Java : Element (XML) - API使用例
Element (Java SE 17 & JDK 17) の使用例まとめです。
だいたいのメソッドを網羅済みです。
API仕様のおともにどうぞ。
概要
ElementインタフェースはXMLの要素を表します。
<root>
<child aa="AA" bb="BB">abcd</child>
</root>
上記XMLの例では root 要素や child 要素が Element です。
Elementインタフェースには、Nodeインタフェースにはない便利なメソッドがいくつかあります。
特に属性(Attr)への操作がやりやすくなっています。
関連記事:XML (DOM) の基本
共通で使うコード
本記事のAPI使用例では、利便性のために以下のメソッドを共通処理として使います。
// DocumentをXMLでコンソールに出力します。
// 見やすくするためにインデントを付け、<?xml ~ ?>は非表示にしています。
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 text = document.createTextNode("abcd");
System.out.println(text); // [#text: abcd]
child.appendChild(text);
//<root>
// <child>abcd</child>
//</root>
printDocument(document);
Nodeで宣言されたフィールド
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
「Java API 使用例 : Node」をご参照ください。
メソッド
String getAttribute (String name)
final var xml = """
<root>
<child aa="AA" bb="BB" />
</root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {
final var attrA = element.getAttribute("aa");
System.out.println(attrA); // AA
final var attrB = element.getAttribute("bb");
System.out.println(attrB); // BB
}
Attr getAttributeNode (String name)
final var xml = """
<root>
<child aa="AA" bb="BB" />
</root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {
final var attrA = element.getAttributeNode("aa");
System.out.println(attrA); // aa="AA"
final var attrB = element.getAttributeNode("bb");
System.out.println(attrB); // bb="BB"
}
Attr getAttributeNodeNS (String namespaceURI, String localName)
final var xml = """
<root xmlns:ns1="sample1" xmlns:ns2="sample2" >
<child ns1:aa="AA1" ns2:aa="AA2" />
</root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {
final var attrA = element.getAttributeNodeNS("sample1", "aa");
System.out.println(attrA); // ns1:aa="AA1"
final var attrB = element.getAttributeNodeNS("sample2", "aa");
System.out.println(attrB); // ns2:aa="AA2"
}
String getAttributeNS (String namespaceURI, String localName)
final var xml = """
<root xmlns:ns1="sample1" xmlns:ns2="sample2" >
<child ns1:aa="AA1" ns2:aa="AA2" />
</root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {
final var attrA = element.getAttributeNS("sample1", "aa");
System.out.println(attrA); // AA1
final var attrB = element.getAttributeNS("sample2", "aa");
System.out.println(attrB); // AA2
}
NodeList getElementsByTagName (String name)
final var xml = """
<root>
<child-a/>
<child-b/>
<child-c>
<child-b/>
<child-b/>
</child-c>
</root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
final var root = document.getDocumentElement();
final var nodesA = root.getElementsByTagName("child-a");
System.out.println("-- child-a --");
for (int i = 0; i < nodesA.getLength(); i++) {
final var item = nodesA.item(i);
System.out.println("node = " + item + " : parent = " + item.getParentNode());
}
// 結果
// ↓
//-- child-a --
//node = [child-a: null] : parent = [root: null]
final var nodesB = root.getElementsByTagName("child-b");
System.out.println("-- child-b --");
for (int i = 0; i < nodesB.getLength(); i++) {
final var item = nodesB.item(i);
System.out.println("node = " + item + " : parent = " + item.getParentNode());
}
// 結果
// ↓
//-- child-b --
//node = [child-b: null] : parent = [root: null]
//node = [child-b: null] : parent = [child-c: null]
//node = [child-b: null] : parent = [child-c: null]
final var nodesC = root.getElementsByTagName("child-c");
System.out.println("-- child-c --");
for (int i = 0; i < nodesC.getLength(); i++) {
final var item = nodesC.item(i);
System.out.println("node = " + item + " : parent = " + item.getParentNode());
}
// 結果
// ↓
//-- child-c --
//node = [child-c: null] : parent = [root: null]
NodeList getElementsByTagNameNS (String namespaceURI, String localName)
final var xml = """
<root xmlns:ns="sample">
<child-a/>
<child-a/>
<child-b/>
<ns:child-b/>
<ns:child-b/>
</root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
final var root = document.getDocumentElement();
final var nodesA = root.getElementsByTagName("child-a");
System.out.println("-- child-a --");
for (int i = 0; i < nodesA.getLength(); i++) {
System.out.println(nodesA.item(i));
}
// 結果
// ↓
//-- child-a --
//[child-a: null]
//[child-a: null]
final var nodesB1 = root.getElementsByTagName("child-b");
System.out.println("-- child-b --");
for (int i = 0; i < nodesB1.getLength(); i++) {
System.out.println(nodesB1.item(i));
}
// 結果
// ↓
