Java，Telnet，检查 InputStream 中的字符串

Question

我很原始。我正在尝试编写一个 Java 类来与 Telnet 交互。我看到 Apache Commons 和 Jsacpe 有 API。我正在使用 Jscape 的 Sinetfactory。一旦 telnet.connect() 发生，我正在连接的 Telnet 会立即发送输入“用户名？：”的提示。我需要验证这个提示是否真的发生了，所以我不只是在可能发生其他事情时写下答案。我对此缺乏经验，并且确信有一个简单的答案，只是想知道是否有人可以提供帮助。

这就是我所拥有的，它有点草率，因为我已经玩了一段时间了，不知道如何真正从流中读取最后一个字符。

import com.jscape.inet.telnet.*;

public class TelnetTest extends TelnetAdapter {

    private final static String USER = "xxx\r";
    private final static String PWORD = "yyy\r";
    private final static String COMMAND = "zzz\r";
    private final static byte[] USER_BYTE = USER.getBytes();
    private final static byte[] PWORD_BYTE = PWORD.getBytes();
    private final static byte[] COMMAND_BYTE = COMMAND.getBytes();
    private Telnet telnet = null;
    private OutputStream output = null;
    private static BufferedReader reader = null;
    private boolean connected = false;
    private String hostname = "qqq";
    //TelnetInputStream tis = null; NOT IN USE AS OF NOW

    public TelnetTest() throws IOException, TelnetException {

        // create new Telnet instance
        telnet = new Telnet(hostname);

        // register this class as TelnetListener
        telnet.addTelnetListener(this);

        // establish Telnet connection
        telnet.connect();
        connected = true;
        output = telnet.getOutputStream();

// HERE IS WHERE I NEED HELP, NOT SURE HOW TO CHECK STREAM
        String str = null;
        if ((str = reader.readline()).equals("User name?:")) {
            telnet.getOutputStream().write(USER_BYTE);
        }
// SAME CHECK WOULD HAPPEN HERE FOR "Password"
        telnet.getOutputStream().write(PWORD_BYTE);
//  ANOTHER SIMILAR CHECK HERE
        telnet.getOutputStream().write(COMMAND_BYTE);

        // sends all data entered at console to Telnet server
        String input = null;
        while ((input = reader.readLine()) != null) {
            if (connected) {
                ((TelnetOutputStream) output).println(input);
            } else {
                break;
            }
        }
    }

    public boolean streamContainsString(Reader reader, String searchString)
            throws IOException {
        Scanner streamScanner = new Scanner(reader);
        if (streamScanner.findWithinHorizon(searchString, 0) != null) {
            return true;
        } else {
            return false;
        }
    }

    // Invoked when Telnet socked is connected.
    public void connected(TelnetConnectedEvent event) {
        System.out.println("Connected");
    }

    // Invoked when Telnet socket is disconnected. Disconnect can
    public void disconnected(TelnetDisconnectedEvent event) {
        connected = false;
        System.out.print("Disconnected.  Press enter key to quit.");
    }

    // Invoked when Telnet server requests that the Telnet client begin performing               specified TelnetOption.
    public void doOption(DoOptionEvent event) {
        // refuse any options requested by Telnet server
        telnet.sendWontOption(event.getOption());
    }

    // Invoked when Telnet server offers to begin performing specified TelnetOption.
    public void willOption(WillOptionEvent event) {
        // refuse any options offered by Telnet server
        telnet.sendDontOption(event.getOption());
    }

    // Invoked when data is received from Telnet server.
    public void dataReceived(TelnetDataReceivedEvent event) {
        // print data recevied from Telnet server to console
        System.out.print(event.getData());
    }

    public Telnet getTelnet() {
        return telnet;
    }

    // starts console program
    public static void main(String[] args) {
        try {
            // create BufferedReader to read data from console
            reader = new BufferedReader(new InputStreamReader(System.in));

            // create new TelnetExample instance
            TelnetTest example = new TelnetTest();

        } catch (Exception e) {
            e.printStackTrace(System.out);
        }
    }
}

Answer 1

如果您正在读/写字符串，那么您应该始终使用Reader 和Writer。 BufferedReader 允许您进行线路操作。因此，包裹在 Reader 周围的 BufferedReader（围绕 InputStreamReader）将允许您执行 readLine() 调用以从连接中获取输入行：

 BufferedReader reader =
     new BufferedReader(new InputStreamReader(telnet.getInputStream()));

要写入连接，您可以在 OutputStreamWriter 周围使用 Writer：

 Writer writer = new OutputStreamWriter(telnet.getOutputStream()));

我不确定这是否适用于来自Telnet 的流，但它适用于原始Socket。然后，您可以执行类似以下伪代码的操作：

 while (true) {
     read a line from the server
     some sort of if/then/else to test for the output
     write your username/password or whatever is appropriate for the connection
     repeat until some logout or IOException...
 }

Apache Telnet 类有许多有趣的侦听器和其他处理程序，如果您愿意，可以使用它们，但学习曲线可能更多。这是一个使用 TelnetClient 的很好的示例应用程序：

http://www.java2s.com/Code/Java/Network-Protocol/ExampleofuseofTelnetClient.htm