The QXmlStreamWriter class provides an XML writer with a simple streaming API. 更多...
The QXmlStreamWriter class provides an XML writer with a simple streaming API.
QXmlStreamWriter 搭档 QXmlStreamReader for writing XML. Like its related class, it operates on a QIODevice 指定采用 setDevice (). The API is simple and straightforward: for every XML token or event you want to write, the writer provides a specialized function.
开始文档采用 writeStartDocument () and end it with writeEndDocument (). This will implicitly close all remaining open tags.
Element tags are opened with writeStartElement () followed by writeAttribute () 或 writeAttributes (), element content, and then writeEndElement (). A shorter form writeEmptyElement () can be used to write empty elements, followed by writeAttributes ().
Element content consists of either characters, entity references or nested elements. It is written with writeCharacters (), which also takes care of escaping all forbidden characters and character sequences, writeEntityReference (), or subsequent calls to writeStartElement (). A convenience method writeTextElement () can be used for writing terminal elements that contain nothing but text.
The following abridged code snippet shows the basic use of the class to write formatted XML with indentation:
QXmlStreamWriter stream(&output);
stream.setAutoFormatting(true);
stream.writeStartDocument();
...
stream.writeStartElement("bookmark");
stream.writeAttribute("href", "http://qt.nokia.com/");
stream.writeTextElement("title", "Qt Home");
stream.writeEndElement(); // bookmark
...
stream.writeEndDocument();
QXmlStreamWriter takes care of prefixing namespaces, all you have to do is specify the namespaceUri when writing elements or attributes. If you must conform to certain prefixes, you can force the writer to use them by declaring the namespaces manually with either writeNamespace () 或 writeDefaultNamespace (). Alternatively, you can bypass the stream writer's namespace support and use overloaded methods that take a qualified name instead. The namespace http://www.w3.org/XML/1998/namespace is implicit and mapped to the prefix xml .
The stream writer can automatically format the generated XML data by adding line-breaks and indentation to empty sections between elements, making the XML data more readable for humans and easier to work with for most source code management systems. The feature can be turned on with the autoFormatting property, and customized with the autoFormattingIndent 特性。
Other functions are writeCDATA (), writeComment (), writeProcessingInstruction (), and writeDTD (). Chaining of XML streams is supported with writeCurrentToken ().
By default, QXmlStreamWriter encodes XML in UTF-8. Different encodings can be enforced using setCodec ().
If an error occurs while writing to the underlying device, hasError () starts returning true and subsequent writes are ignored.
QXmlStream Bookmarks 范例 illustrates how to use a stream writer to write an XML bookmark file (XBEL) that was previously read in by a QXmlStreamReader .
构造流写入器。
另请参阅 setDevice ().
Constructs a stream writer that writes into device ;
Constructs a stream writer that writes into array . This is the same as creating an xml writer that operates on a QBuffer device which in turn operates on array .
Constructs a stream writer that writes into string .
Returns the codec that is currently assigned to the stream.
另请参阅 setCodec ().
返回被当前设备关联的 QXmlStreamWriter , or 0 if no device has been assigned.
另请参阅 setDevice ().
Returns true if the stream failed to write to the underlying device; otherwise returns false.
The error status is never reset. Writes happening after the error occurred are ignored, even if the error condition is cleared.
该函数在 Qt 4.8 引入。
Sets the codec for this stream to codec . The codec is used for encoding any data that is written. By default, QXmlStreamWriter uses UTF-8.
The encoding information is stored in the initial xml tag which gets written when you call writeStartDocument (). Call this function before calling writeStartDocument ().
另请参阅 codec ().
Sets the codec for this stream to the QTextCodec 为指定编码通过 codecName 。常见值对于 codecName include "ISO 8859-1", "UTF-8", and "UTF-16". If the encoding isn't recognized, nothing happens.
另请参阅 QTextCodec.codecForName ().
把当前设备设为 device . If you want the stream to write into a QByteArray , you can create a QBuffer 设备。
另请参阅 device ().
Writes an attribute with name and value , prefixed 为指定 namespaceUri . If the namespace has not been declared yet, QXmlStreamWriter will generate a namespace declaration for it.
This function can only be called after writeStartElement () before any content is written, or after writeEmptyElement ().
这是重载函数。
Writes an attribute with qualifiedName and value .
