iOS学习笔记–10 IOS之云端应用
10.1 GET请求
10.2 XML解析
10.3 JSON解析
10.4 POST请求
10.1 GET请求
通过一个第三方提供的云服务，查询IP归属地：http://www.youdao.com/smartresult-xml/search.s?type=ip&q=218.241.121.186
它的返回格式是xml :
新建个例子：CSSimpleXML，设计原型：
编辑按钮事件：
- (IBAction)query:(id)sender {
NSString* strUrl = [NSString stringWithFormat:@"http://www.youdao.com/smartresult-xml/search.s?type=ip&q=%@", ipText.text];
NSURL* url = [NSURL URLWithString:strUrl];
NSURLRequest* request = [[NSURLRequest alloc]initWithURL:url];
NSURLConnection* connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
[connection release];
[request release];
[activityIndicator startAnimating];
}
定义NSURLConnection的委托：
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
委托（delegate）是一种事件处理机制，当满足条件时候触发。delegate:self说明是委托当前对象处理事件，我们需要实现它们回调方法。
NSURLConnection 回调方法
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 请求成功，并且接收数据。 -(void) connection:(NSURLConnection *)connection didFailWithError: (NSError *)error 请求成功，但是加载数据出现异常。 -(void) connectionDidFinishLoading: (NSURLConnection*) connection加载数据成功，在connection:didReceiveData方法之后执行。
接收数据处理
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData *)data {
//默认对于中文的支持不好
NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
NSString* gbkNSString = [[NSString alloc]initWithData:data encoding:enc];
//如果是黑UTF-8 NSXMLParese会报错
xmlString = [[NSString alloc]initWithString:[gbkNSString stringByReplacingOccurrencesOfString:@"<?xml version=\"1.0\" encoding=\"gbk\"?>" withString:@"<?xml version=\"1.0\" encoding=\"utf-8\"?>"]];
NSLog(@"%@", xmlString);
[gbkNSString release];
}
iPhone SDK提供的XML解析类只能解析utf-8编码，如果从服务器返回的xml编码是gbk等，要转换成utf-8再开始解析。
10.2 XML解析
关于iPhone发送GET请求，就是通过NSURLRequest和NSURLConnection两个类实现的。
在众多的回调方法。解析XML是在 connectionDidFinishLoading:方法开始的。
解析XML文件也是要通过XML回调方式实现解析处理的。
NSXMLParser，是iPhone解析XML SDK工具类。
NSXMLParser采用SAX方式而不是DOM方式解析，SAX是基于事件触发的解析方式，解析器从上到下遍历xml文档，遇到开始标签、结束标签、文档开始、文档结束和字符串都会触发事件。
解析开始处理
-(void)connectionDidFinishLoading:(NSURLConnection*)connection {
[activityIndicator stopAnimating];
//开始解析XML
NSXMLParser* ipParser = [[NSXMLParser alloc]initWithData:[xmlString dataUsingEncoding:NSUTF8StringEncoding ]];;
ipParser.delegate = self;
[ipParser parse];
[ipParser release];
}
NSXMLParser回调方法
- (void)parserDidStartDocument:(NSXMLParser *)parser文档开始的时候触发 - (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError 文档出错的时候触发 - (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *) qualifiedName attributes:(NSDictionary *)attributeDict 遇到一个开始标签时候触发。 - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string 遇到字符串时候触发 - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementNamenamespaceURI:(NSString *) namespaceURIqualifiedName:(NSString *)qName 遇到结束标签时候出发。 - (void)parserDidEndDocument:(NSXMLParser *)parser 遇到文档结束时候触发。
文档开始的回调方法
这个方法在解析过程中只调运一次，一般在这个方法中进行有关解析的初始化处理。
//文档开始的时候触发
- (void)parserDidStartDocument:(NSXMLParser *)parser {
info = [[NSMutableDictionary alloc]initWithCapacity:1];
}
文档出错回调方法
//文档出错的时候触发
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
UIAlertView* errorAlert = [[UIAlertView alloc]initWithTitle:[parseError localizedDescription] message:[parseError localizedFailureReason] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[errorAlert show];
[errorAlert release];
}
遇到开始标签回调方法
参数elementName是标签的名字，attributeDict 是属性列表，namespaceURI 是命名空间，如果有命名空间qualifiedName是指定的前缀名。
//遇到一个开始标签时候触发。
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *) qualifiedName attributes:(NSDictionary *)attributeDict {
NSLog(@"value:%@\n", elementName);
currentTagName = elementName;
}
遇到字符串回调方法
//遇到字符串时候触发
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
NSLog(@"value:%@\n", string);
string = [string stringByReplacingOccurrencesOfString:@"\n" withString:@""];
if ([currentTagName isEqualToString:@"ip"]) {
if (![string isEqualToString:@""]) {
[info setValue:string forKey:currentTagName];
}
} else if([currentTagName isEqualToString:@"location"]) {
if (![string isEqualToString:@""]) {
[info setValue:string forKey:currentTagName];
}
}
}
遇到结束标签回调方法
//遇到结束标签时候出发。
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementNamenamespaceURI:(NSString *)namespaceURIqualifiedName:(NSString *)qName {
}
遇到结束文档回调方法
// 遇到文档结束时候触发。
