使用NSURLConnection的同步方法下载

来源：互联网发布：mac 输入法搜狗百度编辑：程序博客网时间：2024/05/18 21:39

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NSString *urlAsString = @"http://www.jouhu.com/json/info.zip";－－－要下载的全路径名
NSURL *url = [NSURL URLWithString:urlAsString];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSError *error = nil;
 
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&error];
/*下载的数据*/
if (data!=nil) {
NSLog(@"下载成功");
if ([data writeToFile:@"/Users/sunningning/Desktop/activation.zip"atomically:YES]) {－－下载到目的路径名
NSLog(@"保存成功！");
}
else
{
NSLog(@"保存失败！");
}
}
else{
NSLog(@"%@",error);
}

2 使用NSURLConnection的异步方法下载

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NSString *urlAsString = @"http://www.apple.com";
NSURL *url = [NSURL URLWithString:urlAsString];
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
 
[NSURLConnection sendAsynchronousRequest:urlRequest queue:queue completionHandler:^(NSURLResponse *response,NSData *data, NSError *error)
{
if ([data length] >0 && error == nil){
NSString *html = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"HTML = %@", html); }
 
else if ([data length] == 0 && error == nil){
NSLog(@"Nothing was downloaded.");
}
 
else if (error != nil){
NSLog(@"Error happened = %@", error); }
}];

3 使用NSURLConnection的异步+GCD的方法下载

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+ (void)performRequestWithUri:(NSString *)requestUri params:(NSDictionary *)params completionHandler:(void (^)(NSDictionary *, NSError *))completionBlock
{
 
// Generate the URL
NSString *requestUrl = [NSString stringWithFormat:@"http://the.api.com%@", requestUri];
 
// Create the connection
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:requestUrl]];
 
// Make an NSOperationQueue
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue setName:@"com.your.unique.queue.name"];
 
// Send an asyncronous request on the queue
[NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
 
// If there was an error getting the data
if (error) {
 
dispatch_async(dispatch_get_main_queue(), ^(void) {
completionBlock(nil, error);
});
return;
}
 
// Decode the data
NSError *jsonError;
NSDictionary *responseDict = [NSJSONSerialization JSONObjectWithData:data options:0 error:&jsonError];
 
// If there was an error decoding the JSON
if (jsonError) {
 
dispatch_async(dispatch_get_main_queue(), ^(void) {
 
});
return;
}
 
// All looks fine, lets call the completion block with the response data
dispatch_async(dispatch_get_main_queue(), ^(void) {
completionBlock(responseDict, nil);
});
}];
}

具体调用方法：

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[SHAPIController performRequestWithUri:@"http://www.jouhu.com/json/info.php"params:nil completionHandler:^(NSDictionary *response, NSError *error) {
 
if (error) {
NSLog(@"%@", error);
}
 
NSLog(@"%@", response);
}];

返回的数据根据我们而定.
4 实现delegate的方法实现异步

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NSURLConnection *conn= [[NSURLConnection alloc]
initWithRequest:theRequest delegate:self];
[conn start];
if(conn)
{
NSLog(@"Connection Successful");
}
else
{
NSLog(@"Connection could not be made");
}
}

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- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)theResponse {
self.response = theResponse;
[data setLength:0]; // reset data
}
 
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)theData {
[data appendData:theData]; // append incoming data
}
 
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
self.data = nil;
if (handler) { [queue addOperationWithBlock:^{ handler(response, nil, error); }]; }
}
 
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
// TODO: Are we passing the arguments to the block correctly? Should we copy them?
handleData(self.data);//处理数据，需要定义方法
}

我们自身的应用采用的是最后一种方法，对于很多图片更新的，可以采取第三种方法，第一种方法是同步数据下载，容易造成UI阻塞。需要注意。

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