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XmlUtil

XmlUtil

Background

In daily coding, besides JSON, we are most familiar with the XML format. Generally, the first thing we think of is to introduce the Dom4j package, but we are unaware that JDK has already encapsulated XML parsing and construction tools: w3c dom. However, due to the cumbersome API operations, Hutool provides the XmlUtil to simplify the process of creating, reading, and writing XML.

Usage

Reading XML

There are two methods for reading XML:

  • XmlUtil.readXML Reads an XML file.
  • XmlUtil.parseXml Parses an XML string into a Document object.

Writing XML

  • XmlUtil.toStr Converts an XML document into a String.
  • XmlUtil.toFile Writes an XML document to a file.

Creating XML

  • XmlUtil.createXml Creates an XML document. The created XML defaults to UTF-8 encoding, and the process of modifying the encoding occurs during the toStr and toFile methods. That is, the encoding is only defined when the XML is converted to text.

XML Operations

Through the following tool methods, you can complete basic node reading operations.

  • XmlUtil.cleanInvalid Removes invalid characters from the XML text.
  • XmlUtil.getElements Obtains a list of child nodes based on the node name.
  • XmlUtil.getElement Obtains the first child node based on the node name.
  • XmlUtil.elementText Obtains the text content of the first child node based on the node name.
  • XmlUtil.transElements Converts a NodeList to a list of Element objects.

XML to Object Conversion

  • writeObjectAsXml Converts a serializable object to XML and writes it to a file, overwriting any existing files.
  • readObjectFromXml Reads an object from XML.

Note These two methods rely heavily on JDK’s XMLEncoder and XMLDecoder, and there must be a pair for generation and parsing (following a fixed format), or it will fail if using other conversion from XML to Bean.

XPath Operations

For more information on XPath, refer to the article: https://www.ibm.com/developerworks/cn/xml/x-javaxpathapi.html

  • createXPath Creates an XPath object.
  • getByXPath Reads XML nodes and other information through XPath traversal.

Example:

<?xml version="1.0" encoding="utf-8"?>
<returnsms> 
  <returnstatus>Success</returnstatus>  
  <message>ok</message>  
  <remainpoint>1490</remainpoint>  
  <taskID>885</taskID>  
  <successCounts>1</successCounts> 
</returnsms>
Document docResult = XmlUtil.readXML(xmlFile);
// Result: "ok"
Object value = XmlUtil.getByXPath("//returnsms/message", docResult, XPathConstants.STRING);

Summary

XmlUtil is simply a tool encapsulation of w3c dom that simplifies operations on DOM, reducing the difficulty of working with DOM if your project relies heavily on XML, it is still recommended to use the Dom4j framework.

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