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我有一个使用内部声明的实体的 XML 文件。例如：

<?xml version="1.0" encoding="UTF-8"?>

...

<!ENTITY my_symbol "my symbol value">

...

<my_element>
    <my_next_element>foo&my_symbol;bar</my_next_element>
</my_element>

...

使用 NSXMLParser 类，我如何能够解析my_symbol实体引用？

从实验中，parser:foundInternalEntityDeclarationWithName:value:将调用委托方法来my_symbol声明实体，并使用 value "my symbol value"。然后，当my_next_element元素到达时，NSXMLParser会调用parser:didStartElement:namespaceURI:qualifiedName:attributes:委托方法。

在parser:didEndElement:namespaceURI:qualifiedName:调用 for之前</my_next_element>，parser:foundCharacters:将使用字符串调用委托方法两次：

  1. "foo"
  2. "bar"

my_symbol实体引用被忽略。为了解决实体引用需要什么？

编辑：

从 DTD 中删除 的ENTITY声明my_symbol将导致NSXMLParserUndeclaredEntityError. 这表明当实体声明存在，然后在 中引用时<my_next_element>，它会被注意到。由于某种原因，它只是没有被解析为它所代表的字符串。

此外，如果&amp;在元素中使用，解析器将正确解析它，并在调用委托方法"&"时将其作为字符串传递。parser:foundCharacters:

4

1 回答 1

3

我查看了 NSXMLParser.h，其中列出了代表要支持的以下定义方法：

@interface NSObject (NSXMLParserDelegateEventAdditions)
// Document handling methods
- (void)parserDidStartDocument:(NSXMLParser *)parser;
    // sent when the parser begins parsing of the document.
- (void)parserDidEndDocument:(NSXMLParser *)parser;
    // sent when the parser has completed parsing. If this is encountered, the parse was successful.

// DTD handling methods for various declarations.
- (void)parser:(NSXMLParser *)parser foundNotationDeclarationWithName:(NSString *)name publicID:(NSString *)publicID systemID:(NSString *)systemID;

- (void)parser:(NSXMLParser *)parser foundUnparsedEntityDeclarationWithName:(NSString *)name publicID:(NSString *)publicID systemID:(NSString *)systemID notationName:(NSString *)notationName;

- (void)parser:(NSXMLParser *)parser foundAttributeDeclarationWithName:(NSString *)attributeName forElement:(NSString *)elementName type:(NSString *)type defaultValue:(NSString *)defaultValue;

- (void)parser:(NSXMLParser *)parser foundElementDeclarationWithName:(NSString *)elementName model:(NSString *)model;

- (void)parser:(NSXMLParser *)parser foundInternalEntityDeclarationWithName:(NSString *)name value:(NSString *)value;

- (void)parser:(NSXMLParser *)parser foundExternalEntityDeclarationWithName:(NSString *)name publicID:(NSString *)publicID systemID:(NSString *)systemID;

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict;
    // sent when the parser finds an element start tag.
    // In the case of the cvslog tag, the following is what the delegate receives:
    //   elementName == cvslog, namespaceURI == http://xml.apple.com/cvslog, qualifiedName == cvslog
    // In the case of the radar tag, the following is what's passed in:
    //    elementName == radar, namespaceURI == http://xml.apple.com/radar, qualifiedName == radar:radar
    // If namespace processing >isn't< on, the xmlns:radar="http://xml.apple.com/radar" is returned as an attribute pair, the elementName is 'radar:radar' and there is no qualifiedName.

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName;
    // sent when an end tag is encountered. The various parameters are supplied as above.

- (void)parser:(NSXMLParser *)parser didStartMappingPrefix:(NSString *)prefix toURI:(NSString *)namespaceURI;
    // sent when the parser first sees a namespace attribute.
    // In the case of the cvslog tag, before the didStartElement:, you'd get one of these with prefix == @"" and namespaceURI == @"http://xml.apple.com/cvslog" (i.e. the default namespace)
    // In the case of the radar:radar tag, before the didStartElement: you'd get one of these with prefix == @"radar" and namespaceURI == @"http://xml.apple.com/radar"

- (void)parser:(NSXMLParser *)parser didEndMappingPrefix:(NSString *)prefix;
    // sent when the namespace prefix in question goes out of scope.

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string;
    // This returns the string of the characters encountered thus far. You may not necessarily get the longest character run. The parser reserves the right to hand these to the delegate as potentially many calls in a row to -parser:foundCharacters:

- (void)parser:(NSXMLParser *)parser foundIgnorableWhitespace:(NSString *)whitespaceString;
    // The parser reports ignorable whitespace in the same way as characters it's found.

- (void)parser:(NSXMLParser *)parser foundProcessingInstructionWithTarget:(NSString *)target data:(NSString *)data;
    // The parser reports a processing instruction to you using this method. In the case above, target == @"xml-stylesheet" and data == @"type='text/css' href='cvslog.css'"

- (void)parser:(NSXMLParser *)parser foundComment:(NSString *)comment;
    // A comment (Text in a <!-- --> block) is reported to the delegate as a single string

- (void)parser:(NSXMLParser *)parser foundCDATA:(NSData *)CDATABlock;
    // this reports a CDATA block to the delegate as an NSData.

- (NSData *)parser:(NSXMLParser *)parser resolveExternalEntityName:(NSString *)name systemID:(NSString *)systemID;
    // this gives the delegate an opportunity to resolve an external entity itself and reply with the resulting data.

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError;
    // ...and this reports a fatal error to the delegate. The parser will stop parsing.

- (void)parser:(NSXMLParser *)parser validationErrorOccurred:(NSError *)validationError;
    // If validation is on, this will report a fatal validation error to the delegate. The parser will stop parsing.
@end

根据文件中条目的顺序，它看起来找到的声明方法预计会在找到元素之前发生（正如您所发现的那样）。我会尝试处理所有这些方法，看看它们中的任何一个是否发生，但它们看起来都像是为其他用途而设计的。

我想知道是否有一种方法可以检测发送给您的代表的所有未处理的消息，以防文档/界面不完整。

于 2009-10-15T15:05:02.287 回答