在进行数据连接时候需要进行网络状态判断
//判断网络连接
+ (BOOL) isConnectionAvailable{
NSURL*url1 = [NSURLURLWithString:@"http://www.baidu.com"];
NSURLRequest*request = [NSURLRequestrequestWithURL:url1cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheDatatimeoutInterval:5];
NSHTTPURLResponse*response;
[NSURLConnectionsendSynchronousRequest:requestreturningResponse: &responseerror:nil];
if(response ==nil) {
returnNO;
}
else{
returnYES;
}
}
//直接通过BOOL值判断网络是不是真的连通!
-(BOOL)TryCheckNetCanUse {
intsockfd =socket(AF_INET,SOCK_STREAM,0);if(sockfd <0) {
// [self showNetworkStatus:@"未联网"];
returnNO;
}
if([selfsocket_set_non_blocking:sockfd]<0) {
// [self showNetworkStatus:@"未联网"];return NO;
}
inti =0;
while(i<5) {
i++;
//http://61.135.169.121/百度，端口80
if([selftry_connect:sockfdip:"61.135.169.121"port:80timeout:3] ==SUCCESS){
returnYES;
break;
}else{
returnNO;
}
}
returnYES;
}
//通过ip和port连接
-(int)try_connect:(int)sockfd ip:(constchar*)ipport:(unsignedshort)port timeout:(int) timeout{
structsockaddr_inserver_addr;
memset(&server_addr,0,sizeof(server_addr));
server_addr.sin_family=AF_INET;
server_addr.sin_port=htons(port);
if(inet_pton(AF_INET, ip, &server_addr.sin_addr) <0)
returnFAIL;
structtimevaltv;
fd_setwset;
if(connect(sockfd, (structsockaddr*)&server_addr,sizeof(server_addr)) <0) {
if(errno!=EINPROGRESS&&errno!=EWOULDBLOCK)
returnFAIL;
tv.tv_sec= timeout;
tv.tv_usec=0;
FD_ZERO(&wset);
FD_SET(sockfd, &wset);
intn =select(sockfd +1,NULL, &wset,NULL, &tv);
if(n <0) {/* select出错*/
returnFAIL;
}elseif(n ==0) {
/*超时*/
returnFAIL;
}else{
returnSUCCESS;
}
}
intflags;
//在connect成功之后，设成阻塞模式flags = fcntl(sockfd, F_GETFL,0);
flags &= ~O_NONBLOCK;
fcntl(sockfd,F_SETFL, flags);/***************************************************///设置不被SIGPIPE信号中断，物理链路损坏时才不会导致程序直接被Terminate
//在网络异常的时候如果程序收到SIGPIRE是会直接被退出的。
structsigactionsa;
sa.sa_handler=SIG_IGN;
sigaction(SIGPIPE, &sa,0);
//----这个bug折磨死我了----!/***************************************************/
unsignedcharbytes[]={83,83,72,45,50,46,48,45,79,112,101,110,83,83,72,95,53,46,50,13,10,0};
if(send(sockfd, bytes,strlen((char*)bytes),0)<0) {
returnFAIL;
}charbuff[128];
//设置接收时间超时
structtimevalRectimeout={3,0};//3s
intret=setsockopt(sockfd,SOL_SOCKET,SO_RCVTIMEO,(constchar*)&Rectimeout,sizeof(Rectimeout));//如果ret==0则为成功,-1为失败,这时可以查看errno来判断失败原因
if(ret <0) {
returnFAIL;
}
longretr =recv(sockfd, buff,128,0);
if(retr ==-1&&errno==EAGAIN){printf("Recvive timeout\n");
returnFAIL;}
NSLog(@"retr is---->%ld buff is ---> %s",retr,buff);if(retr >0) {
if(strncmp(buff,"SSH",3)==0) {NSLog(@" connect is --->%s",buff);
//[self showNetworkStatus:@"已经联网了"];close(sockfd);
returnSUCCESS;
}
}
close(sockfd);
// [self showNetworkStatus:@"未连接网络!"];
returnFAIL;
}
//检测阻塞还是非阻塞
-(int) socket_set_non_blocking:(int)socked{
intflags;
flags =fcntl(socked,F_GETFL,0);
if(flags == -1) {
return-1;
}
flags |=O_NONBLOCK;
if(fcntl(socked,F_SETFL, flags) == -1) {
return-1;
}
return0;
}