Socket使用BufferedReader和BufferedWriter读不到数据的问题

深藏阁楼爱情的钟 2022-12-10 14:40 177阅读 0赞

BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));

/**
     * 服务端
     */
    public class Server {
        public static void main(String[] args) throws IOException {
            ServerSocket serverSocket = new ServerSocket(8080);
            while (true) {
                Socket socket = serverSocket.accept();
                System.out.println("客户端连接成功...");
                BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
                writer.write("服务端连接成功");
                writer.flush(); // writer.flush()后客户端也读不到数据
                System.out.println("发送消息...");
            }
        }
    }

/**
     * 客户端
     */
    public class Client {
        public static void main(String[] args) throws IOException {
            Socket socket = new Socket("127.0.0.1", 8080);
            BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            String msg = reader.readLine();
            System.out.println(msg);
        }
    }

准确的说不是因为flush方法的问题，而是因为服务器端接受数据时使用的**readLine()**方法必须要接收到一个换行符才能读取一行，再发送一个换行符，如write("\\n")，服务器端就能接收到了。当然，flush()也是必须要执行的。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNzk0OTcz_size_16_color_FFFFFF_t_70][]

/**
     * 服务端
     */
    public class Server {
        public static void main(String[] args) throws IOException {
            ServerSocket serverSocket = new ServerSocket(8080);
            while (true) {
                Socket socket = serverSocket.accept();
                System.out.println("客户端连接成功...");
                BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
                writer.write("服务端连接成功");
                // 以下三个任意一个都可以
                writer.write("\n"); // 换行符
                //writer.write("\r");
                //writer.write("\r\n");
                writer.flush(); // 这个也必须执行
                System.out.println("发送消息...");
            }
        }
    }

/**
     * 服务端
     */
    public class Server {
        public static void main(String[] args) throws IOException {
            ServerSocket serverSocket = new ServerSocket(8080);
            while (true) {
                Socket socket = serverSocket.accept();
                System.out.println("客户端连接成功...");
                PrintStream ps = new PrintStream(socket.getOutputStream());
                ps.println("服务端连接成功"); // 换成 ps.print 同样收不到消息
                System.out.println("发送消息...");
            }
        }
    }

> [https://blog.csdn.net/ge1mina023/article/details/51535505][https_blog.csdn.net_ge1mina023_article_details_51535505]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNzk0OTcz_size_16_color_FFFFFF_t_70]: /images/20221123/c39d399ece0945c2ae6676d4bbbef116.png
[https_blog.csdn.net_ge1mina023_article_details_51535505]: https://blog.csdn.net/ge1mina023/article/details/51535505