我需要将少量文件传输到不同的计算机，每台计算机传输1个文件。现在我只能将1个文件传输到1台计算机。我的IP池中的一些计算机也可以脱机，我该如何避免异常？
此外，我在github中拥有所有代码： https://github.com/xym4uk/Diplom/tree/master/src/xym4uk/test
客户端
package xym4uk.test;
import java.io.*;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;
public class FileClient {
private static Socket sock;
private static String fileName;
private static BufferedReader stdin;
private static PrintStream ps;
public static void main(String[] args) throws IOException {
public static void sendFile(File myFile) {
//connecting
try {
sock = new Socket("localhost", 4444);
ps = new PrintStream(sock.getOutputStream());
ps.println("1");
} catch (Exception e) {
System.err.println("Cannot connect to the server, try again later.");
System.exit(1);
}
try {
byte[] mybytearray = new byte[(int) myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
DataInputStream dis = new DataInputStream(bis);
dis.readFully(mybytearray, 0, mybytearray.length);
OutputStream os = sock.getOutputStream();
//Sending file name and file size to the server
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF(myFile.getName());
dos.writeLong(mybytearray.length);
dos.write(mybytearray, 0, mybytearray.length);
dos.flush();
System.out.println("File " + myFile.getName() + " sent to Server.");
} catch (Exception e) {
System.err.println("File does not exist!");
}
DataBase.setRecord(sock.getInetAddress().toString(), myFile.getName());
try {
sock.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void receiveFile(String fileName) {
try {
sock = new Socket("localhost", 4444);
ps = new PrintStream(sock.getOutputStream());
ps.println("2");
ps.println(fileName);
} catch (Exception e) {
System.err.println("Cannot connect to the server, try again later.");
System.exit(1);
}
try {
int bytesRead;
InputStream in = sock.getInputStream();
DataInputStream clientData = new DataInputStream(in);
fileName = clientData.readUTF();
OutputStream output = new FileOutputStream(("received_from_server_" + fileName));
long size = clientData.readLong();
byte[] buffer = new byte[1024];
while (size > 0 && (bytesRead = clientData.read(buffer, 0, (int) Math.min(buffer.length, size))) != -1) {
output.write(buffer, 0, bytesRead);
size -= bytesRead;
}
output.close();
in.close();
System.out.println("File " + fileName + " received from Server.");
} catch (IOException ex) {
Logger.getLogger(CLIENTConnection.class.getName()).log(Level.SEVERE, null, ex);
}
try {
sock.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
服务器
package xym4uk.test;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
public class FileServer {
private static ServerSocket serverSocket;
private static Socket clientSocket = null;
public static void main(String[] args) throws IOException {
try {
serverSocket = new ServerSocket(4444);
System.out.println("Server started.");
} catch (Exception e) {
System.err.println("Port already in use.");
System.exit(1);
}
while (true) {
try {
clientSocket = serverSocket.accept();
System.out.println("Accepted connection : " + clientSocket.getInetAddress());
Thread t = new Thread(new CLIENTConnection(clientSocket));
t.start();
} catch (Exception e) {
System.err.println("Error in connection attempt.");
}
}
}
}
ClientConnection
package xym4uk.test;
import java.io.*;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;
public class CLIENTConnection implements Runnable {
private Socket clientSocket;
private BufferedReader in = null;
public CLIENTConnection(Socket client) {
this.clientSocket = client;
}
@Override
public void run() {
try {
in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
String clientSelection;
while ((clientSelection = in.readLine()) != null) {
switch (clientSelection) {
case "1":
receiveFile();
break;
case "2":
String outGoingFileName;
while ((outGoingFileName = in.readLine()) != null) {
sendFile(outGoingFileName);
}
break;
default:
System.out.println("Incorrect command received.");
break;
}
in.close();
break;
}
} catch (IOException ex) {
Logger.getLogger(CLIENTConnection.class.getName()).log(Level.SEVERE, null, ex);
}
}
public void receiveFile() {
try {
int bytesRead;
DataInputStream clientData = new DataInputStream(clientSocket.getInputStream());
String fileName = clientData.readUTF();
OutputStream output = new FileOutputStream(("received_from_client_" + fileName));
long size = clientData.readLong();
byte[] buffer = new byte[1024];
while (size > 0 && (bytesRead = clientData.read(buffer, 0, (int) Math.min(buffer.length, size))) != -1) {
output.write(buffer, 0, bytesRead);
size -= bytesRead;
}
output.close();
clientData.close();
System.out.println("File "+fileName+" received from client.");
} catch (IOException ex) {
System.err.println("Client error. Connection closed.");
}
}
public void sendFile(String fileName) {
try {
//handle file read
File myFile = new File(fileName);
byte[] mybytearray = new byte[(int) myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
DataInputStream dis = new DataInputStream(bis);
dis.readFully(mybytearray, 0, mybytearray.length);
//handle file send over socket
OutputStream os = clientSocket.getOutputStream();
//Sending file name and file size to the client
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF(myFile.getName());
dos.writeLong(mybytearray.length);
dos.write(mybytearray, 0, mybytearray.length);
dos.flush();
System.out.println("File "+fileName+" sent to client.");
} catch (Exception e) {
System.err.println("File does not exist!");
}
}
}