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[操作系统]4_1网络学习第一天后感


4_1网络学习第一天后感--网络数据下载

1、网络数据下载包括同步下载和异步下载,一般是使用异步下载,异步下载可以利用NSURLConnection这个类。

 

2、有关数据格式,有JSON格式(多数)、:

 

{} 代表字典,[] 代表数组 ,“” 代表字符串 , 100  代表NSNumber

 

 

 

3、分析网络接口

如:@"http://iappfree.candou.com:8080/free/applications/limited?currency=rmb&page=1&category_id="

http://  (地址使用协议)     iappfree.candou.com   (主机地址)     8080  (主机端口)

free/applications/limited(网络程序文件路径) ?currency=rmb&page=1&category_id=  (程序参数)

 

4、NSURLConnection的同步下载代码:

-(void)testNSURLConnectionSyncDownloadData{  //限免页面接口  NSString *urlString=@"http://iappfree.candou.com:8080/free/applications/limited?currency=rmb&page=1&category_id=";    //发送同步URL请求  //NSURLRequest URL请求对象  NSURL *url=[NSURL URLWithString:urlString];  NSURLRequest *request=[NSURLRequest requestWithURL:url];  NSError *error=nil;  NSData *data=[NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&error];  if (error==nil) {    NSString *str=[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];    NSLog(@"str = %@",str);  }  else {    NSLog(@"下载失败");  }}

5、NSURLConnection的异步下载代码:

-(void)testNSURLConnectionAsyncDownloadData{  _data=[[NSMutableData alloc]init];  //限免页面接口  NSString *urlString=@"http://iappfree.candou.com:8080/free/applications/limited?currency=rmb&page=1&category_id=";  //发起一个异步URL请求  //异步:执行了方法之后,开始下载  _connection=[[NSURLConnection alloc]initWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlString]] delegate:self startImmediately:YES];  }//下面是<NSURLConnectionDataDelegate>代理方法//接收到服务器响应执行-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{  NSLog(@"接收到服务器响应执行");}//接收到数据的时候执行//注意:当数据比较大,可能会多次执行-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{  [_data appendData:data];}//当数据下载完成了-(void)connectionDidFinishLoading:(NSURLConnection *)connection{//  NSLog(@"str =%@",[[NSString alloc]initWithData:_data encoding:NSUTF8StringEncoding]);    //解析JSON (把JSON转化为NSArray或NSDictionary  NSDictionary *dict=[NSJSONSerialization JSONObjectWithData:_data options:NSJSONReadingMutableContainers error:nil];  NSArray *appList=dict[@"applications"];  for (NSDictionary *appDict in appList) {    NSLog(@"name = %@",appDict[@"name"]);  }}//下载失败-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{  NSLog(@"error =%@",error);}

 

 

6、封装NSURLConnection(重点)

先创建一个NSObject类,

#import <Foundation/Foundation.h>@interface ZJHttpRequset : NSObject//data用来保存下载的数据@property (nonatomic,copy) NSMutableData *data;//传人一个网站,下载完成之后,执行target中action的方法-(void)requestWithUrl:(NSString *)url target:(id)target action:(SEL)action;@end

#import "ZJHttpRequset.h"#import "AppModel.h"//消除performSelector的警告#pragma clang diagnostic ignored "-Warc-performSelector-leaks"//类扩展,有些实例变量内部使用,不想放在头文件,就可以放在类扩展里面。@interface ZJHttpRequset ()<NSURLConnectionDataDelegate>{  NSURLConnection *_connection;    //用来保存存进来的url target action  NSString *_url;  id _target;  SEL _action;}@end@implementation ZJHttpRequset-(void)requestWithUrl:(NSString *)url target:(id)target action:(SEL)action{  //保存存进来的变量  _url=url;  _target=target;  _action=action;    //记住要初始化data!!!  _data=[[NSMutableData alloc]init];  //发起异步URL请求  _connection=[[NSURLConnection alloc]initWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url]] delegate:self startImmediately:YES];}//NSURLConnection代理方法//接收数据-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{  [_data appendData:data];}//下载完成了,执行方法-(void)connectionDidFinishLoading:(NSURLConnection *)connection{  if (_target&&[_target respondsToSelector:_action]) {    [_target performSelector:_action withObject:self];  }  //这里面的Object就是这个类本身,目的是把接收到的data传递}

