: Invalid command '" +
                                       command.toString() + "' received");
            }
        } finally {
            ServerSocket serverSocket = awaitSocket;
            awaitThread = null;
            awaitSocket = null;

            // Close the server socket and return
            if (serverSocket != null) {
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    // Ignore
                }
            }
        }

    }


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谁能帮我解释一下tomcat的这段代码,我不是特别明白

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