iOS 解析 HTML

xml,json都有大量的库来解析，我们如何解析html呢？

TFHpple是一个小型的封装，可以用来解析html，它是对libxml的封装，语法是xpath。

今天我看到一个直接用libxml来解析html，参看：http://www.cocoanetics.com/2011/09/taming-html-parsing-with-libxml-1/#comment-3090 那张图画得一目了然，很值得收藏。这个文章中的源码不能遍历所有的html，我做了一点修改可以将html遍历打印出来

001
// NSData data contains the document data 

002
// encoding is the NSStringEncoding of the data 

003
// baseURL the documents base URL, i.e. location  

004
    
005
CFStringEncoding cfenc = CFStringConvertNSStringEncodingToEncoding(encoding); 

006
CFStringRef cfencstr = CFStringConvertEncodingToIANACharSetName(cfenc); 

007
const char*enc = CFStringGetCStringPtr(cfencstr, 0); 

008
    
009
htmlDocPtr _htmlDocument = htmlReadDoc([data bytes], 

010
      [[baseURL absoluteString] UTF8String], 

011
      enc, 

012
      XML_PARSE_NOERROR | XML_PARSE_NOWARNING); 

013
if(_htmlDocument) 

014
{ 

015
   xmlFreeDoc(_htmlDocument); 

016
} 

017
   
018
xmlNodePtr currentNode = (xmlNodePtr)_htmlDocument; 

019
   
020
while(currentNode)  

021
    { 

022
        // output node if it is an element 

023
           
024
        if(currentNode->type == XML_ELEMENT_NODE) 

025
        { 

026
            NSMutableArray *attrArray = [NSMutableArray array]; 

027
               
028
            for(xmlAttrPtr attrNode = currentNode->properties; attrNode; attrNode = attrNode->next) 

029
            { 

030
                xmlNodePtr contents = attrNode->children; 

031
                   
032
                [attrArray addObject:[NSString stringWithFormat:@"%s='%s'", attrNode->name, contents->content]]; 

033
            } 

034
               
035
            NSString *attrString = [attrArray componentsJoinedByString:@" "];  

036
               
037
            if([attrString length]) 

038
            { 

039
                attrString = [@" "stringByAppendingString:attrString]; 

040
            } 

041
               
042
            NSLog(@"<%s%@>", currentNode->name, attrString); 

043
        } 

044
        else if(currentNode->type == XML_TEXT_NODE) 

045
        { 

046
            //NSLog(@"%s", currentNode->content); 

047
            NSLog(@"%@", [NSString stringWithCString:(const char*)currentNode->content encoding:NSUTF8StringEncoding]); 

048
        } 

049
        else if(currentNode->type == XML_COMMENT_NODE) 

050
        { 

051
            NSLog(@"/* %s */", currentNode->name); 

052
        } 

053
       
054
           
055
        if(currentNode && currentNode->children) 

056
        { 

057
            currentNode = currentNode->children; 

058
        } 

059
        else if(currentNode && currentNode->next) 

060
        { 

061
            currentNode = currentNode->next; 

062
        } 

063
        else 

064
        { 

065
            currentNode = currentNode->parent; 

066
               
067
            // close node 

068
            if(currentNode && currentNode->type == XML_ELEMENT_NODE) 

069
            { 

070
                NSLog(@"</%s>", currentNode->name); 

071
            } 

072
               
073
            if(currentNode->next) 

074
            { 

075
                currentNode = currentNode->next; 

076
            } 

077
            else  

078
            { 

079
                while(currentNode) 

080
                { 

081
                    currentNode = currentNode->parent; 

082
                    if(currentNode && currentNode->type == XML_ELEMENT_NODE) 

083
                    { 

084
                        NSLog(@"</%s>", currentNode->name); 

085
                        if (strcmp((const char*)currentNode->name, "table") == 0) 

086
                        { 

087
                            NSLog(@"over"); 

088
                        } 

089
                    } 

090
                       
091
                    if(currentNode == nodes->nodeTab[0]) 

092
                    { 

093
                        break; 

094
                    } 

095
                       
096
                    if(currentNode && currentNode->next) 

097
                    { 

098
                        currentNode = currentNode->next; 

099
                        break; 

100
                    } 

101
                } 

102
            } 

103
        } 

104
           
105
        if(currentNode == nodes->nodeTab[0]) 

106
        { 

107
            break; 

108
        } 

109
    }

不过我还是喜欢用TFHpple，因为它很简单，也好用，但是它的功能不是很完完善。比如，不能获取children node,我就写了两个方法，一个是获取children node,一个是获取所有的contents. 还有node的属性content的key与node's content的key一样，都是@"nodeContent", 正确情况下属性的应是@"attributeContent"，

所以我写了这个方法，同时修改node属性的content key.

