Question

我真的很难弄清楚为什么我的网络服务调用充斥着垃圾数据。

我有一个UITableViewController，可以调用Web服务，也可以作为NSURLConnectionDelegate。

这是感兴趣的委托方法，请注意NSLog语句。

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    NSLog(@"data %@", [[NSString alloc] initWithUTF8String: [data bytes]]);
    NSLog(@"before %@", [NSString stringWithUTF8String: self.rawData.bytes]);
    [self.rawData appendData:data];
    NSLog(@"after %@", [NSString stringWithUTF8String: self.rawData.bytes]);
}

以下是经过多次尝试后生成的日志：

2009-07-10 09:04:20.339 SundialInvoice[91493:20b] data {"items": [], "request": 

"/inventory/delivered.json"}
2009-07-10 09:04:20.339 SundialInvoice[91493:20b] before 
2009-07-10 09:04:20.340 SundialInvoice[91493:20b] after {"items": [], "request": "/inventory/delivered.json"} SundialInvoice] [PID 

2009-07-10 09:04:23.153 SundialInvoice[91493:20b] data {"items": [], "request": "/inventory/delivered.json"}l 4] [Mes
2009-07-10 09:04:23.154 SundialInvoice[91493:20b] before 
2009-07-10 09:04:23.154 SundialInvoice[91493:20b] after {"items": [], "request": "/inventory/delivered.json"} SundialInvoice] [PID 

2009-07-10 09:04:27.913 SundialInvoice[91493:20b] data (null)
2009-07-10 09:04:27.913 SundialInvoice[91493:20b] before 
2009-07-10 09:04:27.914 SundialInvoice[91493:20b] after {"items": [], "request": "/inventory/delivered.json"} SundialInvoice] [PID 

2009-07-10 09:04:30.486 SundialInvoice[91493:20b] data {"items": [], "request": "/inventory/delivered.json"}ice/1.0 CFN
2009-07-10 09:04:30.487 SundialInvoice[91493:20b] before 
2009-07-10 09:04:30.487 SundialInvoice[91493:20b] after {"items": [], "request": "/inventory/delivered.json"} SundialInvoice] [PID

尾随垃圾数据来自何处？我已经多次使用curl运行web服务，垃圾不是来自它。

Answer 1

要从NSString创建NSData，您应该使用initWithData:encoding:，如下所示：

NSString *str = [[NSString alloc] initWithData:self.rawData
                                      encoding:NSUTF8StringEncoding];
NSLog(@"Before: %@", str);
[str release];

将NSData字节视为C字符串可能会导致一些安全漏洞。

Answer 2

我认为垃圾来自日志记录：

[NSString stringWithUTF8String:self.rawData.bytes]

这里你要说的是你想从这个C字符串中获得NSString（=以零结尾的字节数组）。问题是bytes 的NSData方法不会返回以零结尾的数据，因为它是普通数组，而不是C字符串。因此，NSString初始化程序甚至会在接收到的NSData结束后抓取字节，直到它达到先前存储在内存中的某个零字节。

Answer 3

尝试以下方法：

 - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [rawData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"%@",rawData);
}

还有什么声明rawData为???

NSURLConnection委托didReceiveData数据中的尾随字符

3 个答案: