iOS 通过URL网络获取XML数据的两种方式

转载于：http://blog.csdn.net/crayondeng/article/details/8738768

下面简单介绍如何通过url获取xml的两种方式。

第一种方式相对简单，使用NSData的构造函数dataWithContentsOfURL；不多解释，直接上代码咯。

[cpp] view
plaincopy

NSURL *url = [NSURL URLWithString:@"http://222.73.161.212/ispace2/servlet/com.lemon.xml.XmlAction"];

//A Boolean value that turns an indicator of network activity on or off.

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

NSData *xmlData = [NSData dataWithContentsOfURL:url];

[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

NSString *xmlString = [[NSString alloc] initWithData:xmlData encoding:NSUTF8StringEncoding];

if (xmlData == nil) {

NSLog(@"File read failed!:%@", xmlString);

}

else {

NSLog(@"File read succeed!:%@",xmlString);

}

上面的 NSData *xmlData = [NSData dataWithContentsOfURL:url]; 就是获取xml的关键啦。

注意：如果直接输出xmlData的话会是一对unicode，所以用UTF-8编码转换成是String进行输出就好啦。

第二种方式：通过NSURLConnection建立网络连接，并实现它的几个委托方法，从而获取数据。

代码如下，应该可以看懂的。

[cpp] view
plaincopy

@implementation ViewController {

BOOL getXmlDone; //是否停止获取xml数据的标志

NSMutableData *xmlData; //存储获得的xml数据

}

//自定义的一个方法

- (void) getXML {

//获取xml

xmlData = [NSMutableData data];

//Clears the receiver’s cache, removing all stored cached URL responses.

//清除接收器的缓存，删除所有存储的高速缓存的URL的响应。

[[NSURLCache sharedURLCache] removeAllCachedResponses];

NSURL *url = [NSURL URLWithString:@"http://222.73.161.212/ispace2/servlet/com.lemon.xml.XmlAction"];

NSURLRequest *theRequest = [NSURLRequest requestWithURL:url];

//create the connection with the request and start loading the data

NSURLConnection *urlConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

[self performSelectorOnMainThread:@selector(downloadStarted) withObject:nil waitUntilDone:NO];

if (urlConnection != nil) {

do {

[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];

} while (!getXmlDone);

}

}

#pragma mark NSURLConnection Delegate methods

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {

return nil;

}

// Forward errors to the delegate.

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

getXmlDone = YES;

}

// Called when a chunk of data has been downloaded.

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

// Append the downloaded chunk of data.

[xmlData appendData:data];

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

[self performSelectorOnMainThread:@selector(downloadEnded) withObject:nil waitUntilDone:NO];

getXmlDone = YES;

}

- (void)downloadStarted {

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

}

- (void)downloadEnded {

[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

}

- (void)viewDidLoad

{

[super viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

[self getXML];

NSString *xmlString = [[NSString alloc] initWithData:xmlData encoding:NSUTF8StringEncoding];

NSLog(@"data: %@",xmlString);

}

- (void)didReceiveMemoryWarning

{

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

小结一下，第一种简单，一次性获取所有的xml数据，第二种有点复杂，当然其灵活性也更好。

要验证获取的数据的准确性的话，就点击你的url吧！http://222.73.161.212/ispace2/servlet/com.lemon.xml.XmlAction

OK，下一篇文章将会介绍如何解析xml。come on!