網絡編程分爲阻塞和非阻塞兩種方式,如果選擇了阻塞方式進行編程,控制不好很容易導致程序死掉。
下面這段代碼中:
複製代碼
…
TcpListener tcpListener = null;
TcpClient tcpClient = null;
NetworkStream networkStream = null;
…
/// <summary>
/// 接收線程
/// </summary>
private void receive()
{
while (true)
{
Thread.Sleep(TimeSpan.FromSeconds(1));
this.AddTextToCommStateList(DateTime.Now.ToString() + "\t等待連接...");
tcpClient = tcpListener.AcceptTcpClient();
Thread.Sleep(TimeSpan.FromSeconds(1));
this.AddTextToCommStateList(DateTime.Now.ToString() + "\t已連接");
networkStream = tcpClient.GetStream();
// 設置讀取超時時間爲10秒
networkStream.ReadTimeout = 10000;
// 設置寫入超時時間爲10秒
networkStream.WriteTimeout = 10000;
byte[] recvBuff = new byte[8192];
int readBytes = 0;
while (tcpClient != null)
{
try
{
this.AddTextToCommStateList(DateTime.Now.ToString() + "\t開始讀取");
readBytes = networkStream.Read(recvBuff, 0, recvBuff.Length);
this.AddTextToCommStateList(DateTime.Now.ToString() + "\t讀取完畢");
}
catch (IOException ex)
{
this.AddTextToCommStateList(DateTime.Now.ToString() + "\t接收錯誤");
this.AddTextToCommStateList(DateTime.Now.ToString() + "\t錯誤信息:" + ex.Message);
break;
}
...
複製代碼
如果去掉networkStream.ReadTimeout = 10000;和networkStream.WriteTimeout = 10000;兩行,程序就有可能在
readBytes = networkStream.Read(recvBuff, 0, recvBuff.Length);處死掉(筆者在調試到此時將網線拔掉,發現程序就會死在這裏,即使網絡恢復了程序也不會恢復)。
查看MSDN中關於NetworkStream類的幫助信息,發現ReadTimeout和WriteTimeout屬性的默認值都是Infinite(無限),即永不超時,所以networkStream.Read在讀不到數時就永遠不會返回。