//-- child-b --
//[child-b: null]
final var nodesB2 = root.getElementsByTagNameNS("sample", "child-b");
System.out.println("-- ns:child-b --");
for (int i = 0; i < nodesB2.getLength(); i++) {
System.out.println(nodesB2.item(i));
}
// 結果
// ↓
//-- ns:child-b --
//[ns:child-b: null]
//[ns:child-b: null]
TypeInfo getSchemaTypeInfo ()
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) {
System.out.println(element.getSchemaTypeInfo()); // [child: null]
final var attr = element.getAttributeNode("aa");
System.out.println(attr.getSchemaTypeInfo()); // aa="AA"
}
String getTagName ()
final var xml = """
<root>
<child/>
</root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
final var root = document.getDocumentElement();
System.out.println(root.getTagName()); // root
final var child = root.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
System.out.println(element.getTagName()); // child
}
boolean hasAttribute (String name)
final var xml = """
<root>
<child aa="AA" bb="BB"/>
</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.hasAttribute("aa")); // true
System.out.println(element.hasAttribute("bb")); // true
System.out.println(element.hasAttribute("cc")); // false
}
boolean hasAttributeNS (String namespaceURI, String localName)
final var xml = """
<root xmlns:ns1="sample1" xmlns:ns2="sample2">
<child ns1:aa="AA" ns2:bb="BB"/>
</root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().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.hasAttributeNS("sample1", "aa")); // true
System.out.println(element.hasAttributeNS("sample2", "aa")); // false
System.out.println(element.hasAttributeNS("sample1", "bb")); // false
System.out.println(element.hasAttributeNS("sample2", "bb")); // true
}
void removeAttribute (String name)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root><child aa="AA" bb="BB" /></root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root>
// <child aa="AA" bb="BB"/>
//</root>
printDocument(document);
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
element.removeAttribute("aa");
}
//<root>
// <child bb="BB"/>
//</root>
printDocument(document);
Attr removeAttributeNode (Attr oldAttr)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root><child aa="AA" bb="BB" /></root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root>
// <child aa="AA" bb="BB"/>
//</root>
printDocument(document);
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
final var oldAttr = element.getAttributeNode("aa");
System.out.println(oldAttr); // aa="AA"
final var ret = element.removeAttributeNode(oldAttr);
System.out.println(ret); // aa="AA"
}
//<root>
// <child bb="BB"/>
//</root>
printDocument(document);
void removeAttributeNS (String namespaceURI, String localName)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root xmlns:ns1="sample1" xmlns:ns2="sample2" ><child ns1:aa="AA1" ns2:aa="AA2" /></root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child ns1:aa="AA1" ns2:aa="AA2"/>
//</root>
printDocument(document);
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
element.removeAttributeNS("sample1", "aa");
}
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child ns2:aa="AA2"/>
//</root>
printDocument(document);
void setAttribute (String name, String value)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root><child/></root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root>
// <child/>
//</root>
printDocument(document);
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
element.setAttribute("aa", "AA");
element.setAttribute("bb", "BB");
element.setAttribute("cc", "CC");
}
//<root>
// <child aa="AA" bb="BB" cc="CC"/>
//</root>
printDocument(document);
Attr setAttributeNode (Attr newAttr)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root><child/></root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root>
// <child/>
//</root>
printDocument(document);
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
final var attr1 = document.createAttribute("aa");
attr1.setValue("AA");
final var ret1 = element.setAttributeNode(attr1);
System.out.println(ret1); // null
//<root>
// <child aa="AA"/>
//</root>
printDocument(document);
final var attr2 = document.createAttribute("bb");
attr2.setValue("BB-1");
final var ret2 = element.setAttributeNode(attr2);
System.out.println(ret2); // null
//<root>