- (void)parserDidEndDocument:(NSXMLParser *)parser {
NSMutableString* outString = [[NSMutableString alloc]initWithCapacity:1];
for (id key in info) {
[outString appendFormat:@"%@:%@\n", key, [info objectForKey:key]];
}
msgText.text = outString;
[outString release];
[xmlString release];
}
10.3 JSON解析
http://www.geonames.org/export/ws-overview.html
获得JSON：
{
status = {
message = "the daily limit of 30000 credits demo has been exceeded.Please throttle your requests or use the commercial service.";
value = 18;
};
}
10.3.1 JSON解析API
iPhone SDK没有提供JSON解析API，可以使用第三方的API类库json-framework，下载地址：
https://github.com/stig/json-framework/
把Classes/JSON/下面的类拷贝到我们的工程的Classes目录下面，右键添加存在的类文件。
实现回调方法
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data - (void) connectionDidFinishLoading: (NSURLConnection*) connection -(void) connection:(NSURLConnection *)connection didFailWithError: (NSError *)error
connection:didReceiveData:
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData *)data {
outString = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"%@", outString);
}
connectionDidFinishLoading:
outString的 JSONValue消息获得NSMutableDictionary，JSON api中提供了NSString的分类（Catelog）
-(void)connectionDidFinishLoading:(NSURLConnection*)connection {
NSMutableDictionary* jsonObj = [outString JSONValue];
NSLog(@"%@", jsonObj);
NSMutableDictionary* jsonSubObj = [jsonObj objectForKey:@"status"];
NSString* text = [[NSString alloc]initWithFormat:@"message=%@\n\nvalue=%@", [jsonSubObj objectForKey:@"message"],[jsonSubObj objectForKey:@"value"]];
mstText.text = text;
[text release];
[outString release];
[activity stopAnimating];
}
文档出错回调方法
-(void) connection:(NSURLConnection *)connection didFailWithError: (NSError *)error {
UIAlertView* errorAlert = [[UIAlertView alloc]initWithTitle:[error localizedDescription] message:[error localizedFailureReason]
delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[errorAlert show];
[errorAlert release];
}
点击按钮事件
-(IBAction)go:(id)sender{
NSString *strurl =@"http://api.geonames.org/findNearByWeatherJSON?lat=43&lng=-2&username=demo";
NSURL *url = [NSURL URLWithString:strurl];
NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url];
NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
[connection release];
[request release];
[activityIndicatorView startAnimating];
}
10.4 POST请求
为了学习iPhone的POST请求，安排案例如下：
在画面中输入用户名和密码，然后以POST方式提交数据到服务器端。
NSMutableURLRequest
POST请求与GET不同，不使用的NSURLRequest，而是使用NSMutableURLRequest类,这是一个可变的NSURLRequest类。
- (IBAction)login:(id)sender {
//http://www.sunnyer.com/shop/member!login.action
//member.email:[email protected]
//member.password:dfgdfgrf
[activity startAnimating];
NSString* post = [NSString stringWithFormat:@"memberIdOrCellphoneOrEmail=%@&&password=%@", username.text, password.text];
NSData* postData = [post dataUsingEncoding:NSUTF8StringEncoding];
NSURL* postServierURL = [NSURL URLWithString:@"http://www.jinjiang.com/membercenter/member/ordinaryLogin"];
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:postServierURL];
[request setHTTPMethod:@"POST"];
[request setHTTPBody:postData];
NSURLConnection* connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (!connection) {
NSLog(@"Failed to submit request");
} else {
NSLog(@"Request submitted");
}
[connection release];
}
POST参数是以一个字符串方式传递： memberIdOrCellphoneOrEmail=%@&&password=%@
[request setHTTPMethod:@"POST"];
知道请求方法为POST方法，但是要注意POST必须大写。
[request setHTTPBody:postData];该语句是将要提交的数据放到请求体中。
connection:didReceiveData:
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData *)data {
outString = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"%@", outString);
}
connectionDidFinishLoading:
-(void)connectionDidFinishLoading:(NSURLConnection*)connection{
NSLog(@"%@", outString);
[webView loadHTMLString:outString baseURL:[[NSURL alloc]initWithString:@"http://www.jinjiang.com"]];
[activity stopAnimating];
}
文档出错回调方法
-(void) connection:(NSURLConnection *)connection didFailWithError: (NSError *)error {
UIAlertView* errorAlert = [[UIAlertView alloc]initWithTitle:[error localizedDescription] message:[error localizedFailureReason]
delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[errorAlert show];
[errorAlert release];
}
注：
1 本教程是基于关东升老师的教程