Question

当我向服务器发送nullbyte时，我想显示通过二进制流获得的PNG图像。我从流中获取信息。但是图像从未显示过，我不知道为什么。也许有人看到了错误。

我的代码如下：

#import <UIKit/UIKit.h>
NSInputStream *inputStream;
NSOutputStream *outputStream;
@interface ViewController : UIViewController <NSStreamDelegate>
@property (weak, nonatomic) IBOutlet UIView *secondView;
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

- (IBAction)sendNullbyte:(id)sender;
@property (weak, nonatomic) IBOutlet UIView *firstView;

@property (nonatomic, strong, readwrite) NSOutputStream *fileStream;

@end

和

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self initNetworkCommunication];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

- (void)initNetworkCommunication {
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;
    CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)@"localhost", 80, &readStream, &writeStream);
    inputStream = (__bridge NSInputStream *)readStream;
    outputStream = (__bridge NSOutputStream *)writeStream;
    [inputStream setDelegate:self];
    [outputStream setDelegate:self];
    [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [inputStream open];
    [outputStream open];
}

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent{
    switch (streamEvent) {
        case NSStreamEventOpenCompleted:
            NSLog(@"Stream opened");
            break;
        case NSStreamEventHasBytesAvailable:
            NSLog(@"Has bytes available.");
            //be sure that event comes from input stream
            if(theStream == inputStream){
                UInt8 buffer[500000];
                long len;
                BOOL firstbytes = true;
                 //read method returns 0 when there is nothing left in the stream
                 len = [inputStream read:buffer maxLength:sizeof(buffer)];
                 if (len > 0){
                     NSData *output = [[NSData alloc] initWithBytes:buffer length:len-4];
                     if (output != nil){
                         NSLog(@"server said: %@", output);
                         UIImage *image = [[UIImage alloc] initWithData:output];;
                         _imageView.image = image;
                     }
                 }
            }

            break;
        case NSStreamEventErrorOccurred:
            NSLog(@"Cant not connect to the host");
            break;
        case NSStreamEventEndEncountered:
            break;
        default:
            break;
    }
}

- (IBAction)sendNullbyte:(id)sender {
    NSInteger nullbyte = 0x00;
    NSData *data =[[NSData alloc] initWithBytes:&nullbyte length:1];
    [outputStream write:[data bytes] maxLength:[data length]];
    [self.view bringSubviewToFront:_secondView];
}

@end

Answer 1

尝试使用unit8_t而不是UInt8，并确保你处理单个数据包中图像无法获取的情况......

你可以这样做：

{
  NSMutableData *data; // ivar
}

  // init it somewhere
  data = [NSMutableData new];

case NSStreamEventHasBytesAvailable:

if (theStream == inputStream) {

    uint8_t buffer[5000]; 
    int length;

    while ([inputStream hasBytesAvailable]) {
        length = [inputStream read:buffer maxLength:sizeof(buffer)];
        if (length > 0) {
            [data appendBytes:(const void *)buffer length];
        }
    }
}
break;

case NSStreamEventEndEncountered:
{
    if (theStream == inputStream) {
        UIImage *imagess = [[UIImage alloc]initWithData:data];
        [imagesview setImage:imagess];
    }
}   break;

从二进制流中显示图像

1 个答案: