SAX, JSON , DOM 数据解析

//解析:将特定数据格式(如:xml,json)中提取出来所需的内容

    //SAX: Simply API for XML, xml解析的一种方式,逐行解析,读一行内容,取一行内容,速度慢,占用内存小,如果内容格式不对,不影响之前内容的读取
    //iOS采取SAX解析方法

一 SAX
   
<students name = "123"]]>
  <student positon = "班长"]]>
      <name>小明</name>
      <sex>男</sex>
      <age>20</age>
  </student>
  <student>
      <name>小强</name>
      <sex>男</sex>
      <age>18</age>
  </student>
  <student>
      <name>小红</name>
      <sex>女</sex>
      <age>16</age>
  </student>
</students>

@property (nonatomic, retain) NSMutableArray *studentArray;

@property (nonatomic, retain) Student *student;
    //存放节点信息
@property (nonatomic, retain) NSString *tempString;
- (void)viewDidLoad {
    [super viewDidLoad];

//    NSXMLParser, 用于解析xml 的类,使用SAX解析方式

//NSXMLParser使用步骤

        //1.读取数据
        //获取文件路径
    NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Student" ofType:@"xml"];

        //1
        //创建URL
    NSURL *url = [[NSURL alloc] initFileURLWithPath:filePath];
        //创建NSXMLParser
    NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url];
    [url release];

        //2
        //创建NSData
//    NSData *data = [NSData dataWithContentsOfFile:filePath];
//
//        //创建NSXMLParser
//    NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithData:data];

        //2.开始解析(整个的解析过程在delegate中)
        //设置代理
    xmlParser.delegate = self;
        //开始解析
    BOOL resutle = [xmlParser parse];
    NSLog(@"%d", resutle);
        //解析前思考,将数据以什么形式存储(数组或字典)
        //对于一些固定的数据结构,一般封装成数据模型(如:Student)


    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - NSXMLParserDelegate

    //开始解析
- (void)parserDidStartDocument:(NSXMLParser *)parser
{
    NSLog(@"star");
    self.studentArray = [NSMutableArray arrayWithCapacity:3];
}

    //解析出现错误
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
    NSLog(@"error:%@", parseError);
}    //遇到开始标签
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
        //elementName:标签名字
        //attributeDic:标签属性
        //namespaceURI:命名空间(了解)
    NSLog(@"StarElentment:%@", elementName);
  if ([elementName isEqualToString:@"student"]) {
        self.student = [[Student alloc] init];

    }
} //开始和结束标签之间的内容
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
  self.tempString = string;
}

    //遇到结束标签
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
   if ([elementName isEqualToString:@"student"]) {
         [_studentArray addObject:_student];
         [_student release];
     } else if ([elementName isEqualToString:@"name"]) {
         self.student.name = _tempString;
     } else if ([elementName isEqualToString:@"sex"]) {
         self.student.sex = _tempString;
     } else if ([elementName isEqualToString:@"age"]) {
         self.student.age = _tempString;
     }
}

  //结束解析
- (void)parserDidEndDocument:(NSXMLParser *)parser
{
    NSLog(@"end");
    NSLog(@"%@", _studentArray);
}