所以我正在开发一个聊天程序，现在我想添加一个发送文件选项。 我尝试添加它并且它工作但文件传输完成后，两个套接字关闭（两个客户端的套接字）。 这是聊天客户端的SSCCE：
public class SSCCEChatClient extends JFrame {
private JPanel contentPane;
private JTextField inputUsernameField;
private JTextArea textArea;
String serversock = "84.252.37.82";
String username;
Socket sock;
BufferedReader reader;
PrintWriter writer;
InputStreamReader streamreader;
public class IncomingReader implements Runnable{
public void run() {
String stream;
String[] data;
try {
while ((stream = reader.readLine()) != null) {
data = stream.split("`");
if(data[2].equals("receiveFile")&&(!data[3].equals(username))){
DataInputStream in = new DataInputStream(sock.getInputStream());
byte[] bytes = new byte[Integer.parseInt(data[1])];
in.read(bytes);
FileOutputStream fos = new FileOutputStream(System.getProperty("user.home") + "\\Desktop\\" + data[0]);
fos.write(bytes);
fos.close();
in.close();
textArea.append("Success!");
}else if(data[2].equals("server")){
textArea.append(data[0]);
}
}
}catch(Exception ex) {
}
}
}//Incoming Reader
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
SSCCEChatClient frame = new SSCCEChatClient();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public SSCCEChatClient() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
setContentPane(contentPane);
textArea = new JTextArea();
contentPane.add(textArea, BorderLayout.SOUTH);
JButton btnNewButton = new JButton("Send File");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
File transferFile = new File (System.getProperty("user.home") + "\\Desktop\\PNG\\Night.png");
byte [] bytearray = new byte [(int)transferFile.length()];
try {
BufferedInputStream bin = new BufferedInputStream(new FileInputStream(transferFile));
bin.read(bytearray,0,bytearray.length);
DataOutputStream os = new DataOutputStream(sock.getOutputStream());
writer.println(transferFile.getName() + "`" + transferFile.length() + "`receiveFile`" + username);
writer.flush();
os.write(bytearray,0,bytearray.length);
os.flush();
bin.close();
os.close();
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("File transfer complete");
}
});
contentPane.add(btnNewButton, BorderLayout.CENTER);
JButton btnNewButton_1 = new JButton("Connect");
btnNewButton_1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
username = inputUsernameField.getText();
sock = new Socket(serversock, 5000);
streamreader = new InputStreamReader(sock.getInputStream());
reader = new BufferedReader(streamreader);
writer = new PrintWriter(sock.getOutputStream());
Thread IncomingReader = new Thread(new IncomingReader());
IncomingReader.start();
writer.println(username + "``connect");
writer.flush();
} catch (Exception ex) {
textArea.append("\nCannot Connect!");
}
}
});
contentPane.add(btnNewButton_1, BorderLayout.WEST);
inputUsernameField = new JTextField();
contentPane.add(inputUsernameField, BorderLayout.NORTH);
inputUsernameField.setColumns(10);
}
}
这是服务器端：
public class SSCCEServer {
static ArrayList<PrintWriter> clientOutputStreams;
static ArrayList<DataOutputStream> clientDataOutputStreams;
static ArrayList<String> onlineUsers = new ArrayList<>();
public class ClientHandler implements Runnable {
BufferedReader reader;
Socket sock;
PrintWriter client;
public ClientHandler(Socket clientSocket, PrintWriter user) {
// new inputStreamReader and then add it to a BufferedReader
client = user;
try {
sock = clientSocket;
System.out.println(clientSocket.getRemoteSocketAddress().toString() + " - ");
InputStreamReader isReader = new InputStreamReader(sock.getInputStream());
reader = new BufferedReader(isReader);
}
catch (Exception ex) {
System.out.println("error beginning StreamReader");
}
}
public void run() {
String message;
String[] data;
try {
while ((message = reader.readLine()) != null) {
data = message.split("`");
if(data[2].equals("receiveFile")){
DataInputStream in = new DataInputStream(sock.getInputStream());
byte[] bytes = new byte[Integer.parseInt(data[1])];
in.read(bytes);
tellEveryone(data[0] + "`" + data[1] + "`" + data[2] + "`" + data[3]);
for(DataOutputStream dos:clientDataOutputStreams){
try {
dos.write(bytes);
dos.close();
}
catch (Exception ex) {
System.out.println("error telling everyone");
}
}
tellEveryone("File transfer complete``server");
}else if(data[2].equals("connect")){
System.out.println(data[0] + "has connected.");
}else {
System.out.println("No Conditions were met.");
}
}
}
catch (Exception ex) {
System.out.println("lost a connection");
System.out.println(ex.getMessage().toString());
clientOutputStreams.remove(client);
}
}
}
public void tellEveryone(String message) {
// sends message to everyone connected to server
for(PrintWriter writer:clientOutputStreams){
try {
writer.println(message);
//pop("Sending: " + message);
writer.flush();
}
catch (Exception ex) {
System.out.println("error telling everyone");
}
}
}
public static void main(String[] args) {
new SSCCEServer().go();
}
public void go(){
clientOutputStreams = new ArrayList<PrintWriter>();
clientDataOutputStreams = new ArrayList<>();
try {
@SuppressWarnings("resource")
ServerSocket serverSock = new ServerSocket(5000);
while(true){
Socket clientSock = serverSock.accept();
PrintWriter writer = new PrintWriter(clientSock.getOutputStream());
clientOutputStreams.add(writer);
clientDataOutputStreams.add(new DataOutputStream(clientSock.getOutputStream()));
Thread listener = new Thread(new ClientHandler(clientSock, writer));
listener.start();
}
}
catch (Exception ex)
{
System.out.println("error making a connection");
}
}
}
很抱歉，如果它真的很长，但这是我可以带来的最小数量。此外，它不是整件事，因为它错过了发送文本方法但不影响SSCCE。我已经从服务器端使用'tellEveryone'方法演示了send方法。 此外，“\ PNG \ Night.png”只是一个示例，您可以创建自己的文件夹和文件以运行SSCCE。 在发送文件后，我该怎么做才能解决套接字的关闭问题？
答案 0 :(得分：3)
关闭Objects区块中的所有finally（try - catch - finally）
您遇到了Concurency in Swing的问题，但有三种方式
a）正确的方法
将代码包装到Runnable#Thread（最简单），必须将对Swing GUI的任何更改包装到invokeLater()
使用SwingWorker（以标准方式实施），其中方法publish，process和done非常确保所有events都已完成EDT
b）快捷方式，有效但不合适
invokeLater() 答案 1 :(得分：1)
关闭输出流时，套接字会关闭。如果要保持套接字打开，请不要关闭流。有关参考，请查看SocketOutputStream.java