线程“main”中的异常 java.net.SocketException：连接重置 -

Exception in thread "main" java.net.SocketException: Connection reset -

提问by Rastamouse

I have created a simple Client/Server program where the client takes a file from command line arguments. The client then sends the file to the server, where it is compressed with GZIP and sent back to the client.

我创建了一个简单的客户端/服务器程序，其中客户端从命令行参数中获取文件。然后客户端将文件发送到服务器，在那里用 GZIP 压缩并发送回客户端。

The server program when ran first is fine, and produces no errors but after running the client I get the error.

第一次运行时服务器程序很好，并且不会产生任何错误，但是在运行客户端后我得到了错误。

I am getting an error saying the connection is reset, and i've tried numerous different ports so i'm wondering if there is something wrong with my code or time at which i've closed the streams?

我收到一条错误消息，说连接已重置，我尝试了许多不同的端口，所以我想知道我的代码或关闭流的时间是否有问题？

Any help would be greatly appreciated!

任何帮助将不胜感激！

EDIT - Made changes to both programs.

编辑 - 对两个程序进行了更改。

Client:

客户：

import java.io.*;
import java.net.*;

//JZip Client

public class NetZip {

    //Declaring private variables.
    private Socket socket = null;
    private static String fileName = null;
    private File file = null;
    private File newFile = null;
    private DataInputStream fileIn = null;
    private DataInputStream dataIn = null;
    private DataOutputStream dataOut = null;
    private DataOutputStream fileOut = null;


    public static void main(String[] args) throws IOException {
    try {
        fileName = args[0];
        }
    catch (ArrayIndexOutOfBoundsException error) {
        System.out.println("Please Enter a Filename!");
    }
    NetZip x = new NetZip();
    x.toServer();
    x.fromServer();

    }

    public void toServer() throws IOException{
    while (true){
    //Creating socket
       socket = new Socket("localhost", 4567);
       file = new File(fileName);

       //Creating stream to read from file.
       fileIn = new DataInputStream(
           new BufferedInputStream(
               new FileInputStream(
                   file)));

       //Creating stream to write to socket.
       dataOut = new DataOutputStream(
           new BufferedOutputStream(
               socket.getOutputStream()));

       byte[] buffer = new byte[1024];

           int len;
           //While there is data to be read, write to socket.
        while((len = fileIn.read(buffer)) != -1){
            try{
            System.out.println("Attempting to Write " + file
                + "to server.");
            dataOut.write(buffer, 0, len);
            }
            catch(IOException e){
            System.out.println("Cannot Write File!");
            }
           } 
        fileIn.close();
        dataOut.flush();
        dataOut.close();

        }

    }
  //Read data from the serversocket, and write to new .gz file.
    public void fromServer() throws IOException{

    dataIn = new DataInputStream(
           new BufferedInputStream(
                   socket.getInputStream()));

    fileOut = new DataOutputStream(
           new BufferedOutputStream(
               new FileOutputStream(
                   newFile)));

    byte[] buffer = new byte[1024];

        int len;
        while((len = dataIn.read(buffer)) != -1){
            try {
            System.out.println("Attempting to retrieve file..");
            fileOut.write(buffer, 0, len);
            newFile = new File(file +".gz");

            }
            catch (IOException e ){
            System.out.println("Cannot Recieve File");
            }
        } 
        dataIn.close();
        fileOut.flush();
        fileOut.close();
        socket.close();

    }


}

Server:

服务器：

import java.io.*;
import java.net.*;
import java.util.zip.GZIPOutputStream;

//JZip Server

public class ZipServer {

    private ServerSocket serverSock = null;
    private Socket socket = null;
    private DataOutputStream zipOut = null;
    private DataInputStream dataIn = null;

    public void zipOut() throws IOException {

    //Creating server socket, and accepting from other sockets.
    try{
    serverSock = new ServerSocket(4567);
    socket = serverSock.accept();
    }
    catch(IOException error){
        System.out.println("Error! Cannot create socket on port");
    }

    //Reading Data from socket
    dataIn = new DataInputStream(
           new BufferedInputStream(
                   socket.getInputStream()));

    //Creating output stream.
    zipOut= new DataOutputStream(
        new BufferedOutputStream(
            new GZIPOutputStream(
                socket.getOutputStream())));

    byte[] buffer = new byte[1024];

        int len;
        //While there is data to be read, write to socket.
        while((len = dataIn.read(buffer)) != -1){
            System.out.println("Attempting to Compress " + dataIn
                + "and send to client");
            zipOut.write(buffer, 0, len);
        } 
        dataIn.close();
        zipOut.flush();
        zipOut.close(); 
        serverSock.close();
        socket.close();
    }

    public static void main(String[] args) throws IOException{
    ZipServer run = new ZipServer();
    run.zipOut();

    }

}

Error Message:

错误信息：

Exception in thread "main" java.net.SocketException: Connection reset
    at java.net.SocketInputStream.read(SocketInputStream.java:196)
    at java.net.SocketInputStream.read(SocketInputStream.java:122)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
    at java.io.BufferedInputStream.read1(BufferedInputStream.java:275)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:334)
    at java.io.DataInputStream.read(DataInputStream.java:100)
    at ZipServer.<init>(ZipServer.java:38)
    at ZipServer.main(ZipServer.java:49)

回答by Gren

First, the error occurs because the client fails and ends before sending any data, so that the connection is closed at the time the server wants to read.
The error occurs because you assign the File objects to unused local variables (did your compiler not warn?)

第一，出现错误是因为客户端在发送任何数据之前失败并结束，从而在服务器想要读取的时候关闭连接。
发生错误是因为您将 File 对象分配给未使用的局部变量（您的编译器没有警告吗？）

public File file = null;
public File newFile = null;

public static void main(String[] args) throws IOException {
try {
    String fileName = args[0];
    File file = new File(fileName);
    File newFile = new File(file +".gz");
    } 
catch (ArrayIndexOutOfBoundsException error) {
    System.out.println("Please Enter a Filename!");
}

but In your toServer method you use the class variable file as parameter for FileInputStream and this variable is null and this results in an error which ends the program.

但是在您的 toServer 方法中，您使用类变量文件作为 FileInputStream 的参数，并且此变量为空，这会导致结束程序的错误。

Second, if you finished the writing to the outputstream, you should call

其次，如果你完成了对输出流的写入，你应该调用

socket.shtdownOutput();

Otherwise, the server tries to read until a timeout occurs.

否则，服务器会尝试读取，直到发生超时。

回答by Aditya Bittu

Problem is that server is not able to download apache maven.

问题是服务器无法下载 apache maven。

So what you can do is just copy the apache maven folder and paste it in the wrapper folder inside the project.

因此，您可以做的只是复制 apache maven 文件夹并将其粘贴到项目内的包装文件夹中。

It will manually download the apache maven, and it will definitely work.

它将手动下载apache maven，它肯定会工作。