Java 通过套接字的客户机-服务器通信
我试图通过套接字通信将数据从服务器发送到客户端，但在接收端收到一个错误 下面是我的代码片段- 服务器-此类称为CLIENTConnection，负责从服务器到客户端的所有连接Java 通过套接字的客户机-服务器通信,java,client-server,Java,Client Server,我试图通过套接字通信将数据从服务器发送到客户端，但在接收端收到一个错误 下面是我的代码片段- 服务器-此类称为CLIENTConnection，负责从服务器到客户端的所有连接 import java.net.*; import java.util.logging.Level; import java.util.logging.Logger; import java.io.*; public class CLIENTConnection implements
import java.net.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.io.*;
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=in.readLine();
while (clientSelection != null) {
switch (clientSelection) {
case "1":
receiveFile();
break;
case "2":
System.out.println("inside case 2");
String outGoingFileName = in.readLine();
System.out.println(outGoingFileName);
while (outGoingFileName != null) {
System.out.println("Inside while loop");
sendFile(outGoingFileName);
}
System.out.println("Out of while");
break;
case "3":
receiveFile();
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();
System.out.println(filename+" is received on server side");
OutputStream output = new FileOutputStream(("C://Users/Personal/workspace/ClientServer/src/dir/"+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("C://Users/Personal/workspace/ClientServer/src/dir/"+fileName);
byte[] mybytearray = new byte[(int) myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
//bis.read(mybytearray, 0, mybytearray.length);
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 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 "+fileName+" sent to client.");
} catch (Exception e) {
System.err.println("File does not exist!");
}
}
}
public class FileClient {
private static Socket sock;
private static String fileName;
private static BufferedReader stdin;
private static PrintStream os;
public static void main(String[] args) throws IOException, ClassNotFoundException {
ObjectInputStream inFromServer;
try
{
sock = new Socket("localhost", 7777);
stdin = new BufferedReader(new InputStreamReader(System.in));
} catch (Exception e) {
System.err.println("Cannot connect to the server, try again later.");
System.exit(1);
}
inFromServer= new ObjectInputStream(sock.getInputStream());
os = new PrintStream(sock.getOutputStream());
try {
switch (Integer.parseInt(selectAction())) {
case 1:
os.println("1");
sendFile();
break;
case 2:
os.println("2");
System.err.print("Enter file name: ");
fileName = stdin.readLine();
os.println(fileName);
receiveFile(fileName);
break;
case 3:
os.println("3");
Synchronise();
}
} catch (Exception e) {
System.err.println("not valid input");
}
sock.close();
}
private static void Synchronise()
{
HashMap<String, Calendar> ClientFileList=getTimeStamp("C://Users/Personal/workspace/ClientServer/Client/");//getting the filename and timestamp of all the files present in client folder.
/*System.out.println("Client File List : \n");
for(String s : ClientFileList.keySet())
System.out.println(s);*/
HashMap<String, Calendar> ServerFileList=getTimeStamp("C://Users/Personal/workspace/ClientServer/src/dir/");//(HashMap<String, Calendar>) inFromServer.readObject();
/*System.out.println("\nServer File List : \n");
for(String s : ClientFileList.keySet())
System.out.println(s);*/
System.out.println("File comparision output");
compareTimestamp(ClientFileList,ServerFileList);
}
private static void compareTimestamp(HashMap<String, Calendar> ClientFileList, HashMap<String, Calendar> serverFileList)
{
LinkedList<String> fileToUpload=new LinkedList<String>();
LinkedList<String> fileToDownload=new LinkedList<String>();
LinkedList<String> fileToDeleteFromClient=new LinkedList<String>();
LinkedList<String> fileToDeleteFromServer=new LinkedList<String>();
Calendar clientCalender = null,serverCalendar=null;
for (String filename : serverFileList.keySet())
{
serverCalendar=serverFileList.get(filename);
if(ClientFileList.containsKey(filename))
{
clientCalender=ClientFileList.get(filename);
if(clientCalender.before(serverCalendar))
{
fileToDownload.add(filename);
}
else
{
fileToUpload.add(filename);
}
}
else
{
fileToDeleteFromClient.add(filename);
}
}
for (String filename : ClientFileList.keySet())
{
clientCalender=ClientFileList.get(filename);
if(!serverFileList.containsKey(filename))
{
fileToDeleteFromServer.add(filename);
}
}
System.out.println("Files to download to client: "+fileToDownload);
System.out.println("Files to upload to Server: "+fileToUpload);
System.out.println("Files to delete from client: "+fileToDeleteFromClient);
System.out.println("Files to delete from Server: "+fileToDeleteFromServer);
sendFile(fileToDeleteFromServer);
}
private static HashMap<String, Calendar> getTimeStamp(String location)
{
HashMap<String,Calendar> fileList = new HashMap<String,Calendar>();
File dir = new File(location);
File[] files = dir.listFiles();
if (files.length == 0)
{
System.out.println("No file found");
//System.exit(1);
}
else
{
for (int i = 0; i < files.length; i++)
{
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(files[i].lastModified());
fileList.put(files[i].getName(), calendar);
}
}
return fileList;
}
public static String selectAction() throws IOException
{
System.out.println("1. Send file.");
System.out.println("2. Recieve file.");
System.out.println("3. Synchronize");
System.out.print("\nMake selection: ");
return stdin.readLine();
}
public static void sendFile()
{
try {
System.err.print("Enter file name: ");
fileName = stdin.readLine();
File myFile = new File("C:/Users/Personal/workspace/ClientServer/Client/"+fileName);
byte[] mybytearray = new byte[(int) myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
//bis.read(mybytearray, 0, mybytearray.length);
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();
dis.close();
System.out.println("File "+fileName+" sent to Server.");
}
catch (Exception e)
{
System.err.println("File does not exist!");
}
}
//receive a list of file to upload to server from client.
