iOS开发中会经常用到文件上传下载的功能,这篇文件将介绍一下使用asp.net webservice实现文件上传下载。
首先,让我们看下文件下载。
这里我们下载cnblogs上的一个zip文件。使用NSURLRequest+NSURLConnection可以很方便的实现这个功能。
同步下载文件:
NSString *urlAsString = @"";
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:@"UIWebViewDemo.zip" atomically:YES]) {
NSLog(@"保存成功.");
}
else
{
NSLog(@"保存失败.");
}
} else {
NSLog(@"%@", error);
}
异步下载文件:
- (void)viewDidLoad
{
[super viewDidLoad];
//文件地址
NSString *urlAsString = @"";
NSURL *url = [NSURL URLWithString:urlAsString];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSMutableData *data = [[NSMutableData alloc] init];
self.connectionData = data;
[data release];
NSURLConnection *newConnection = [[NSURLConnection alloc]
initWithRequest:request
delegate:self
startImmediately:YES];
self.connection = newConnection;
[newConnection release];
if (self.connection != nil){
NSLog(@"Successfully created the connection");
} else {
NSLog(@"Could not create the connection");
}
}
- (void) connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error{
NSLog(@"An error happened");
NSLog(@"%@", error);
}
- (void) connection:(NSURLConnection *)connection
didReceiveData:(NSData *)data{
NSLog(@"Received data");
[self.connectionData appendData:data];
}
- (void) connectionDidFinishLoading
:(NSURLConnection *)connection{
/* 下载的数据 */
NSLog(@"下载成功");
if ([self.connectionData writeToFile:@"UIWebViewDemo.zip" atomically:YES]) {
NSLog(@"保存成功.");
}
else
{
NSLog(@"保存失败.");
}
/* do something with the data here */
}
- (void) connection:(NSURLConnection *)connection
didReceiveResponse:(NSURLResponse *)response{
[self.connectionData setLength:0];
}
- (void) viewDidUnload{
[super viewDidUnload];
[self.connection cancel];
self.connection = nil;
self.connectionData = nil;
}
从上面两段代码中可以看到同步与异步下载的区别,大部分时候我们使用异步下载文件。在asp.net webservice中可以将文件的地址返回到iOS系统,iOS系统在去请求下载该文件。
上传文件
我们先使用VB.Net写一个webservice方法,用于接收上传上来的文件数据,代码如下。
|
文件上传接口
定义一个类PicOperation用于处理上传图片:
|
[objc]
1. //
2. // PicOperation.m
3. // DownLoading
4. //
5. // Created by skylin zhu on 11-7-30.
6. // Copyright 2011年 mysoft. All rights reserved.
7. //
8.
9. #import "PicOperation.h"
10.
11. #define NOTIFY_AND_LEAVE(X) {[self cleanup:X]; return;}
12. #define DATA(X) [X dataUsingEncoding:NSUTF8StringEncoding]
13.
14. // Posting constants
15. #define IMAGE_CONTENT @"Content-Disposition: form-data; name=\"%@\"; filename=\"image.jpg\"\r\nContent-Type: image/jpeg\r\n\r\n"
16. #define STRING_CONTENT @"Content-Disposition: form-data; name=\"%@\"\r\n\r\n"
17. #define MULTIPART @"multipart/form-data; boundary=------------0x0x0x0x0x0x0x0x"
18.
19. @implementation PicOperation
20. @synthesize theImage;
21.
22. //创建postdata
23. - (NSData*)generateFormDataFromPostDictionary:(NSDictionary*)dict
24. {
25. id boundary = @"------------0x0x0x0x0x0x0x0x";
26. allKeys];
27. data];
28.
29. for (int i = 0; i < [keys count]; i++)
30. {
31. id value = [dict valueForKey: [keys objectAtIndex:i]];
32. appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
33.
34. if ([value isKindOfClass:[NSData class]])
35. {
36. // handle image data
37. NSString *formstring = [NSString stringWithFormat:IMAGE_CONTENT, [keys objectAtIndex:i]];
38. appendData: DATA(formstring)];
39. appendData:value];
40. }
41. else
42. {
43. // all non-image fields assumed to be strings
44. NSString *formstring = [NSString stringWithFormat:STRING_CONTENT, [keys objectAtIndex:i]];
45. appendData: DATA(formstring)];
46. appendData:DATA(value)];
47. }
48.
49. NSString *formstring = @"\r\n";
50. appendData:DATA(formstring)];
51. }
52.
53. NSString *formstring =[NSString stringWithFormat:@"--%@--\r\n", boundary];
54. appendData:DATA(formstring)];
55. return result;
56. }
57. //上传图片
58. - (NSString *) UpLoading
59. {
60. if (!self.theImage)
61. @"Please set image before uploading.");
62.
