I am using Linux Mint 14 KDE. I've successfully created Java tcp server and client, server IP:port is 10.10.1.10:9900 and my client IP:port 10.10.1.10:9901. When i connect my client for the first time everything is OK. The client connects and sends some data and disconnects. When i try connecting the client with the server right after disconnecting i get the next Exception.
我正在使用Linux Mint 14 KDE。我已經成功創建了Java tcp服務器和客戶端，服務器IP：端口是10.10.1.10:9900，我的客戶端IP：端口10.10.1.10:9901。當我第一次連接我的客戶端時一切正常。客戶端連接並發送一些數據並斷開連接。當我嘗試在斷開連接後立即將客戶端與服務器連接時，我得到下一個異常。
java.net.BindException: Address already in use
If i wait more than 1 minute everything is OK. On other forums i read that after closing the socket there is a tcp time_wait that is 60 seconds (1 minute). After changing it to 0 everything worked (If someone want to change it just add this line net.ipv4.tcp_fin_timeout=0 in /etc/sysctl.conf and execute this line in your terminal as root service networking restart). The next day i tried to do one more test and i got the same exception. I checked if the time is still 0 (U can check it with writing this in command line cat /proc/sys/net/ipv4/tcp_fin_timeout as root) and it was 0. I still had to wait 1 minute before reconnecting the client.
如果我等待超過1分鍾，一切都會好的。在其他論壇上，我讀到關閉套接字後，有一個60秒(1分鍾)的tcp time_wait。將其更改為0後，一切正常(如果有人想要更改它，隻需在/etc/sysctl.conf中添加此行net.ipv4.tcp_fin_timeout = 0並在終端中執行此行作為root service networking restart)。第二天，我試圖再做一次測試，我得到了同樣的例外。我檢查時間是否仍為0(你可以在指令行cat / proc / sys / net / ipv4 / tcp_fin_timeout中以root身份寫這個來檢查它)它是0.我仍然需要等待1分鍾再重新連接客戶端。
Can someone help me how to configure that way so i don't get this exception. Waiting 1 minute is too much for real-time application. I know i can do this with letting the OS dynamically assign port number that is free, but that is not what my application needs are.
有人可以幫助我如何配置，是以我沒有得到這個例外。等待1分鍾對於實時應用來說太多了。我知道我可以通過讓操作系統動態配置設定免費的端口號來實現這一點，但這不是我的應用程式所需要的。
2 個解決方案
#1
1
After creating your client socket, but before binding it or connecting to the remote server, you should call Socket.setReuseAddress(true) to enable reusing the client port.
創建客戶端套接字後，但在綁定它或連接到遠程服務器之前，應調用Socket.setReuseAddress(true)以啟用重用客戶端端口。
#2
Don't specify a fixed client port, use zero. That way you will get a fresh one every time, or until you run out, which means you should be doing connection pooling at the client.
不要指定固定的客戶端端口，使用零。這樣你每次都會得到一個新的，或者直到你用完為止，這意味着你應該在客戶端進行連接池。