QXmlStreamWriter 类

QXmlStreamWriter 类提供采用简单流化 API 的 XML 写入器。 更多...

头: #include <QXmlStreamWriter>
CMake: find_package(Qt6 REQUIRED COMPONENTS Core)
target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake: QT += core

注意: 此类的所有函数 可重入 .

特性

公共函数

QXmlStreamWriter ()
QXmlStreamWriter (QIODevice * device )
QXmlStreamWriter (QByteArray * array )
QXmlStreamWriter (QString * string )
~QXmlStreamWriter ()
bool autoFormatting () const
int autoFormattingIndent () const
QIODevice * device () const
bool hasError () const
void setAutoFormatting (bool enable )
void setAutoFormattingIndent (int spacesOrTabs )
void setDevice (QIODevice * device )
void writeAttribute (QAnyStringView namespaceUri , QAnyStringView name , QAnyStringView value )
void writeAttribute (QAnyStringView qualifiedName , QAnyStringView value )
void writeAttribute (const QXmlStreamAttribute & 属性 )
void writeAttributes (const QXmlStreamAttributes & 属性 )
void writeCDATA (QAnyStringView text )
void writeCharacters (QAnyStringView text )
void writeComment (QAnyStringView text )
void writeCurrentToken (const QXmlStreamReader & reader )
void writeDTD (QAnyStringView dtd )
void writeDefaultNamespace (QAnyStringView namespaceUri )
void writeEmptyElement (QAnyStringView namespaceUri , QAnyStringView name )
void writeEmptyElement (QAnyStringView qualifiedName )
void writeEndDocument ()
void writeEndElement ()
void writeEntityReference (QAnyStringView name )
void writeNamespace (QAnyStringView namespaceUri , QAnyStringView prefix = {})
void writeProcessingInstruction (QAnyStringView target , QAnyStringView data = {})
void writeStartDocument (QAnyStringView version )
void writeStartDocument ()
void writeStartDocument (QAnyStringView version , bool standalone )
void writeStartElement (QAnyStringView namespaceUri , QAnyStringView name )
void writeStartElement (QAnyStringView qualifiedName )
void writeTextElement (QAnyStringView namespaceUri , QAnyStringView name , QAnyStringView text )
void writeTextElement (QAnyStringView qualifiedName , QAnyStringView text )

详细描述

QXmlStreamWriter 搭档 QXmlStreamReader 为写入 XML。像其相关类,它操作 QIODevice 指定采用 setDevice ()。API 简单明了:为想要编写每个 XML 令牌或事件,写入器提供专用功能。

开始文档采用 writeStartDocument () 和结束它采用 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-project.org/");
    stream.writeTextElement("title", "Qt Project");
    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 (),和 writeDTD (). Chaining of XML streams is supported with writeCurrentToken ().

QXmlStreamWriter always encodes XML in UTF-8.

If an error occurs while writing to the underlying device, hasError () starts returning true and subsequent writes are ignored.

The QXmlStream 书签范例 illustrates how to use a stream writer to write an XML bookmark file (XBEL) that was previously read in by a QXmlStreamReader .

特性文档编制

autoFormatting : bool

This property holds the auto-formatting flag of the stream writer.

This property controls whether or not the stream writer automatically formats the generated XML data. If enabled, the writer automatically adds line-breaks and indentation to empty sections between elements (ignorable whitespace). The main purpose of auto-formatting is to split the data into several lines, and to increase readability for a human reader. The indentation depth can be controlled through the autoFormattingIndent 特性。

默认情况下,自动格式化被禁用。

访问函数:

bool autoFormatting () const
void setAutoFormatting (bool enable )

autoFormattingIndent : int

This property holds the number of spaces or tabs used for indentation when auto-formatting is enabled. Positive numbers indicate spaces, negative numbers tabs.

默认缩进为 4。

访问函数:

int autoFormattingIndent () const
void setAutoFormattingIndent (int spacesOrTabs )

另请参阅 autoFormatting .

成员函数文档编制

QXmlStreamWriter:: QXmlStreamWriter ()

构造流写入器。

另请参阅 setDevice ().

[explicit] QXmlStreamWriter:: QXmlStreamWriter ( QIODevice * device )

Constructs a stream writer that writes into device ;

[explicit] QXmlStreamWriter:: QXmlStreamWriter ( QByteArray * array )

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 .

[explicit] QXmlStreamWriter:: QXmlStreamWriter ( QString * string )

Constructs a stream writer that writes into string .

[noexcept] QXmlStreamWriter:: ~QXmlStreamWriter ()

析构函数。

bool QXmlStreamWriter:: autoFormatting () const

返回 true if auto formatting is enabled, otherwise false .

注意: getter 函数对于特性 autoFormatting。

另请参阅 setAutoFormatting ().

