iOS 通过URL网络获取XML数据的两种方式

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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