java - 使用 BufferedReader/BufferedWriter 进行套接字连接

Question

我的服务器未向客户端发送带有 BufferedWriter 的响应。代码似乎停在 int amountOfNumbersToBeGenerate = Integer.parseInt(bufferedReader.readLine()); 我相信客户端的 bufferedreader.readline() 调用在某种意义上导致并发出并阻塞连接。

import java.io.*;
import java.net.Socket;
import java.util.ArrayList;

public class ThreadedConnection implements Runnable {

    private Socket connection;
    private InputStream in;
    private OutputStream out;

    public ThreadedConnection(Socket connection) {
        this.connection = connection;
        try {
            this.in = this.connection.getInputStream();
            this.out = this.connection.getOutputStream();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in));
        BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(out));
        try {

            String lotteryType = bufferedReader.readLine(); //reads first line of input stream

            int amountOfNumbersToBeGenerated = Integer.parseInt(bufferedReader.readLine());
            System.out.println("3"+amountOfNumbersToBeGenerated);
            switch (lotteryType) {
                case "LuckyForLife":

                        generateLotteryNumbers(amountOfNumbersToBeGenerated, 48, 18, bufferedWriter);
                    break;
                case "MegaMillions":
                    generateLotteryNumbers(amountOfNumbersToBeGenerated, 70, 25, bufferedWriter);
                    break;
                case "PowerBall":
                    generateLotteryNumbers(amountOfNumbersToBeGenerated, 69, 26, bufferedWriter);
                    break;
                default:
                    break;
            }
            bufferedWriter.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                connection.close();
                bufferedReader.close();
                bufferedWriter.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public void generateLotteryNumbers(int amountOfNumbersToBeGenerated, int upperLimitOfGeneratedNumbers, int upperLimitOfExtraNumber, BufferedWriter bufferedWriter){
        RandomNumberGenerator randomNumbers = new RandomNumberGenerator(amountOfNumbersToBeGenerated,upperLimitOfGeneratedNumbers);
        RandomNumberGenerator extraNumber = new RandomNumberGenerator(1,upperLimitOfExtraNumber);
        ArrayList randomNumbersArrayList = randomNumbers.NumberGenerator();
        ArrayList extraNumberArrayList = extraNumber.NumberGenerator();
        String randomNumbersString = randomNumbersArrayList.toString();
        randomNumbersString = randomNumbersString.substring(1, randomNumbersString.length()-1);
        String extraNumberString = extraNumberArrayList.toString();
        extraNumberString = extraNumberString.substring(1, extraNumberString.length()-1);

        try {
            bufferedWriter.write(randomNumbersString);
            bufferedWriter.newLine();
            bufferedWriter.write(extraNumberString);
            bufferedWriter.newLine();
            bufferedWriter.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }

//        System.out.println(randomNumbersString);
//        System.out.println(extraNumberString);
    }
}

这是客户端的代码。我认为第一个 String gerneretedNumber = bufferedReader.readLine(); 导致了问题。几乎就好像当服务器没有写出任何内容时调用它来读取，然后扰乱服务器端读取。如果我阻止两个 readline() 调用，服务器上的代码就会起作用，并且我可以在控制台上打印一些内容。

static void runClient(){
        OutputStream outputStream;
        InputStream inputStream;

        Socket client;
        BufferedWriter bufferedWriter;
        BufferedReader bufferedReader;

        try {
            System.out.println("Creating client socket ");
            client = new Socket("127.0.0.1", 5000);

            outputStream = client.getOutputStream();
            inputStream = client.getInputStream();
            bufferedWriter = new BufferedWriter(new 
OutputStreamWriter(outputStream));
            //bufferedReader = new BufferedReader(new 
InputStreamReader(System.in));
            bufferedReader = new BufferedReader(new 
InputStreamReader(inputStream));

            bufferedWriter.write("LuckyForLife");
            bufferedWriter.newLine();
            bufferedWriter.write("5");
            bufferedWriter.flush();

            String generetedNumber = bufferedReader.readLine();
            String extraNumber = bufferedReader.readLine();

                System.out.println(gerneretedNumber);
                System.out.println(extraNumber);


            System.out.println("Guess its null");
            bufferedReader.close();
            bufferedWriter.close();
            client.close();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

如果需要更多信息，我很乐意发布。

Answer 1

你的客户端永远不会发送第二个换行符。根据您的协议(protocol)，客户端不会半关闭(输出关闭)，因此服务器无法检测到流结束。

顺便说一句，在关闭套接字(tcp RST)之前尝试关闭流(tcp FIN)；这更“道德”!开个玩笑，tcp rst 是一个kill，并且挂起的字节可能不会被刷新(尽管这里有很多刷新，但这只是一个很好的做法)。