如何在java中使用BufferdReader读取数据直到eof()

Question

你好，我遇到了一个小问题eof()

我在客户端和服务器之间创建了一个tcp连接，将文本发送到服务器和

接收回大写字母但是问题是它只读取一行所以

我想修改代码，使其读取，直到我键入&;stop &;。当我同时输入stop

客户端和接收端同时终止。

这是客户端类

import java.io.*;
import java.net.*;
public class Klient {
/**
* @param args
* @throws IOException 
* @throws UnknownHostException 
*/
public static void main(String[] args) throws UnknownHostException, 
IOException {
String sentence;
String modifiedSentence;
BufferedReader inFromUser = new BufferedReader(new 
InputStreamReader(System.in));
Socket clientSocket = new Socket("127.0.0.1", 6789);
DataOutputStream outToServer = new 
DataOutputStream(clientSocket.getOutputStream());
BufferedReader inFromServer = new BufferedReader(new 
InputStreamReader(clientSocket.getInputStream()));
while (true){
sentence = inFromUser.readLine();
outToServer.writeBytes(sentence + 'n');
modifiedSentence = inFromServer.readLine();
System.out.println(modifiedSentence);
}
//clientSocket.close();
}
}

服务器类

import java.io.*;
import java.net.*;
public class TCPServer {
/**
* @param args
* @throws IOException 
*/
public static void main(String[] args) throws IOException {
String clientSentence;
String capitalizedSentence;
ServerSocket welcomeSocket = new ServerSocket(6789);
while (true){
Socket connectionSocket = welcomeSocket.accept();
BufferedReader inFromClient = new BufferedReader(new 
InputStreamReader(connectionSocket.getInputStream()));
DataOutputStream outToClient = new 
DataOutputStream(connectionSocket.getOutputStream());
clientSentence = inFromClient.readLine();
capitalizedSentence = clientSentence.toUpperCase() + 'n';
outToClient.writeBytes(capitalizedSentence);
}
}

Answer 1

它只读取一个句子，因为服务器没有重复请求新的输入。当然，您有一个while(true)循环，但该循环反复接受新连接(这就是welcomeSocket.accept()所做的)。一旦请求了一行输入，就返回到循环的起点，等待另一个连接的到来。当然，没有更多的连接到来，所以服务器永远什么也不做。

你应该添加一个内循环，

while (true){
Socket connectionSocket = welcomeSocket.accept();
BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
while(true) {
clientSentence = inFromClient.readLine();
if (clientSentence.equalsIgnoreCase("stop")) {
connectionSocket.close();
break;
}
capitalizedSentence = clientSentence.toUpperCase() + 'n';
outToClient.writeBytes(capitalizedSentence);
}
}

一旦服务器收到&;stop&;，它将关闭与当前客户端的连接，并等待另一个客户端连接，因为它返回到外部循环的顶部。如果您希望服务器完全终止(因此只接受一个连接)，只需删除外部循环，并关闭welcomeSocket:

ServerSocket welcomeSocket = new ServerSocket(6789);
Socket connectionSocket = welcomeSocket.accept();
BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
while(true) {
clientSentence = inFromClient.readLine();
if (clientSentence.equalsIgnoreCase("stop")) {
connectionSocket.close();
break;
}
capitalizedSentence = clientSentence.toUpperCase() + 'n';
outToClient.writeBytes(capitalizedSentence);
}
welcomeSocket.close();

对于客户端来说，inFromServer.readLine返回null时可以跳出循环，表示连接已经关闭。

while (true){
sentence = inFromUser.readLine();
outToServer.writeBytes(sentence + 'n');
modifiedSentence = inFromServer.readLine();
if (modifiedSentence == null) {
break;
}
System.out.println(modifiedSentence);
}