再传入网络接口,利用这个封装好的NSURLConnection类接收

@implementation ViewController- (void)viewDidLoad{  [super viewDidLoad];  //数据接口  NSString *urlString=@"http://iappfree.candou.com:8080/free/applications/limited?currency=rmb&page=1&category_id=";  //初始化数组(tabelView的数据总数组)  _dataArray =[NSMutableArray array];  //初始化自封装好的NSURLConnection类  _request=[[ZJHttpRequset alloc]init];  [_request requestWithUrl:urlString target:self action:@selector(dealDownloadFinish:)];    //创建表视图  [self createTableView];}//接收完成之后会触发的方法(在自封装的URL类中 使用PerformSelector)-(void)dealDownloadFinish:(ZJHttpRequset *)request{  //JSON解析,(获得的是数组还是字典,需要在JASON软件中查看)  NSDictionary *dict=[NSJSONSerialization JSONObjectWithData:request.data options:NSJSONReadingMutableContainers error:nil];  NSArray *appList=dict[@"applications"];  //利用数据模型保存网络接口下的数据,然后把模型添加到tableView总数组  for (NSDictionary *appDict in appList) {        AppModel *model=[[AppModel alloc]initWithDict:appDict];        [_dataArray addObject:model];  }  //下载完数据,更新了总数组,一定要刷新tableview!!!  [_tableView reloadData];}

 

7、作业

scrollView滑动

//第一步:初始化,从网络接口下载数据-(void)createScrollView{  _allData1=[NSMutableArray array];  //陈奕迅网络接口  NSString *urlString=@"http://mapi.damai.cn/hot201303/nindex.aspx?cityid=0&source=10099&version=30602";  _request1 =[[LCHttpRequest alloc]init];  [_request1 requestUrl:urlString withTarget:self andAction:@selector(scrollViewDownload:)];  }//第二步:下载完成后触发的方法,把下载好的data 存入总数组-(void)scrollViewDownload:(LCHttpRequest *)request{  NSArray *arr=[NSJSONSerialization JSONObjectWithData:request.data options:NSJSONReadingMutableContainers error:nil];  for (NSDictionary *dict in arr) {    NSString *str=dict[@"Pic"];    [_allData1 addObject:str];  }  [self loadImage];}//第三步:根据下载的总数组,改变ScrollView的contenSize 同时设置其imageView-(void)loadImage{  _scrollView.contentSize=CGSizeMake(320*_allData1.count, 0);  for (int i=0; i<_allData1.count; i++) {    UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(320*i, 0, 320, 165)];    NSString *str= _allData1[i];    [imageView setImageWithURL:[NSURL URLWithString:str]];    [_scrollView addSubview:imageView];  }  //设置pageControl   _pageControl.numberOfPages=_allData1.count;  _pageControl.enabled=NO;  [self.view bringSubviewToFront:_pageControl];  _pageControl.pageIndicatorTintColor=[UIColor redColor];  //启动定时器,让scroView滑动  [NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector(scrollViewMove) userInfo:nil repeats:YES];}//定时器触发的方法-(void)scrollViewMove{  CGPoint pp=_scrollView.contentOffset;  if (pp.x==320*(_allData1.count-1)) {    pp.x=0;    _scrollView.contentOffset=pp;  }  else{    pp.x+=320;  [UIView animateWithDuration:2.0 animations:^{    _scrollView.contentOffset=pp;  }];  }}//<UIScrllViewDelegate> 代理方法让pageControl跟着移动-(void)scrollViewDidScroll:(UIScrollView *)scrollView{  int page =scrollView.contentOffset.x/320;  _pageControl.currentPage=page;}