客户端

   public static void main(String[] args) throws UnknownHostException, IOException {// TODO Auto-generated method stubSocket socket = new Socket("192.168.43.195", 12344);BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));System.out.println(br.readLine());socket.close();}

服务端

  public static void main(String[] args) throws IOException {// TODO Auto-generated method stubServerSocket server = new ServerSocket(12344);Socket socket  = server.accept();BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));String line = "hello";bw.write(line);}

代码很简单，可以看到从服务端发出的hello要在客户端输出，但是在运行后并没有达到预期的效果。

除非把server端的输出流关闭才可以在client端输出，在输出流关闭后bw.close()会返回一个null。readline()是一个阻塞函数，在没有数据读的时候会一直卡在那里等待/r/n的出现

分析程序在服务端写入的hello之后客户端则读取，这里选用bufferedreader是因为他里面有一个可以读取整行的方法。调用br.readline()方法之后返回的是string，但是在行的末尾没有/r和/n,readline方法也就没办法停止，一直卡在这里。知道问题出在这里想了一下解决办法，在输入的字符串的末尾加/r/n但是我没有成功，改善的代码如下：

客户端：

  public static void main(String[] args) throws UnknownHostException, IOException {// TODO Auto-generated method stubSocket socket = new Socket("192.168.43.195", 12344);BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));PrintStream ps = new PrintStream(socket.getOutputStream());System.out.println(br.readLine());socket.close();}

服务端：

        public static void main(String[] args) throws IOException {ServerSocket server = new ServerSocket(12344);Socket socket  = server.accept();BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));PrintStream ps = new PrintStream(socket.getOutputStream());ps.println("hello");}

可以看到在ps调用的println方法后会自动换行，此时跳到client端当读到hello的末尾会识别到换行符，就可以打印输出了。