63.
64. alloc] init];
65.
66. setObject:@"Posted from iPhone" forKey:@"message"];
67. setObject:UIImageJPEGRepresentation(self.theImage, 0.75f) forKey:@"media"];
68.
69. NSData *postData = [self generateFormDataFromPostDictionary:post_dict];
70. release];
71.
72. NSString *baseurl = @"http://10.5.23.121:7878/WorkflowService.asmx/UploadFile";
73. NSURL *url = [NSURL URLWithString:baseurl];
74. NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url];
75. if (!urlRequest) NOTIFY_AND_LEAVE(@"Error creating the URL Request");
76.
77. setHTTPMethod: @"POST"];
78. setValue:MULTIPART forHTTPHeaderField: @"Content-Type"];
79. setHTTPBody:postData];
80.
81. // Submit & retrieve results
82. NSError *error;
83. NSURLResponse *response;
84. @"Contacting TwitPic....");
85. sendSynchronousRequest:urlRequest returningResponse:&response error:&error];
86. if (!result)
87. {
88. self cleanup:[NSString stringWithFormat:@"Submission error: %@", [error localizedDescription]]];
89. return;
90. }
91.
92. // Return results
93. NSString *outstring = [[[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding] autorelease];
94. return outstring;
95. }
96. @end
这里我主要定义了两个方法,一个是generateFormDataFromPostDictionary用于创建post form data,一个是UpLoading供调用的类上传图片,这个类需要一个UIimage的对象。
类定义好了,上传图片就非常方便了,看下面代码:
[objc]
1. PicOperation *pic = [[PicOperation alloc] init];
2. pic.theImage=[UIImage imageNamed:@"meinv4.jpg"];;
3. NSString *result = [pic UpLoading];
4. NSLog(result);
总结:这篇文章讲述了如何在iOS中结合asp.net webservice实现文件的上传和下载功能。
NSURLConnection 下载数据 -- IOS(实例
iPhone网络开发中如何使用NSURLConnection是本文要介绍的内容,这篇文章是翻译的苹果官方文档,想要看英文原版的可以到苹果网站查看,来看详细内容。
NSURLConnection 提供了很多灵活的方法下载URL内容也提供了一个简单的接口去创建和放弃连接,同时使用很多的delegate方法去支持连接过程的反馈和控制
如何创建一个连接呢?
为了下载url的内容,程序需要提供一个delegate对象,并且至少实现下面的方法
1. - (void)connection:(NSURLConnection*)connection didReceiveResponse:(NSHTTPURLResponse*)response
2. - (void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
3. - (void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error
4. - (void)connectionDidFinishLoading:(NSURLConnection *)connection
NSURLConnect还提供了一个方便的类方法(class method) : sendSynchronousRequest:returningResponse:error: 可用来 同步地加载一个URL请求
1. + (NSData *)sendSynchronousRequest: (NSURLRequest *)request returningResponse: (NSURLResponse **)response error: (NSError **)error
1. request 要装载的URL请求. 这个request 对象 作为初始化进程的一部分,被深度复制(deep-copied). 在这个方法返回之后, 再修改request, 将不会影响用在装载的过程中的request
2. reponse 输出参数, 由服务器返回的URL响应
3. error 输出参数, 如果在处理请求的过程中发生错误,就会使用. 无错误,就为NULL
举例一
1、先创建一个NSURL
2、在通过NSURL创建NSURLRequest,可以指定缓存规则和超时时间
3、创建NSURLConnection实例,指定NSURLRequest和一个delegate对象
如果创建失败,则会返回nil,如果创建成功则创建一个NSMutalbeData的实例用来存储数据
代码:
1. NSURLRequest *theRequest=[NSURLRequest requestWithURL:
2. //www.sina.com.cn/”]
3. cachePolicy:NSURLRequestUseProtocolCachePolicy
4. timeoutInterval:60.0];
5. NSURLConnection *theCnotallow=[[NSURLConnection alloc]
6. initWithRequest:theRequest delegate:self];
7. if(theConnection)
8. {
9. //创建NSMutableData
10. receivedData=[[NSMutableData data] retain];
11. }else // 创建失败
- NSURLRequestUseProtocolCachePolicy //NSURLRequest默认的cache policy, 是最能保持一致性的协议。
- NSURLRequestReloadIgnoringCacheData //忽略缓存直接从原始地址下载
- NSURLRequestReturnCacheDataElseLoad //只有在cache中不存在data时才从原始地址下载
- NSURLRequestReturnCacheDataDontLoad //允许app确定是否要返回cache数据,如果使用这种协议当本地不存在response的时候,创建NSURLConnection or NSURLDownload实例时将会马上返回nil;这类似于离线模式,没有建立网络连接;
NSURLConnection还有几个初始化函数,有个初始化函数可以做到创建连接但是并不马上开始下载,而是通过start:开始
