Java : Attr (XML) 示例

Attr (Java SE 22 & JDK 22) 示例。
您将在大多数 Attr 方法中找到代码示例。

注解 :

本文可能使用了翻译软件以方便阅读。另请查看英文原文。

简介

Attr 接口表示 Element 对象中的属性。通常，属性的允许值在与文档关联的架构中定义。 (机器翻译)

Class diagram

Code examples on this page use the printDocument method below.

public void printDocument(Document document) throws TransformerException {
    final var transformer = TransformerFactory.newInstance().newTransformer();
    transformer.setOutputProperty(OutputKeys.INDENT, "yes");
    transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

    final var result = new StreamResult(new StringWriter());
    transformer.transform(new DOMSource(document), result);

    System.out.print(result.getWriter());
}

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.newDocument();

final var root = document.createElement("root");
System.out.println(root); // [root: null]

document.appendChild(root);

final var child = document.createElement("child");
System.out.println(child); // [child: null]

root.appendChild(child);

final var attrA = document.createAttribute("aa");
attrA.setValue("AA");
System.out.println(attrA); // aa="AA"

child.setAttributeNode(attrA);

final var attrB = document.createAttribute("bb");
attrB.setValue("BB");
System.out.println(attrB); // bb="BB"

child.setAttributeNode(attrB);

//<root>
//    <child aa="AA" bb="BB"/>
//</root>
printDocument(document);

Fields declared in Node

ATTRIBUTE_NODE, CDATA_SECTION_NODE, COMMENT_NODE, DOCUMENT_FRAGMENT_NODE, DOCUMENT_NODE, DOCUMENT_POSITION_CONTAINED_BY, DOCUMENT_POSITION_CONTAINS, DOCUMENT_POSITION_DISCONNECTED, DOCUMENT_POSITION_FOLLOWING, DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC, DOCUMENT_POSITION_PRECEDING, DOCUMENT_TYPE_NODE, ELEMENT_NODE, ENTITY_NODE, ENTITY_REFERENCE_NODE, NOTATION_NODE, PROCESSING_INSTRUCTION_NODE, TEXT_NODE

请参阅下面的链接。

Node 示例

Methods

String getName ()

返回此属性的名称。 (机器翻译)

final var xml = """
        <root>
            <child aa="AA"/>
        </root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    final var attr = element.getAttributeNode("aa");
    System.out.println(attr); // aa="AA"

    System.out.println(attr.getName()); // aa
    System.out.println(attr.getValue()); // AA
    System.out.println(attr.getSchemaTypeInfo()); // aa="AA"
}

Element getOwnerElement ()

此属性所附加到的元素节点；如果此属性未使用，则为空。 (机器翻译)

final var xml = """
        <root>
            <child aa="AA"/>
        </root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    final var attr = element.getAttributeNode("aa");
    System.out.println(attr); // aa="AA"

    final var owner = attr.getOwnerElement();
    System.out.println(owner); // [child: null]
    System.out.println(owner.isSameNode(child)); // true
}

TypeInfo getSchemaTypeInfo ()

与此属性相关的类型信息。 (机器翻译)

final var xml = """
        <root>
            <child aa="AA"/>
        </root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    final var attr = element.getAttributeNode("aa");
    System.out.println(attr); // aa="AA"

    System.out.println(attr.getName()); // aa
    System.out.println(attr.getValue()); // AA
    System.out.println(attr.getSchemaTypeInfo()); // aa="AA"
}

boolean getSpecified ()

如果此属性在实例文档中明确赋值，则为 True，否则为 false。 (机器翻译)

final var xml = """
        <!DOCTYPE root [
          <!ATTLIST child answer (yes|no) "no">
        ]>
        <root>
            <child a="A"/>
        </root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    System.out.println(element); // [child: null]

    final var attrAnswer = element.getAttributeNode("answer");
    System.out.println(attrAnswer); // answer="no"
    System.out.println(attrAnswer.getSpecified()); // false

    final var attrA = element.getAttributeNode("a");
    System.out.println(attrA); // a="A"
    System.out.println(attrA.getSpecified()); // true
}

String getValue ()

检索时，属性的值将以字符串形式返回。 (机器翻译)

final var xml = """
        <root>
            <child aa="AA"/>
        </root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    final var attr = element.getAttributeNode("aa");
    System.out.println(attr); // aa="AA"

    System.out.println(attr.getName()); // aa
    System.out.println(attr.getValue()); // AA
    System.out.println(attr.getSchemaTypeInfo()); // aa="AA"
}

boolean isId ()

返回此属性是否已知为 ID 类型（即包含其所有者元素的标识符）。 (机器翻译)

final var xml = """
        <!DOCTYPE root [
          <!ATTLIST child id-a ID "ID-A">
        ]>
        <root>
            <child id-a="ID-A" b="B"/>
        </root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var child = document.getElementById("ID-A");
System.out.println(child); // [child: null]

final var attrId = child.getAttributeNode("id-a");
System.out.println(attrId); // id-a="ID-A"
System.out.println(attrId.isId()); // true

final var attrB = child.getAttributeNode("b");
System.out.println(attrB); // b="B"
System.out.println(attrB.isId()); // false

void setValue (String value)

检索时，属性的值将以字符串形式返回。 (机器翻译)

final var xml = """
        <root><child aa="AA"/></root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {

    //<root>
    //    <child aa="AA"/>
    //</root>
    printDocument(document);

    final var attrA = element.getAttributeNode("aa");
    System.out.println(attrA); // aa="AA"

    attrA.setValue("XYZ");
    System.out.println(attrA); // aa="XYZ"

    //<root>
    //    <child aa="XYZ"/>
    //</root>
    printDocument(document);

    final var attrB = document.createAttribute("bb");
    attrB.setValue("BB");
    System.out.println(attrB); // bb="BB"

    element.setAttributeNode(attrB);

    //<root>
    //    <child aa="XYZ" bb="BB"/>
    //</root>
    printDocument(document);
}

Methods declared in Node

appendChild, cloneNode, compareDocumentPosition, getAttributes, getBaseURI, getChildNodes, getFeature, getFirstChild, getLastChild, getLocalName, getNamespaceURI, getNextSibling, getNodeName, getNodeType, getNodeValue, getOwnerDocument, getParentNode, getPrefix, getPreviousSibling, getTextContent, getUserData, hasAttributes, hasChildNodes, insertBefore, isDefaultNamespace, isEqualNode, isSameNode, isSupported, lookupNamespaceURI, lookupPrefix, normalize, removeChild, replaceChild, setNodeValue, setPrefix, setTextContent, setUserData

请参阅下面的链接。

Node 示例

API 示例
- Node
  - CharacterData
  - Comment
  - Document
  - Element
  - Entity
  - EntityReference

Java : Attr (XML) 示例

简介

Fields declared in Node

Methods

String getName ()

Element getOwnerElement ()

TypeInfo getSchemaTypeInfo ()

boolean getSpecified ()

String getValue ()

boolean isId ()

void setValue (String value)

Methods declared in Node

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