判断联网 phone

-(BOOL) isConnected

{
 //创建零地址，0.0.0.0的地址表示查询本机的网络连接状态 
 struct sockaddr_in zeroAddress;
 bzero(&zeroAddress, sizeof(zeroAddress)); 
 zeroAddress.sin_len = sizeof(zeroAddress); 
 zeroAddress.sin_family = AF_INET; 

 // Recover reachability flags 
 SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress); 
 SCNetworkReachabilityFlags flags;
 
 //获得连接的标志 
 BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags); 
 CFRelease(defaultRouteReachability);
 
 //如果不能获取连接标志，则不能连接网络，直接返回 
 if (!didRetrieveFlags)
 {
  return NO;
 }
 
 //根据获得的连接标志进行判断
 BOOL isReachable = flags & kSCNetworkFlagsReachable;
 BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
 return (isReachable && !needsConnection) ? YES : NO;
 
}

 

2.发送数据

-(NSData *)sendPostRequest:(NSString *)postString theUrl:(NSString *)urlString{
    //NSError *error=[[NSError alloc] autorelease];
 NSData *postData = [postString dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];   
 NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];   
 NSURL *url=[[NSURL alloc]initWithString:urlString];
 NSMutableURLRequest  *request=[[NSMutableURLRequest alloc]init];
 [request setURL: url]; 
 [request setHTTPMethod:@"POST"];   
 [request setValue:postLength forHTTPHeaderField:@"Content-Length"];   
 [request setValue:@"text/xml" forHTTPHeaderField:@"Content-Type"];  
 // [request setTimeoutInterval:15];
 [request setCachePolicy:NSURLRequestReloadIgnoringLocalCacheData];
 [request setHTTPBody:postData];  
    //定义一个计时器
 
 connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:true];
 [NSTimer scheduledTimerWithTimeInterval:60.0 target:self selector:@selector(cancelConnection:) userInfo:nil repeats:NO];
 [url release];
 [request release];
 if(connection)
 {
  receivedData = [[NSMutableData data] retain];
 }
 else
 {
  NSLog(@"<<Net_Http.m-->sendPostRequest-->connection-->nil");
 }

//暂停，等待NSTimer的结束
 while(!finished) {
  [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
 } 
 
 return receivedData;
}
3.接受数据

-(NSData *)sendGetRequest:(NSString *)getString theUrl:(NSString *)urlString{
    //NSError *error=[[NSError alloc] autorelease];
 NSData *getData = [getString dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];   
 NSString *getLength = [NSString stringWithFormat:@"%d", [getData length]];   
 NSURL *url=[[NSURL alloc]initWithString:urlString];
 NSMutableURLRequest  *request=[[NSMutableURLRequest alloc]init];
 [request setURL: url]; 
 [request setHTTPMethod:@"GET"];   
 [request setValue:getLength forHTTPHeaderField:@"Content-Length"];   
 [request setValue:@"text/xml" forHTTPHeaderField:@"Content-Type"];  
 // [request setTimeoutInterval:15];
 [request setCachePolicy:NSURLRequestReloadIgnoringLocalCacheData];
 [request setHTTPBody:getData];  
    //定义一个计时器
 
 connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:true];
 [NSTimer scheduledTimerWithTimeInterval:60.0 target:self selector:@selector(cancelConnection:) userInfo:nil repeats:NO];
 [url release];
 [request release];
 if(connection)
 {
  receivedData = [[NSMutableData data] retain];
 }
 else
 {
  NSLog(@"<<Net_Http.m-->sendGetRequest-->connection-->nil");
 }
 while(!finished) {
  [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
 } 
 
 return receivedData;
}
4.json连接网络的代理函数

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{
 NSLog(@"<<Net_Http.m-->connection-->didReceiveResponse-->get the whole response:%@",response);
 [receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{
 NSLog(@"<<Net_Http.m-->connection-->didReceiveData-->getting data");
 [receivedData appendData:data];
}

-(void)connection:(NSURLConnection *)connection_ didFailWithError:(NSError *)error

{
    if (mianViewLoadFlag==YES) 
 {
  NSLog(@"<<Net_Http.m-->connection-->didFailWithError-->加载完成!");
  receivedData=nil;
  [self connectionDidFinishLoading:connection_];
  
 }else 
 {
  NSLog(@"<<Net_Http.m-->connection-->didFailWithError-->加载出错!");
  [self showErrorAlert:@"网络错误\n请检查您的网络或稍后重试"];
  [self connectionDidFinishLoading:connection_];
 } 
 
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection

{
 finished=YES;
 mianViewLoadFlag=YES;
 NSLog(@"<<Net_Http.m-->connectionDidFinishLoading-->YES"); 
}
4.

-(void)cancelConnection:(NSTimer *)timer{
 
 //取消连接 
 NSLog(@"<<Net_Http.m-->cancelConnection-->计时器已到时间");
 [self connection:connection didFailWithError:error];
 [connection cancel];
 
}
-(void)showErrorAlert:(NSString *)message{
 myAlert = [[UIAlertView alloc]
      initWithTitle:@""
      message:message       
      delegate:self
      cancelButtonTitle:nil
      otherButtonTitles:@"确定",nil];
 
 [myAlert show];
 [myAlert release];
}
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
// if (alertView == myAlert) {
  switch (buttonIndex) {
   case 0: 
    //[[UIApplication sharedApplication] terminateWithSuccess];
    break;
   case 1:    
    break;
    
   default:
    break;
  }
// }
}
-(void)setMainViewLoadFlag:(BOOL)mainFlag{
 mianViewLoadFlag=mainFlag;
}

5.NET_HTTP.h

  BOOL mianViewLoadFlag;
@interface Net_Http : NSObject {
    NSURLConnection *connection;
 NSMutableData *receivedData;
 BOOL finished;
 UIAlertView *myAlert;
 NSError *error;
}

-(NSData *)sendPostRequest:(NSString *)postString theUrl:(NSString *)urlString;
-(NSData *)sendGetRequest:(NSString *)getString  theUrl:(NSString *)urlString;
-(void)showErrorAlert:(NSString *)message;
-(BOOL) isConnected;
-(BOOL)setMainViewLoadFlag;