1、同步请求可以从因特网请求数据,一旦发送同步请求,程序将停止用户交互,直至服务器返回数据完成,才可以进行下一步操作,
2、异步请求不会阻塞主线程,而会建立一个新的线程来操作,用户发出异步请求后,依然可以对UI进行操作,程序可以继续运行
3、GET请求,将参数直接写在访问路径上。操作简单,不过容易被外界看到,安全性不高,地址最多255字节;
4、POST请求,将参数放到body里面。POST请求操作相对复杂,需要将参数和地址分开,不过安全性高,参数放在body里面,不易被捕获。
为简化起见,直接下载AppDelegate里面了
<!--------------------AppDelegate.h文件------------------------->
#import <UIKit/UIKit.h>
@interface AppDelegate : UIResponder <UIApplicationDelegate , NSURLConnectionDataDelegate, NSURLConnectionDelegate>{
NSMutableData *receiveData;
}
@property (nonatomic, retain) NSMutableData *receiveData;
@property (strong, nonatomic) UIWindow *window;
@end
<!--------------------AppDelegate.m文件------------------------->
#import "AppDelegate.h"
@implementation AppDelegate
@synthesize receiveData;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
// //1、同步GET请求
// //第一步,创建URL
// NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do?type=focus-c"];
// //第二步,通过URL创建网络请求
// NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
// //NSURLRequest初始化方法第一个参数:请求访问路径,第二个参数:缓存协议,第三个参数:网络请求超时时间(秒)
//// 其中缓存协议是个枚举类型包含:
//// NSURLRequestUseProtocolCachePolicy(基础策略)
//// NSURLRequestReloadIgnoringLocalCacheData(忽略本地缓存)
//// NSURLRequestReturnCacheDataElseLoad(首先使用缓存,如果没有本地缓存,才从原地址下载)
//// NSURLRequestReturnCacheDataDontLoad(使用本地缓存,从不下载,如果本地没有缓存,则请求失败,此策略多用于离线操作)
//// NSURLRequestReloadIgnoringLocalAndRemoteCacheData(无视任何缓存策略,无论是本地的还是远程的,总是从原地址重新下载)
//// NSURLRequestReloadRevalidatingCacheData(如果本地缓存是有效的则不下载,其他任何情况都从原地址重新下载)
// //第三步,连接服务器
// NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
// NSString *str = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];
// NSLog(@"%@",str);
// //2、同步POST请求
// //第一步,创建URL
// NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do"];
// //第二步,创建请求
// NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
// [request setHTTPMethod:@"POST"];//设置请求方式为POST,默认为GET
// NSString *str = @"type=focus-c";//设置参数
// NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
// [request setHTTPBody:data];
// //第三步,连接服务器
// NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
// NSString *str1 = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];
// NSLog(@"%@",str1);
//3、异步GET请求
// //第一步,创建url
// NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do?type=focus-c"];
// //第二步,创建请求
// NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
// //第三步,连接服务器
// NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
//4、异步POST请求
//第一步,创建url
NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do"];
//第二步,创建请求
NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
[request setHTTPMethod:@"POST"];
NSString *str = @"type=focus-c";
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPBody:data];
//第三步,连接服务器
NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
return YES;
}
//5、异步请求的代理方法
//接收到服务器回应的时候调用此方法
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;
//NSLog(@"%@",[res allHeaderFields]);
self.receiveData = [NSMutableData data];
}
//接收到服务器传输数据的时候调用,此方法根据数据大小执行若干次
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[self.receiveData appendData:data];
}
//数据传完之后调用此方法
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *receiveStr = [[NSString alloc]initWithData:self.receiveData encoding:NSUTF8StringEncoding];
NSLog(@"%@",receiveStr);
}
//网络请求过程中,出现任何错误(断网,连接超时等)会进入此方法
-(void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error
{
NSLog(@"%@",[error localizedDescription]);
}