This function can only be called after writeStartElement () before any content is written, or after writeEmptyElement ().
这是重载函数。
写入 attribute .
This function can only be called after writeStartElement () before any content is written, or after writeEmptyElement ().
Writes the attribute vector attributes . If a namespace referenced in an attribute not been declared yet, QXmlStreamWriter will generate a namespace declaration for it.
This function can only be called after writeStartElement () before any content is written, or after writeEmptyElement ().
另请参阅 writeAttribute () 和 writeNamespace ().
写入 text as CDATA section. If text contains the forbidden character sequence "]]>", it is split into different CDATA sections.
This function mainly exists for completeness. Normally you should not need use it, because writeCharacters () automatically escapes all non-content characters.
写入 text . The characters "<", "&", and """ are escaped as entity references "<", "&, and """. To avoid the forbidden sequence "]]>", ">" is also escaped as ">".
另请参阅 writeEntityReference ().
写入 text as XML comment, where text 不必 contain the forbidden sequence "--" or end with "-". Note that XML does not provide any way to escape "-" in a comment.
Writes the current state of the reader . All possible valid states are supported.
The purpose of this function is to support chained processing of XML data.
另请参阅 QXmlStreamReader.tokenType ().
Writes a default namespace declaration for namespaceUri .
若 writeStartElement () or writeEmptyElement () was called, the declaration applies to the current element; otherwise it applies to the next child element.
Note that the namespaces http://www.w3.org/XML/1998/namespace (bound to xmlns ) and http://www.w3.org/2000/xmlns/ (bound to xml ) by definition cannot be declared as default.
Writes a DTD section. The dtd represents the entire doctypedecl production from the XML 1.0 specification.
Writes an empty element with name , prefixed for the specified namespaceUri . If the namespace has not been declared, QXmlStreamWriter will generate a namespace declaration for it. Subsequent calls to writeAttribute () will add attributes to this element.
另请参阅 writeNamespace ().
这是重载函数。
Writes an empty element with qualified name qualifiedName . Subsequent calls to writeAttribute () will add attributes to this element.
Closes all remaining open start elements and writes a newline.
另请参阅 writeStartDocument ().
Closes the previous start element.
另请参阅 writeStartElement ().
Writes the entity reference name to the stream, as "& name ;".
Writes a namespace declaration for namespaceUri with prefix 。若 prefix is empty, QXmlStreamWriter assigns a unique prefix consisting of the letter 'n' followed by a number.
若 writeStartElement () or writeEmptyElement () was called, the declaration applies to the current element; otherwise it applies to the next child element.
Note that the prefix xml is both predefined and reserved for http://www.w3.org/XML/1998/namespace , which in turn cannot be bound to any other prefix. The prefix xmlns and its URI http://www.w3.org/2000/xmlns/ are used for the namespace mechanism itself and thus completely forbidden in declarations.
Writes an XML processing instruction with target and data , where data must not contain the sequence "?>".
Writes a document start with the XML version number version .
另请参阅 writeEndDocument ().
Writes a document start with the XML version number version and a standalone attribute standalone .
该函数在 Qt 4.5 引入。
另请参阅 writeEndDocument ().
这是重载函数。
Writes a document start with XML version number "1.0". This also writes the encoding information.
该函数在 Qt 4.5 引入。
另请参阅 writeEndDocument () 和 setCodec ().
Writes a start element with name , prefixed for the specified namespaceUri . If the namespace has not been declared yet, QXmlStreamWriter will generate a namespace declaration for it. Subsequent calls to writeAttribute () will add attributes to this element.
另请参阅 writeNamespace (), writeEndElement ()，和 writeEmptyElement ().
这是重载函数。
Writes a start element with qualifiedName . Subsequent calls to writeAttribute () will add attributes to this element.
另请参阅 writeEndElement () 和 writeEmptyElement ().
Writes a text element with name , prefixed for the specified namespaceUri ，和 text . If the namespace has not been declared, QXmlStreamWriter will generate a namespace declaration for it.
This is a convenience function equivalent to:
writeStartElement(namespaceUri, name);
writeCharacters(text);
writeEndElement();
这是重载函数。
Writes a text element with qualifiedName and text .
This is a convenience function equivalent to:
writeStartElement(qualifiedName);
writeCharacters(text);
writeEndElement();