// <child aa="AA" bb="BB-1"/>
//</root>
printDocument(document);
final var attr3 = document.createAttribute("bb");
attr3.setValue("BB-2");
final var ret3 = element.setAttributeNode(attr3);
System.out.println(ret3); // bb="BB-1"
//<root>
// <child aa="AA" bb="BB-2"/>
//</root>
printDocument(document);
}
Attr setAttributeNodeNS (Attr newAttr)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root xmlns:ns1="sample1" xmlns:ns2="sample2"><child/></root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child/>
//</root>
printDocument(document);
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
final var attr1 = document.createAttributeNS("sample1", "ns1:aa");
attr1.setValue("AA-1");
final var ret1 = element.setAttributeNode(attr1);
System.out.println(ret1); // null
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child ns1:aa="AA-1"/>
//</root>
printDocument(document);
final var attr2 = document.createAttributeNS("sample1", "ns1:aa");
attr2.setValue("AA-2");
final var ret2 = element.setAttributeNode(attr2);
System.out.println(ret2); // ns1:aa="AA-1"
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child ns1:aa="AA-2"/>
//</root>
printDocument(document);
final var attr3 = document.createAttributeNS("sample2", "ns2:aa");
attr3.setValue("AA-3");
final var ret3 = element.setAttributeNode(attr3);
System.out.println(ret3); // null
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child ns1:aa="AA-2" ns2:aa="AA-3"/>
//</root>
printDocument(document);
}
void setAttributeNS (String namespaceURI, String qualifiedName, String value)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root xmlns:ns1="sample1" xmlns:ns2="sample2"><child/></root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child/>
//</root>
printDocument(document);
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
element.setAttributeNS("sample1", "ns1:aa", "AA-1");
element.setAttributeNS("sample2", "ns2:aa", "AA-2");
}
//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
// <child ns1:aa="AA-1" ns2:aa="AA-2"/>
//</root>
printDocument(document);
void setIdAttribute (String name, boolean isId)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root><child id-a="ID-A"/></root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root>
// <child id-a="ID-A"/>
//</root>
printDocument(document);
// まだidを使った取得はできません。
final var before = document.getElementById("ID-A");
System.out.println(before); // null
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
element.setIdAttribute("id-a", true);
}
// idを使った取得ができます。
final var after = document.getElementById("ID-A");
System.out.println(after); // [child: null]
//<root>
// <child id-a="ID-A"/>
//</root>
printDocument(document);
void setIdAttributeNode (Attr idAttr, boolean isId)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root><child id-a="ID-A"/></root>
""";
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root>
// <child id-a="ID-A"/>
//</root>
printDocument(document);
// まだidを使った取得はできません。
final var before = document.getElementById("ID-A");
System.out.println(before); // null
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
final var attr = element.getAttributeNode("id-a");
System.out.println(attr); // id-a="ID-A"
element.setIdAttributeNode(attr, true);
}
// idを使った取得ができます。
final var after = document.getElementById("ID-A");
System.out.println(after); // [child: null]
//<root>
// <child id-a="ID-A"/>
//</root>
printDocument(document);
void setIdAttributeNS (String namespaceURI, String localName, boolean isId)
printDocumentメソッドについてはこちらをご参照ください。
final var xml = """
<root xmlns:ns="sample"><child ns:id-a="ID-A"/></root>
""";
final var builder = DocumentBuilderFactory.newNSInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));
//<root xmlns:ns="sample">
// <child ns:id-a="ID-A"/>
//</root>
printDocument(document);
// まだidを使った取得はできません。
final var before = document.getElementById("ID-A");
System.out.println(before); // null
final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
element.setIdAttributeNS("sample", "id-a", true);
}
// idを使った取得ができます。
final var after = document.getElementById("ID-A");
System.out.println(after); // [child: null]
//<root xmlns:ns="sample">
// <child ns:id-a="ID-A"/>
//</root>
printDocument(document);
Nodeで宣言されたメソッド
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
「Java API 使用例 : Node」をご参照ください。