[英]Missing bytes in sending files over TCP connection
通过TCP连接发送文件时缺少一些字节。 尽管有时文件传输已完成。
发送方:
class SendFile extends Thread {
Socket s;
String toIP;
String fileName;
PrintWriter pw;
BufferedReader br;
String fromIP;
String nextHopIP;
String transferTime;
int routingIndex;
final int bufferSize = 65536;
int readFile;
byte[] buffer;
FileInputStream fileIn;
OutputStream fileOut;
long fileTransferTime;
SendFile(String toIP, String fileName) {
this.toIP = toIP;
this.fileName = fileName;
}
public void run() {
while (true) {
try {
fromIP = InetAddress.getLocalHost().getHostAddress();
nextHopIP = Tables.checkRoutingTable(toIP);
if (nextHopIP.equals("none")) {
System.out.println("Invalid IP address");
} else {
s = new Socket(nextHopIP, 3434);
fileIn = new FileInputStream(fileName);
fileOut = s.getOutputStream();
buffer = new byte[bufferSize];
pw = new PrintWriter(s.getOutputStream());
br = new BufferedReader(new InputStreamReader(s.getInputStream()));
pw.println(fromIP);
pw.println(toIP);
pw.println(fileName.split("\\\\")[fileName.split("\\\\").length - 1]);
pw.flush();
//Send file
fileTransferTime = System.currentTimeMillis();
int sum = 0;
while ((readFile = fileIn.read(buffer)) != -1) {
fileOut.write(buffer, 0, readFile);
sum += readFile;
}
System.out.println(sum);
fileIn.close();
s.shutdownOutput();
br.readLine();
fileTransferTime = System.currentTimeMillis() - fileTransferTime;
System.out.println("File transfer time: " + fileTransferTime + " ms");
s.close();
break;
}
} catch (IOException ex) {
//Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Connection timed out. Retrying...");
}
}
}
}
接收方:
class FileTransferThread extends Thread {
Socket fromSocket;
Socket toSocket;
String ip;
BufferedReader fromBR;
BufferedReader toBR;
PrintWriter fromPW;
PrintWriter toPW;
String[][] delta;
String token;
String toIP;
String fromIP;
String nextHopIP;
String absoluteFileName;
String fileName;
int deltaCount;
int entryCount;
int socketIndex;
int i;
int j;
int readFile;
final int bufferSize = 65536;
byte[] buffer;
InputStream fileIn;
FileOutputStream fileOut;
OutputStream fileHopOut;
File directory;
long fileTransferTime;
FileTransferThread(Socket s) {
this.fromSocket = s;
}
public void run() {
try {
ip = InetAddress.getLocalHost().getHostAddress();
fromBR = new BufferedReader(new InputStreamReader(fromSocket.getInputStream()));
fromPW = new PrintWriter(fromSocket.getOutputStream());
fromIP = fromBR.readLine();
toIP = fromBR.readLine();
nextHopIP = Tables.checkRoutingTable(toIP);
buffer = new byte[bufferSize];
fileIn = fromSocket.getInputStream();
fileName = fromBR.readLine();
if (!fileName.equals("\\send")) {
directory = new File("c:\\" + fromIP);
directory.mkdirs();
absoluteFileName = "c:\\" + fromIP + "\\" + fileName;
fileOut = new FileOutputStream(absoluteFileName);
while (true) {
try {
//if not yet the destination IP, pass to next hop
if (!toIP.equals(ip)) {
toSocket = new Socket(toIP, 3434);
fileHopOut = toSocket.getOutputStream();
toBR = new BufferedReader(new InputStreamReader(toSocket.getInputStream()));
toPW = new PrintWriter(toSocket.getOutputStream());
toPW.println(fromIP);
toPW.println(toIP);
toPW.println(fileName);
toPW.flush();
//Send file
while ((readFile = fileIn.read(buffer)) != -1) {
fileHopOut.write(buffer, 0, readFile);
}
toSocket.shutdownOutput();
fromPW.println(toBR.readLine());
fromPW.flush();
toSocket.close();
} else {
int sum = 0;
while ((readFile = fileIn.read(buffer)) != -1) {
fileOut.write(buffer, 0, readFile);
sum += readFile;
}
System.out.println(sum);
fileOut.flush();
fileOut.close();
fromPW.println("1");
fromPW.flush();
}
fromSocket.close();
break;
} catch (IOException ex) {
//Logger.getLogger(FileTransferThread.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Connection timed out. Retrying...");
}
}
} else {
while(true) {
try {
//if not yet the destination IP, pass to next hop
if (!toIP.equals(ip)) {
toSocket = new Socket(toIP, 3434);
fileHopOut = toSocket.getOutputStream();
toBR = new BufferedReader(new InputStreamReader(toSocket.getInputStream()));
toPW = new PrintWriter(toSocket.getOutputStream());
toPW.println(fromIP);
toPW.println(toIP);
toPW.println(fileName);
toPW.flush();
//Send file
while ((readFile = fileIn.read(buffer)) != -1) {
fileHopOut.write(buffer, 0, readFile);
}
toSocket.shutdownOutput();
fromPW.println(toBR.readLine());
fromPW.flush();
toSocket.close();
} else {
while ((readFile = fileIn.read(buffer)) != -1) {
}
fromPW.println("1");
fromPW.flush();
}
fromSocket.close();
break;
}
catch (IOException ex) {
//Logger.getLogger(FileTransferThread.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Connection timed out. Retrying...");
}
}
}
fromSocket.close();
} catch (IOException ex) {
Logger.getLogger(FileTransferThread.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
您没有关闭-因此也没有刷新-名为fileout
。 (您确实应该考虑减少误导性的名称...)。
嗯...看来shutdownOutput可以做到; 其javadoc写道:
禁用此套接字的输出流。 对于TCP套接字,将发送任何先前写入的数据,然后是TCP的正常连接终止序列。
如果在套接字上调用shutdownOutput()后写入套接字输出流,则该流将抛出IOException。
万一其他人有相同的想法,我就离开这个。
请注意, socket.getInputStream指定使用该工具可能发生的各种数据丢失。 尤其是:
网络软件可能会丢弃套接字缓冲的字节。
发现错误。 似乎BufferedReader正在获取应该用于文件的数据块。
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