IOS解析XML文檔

2019-11-14 20:04:01

字體：大中小

來源：轉載

供稿：網友

前段時間想找點事做，就是試著看能不能用豆瓣的API做點什么，于是就碰到了這個問題——xml解析。

　　老師還沒講，只能自己去查。

　　XML文檔解析主要有SAX和DOM兩種模式，IOS上兩種模式都可以用，這里就不做過多介紹，我選擇的SAX模式。

IOS解析XML用的是自帶的NSXML框架，框架的核心是NSXMLParser類和它的委托協議NSXMLParserDelegate，其主要的解析工作是在NSXMLParserDelegate實現類中完成的。委托中定義了許多回掉方法，在SAX解析器從上到下遍歷XML文檔的過程中，遇到開始標簽、結束標簽、文檔開始、文檔結束和字符串結束是就會觸發這些方法。這些方法有很多，下面我們列出5個常用的方法。

在文檔開始時觸發

 -(void)parserDidStartDocument:(NSXMLParser *)parser

　　遇到一個新標簽是觸發，其中namespaceURI是命名空間，qualifiedName是限定名，attributes是字典類型的屬性集合。

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict

　　找到字符串時觸發

    -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

　　遇到結束標簽時觸發

    -(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName

　　在文檔結束時觸發

-(void)parserDidEndDocument:(NSXMLParser *)parser

下面通過一個具體的例子來看整個的調用與解析過程

首先這是我們將要解析的XML文件 "info.xml"

    ?    ?    ?<?xml version="1.0" encoding="UTF-8"?>    ?    ?    ?<root>  ?    ?    ?    ?    ?    ? <person id="1">    ?    ?    ?    ?    ? <firstName>Wythe</firstName>   ?    ?    ?    ?    ?    ?    ?    ?    ?    ? <lastName>xu</lastName>   ?    ?    ?    ?    ?    ?    ?    ?    ?    ? <age>22</age>  ?    ?    ?    ?    ?    ?    ?    ? </person>  ?    ?    ?   ?    ?    ?    ? <person id="2">   ?    ?    ?    ?    ?    ?    ?    ?    ? <firstName>li</firstName>    ?    ?    ?    ?    ?    ?    ?    ?    ?    ? <lastName>si</lastName>    ?    ?    ?    ?    ?    ?    ?    ?    ?    ? <age>31</age>  ?    ?    ?    ?    ?    ?    ?    ? </person>    ?    ?    ?    ?    ?    ?    ?    ?    ?<person id="3">   ?    ?    ?    ?    ?        ?    ?    ?    ?    ? <firstName>Dipen</firstName>    ?    ?    ?    ?    ?        ?    ?    ?    ?    ? <lastName>Shah</lastName>    ?    ?    ?    ?    ?        ?    ?    ?    ?    ? <age>24</age>    ?    ?    ?    ?        ?    ?    ?    ? </person>    ?    ?    ?    ?    ?    ?    ?</root>

接來來是一個頭文件 "ViewController.h"

#import <UIKit/UIKit.h>@interface ViewController : UIViewController<NSXMLParserDelegate>@PRoperty NSXMLParser *parser;@property NSMutableArray *person;@property NSString *currenttag;@end

然后是它的實現文件 "ViewController.m"

#import "ViewController.h"@interface ViewController ()@end@implementation ViewController@synthesize  parser = _parser , person = _person , currenttag = _currenttag;- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        // Custom initialization    }    return self;}- (void)viewDidLoad{    [super viewDidLoad];        NSString *xmlFilePath = [[NSBundle mainBundle]pathForResource:@"info"ofType:@"xml"];        NSData *data = [[NSData alloc]initWithContentsOfFile:xmlFilePath];        self.parser = [[NSXMLParser alloc]initWithData:data];        self.parser.delegate = self;        [self.parser parse];        NSLog(@"%@",_person);    }- (void)didReceiveMemoryWarning{    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}#pragma mark delegate method-(void)parserDidStartDocument:(NSXMLParser *)parser{    _person = [[NSMutableArray alloc]init];    NSLog(@"start parse 1");}-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{    _currenttag = elementName;        if ([_currenttag isEqualToString:@"person"]) {        NSString *_id = [attributeDict objectForKey:@"id"];        NSMutableDictionary *dict = [[NSMutableDictionary alloc]init];        [dict setObject:_id forKey:@"id"];        [_person addObject:dict];    }        NSLog(@"start element");}-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{    NSMutableDictionary *dict = [_person lastObject];        if ([_currenttag isEqualToString:@"firstName"] && dict) {        [dict setObject:string forKey:@"firstName"];    }    if ([_currenttag isEqualToString:@"lastName"] && dict) {        [dict setObject:string forKey:@"lastName"];    }    if ([_currenttag isEqualToString:@"age"] && dict) {        [dict setObject:string forKey:@"age"];    }        NSLog(@"found characters");}-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{    _currenttag = nil;        NSLog(@"end element");}-(void)parserDidEndDocument:(NSXMLParser *)parser{    NSLog(@"parse end");}@end