static void sendFile(LinkedList<String> fileList)
{
for(String file: fileList)
sendFile(file);
}
public static void sendFile(String filename) {
File file = new File("C:/Users/Personal/workspace/ClientServer/Client/"+filename);
byte[] mybytearray = new byte[(int) file.length()];
FileInputStream fis;
try
{
fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
//bis.read(mybytearray, 0, mybytearray.length);
DataInputStream dis = new DataInputStream(bis);
dis.readFully(mybytearray, 0, mybytearray.length);
OutputStream os = sock.getOutputStream();
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF(file.getName());
dos.writeLong(mybytearray.length);
dos.write(mybytearray, 0, mybytearray.length);
dos.flush();
dis.close();
System.out.println("File "+filename+" sent to Server.");
}
catch (Exception e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void receiveFile(String fileName) {
try {
int bytesRead;
InputStream in = sock.getInputStream();
DataInputStream clientData = new DataInputStream(in);
fileName = clientData.readUTF();
OutputStream output = new FileOutputStream(("received_from_server_"));
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);
}
}
此异常主要由数据输入流用于向流结束发送信号。请注意，许多其他输入操作在流结束时返回一个特殊值，而不是引发异常。您正在获取该文件吗
public static void receiveFile(String fileName) {
boolean recieving = true; //new
while(recieving){ //new
try {
int bytesRead;
InputStream in = sock.getInputStream();
DataInputStream clientData = new DataInputStream(in);
fileName = clientData.readUTF();
OutputStream output = new FileOutputStream(("received_from_server_"));
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 (EOFException e){ // new
Logger.getLogger(CLIENTConnection.class.getName()).log(Level.SEVERE, null, ex);
recieving = false;
} catch (IOException ex) {
Logger.getLogger(CLIENTConnection.class.getName()).log(Level.SEVERE, null, ex);
}
} //new
}
它显示了什么错误？请添加stacktrace。是否正在尝试为方法参数赋值？如果您以后不需要它，您应该使用本地var，或者如果调用方需要它，则返回它，而不是使方法无效，2014年6:00:43 AM FileClient接收文件严重：null java.io.DataInputStream.readFullyUnknown Source at java.io.DataInputStream.readUTFUnknown Source at java.io.DataInputStream.readUTFUnknown Source at FileClient.receiveFileFileClient.java:280 atjava:53能否将FileClient.main添加到问题中的代码片段中？在这种情况下，您应该提供一个可执行示例。。。补充。请查收，没错！文件已发送，但我无法捕获它。您能建议我们如何捕获它吗？正如这所建议的，您应该添加一个适当的终止条件现在，数据甚至没有被发送。不要使用可用的。它不会做你期望的事情！试过了，似乎不起作用。无法接收文件。
public static void receiveFile(String fileName) {
boolean recieving = true; //new
while(recieving){ //new
try {
int bytesRead;
InputStream in = sock.getInputStream();
DataInputStream clientData = new DataInputStream(in);
fileName = clientData.readUTF();
OutputStream output = new FileOutputStream(("received_from_server_"));
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 (EOFException e){ // new
Logger.getLogger(CLIENTConnection.class.getName()).log(Level.SEVERE, null, ex);
recieving = false;
} catch (IOException ex) {
Logger.getLogger(CLIENTConnection.class.getName()).log(Level.SEVERE, null, ex);
}
} //new
}