http编程综述:亦可称为soap编程。通常情况下,http编程要比socket编程相对要简单易用得多。所以用的最广广泛。
一、http编程其实就是http请求。http请求最长用的方法是 get 和 post 方法。
==》get方法和post方法相比理解起来比较简单,get方法可以直接请求一个url,也可以url后面拼接上参数作为一个新的url地址进行请求。get方法后面的value要经过unicode编码。form的enctype属性默认为application/x-www-form-urlencoded。不能发送二进制文件。 ==》post方法相对要复杂一些。首先post方法要设置key和value ,所有的key和value都会拼接成 key1=value1&key2=value2的样式的字符串,然后这个字符串转化为二进制放到 http请求的body中。当请求发送的时候,也就跟随body一起传给服务器。http请求Content-Type设置为:application/x-www-form-urlencoded。这里讲的只是简单的post请求,一般发送文件不会选择这种方式(从技术方面考虑也可以发送文件,就是把文件以 key 和 value的方式放入)。下面我们再讨论一下post发送二进制文件更加普遍的方法。
二、HTTP协议是什么? 简单来说,就是一个基于应用层的通信规范:双方要进行通信,大家都要遵守一个规范,这个规范就是HTTP协议。 HTTP协议能做什么? 很多人首先一定会想到:浏览网页。没错,浏览网页是HTTP的主要应用,但是这并不代表HTTP就只能应用于网页的浏览。HTTP是一种协议,只要通信的双方都遵守这个协议,HTTP就能有用武之地。比如咱们常用的QQ,迅雷这些软件,都会使用HTTP协议(还包括其他的协议)。 HTTP协议如何工作? 大家都知道一般的通信流程:首先客户端发送一个请求(request)给服务器,服务器在接收到这个请求后将生成一个响应(response)返回给客户端。 在这个通信的过程中HTTP协议在以下4个方面做了规定:
1. Request和Response的格式() 2. 建立连接的方式(1、非持久连接 2、持久连接) 3. 缓存的机制 4. 响应授权激发机制
(应用场合) 5. 基于HTTP的应用(1、 HTTP代理 2、多线程下载 3、 HTTPS传输协议原理 4、开发web程序时常用的Request Methods 5、用户与服务器的交互)
常用cocoa内部类:
1,Reachability.h 苹果demo支持网络连接诊断
2,NSConnection连接、NSMutableURLRequest URL网址的请求封装包
3,NSXMLParser XML解析
常用第三方库:
1,ASIHttprequest 库
操作步骤:
1:检查网络环境(3G/WIFI) 2:发起NSConnection请求 3:处理返回xml数据包(NSXMLParser解析xml文件),或者返回文件png、pdf之类 4:若返回数据包中含有待下载的图片下载地址。则重复2、3步骤下载下来图片。只不过3中返回的是文件。
socket编程综述:
常用cocoa内部类:
常用第三方库:1,Asyncsocket库
操作步骤:
一:确认网络环境3G/WIFI
1. 添加源文件和framework 开发Web等网络应用程序的时候,需要确认网络环境,连接情况等信息。如果没有处理它们,是不会通过Apple的审查的。 Apple 的 例程 Reachability 中介绍了取得/检测网络状态的方法。要在应用程序程序中使用Reachability,首先要完成如下两部: 1.1. 添加源文件: 在你的程序中使用 Reachability 只须将该例程中的 Reachability.h 和 Reachability.m 拷贝到你的工程中。如下图: 1.2.添加framework: 将SystemConfiguration.framework 添加进工程。如下图: 2. 网络状态 Reachability.h中定义了三种网络状态: typedef enum { NotReachable = 0, //无连接 ReachableViaWiFi, //使用3G/GPRS网络 ReachableViaWWAN //使用WiFi网络 } NetworkStatus; 因此可以这样检查网络状态: Reachability *r = [Reachability reachabilityWithHostName:@“www.apple.com”]; switch ([r currentReachabilityStatus]) { case NotReachable: // 没有网络连接 break; case ReachableViaWWAN: // 使用3G网络 break; case ReachableViaWiFi: // 使用WiFi网络 break; } 3.检查当前网络环境 程序启动时,如果想检测可用的网络环境,可以像这样 // 是否wifi + (BOOL) IsEnableWIFI { return ([[Reachability reachabilityForLocalWiFi] currentReachabilityStatus] != NotReachable); } // 是否3G + (BOOL) IsEnable3G { return ([[Reachability reachabilityForInternetConnection] currentReachabilityStatus] != NotReachable); } 例子: - (void)viewWillAppear:(BOOL)animated { if (([Reachability reachabilityForInternetConnection].currentReachabilityStatus == NotReachable) && ([Reachability reachabilityForLocalWiFi].currentReachabilityStatus == NotReachable)) { self.navigationItem.hidesBackButton = YES; [self.navigationItem setLeftBarButtonItem:nil animated:NO]; } } 4. 链接状态的实时通知 网络连接状态的实时检查,通知在网络应用中也是十分必要的。接续状态发生变化时,需要及时地通知用户: Reachability 1.5版本 // My.AppDelegate.h #import “Reachability.h” @interface MyAppDelegate : NSObject <UIApplicationDelegate> { NetworkStatus remoteHostStatus; } @property NetworkStatus remoteHostStatus; @end // My.AppDelegate.m #import “MyAppDelegate.h” @implementation MyAppDelegate @synthesize remoteHostStatus; // 更新网络状态 - (void)updateStatus { self.remoteHostStatus = [[Reachability sharedReachability] remoteHostStatus]; } // 通知网络状态 - (void)reachabilityChanged:(NSNotification *)note { [self updateStatus]; if (self.remoteHostStatus == NotReachable) { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@”AppName”, nil) message:NSLocalizedString (@”NotReachable”, nil) delegate:nil cancelButtonTitle:@”OK” otherButtonTitles: nil]; [alert show]; [alert release]; } } // 程序启动器,启动网络监视 - (void)applicationDidFinishLaunching:(UIApplication *)application { // 设置网络检测的站点 [[Reachability sharedReachability] setHostName:@”www.apple.com”]; [[Reachability sharedReachability] setNetworkStatusNotificati*****Enabled:YES]; // 设置网络状态变化时的通知函数 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:@”kNetworkReachabilityChangedNotification” object:nil]; [self updateStatus]; } - (void)dealloc { // 删除通知对象 [[NSNotificationCenter defaultCenter] removeObserver:self]; [window release]; [super dealloc]; } Reachability 2.0版本 // MyAppDelegate.h @class Reachability; @interface MyAppDelegate : NSObject <UIApplicationDelegate> { Reachability *hostReach; } @end // MyAppDelegate.m - (void)reachabilityChanged:(NSNotification *)note { Reachability* curReach = [note object]; NSParameterAssert([curReach isKindOfClass: [Reachability class]]); NetworkStatus status = [curReach currentReachabilityStatus]; if (status == NotReachable) { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@”AppName”" message:@”NotReachable” delegate:nil cancelButtonTitle:@”YES” otherButtonTitles:nil]; [alert show]; [alert release]; } } - (void)applicationDidFinishLaunching:(UIApplication *)application { // … // 监测网络情况 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name: kReachabilityChangedNotification object: nil]; hostReach = [[Reachability reachabilityWithHostName:@"www.google.com"] retain]; hostReach startNotifer]; // … } 二:使用NSConnection下载数据 1.创建NSConnection对象,设置委托对象 NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[self urlString]]]; [NSURLConnection connectionWithRequest:request delegate:self]; 2. NSURLConnection delegate委托方法 - (void)connection:(NSURLConnection *)connection didReceiveResp*****e:(NSURLResp*****e *)resp*****e; - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error; - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data; - (void)connectionDidFinishLoading:(NSURLConnection *)connection; 3. 实现委托方法 - (void)connection:(NSURLConnection *)connection didReceiveResp*****e:(NSURLResp*****e *)resp*****e { // store data [self.receivedData setLength:0]; //通常在这里先清空接受数据的缓存 } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { /* appends the new data to the received data */ [self.receivedData appendData:data]; //可能多次收到数据,把新的数据添加在现有数据最后 } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { // 错误处理 } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { // disconnect [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; NSString *returnString = [[NSString alloc] initWithData:self.receivedData encoding:NSUTF8StringEncoding]; NSLog(returnString); [self urlLoaded:[self urlString] data:self.receivedData]; firstTimeDownloaded = YES; } 三:使用NSXMLParser解析xml文件 1. 设置委托对象,开始解析 NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data]; //或者也可以使用initWithContentsOfURL直接下载文件,但是有一个原因不这么做: // It’s also possible to have NSXMLParser download the data, by passing it a URL, but this is not desirable // because it gives less control over the network, particularly in responding to connection errors. [parser setDelegate:self]; [parser parse]; 2. 常用的委托方法 - (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict; - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName; - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string; - (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError; static NSString *feedURLString = @”http://www.yifeiyang.net/test/test.xml”; 3. 