通過斷電和輸出信息，我們可以知道整個解析過程是開始解析文檔、開始標簽、找到字符串、結束標簽、文檔結束。

2014-09-10 16:45:32.920 xmlforblog[3820:60b] start parse 12014-09-10 16:45:32.921 xmlforblog[3820:60b] start element2014-09-10 16:45:32.922 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.922 xmlforblog[3820:60b] start element2014-09-10 16:45:32.922 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.922 xmlforblog[3820:60b] start element2014-09-10 16:45:32.923 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.923 xmlforblog[3820:60b] end element2014-09-10 16:45:32.923 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.923 xmlforblog[3820:60b] start element2014-09-10 16:45:32.924 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.924 xmlforblog[3820:60b] end element2014-09-10 16:45:32.924 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.924 xmlforblog[3820:60b] start element2014-09-10 16:45:32.925 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.925 xmlforblog[3820:60b] end element2014-09-10 16:45:32.925 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.925 xmlforblog[3820:60b] end element2014-09-10 16:45:32.926 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.926 xmlforblog[3820:60b] start element2014-09-10 16:45:32.928 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.929 xmlforblog[3820:60b] start element2014-09-10 16:45:32.929 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.929 xmlforblog[3820:60b] end element2014-09-10 16:45:32.930 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.930 xmlforblog[3820:60b] start element2014-09-10 16:45:32.930 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.930 xmlforblog[3820:60b] end element2014-09-10 16:45:32.931 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.931 xmlforblog[3820:60b] start element2014-09-10 16:45:32.931 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.931 xmlforblog[3820:60b] end element2014-09-10 16:45:32.931 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.932 xmlforblog[3820:60b] end element2014-09-10 16:45:32.932 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.932 xmlforblog[3820:60b] start element2014-09-10 16:45:32.932 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.933 xmlforblog[3820:60b] start element2014-09-10 16:45:32.933 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.933 xmlforblog[3820:60b] end element2014-09-10 16:45:32.933 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.934 xmlforblog[3820:60b] start element2014-09-10 16:45:32.934 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.934 xmlforblog[3820:60b] end element2014-09-10 16:45:32.934 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.935 xmlforblog[3820:60b] start element2014-09-10 16:45:32.935 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.935 xmlforblog[3820:60b] end element2014-09-10 16:45:32.935 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.936 xmlforblog[3820:60b] end element2014-09-10 16:45:32.936 xmlforblog[3820:60b] found characters2014-09-10 16:45:32.936 xmlforblog[3820:60b] end element2014-09-10 16:45:32.936 xmlforblog[3820:60b] parse end2014-09-10 16:45:32.936 xmlforblog[3820:60b] (        {        age = 22;        firstName = Wythe;        id = 1;        lastName = xu;    },        {        age = 31;        firstName = li;        id = 2;        lastName = si;    },        {        age = 24;        firstName = Dipen;        id = 3;        lastName = Shah;    })

執行結果

而我們的處理主要是在 開始標簽、找到字符串（

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

）中。

遇到開始標簽時，我們現判斷標簽，名字，如果是person，表明接下來就是person的信息，這樣我們就先創建一個可變字典，以便將來存放它的值。

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{    _currenttag = elementName;        if ([_currenttag isEqualToString:@"person"]) {        NSString *_id = [attributeDict objectForKey:@"id"];        NSMutableDictionary *dict = [[NSMutableDictionary alloc]init];        [dict setObject:_id forKey:@"id"];        [_person addObject:dict];    }        NSLog(@"start element");}

在找到字符串時，我們就是通過判斷當前標簽名，將對應的信息保存到剛剛創建的字典中

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{    NSMutableDictionary *dict = [_person lastObject];        if ([_currenttag isEqualToString:@"firstName"] && dict) {        [dict setObject:string forKey:@"firstName"];    }    if ([_currenttag isEqualToString:@"lastName"] && dict) {        [dict setObject:string forKey:@"lastName"];    }    if ([_currenttag isEqualToString:@"age"] && dict) {        [dict setObject:string forKey:@"age"];    }        NSLog(@"found characters");}