当收到initWithRequest: delegate: 消息时,下载会立即开始,在代理(delegate)收到connectionDidFinishLoading:或者 connection:didFailWithError:消息之前可以通过给连接发送一个cancel:消息来中断下载。
当服务器提供了足够客户程序创建NSURLResponse对象的信息时,代理对象会收到一个connection:didReceiveResponse:消息,在消息内可以检查NSURLResponse对象和确定数据的预期长途,mime类型,文件名以及其他服务器提供的元信息
要注意,一个简单的连接也可能会收到多个connection:didReceiveResponse:消息当服务器连接重置或者一些罕见的原因(比如多组mime文档),代理都会收到该消息这时候应该重置进度指示,丢弃之前接收的数据
1. -(void)connection:(NSURLConnection *) connectiondidReceiveResponse:
2. (NSURLResponse*)response
3. {
4. [receiveData setLength:0];
5. }
当下载开始的时候,每当有数据接收,代理会定期收到connection:didReceiveData:消息代理应当在实现中储存新接收的数据,下面的例子既是如此
1. -(void) connection:(NSURLConnection *) connection didReceiveData:
2. (NSData *) data
3. {
4. [receiveData appendData:data];
5.
6. }
在上面的方法实现中,可以加入一个进度指示器,提示用户下载进度
当下载的过程中有错误发生的时候,代理会收到一个connection:didFailWithError消息,消息参数里面的NSError对象提供了具体的错误细节,它也能提供在用户信息字典里面失败的url请求(使用NSErrorFailingURLStringKey)
当代理接收到连接的connection:didFailWithError消息后,对于该连接不会在收到任何消息
举例
1. -(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
2. {
3. [connection release];
4.
5. [receivedData release];
6. "Connection failed! Error - %@ %@",
7. [error localizedDescription],
8. [[error userInfo] objectForKey:NSErrorFailingURLStringErrorKey]);
9. }
最后,如果连接请求成功的下载,代理会接收connectionDidFinishLoading:消息代理不会收到其他的消息了,在消息的实现中,应该释放掉连接
举例:
1. -(void)connectionDidFinishLoading:(NSURLConnection *)connection
2. {
3. //do something with the data
4. "succeeded %d byte received",[receivedData length]);
5.
6. [connection release];
7. [receivedData release];
8. }
一个实现异步get请求的例子:
1. NSString *url = [NSString stringWithFormat:@"http://localhost/chat/messages.php?past=%ld&t=%ld",
2. lastId, time(0) ];
3.
4. NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
5. [request setURL:[NSURL URLWithString:url]];
6. "GET"];
7.
8. NSURLConnection *cnotallow=[[NSURLConnection alloc] initWithRequest:request delegate:self];
9. if
10. {
11. receivedData = [[NSMutableData data] retain];
12. }
13. else
14. {
15. }
16.
17. - (void)timerCallback {
18. //[timer release];
19. [self getNewMessages];
20. }
21.
22. - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
23. {
24. [receivedData setLength:0];
25. }
26.
27. - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
28. {
29. [receivedData appendData:data];
30. }
31.
32. - (void)connectionDidFinishLoading:(NSURLConnection *)connection
33. {
34. if
35. [chatParser release];
36.
37. if
38. messages = [[NSMutableArray alloc] init];
39.
40. chatParser = [[NSXMLParser alloc] initWithData:receivedData];
41. //set the delegate
42. //start parse
43.
44. [receivedData release];
45.
46. [messageList reloadData];
47.
48. NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:
49. [self methodSignatureForSelector: @selector(timerCallback)]];
50. [invocation setTarget:self];
51. [invocation setSelector:@selector(timerCallback)];
52. //timer = [NSTimer scheduledTimerWithTimeInterval:5.0 invocation:invocation repeats:NO];
53. //if set yes,then very 5 seconds updata the table
54. }
一个实现同步Get请求的例子:
1. // 初始化请求
2. NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
3. // 设置URL
4. [request setURL:[NSURL URLWithString:urlStr]];
5. // 设置HTTP方法
6. [request setHTTPMethod:@"GET"];
7. // 发 送同步请求, 这里得returnData就是返回得数据了
8. NSData *returnData = [NSURLConnection sendSynchronousRequest:request
9. returningResponse:nil error:nil];
10. // 释放对象
11. [request release];
来源:
http://mobile.51cto.com/iphone-281460.htm