java.net.SocketException: Connection reset by peer: socket write error 提供文件时
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java.net.SocketException: Connection reset by peer: socket write error When serving a file
提问by Charles-Eugene Loubao
I am trying to implement an HTTP Server using Sockets. If the Client (For example a browser) requests a directory the server displays a list of available files. The problem arises when the client is requesting a file. I get the following error:
我正在尝试使用套接字实现 HTTP 服务器。如果客户端（例如浏览器）请求目录，则服务器会显示可用文件列表。当客户端请求文件时会出现问题。我收到以下错误：
java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:113)
at java.net.SocketOutputStream.write(SocketOutputStream.java:159)
at cf.charly1811.java.web.RequestHandler.writeFile(RequestHandler.java:152)
at cf.charly1811.java.web.RequestHandler.processRequest(RequestHandler.java:139)
at cf.charly1811.java.web.RequestHandler.handleRequest(RequestHandler.java:110)
at cf.charly1811.java.web.RequestHandler.run(RequestHandler.java:86)
at java.lang.Thread.run(Thread.java:745)
The stacktrace shows that the problem is coming from the writeFile()methods:
堆栈跟踪显示问题来自以下writeFile()方法：
private void writeFile(File request) throws IOException
{
InputStream byteReader = new BufferedInputStream(new FileInputStream(request));
byte[] buffer = new byte[1024];
int bytesRead;
while ((bytesRead = byteReader.read(buffer)) != -1)
{
outputStream.write(buffer, 0, bytesRead);
}
byteReader.close();
}
But I can't figure out what's wrong. Can you help me?
但我无法弄清楚出了什么问题。你能帮助我吗？
EDIT
编辑
Thanks everyone for your answers. After I read your answers I understood that the problem was that the Socket when an error occured. Here's was my wrong code:
谢谢大家的回答。阅读您的答案后，我明白问题出在发生错误时的 Socket。这是我的错误代码：
// Method to process a single request
handleRequest() throw IOException
{
// process here
// if the client request a file
writeFile();
// close socket when the request is processed
}
// The method is called
public run()
{
try{
// If an error occurs the try/catch won't be called because it is implemented outside the loop. So when an IOException occurs, the loop just stop and exit the program
while(true)
{
handleRequest();
}
}
catch(IOException e) {
// Handle exception here
}
}
And my new code was looking like this:
我的新代码如下所示：
// Method to process a single request
handleRequest()
{
try {
// process here
// if the client request a file
writeFile();
// close socket when the request is processed
}
// If this exception occurs the catch() method will be called
catch(IOException e)
{
// handle exception here
}
}
// The method is called
public run()
{
while(true)
{
handleRequest();
}
}
}
采纳答案by bond
It is possible for the TCP socket to be "closing" and your code to not have yet been notified.
TCP 套接字可能“关闭”并且您的代码尚未收到通知。
Here is a animation for the life cycle. http://tcp.cs.st-andrews.ac.uk/index.shtml?page=connection_lifecycle
这是生命周期的动画。http://tcp.cs.st-andrews.ac.uk/index.shtml?page=connection_lifecycle
Basically, the connection was closed by the client. You already have throws IOExceptionand SocketExceptionextends IOException. This is working just fine. You just need to properly handle IOExceptionbecause it is a normal part of the api.
基本上，连接已被客户端关闭。您已经拥有throws IOException并SocketException扩展了IOException. 这工作得很好。您只需要正确处理，IOException因为它是 api 的正常部分。
EDIT: The RSTpacket occurs when a packet is received on a socket which does not exist or was closed. There is no difference to your application. Depending on the implementation the resetstate may stick and closedwill never officially occur.
编辑：RST当在不存在或已关闭的套接字上接收到数据包时，会发生数据包。您的应用程序没有区别。根据实施情况，reset状态可能会坚持下去，并且closed永远不会正式发生。
回答by user207421
This problem is usually caused by writing to a connection that had already been closed by the peer. In this case it could indicate that the user cancelled the download for example.
此问题通常是由写入已被对等方关闭的连接引起的。例如，在这种情况下，它可能表明用户取消了下载。
