我正在尝试制作一个套接字程序来同步来自两台 PC 的文件。所以基本上，我试图先进行单向同步。所以发生的事情是..
- 服务器和客户端通过套接字连接在一起。（好的）
- 服务器通过 ObjectOutputStream 发送他拥有的文件列表，客户端通过 ObjectInputStream 接收它。（好的）
- 客户端比较文件列表并将他没有的文件发送回服务器（通过 ObjectOutputStream）。（好的）
- 服务器将丢失的文件发送给客户端。（这里有问题）
我的错误出现在服务器端，它显示：
java.net.SocketException: Socket is closed
at java.net.Socket.getOutputStream(Unknown Source)
at ee4210.TcpServer$ConnectionRequestHandler.run(TcpServer.java:116)
at ee4210.TcpServer.handleClientRequest(TcpServer.java:80)
at ee4210.TcpServer.startServer(TcpServer.java:72)
at ee4210.TcpServer.main(TcpServer.java:39)
我相信它与 ObjectOutputStream 和 ObjectInputStream 有关，因为如果我不关闭 ObjectOutputStream 或 ObjectInputStream，它可以工作。
客户端可以同时拥有 ObjectOutputStream 和 ObjectInputStream 来发送/接收对象吗？同样，服务器也可以两者兼得吗？
感谢你的帮助。对不起，很长的帖子。我喜欢尽可能详细。
我的客户代码：
package ee4210;
import java.io.* ;
import java.net.* ;
import java.util.* ;public class TcpClient{
static ObjectOutputStream out;
static ObjectInputStream in;
String message;
int portNo=2004;
static Socket _socket = null;
InetAddress host = null;
static LinkedList destinationfiles = new <String>LinkedList();
static LinkedList sourcefiles = new <String>LinkedList();
static LinkedList missingfiles = new <String>LinkedList();
String filename=null;
TcpClient(){}
public static void listFilesForFolder(final File folder) { //no need to read this
for (final File fileEntry : folder.listFiles()) {
if (fileEntry.isDirectory()) {
listFilesForFolder(fileEntry);
} else {
//System.out.println(fileEntry.getName());
destinationfiles.add(fileEntry.getName());
}
}
}
public static void getListfromPeer() {
try {
in=new ObjectInputStream(_socket.getInputStream());
sourcefiles = (LinkedList) in.readObject();
//in.close(); //if i close, got error
} catch (ClassNotFoundException | IOException classNot) {
System.err.println("data received in unknown format");
}
}
public static void compareList() {
// go through each of the peer's filename, check against urs. If dont
// have, download
ListIterator iter = sourcefiles.listIterator();
String filename;
while (iter.hasNext()) {
// System.out.println(iter.next());
filename=(String) iter.next();
if (!destinationfiles.contains(filename)) //file cannot be found
{
missingfiles.add(filename);
}
}
}
public static void main(String[] args) {
/*Check if directory exist, create one if doesnt exit*/
File theDir = new File("src/ee4210/files");
// if the directory does not exist, create it
if (!theDir.exists()) {
System.out.println("creating directory..");
boolean result = theDir.mkdir();
if (result) {
System.out.println("Successfully created directory");
}
}
/*Get the list of files in that directory and store the names in array*/
listFilesForFolder(theDir);
/*Connect to peer*/
try {
new TcpClient().connect();
//new TcpClient().checkForInput();
} catch (Exception e) {
System.out.println("Something falied: " + e.getMessage());
e.printStackTrace();
}
}
public void connect() throws IOException
{
try {
host = InetAddress.getLocalHost();
//_socket = new Socket(host.getHostName(), portNo);
_socket = new Socket("172.28.177.125", portNo);
//System.out.println(host.getHostAddress()); //get the IP address of client
/*Get list from peer and compare list*/
getListfromPeer(); //receive from Server
compareList();
System.out.println(missingfiles);
/*Send to server the list of missing files*/
do
{
//busy wait till socket is open
}while (_socket.isClosed());
out = new ObjectOutputStream(_socket.getOutputStream());
out.flush();
out.writeObject(missingfiles);
out.flush();
System.out.println("Client have finished sending missing linkedList over");
out.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
服务器代码：
package ee4210;
import java.io.*;
import java.net.*;
import java.util.*;
public class TcpServer extends Thread
{
ServerSocket providerSocket;
Socket connection = null;
static ObjectOutputStream out;
ObjectInputStream in;
String message;
int portNo=2004; //portNo is 2004
TcpClient tcpclientobject = new TcpClient();
static LinkedList destinationfiles = new <String>LinkedList();
static LinkedList missingfiles = new <String>LinkedList();
public static void main(String[] args)
{
/*Check if directory exist, create one if doesnt exit*/
File theDir = new File("src/ee4210/files");
// if the directory does not exist, create it
if (!theDir.exists()) {
System.out.println("creating directory..");
boolean result = theDir.mkdir();
if (result) {
System.out.println("Successfully created directory");
}
}
/*Get the list of files in that directory and store the names in array*/
listFilesForFolder(theDir);
/*Connect*/
try {
new TcpServer().startServer();
} catch (Exception e) {
System.out.println("I/O failure: " + e.getMessage());
e.printStackTrace();
}
/*Rest of the code in run()*/
}
public static void listFilesForFolder(final File folder) {
for (final File fileEntry : folder.listFiles()) {
if (fileEntry.isDirectory()) {
listFilesForFolder(fileEntry);
} else {
//System.out.println(fileEntry.getName());
destinationfiles.add(fileEntry.getName());
}
}
}
public void startServer() throws Exception {
ServerSocket serverSocket = null;
boolean listening = true;
try {
serverSocket = new ServerSocket(portNo);
} catch (IOException e) {
System.err.println("Could not listen on port: " + portNo);
System.exit(-1);
}
while (listening) {
handleClientRequest(serverSocket);
}
serverSocket.close();
}
private void handleClientRequest(ServerSocket serverSocket) {
try {
new ConnectionRequestHandler(serverSocket.accept()).run();
} catch (IOException e) {
e.printStackTrace();
}
}
public class ConnectionRequestHandler implements Runnable{
private Socket _socket = null;
public ConnectionRequestHandler(Socket socket) {
_socket = socket;
}
public void run() {
System.out.println("Client connected to socket: " + _socket.toString());
/*Send the linkedlist over*/
try {
out = new ObjectOutputStream(_socket.getOutputStream());
//out.flush();
out.writeObject(destinationfiles);
out.flush();
//out.close(); //if I close, will have errors
} catch (IOException e) {
e.printStackTrace();
}
receiveMissingFileNames(); //this one is still ok
try { //if i put the close here its ok
out.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
out = new ObjectOutputStream(_socket.getOutputStream()); //when I add this line it shows the error
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void receiveMissingFileNames()
{
try {
in=new ObjectInputStream(_socket.getInputStream());
System.out.println("Is the socket connected="+_socket.isConnected());
missingfiles=(LinkedList) in.readObject();
System.out.println(missingfiles);
in.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}