应用举例 - (void)parseXMLFileAtURL:(NSURL *)URL parseError:(NSError **)error { NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL:URL]; [parser setDelegate:self]; [parser setShouldProcessNamespaces:NO]; [parser setShouldReportNamespacePrefixes:NO]; [parser setShouldResolveExternalEntities:NO]; [parser parse]; NSError *parseError = [parser parserError]; if (parseError && error) { *error = parseError; } [parser release]; } - (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString*)qName attributes:(NSDictionary *)attributeDict{ // 元素开始句柄 if (qName) { elementName = qName; } if ([elementName isEqualToString:@"user"]) { // 输出属性值 NSLog(@”Name is %@ , Age is %@”, [attributeDict objectForKey:@"name"], [attributeDict objectForKey:@"age"]); } } - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName { // 元素终了句柄 if (qName) { elementName = qName; } } - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string { // 取得元素的text } NSError *parseError = nil; [self parseXMLFileAtURL:[NSURL URLWithString:feedURLString] parseError:&parseError];
//实例
//
// NLViewController.m
// NetWorkTest
//
// Created by Nono on 12-5-16.
// Copyright (c) 2012年 NonoWithLilith. All rights reserved.
//
#import “NLViewController.h”
@interface NLViewController ()
@implementation NLViewController
@synthesize label = _label;
@synthesize data = _data;
@synthesize connection = _connection;
- (void)dealloc{
[self.label release];
[self.data release];
[super dealloc];
}
- (void)viewDidLoad
{
[super viewDidLoad];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10.0, 10.0, 300.0, 400)];
self.label = label;
label.textAlignment = UITextAlignmentCenter;
[label setNumberOfLines:0];
label.lineBreakMode = UILineBreakModeWordWrap;
self.label.text = @”正在在请求数据”;
[self.view addSubview:label];
[label release];
//step 1:请求地址
NSString *urlString = @”http://www.google.com”;
NSURL *url = [NSURL URLWithString:urlString];
//step 2:实例化一个request
NSURLRequest *requrst = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0];
//step 3:创建链接
self.connection = [[NSURLConnection alloc] initWithRequest:requrst delegate:self];
if ( self.connection) {
NSLog(@”链接成功”);
}else {
NSLog(@”链接失败”);
}
[url release];
[urlString release];
[requrst release];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)viewDidUnload
{
self.label = nil;
self.data = nil;
[super viewDidUnload];
// Release any retained subviews of the main view.
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}
#pragma mark-
#pragma NSUrlConnectionDelegate methods
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
//接受一个服务端回话,再次一般初始化接受数据的对象
NSLog(@”返回数据类型:%@”,[response textEncodingName]);
NSMutableData *d = [[NSMutableData alloc] init];
self.data = d;
[d release];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
//接受返回数据,这个方法可能会被调用多次,因此将多次返回数据加起来
NSUInteger datalength = [data length];
NSLog(@”返回数据量:%d”,datalength);
[self.data appendData:data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
//连接结束
NSLog(@”%d:”,[self.data length]);
NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
NSString *mystr = [[NSString alloc] initWithData:_data encoding:enc];
// string i
NSLog(@”最后的结果:%@”,mystr);
self.label.text = mystr;
[mystr release];
[self.connection release];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
//链接错误
}