01
NSDictionary *DictionaryForNode2(xmlNodePtr currentNode, NSMutableDictionary *parentResult) 

02
{ 

03
    NSMutableDictionary *resultForNode = [NSMutableDictionary dictionary]; 

04
       
05
    if(currentNode->name) 

06
    { 

07
        NSString *currentNodeContent = 

08
        [NSString stringWithCString:(const char*)currentNode->name encoding:NSUTF8StringEncoding]; 

09
        [resultForNode setObject:currentNodeContent forKey:@"nodeName"]; 

10
    } 

11
       
12
    if(currentNode->content) 

13
    { 

14
        NSString *currentNodeContent = [NSString stringWithCString:(const char*)currentNode->content encoding:NSUTF8StringEncoding]; 

15
           
16
        if(currentNode->type == XML_TEXT_NODE) 

17
        { 

18
            if(currentNode->parent->type == XML_ELEMENT_NODE) 

19
            { 

20
                [parentResult setObject:currentNodeContent forKey:@"nodeContent"]; 

21
                returnnil; 

22
            } 

23
               
24
            if(currentNode->parent->type == XML_ATTRIBUTE_NODE) 

25
            { 

26
                [parentResult 

27
                 setObject: 

28
                 [currentNodeContent 

29
                  stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] 

30
                 forKey:@"attributeContent"]; 

31
                returnnil; 

32
   
33
            } 

34
        } 

35
    } 

36
       
37
   
38
       
39
    xmlAttr *attribute = currentNode->properties; 

40
    if(attribute) 

41
    { 

42
        NSMutableArray *attributeArray = [NSMutableArray array]; 

43
        while(attribute) 

44
        { 

45
            NSMutableDictionary *attributeDictionary = [NSMutableDictionary dictionary]; 

46
            NSString *attributeName = 

47
            [NSString stringWithCString:(const char*)attribute->name encoding:NSUTF8StringEncoding]; 

48
            if(attributeName) 

49
            { 

50
                [attributeDictionary setObject:attributeName forKey:@"attributeName"]; 

51
            } 

52
               
53
            if(attribute->children) 

54
            { 

55
                NSDictionary *childDictionary = DictionaryForNode2(attribute->children, attributeDictionary); 

56
                if(childDictionary) 

57
                { 

58
                    [attributeDictionary setObject:childDictionary forKey:@"attributeContent"]; 

59
                } 

60
            } 

61
               
62
            if([attributeDictionary count] > 0) 

63
            { 

64
                [attributeArray addObject:attributeDictionary]; 

65
            } 

66
            attribute = attribute->next; 

67
        } 

68
           
69
        if([attributeArray count] > 0) 

70
        { 

71
            [resultForNode setObject:attributeArray forKey:@"nodeAttributeArray"]; 

72
        } 

73
    } 

74
       
75
    xmlNodePtr childNode = currentNode->children; 

76
    if(childNode) 

77
    { 

78
        NSMutableArray *childContentArray = [NSMutableArray array]; 

79
        while(childNode) 

80
        { 

81
            NSDictionary *childDictionary = DictionaryForNode2(childNode, resultForNode); 

82
            if(childDictionary) 

83
            { 

84
                [childContentArray addObject:childDictionary]; 

85
            } 

86
            childNode = childNode->next; 

87
        } 

88
        if([childContentArray count] > 0) 

89
        { 

90
            [resultForNode setObject:childContentArray forKey:@"nodeChildArray"]; 

91
        } 

92
    } 

93
       
94
    returnresultForNode; 

95
}

TFHppleElement.m里加了两个key 常量

1
NSString * constTFHppleNodeAttributeContentKey  = @"attributeContent"; 

2
NSString * const TFHppleNodeChildArrayKey        = @"nodeChildArray";

并修改获取属性方法为：

1
- (NSDictionary *) attributes 

2
{ 

3
  NSMutableDictionary * translatedAttributes = [NSMutableDictionary dictionary]; 

4
  for(NSDictionary * attributeDict in [node objectForKey:TFHppleNodeAttributeArrayKey]) { 

5
    [translatedAttributes setObject:[attributeDict objectForKey:TFHppleNodeAttributeContentKey] 

6
                             forKey:[attributeDict objectForKey:TFHppleNodeAttributeNameKey]]; 

7
  } 

8
  returntranslatedAttributes; 

9
}

并添加获取children node 方法：

01
- (BOOL) hasChildren 

02
{ 

03
    NSArray *childs = [node objectForKey: TFHppleNodeChildArrayKey]; 

04
       
05
    if(childs)  

06
    { 

07
        return YES; 

08
    } 

09
       
10
    return NO; 

11
} 

12
   
13
- (NSArray *) children 

14
{ 

15
    if([self hasChildren]) 

16
        return[node objectForKey: TFHppleNodeChildArrayKey]; 

17
    returnnil; 

18
}

最后我还加了一个获取所有content的主法：

1
- (NSString *)contentsAt:(NSString *)xPathOrCss;

请看源码。