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 =@"http://files.cnblogs.com/zhuqil/UIWebViewDemo.zip";
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 =@"http://files.cnblogs.com/zhuqil/UIWebViewDemo.zip";
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。
<WebMethod(Description:=
"上传文件！"
)> _
Public
Function
UploadFile()
As
XmlDocument
Dim
doc
As
XmlDocument =
New
XmlDocument()
Try
Dim
postCollection
As
HttpFileCollection = Context.Request.Files
Dim
aFile
As
HttpPostedFile = postCollection(
"media"
)
aFile.SaveAs(Server.MapPath(
"."
) +
"/"
+ Path.GetFileName(aFile.FileName))
doc.LoadXml(
"<xml>ok</xml>"
)
Return
doc
Catch
ex
As
Exception
doc.LoadXml(
"<xml>fail</xml>"
)
Return
doc
End
Try
End
Function
|
文件上传接口
定义一个类PicOperation用于处理上传图片：
@interface PicOperation : NSOperation
{
UIImage *theImage;
}
@property (retain) UIImage *theImage;
@end
|
//
// PicOperation.m
// DownLoading
//
// Created by skylin zhu on 11-7-30.
// Copyright 2011年 mysoft. All rights reserved.
//
#import "PicOperation.h"
#define NOTIFY_AND_LEAVE(X) {[self cleanup:X]; return;}
#define DATA(X) [X dataUsingEncoding:NSUTF8StringEncoding]
// Posting constants
#define IMAGE_CONTENT @"Content-Disposition: form-data; name=\"%@\"; filename=\"image.jpg\"\r\nContent-Type: image/jpeg\r\n\r\n"
#define STRING_CONTENT @"Content-Disposition: form-data; name=\"%@\"\r\n\r\n"
#define MULTIPART @"multipart/form-data; boundary=------------0x0x0x0x0x0x0x0x"
@implementation
PicOperation
@synthesize
theImage;
//创建postdata
- (
NSData
*)generateFormDataFromPostDictionary:(
NSDictionary
*)dict
{
id
boundary = @
"------------0x0x0x0x0x0x0x0x"
;
NSArray
* keys = [dict allKeys];
NSMutableData
* result = [
NSMutableData
data];
for
(
int
i = 0; i < [keys count]; i++)
{
id
value = [dict valueForKey: [keys objectAtIndex:i]];
[result appendData:[[
NSString
stringWithFormat:@
"--%@\r\n"
, boundary] dataUsingEncoding:
NSUTF8StringEncoding
]];
if
([value isKindOfClass:[
NSData
class
]])
{
// handle image data
NSString
*formstring = [
NSString
stringWithFormat:IMAGE_CONTENT, [keys objectAtIndex:i]];
[result appendData: DATA(formstring)];
[result appendData:value];
}
else
{
// all non-image fields assumed to be strings
NSString
*formstring = [
NSString
stringWithFormat:STRING_CONTENT, [keys objectAtIndex:i]];
[result appendData: DATA(formstring)];
[result appendData:DATA(value)];
}
NSString
*formstring = @
"\r\n"
;
[result appendData:DATA(formstring)];
}
NSString
*formstring =[
NSString
stringWithFormat:@
"--%@--\r\n"
, boundary];
[result appendData:DATA(formstring)];
return
result;
}
//上传图片
- (
NSString
*) UpLoading
{
if
(!
self
.theImage)
NOTIFY_AND_LEAVE(@
"Please set image before uploading."
);
NSMutableDictionary
* post_dict = [[
NSMutableDictionary
alloc] init];
[post_dict setObject:@
"Posted from iPhone"
forKey:@
"message"
];
[post_dict setObject:UIImageJPEGRepresentation(
self
.theImage, 0.75f) forKey:@
"media"
];
NSData
*postData = [
self
generateFormDataFromPostDictionary:post_dict];
[post_dict release];
NSString
*baseurl = @
"http://10.5.23.121:7878/WorkflowService.asmx/UploadFile"
;
NSURL
*url = [
NSURL
URLWithString:baseurl];
NSMutableURLRequest
*urlRequest = [
NSMutableURLRequest
requestWithURL:url];
if
(!urlRequest) NOTIFY_AND_LEAVE(@
"Error creating the URL Request"
);
[urlRequest setHTTPMethod: @
"POST"
];
[urlRequest setValue:MULTIPART forHTTPHeaderField: @
"Content-Type"
];
[urlRequest setHTTPBody:postData];
// Submit & retrieve results
NSError
*error;
NSURLResponse
*response;
NSLog
(@
"Contacting TwitPic...."
);
NSData
* result = [
NSURLConnection
sendSynchronousRequest:urlRequest returningResponse:&response error:&error];
if
(!result)
{
[
self
cleanup:[
NSString
stringWithFormat:@
"Submission error: %@"
, [error localizedDescription]]];
return
;
}
// Return results
NSString
*outstring = [[[
NSString
alloc] initWithData:result encoding:
NSUTF8StringEncoding
] autorelease];
return
outstring;
}
@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：
PicOperation *pic = [[PicOperation alloc] init];
pic.theImage=[UIImage imageNamed:@
"meinv4.jpg"
];;
NSString
*result = [pic UpLoading];
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。
本文转自麒麟博客园博客，原文链接：http://www.cnblogs.com/zhuqil/archive/2011/07/30/2122019.html，如需转载请自行联系原作者
