Play XML with Dom4j

Posted on Edited on In Views:
  • Add, Delete, Update, Read
  • Using XPath

Add, Delete, Update, Read

XML sample

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<shelf> 
  <book name="Java Web"> 
    <name>Java Web</name>  
    <author>Ryan</author>  
    <price>99.0</price>  
  </book> 
  <book name="Spring"> 
    <name>Spring</name>  
    <author>AK</author>  
    <price>299.0</price>  
  </book> 
</shelf>

Read

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@Test
public void read() throws DocumentException {
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/book.xml");
	
	Element root = document.getRootElement();
	Element book = root.elements("book").get(0);
	String bookName = book.element("name").getText();
	System.out.println(bookName);
	
	String bookAttribute = book.attributeValue("name");
	System.out.println(bookAttribute);
}

Add

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// Add content to XML
@Test
public void add() throws DocumentException, IOException {
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/book.xml");
	
	Element book = document.getRootElement().element("book");
	book.addElement("price").setText("199.0");
	
	OutputFormat format = OutputFormat.createPrettyPrint();
	
	XMLWriter writer = new XMLWriter(new FileWriter("src/book.xml"),format);
	writer.write(document);
	writer.close();
}

// Add content to XML in specific position
@Test
public void add2() throws DocumentException, IOException {
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/book.xml");
	
	Element book = document.getRootElement().element("book");
	List list = book.elements(); // [book, name, price]
	
	Element author = DocumentHelper.createElement("author");
	author.setText("Ryan");
	list.add(1, author);
	
	OutputFormat format = OutputFormat.createPrettyPrint();
	XMLWriter writer = new XMLWriter(new FileWriter("src/book.xml"),format);
	writer.write(document);
	writer.close();
}

Update

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@Test
public void update() throws DocumentException, IOException {
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/book.xml");
	
	Element author = document.getRootElement().element("book").element("author");
	author.setText("Ryan Luo");
	
	OutputFormat format = OutputFormat.createPrettyPrint();
	XMLWriter writer = new XMLWriter(new FileWriter("src/book.xml"),format);
	writer.write(document);
	writer.close();
}

Delete

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@Test
public void delete() throws DocumentException, IOException {
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/book.xml");
	
	Element book = document.getRootElement().element("book");
	List list = book.elements(); // [book, name, price]
	
	list.remove(4);
	
	OutputFormat format = OutputFormat.createPrettyPrint();
	XMLWriter writer = new XMLWriter(new FileWriter("src/book.xml"),format);
	writer.write(document);
	writer.close();
}

@Test
public void delete2() throws DocumentException, IOException {
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/book.xml");
	
	Element author = document.getRootElement().element("book").element("author");
	author.getParent().remove(author);
	
	OutputFormat format = OutputFormat.createPrettyPrint();
	XMLWriter writer = new XMLWriter(new FileWriter("src/book.xml"),format);
	writer.write(document);
	writer.close();
}

using Xpath

Read

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@Test
public void getByXPath() throws DocumentException, IOException {
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/book.xml");
	
	String author = document.selectSingleNode("//author").getText();
	System.out.println(author);
}

Example: login

XML sample

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<users> 
  <user id="1" username="ryan" password="ryan"/>
  <user id="2" username="peter" password="peter"/>
  <user id="3" username="melvin" password="melvin"/> 
</users>

Authorization

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@Test
public void verify() throws DocumentException, IOException {
	
	String username="ryan";
	String password="ryan";
	
	SAXReader reader = new SAXReader();
	Document document = reader.read("src/users.xml");
	
	String xPath="//user[@username='"+username+"' and @password='"+password+"']";
	Node user = document.selectSingleNode(xPath);
	if(user==null) {
		System.out.println("Invalid credential..");
	} else {
		System.out.println("Successfully login..");
	}
}