QIODevice *QXmlStreamWriter:: device () const

返回被当前设备关联的 QXmlStreamWriter ,或 nullptr 若没有设备被赋值。

另请参阅 setDevice ().

bool QXmlStreamWriter:: hasError () const

返回 true 若写入失败。

This can happen if the stream failed to write to the underlying device or if the data to be written contained invalid characters.

The error status is never reset. Writes happening after the error occurred may be ignored, even if the error condition is cleared.

void QXmlStreamWriter:: setAutoFormatting ( bool enable )

启用自动格式化若 enable is true ,否则禁用它。

默认值为 false .

注意: setter 函数对于特性 autoFormatting .

另请参阅 autoFormatting ().

void QXmlStreamWriter:: setDevice ( QIODevice * device )

把当前设备设为 device . If you want the stream to write into a QByteArray ,可以创建 QBuffer 设备。

另请参阅 device ().

void QXmlStreamWriter:: writeAttribute ( QAnyStringView namespaceUri , QAnyStringView name , QAnyStringView value )

Writes an attribute with name and value , prefixed for the specified 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 ().

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeAttribute ( QAnyStringView qualifiedName , QAnyStringView value )

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 ().

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeAttribute (const QXmlStreamAttribute & 属性 )

这是重载函数。

写入 属性 .

This function can only be called after writeStartElement () before any content is written, or after writeEmptyElement ().

void QXmlStreamWriter:: writeAttributes (const QXmlStreamAttributes & 属性 )

Writes the attribute vector 属性 . 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 ().

void QXmlStreamWriter:: writeCDATA ( QAnyStringView text )

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.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeCharacters ( QAnyStringView text )

写入 text . The characters "<", "&", and """ are escaped as entity references "<", "&, and """. To avoid the forbidden sequence "]]>", ">" is also escaped as ">".

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

另请参阅 writeEntityReference ().

void QXmlStreamWriter:: writeComment ( QAnyStringView text )

写入 text as XML comment, where text must not contain the forbidden sequence -- or end with - . Note that XML does not provide any way to escape - in a comment.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeCurrentToken (const QXmlStreamReader & reader )

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 ().

void QXmlStreamWriter:: writeDTD ( QAnyStringView dtd )

Writes a DTD section. The dtd represents the entire doctypedecl production from the XML 1.0 specification.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeDefaultNamespace ( QAnyStringView namespaceUri )

Writes a default namespace declaration for namespaceUri .

writeStartElement () 或 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 ) 和 http://www.w3.org/2000/xmlns/ (bound to xml ) by definition cannot be declared as default.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeEmptyElement ( QAnyStringView namespaceUri , QAnyStringView name )

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.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

另请参阅 writeNamespace ().

void QXmlStreamWriter:: writeEmptyElement ( QAnyStringView qualifiedName )

这是重载函数。

Writes an empty element with qualified name qualifiedName . Subsequent calls to writeAttribute () will add attributes to this element.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeEndDocument ()

Closes all remaining open start elements and writes a newline.

另请参阅 writeStartDocument ().

void QXmlStreamWriter:: writeEndElement ()

Closes the previous start element.

另请参阅 writeStartElement ().

void QXmlStreamWriter:: writeEntityReference ( QAnyStringView name )

Writes the entity reference name to the stream, as "& name ;".

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeNamespace ( QAnyStringView namespaceUri , QAnyStringView prefix = {})

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.

writeStartElement () 或 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.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeProcessingInstruction ( QAnyStringView target , QAnyStringView data = {})

Writes an XML processing instruction with target and data ,其中 data must not contain the sequence "?>".

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeStartDocument ( QAnyStringView version )

Writes a document start with the XML version number version .

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

另请参阅 writeEndDocument ().

void QXmlStreamWriter:: writeStartDocument ()

这是重载函数。

Writes a document start with XML version number "1.0".

另请参阅 writeEndDocument ().

void QXmlStreamWriter:: writeStartDocument ( QAnyStringView version , bool standalone )

Writes a document start with the XML version number version and a standalone attribute standalone .

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

另请参阅 writeEndDocument ().

void QXmlStreamWriter:: writeStartElement ( QAnyStringView namespaceUri , QAnyStringView name )

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.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

另请参阅 writeNamespace (), writeEndElement (),和 writeEmptyElement ().

void QXmlStreamWriter:: writeStartElement ( QAnyStringView qualifiedName )

这是重载函数。

Writes a start element with qualifiedName . Subsequent calls to writeAttribute () will add attributes to this element.

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

另请参阅 writeEndElement () 和 writeEmptyElement ().

void QXmlStreamWriter:: writeTextElement ( QAnyStringView namespaceUri , QAnyStringView name , QAnyStringView text )

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();
					

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

void QXmlStreamWriter:: writeTextElement ( QAnyStringView qualifiedName , QAnyStringView text )

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();
					

注意: In Qt versions prior to 6.5, this function took QString , not QAnyStringView .