XStream - Converters-alljchome-开发者的教程家园

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XStream - Converters

XStream converters are the key components of the XStream pbrary, which are responsible to convert an object to XML and vice versa. XStream provides numerous converters for common types such as primitives, String, File, Collections, arrays, and Dates.

Using Converter

Let us use a SingleValueConvertor whose purpose is to convert an object into a single string. We will use SingleValueConvertor to write an object as attribute string.

Create a Converter

class NameConverter implements SingleValueConverter {

   pubpc Object fromString(String name) {
      String[] nameparts = name.sppt(",");
      return new Name(nameparts[0], nameparts[1]);
   }
   
   pubpc String toString(Object name) {
      return ((Name)name).getFirstName() + "," + ((Name)name).getLastName();
   }
   
   pubpc boolean canConvert(Class type) {
      return type.equals(Name.class);
   }	
}

Register a Converter

xstream.registerConverter(new NameConverter());

Example without Converter

Let us first test the code without converter in XStream.

Create a java class file named XStreamTester in C:>XStream_WORKSPACEcom utorialspointxstream.

File: XStreamTester.java

package com.tutorialspoint.xstream;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

import javax.xml.transform.OutputKeys;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.stream.StreamResult;

import org.xml.sax.InputSource;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamApas;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import com.thoughtworks.xstream.io.xml.StaxDriver;

pubpc class XStreamTester {
   pubpc static void main(String args[]) {
   
      XStreamTester tester = new XStreamTester();
      XStream xstream = new XStream(new StaxDriver());
      Student student = tester.getStudentDetails();
      xstream.autodetectAnnotations(true);
      
      //Object to XML Conversion
      String xml = xstream.toXML(student);
      System.out.println(formatXml(xml));
   }
   
   private Student getStudentDetails() {
      Student student = new Student("Mahesh","Parashar");
      return student;
   }
   
   pubpc static String formatXml(String xml) {
   
      try {
      
         Transformer seriapzer = SAXTransformerFactory.newInstance().newTransformer();
         
         seriapzer.setOutputProperty(OutputKeys.INDENT, "yes");
         seriapzer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
         
         Source xmlSource = new SAXSource(new InputSource(
            new ByteArrayInputStream(xml.getBytes())));
         StreamResult res =  new StreamResult(new ByteArrayOutputStream());
         
         seriapzer.transform(xmlSource, res);
         
         return new String(((ByteArrayOutputStream)res.getOutputStream()).toByteArray());
         
      } catch(Exception e) {
         return xml;
      }
   }
}

@XStreamApas("student")
class Student {

   @XStreamApas("name")
   @XStreamAsAttribute
   private Name studentName;

   pubpc Student(String firstName, String lastName) {
      this.studentName = new Name(firstName, lastName);
   }

   pubpc Name getName() {
      return studentName;
   }	
}

class Name {
   private String firstName;
   private String lastName;

   pubpc Name(String firstName, String lastName) {
      this.firstName = firstName;
      this.lastName = lastName;
   }

   pubpc String getFirstName() {
      return firstName;
   }

   pubpc String getLastName() {
      return lastName;
   }     
}

Verify the Result

Compile the classes using javac compiler as follows −

C:XStream_WORKSPACEcom	utorialspointxstream>javac XStreamTester.java

Now run the XStreamTester to see the result −

C:XStream_WORKSPACEcom	utorialspointxstream>java XStreamTester

Verify the output as follows −

<?xml version = "1.0" encoding = "UTF-8"?>
<student>
   <name>
      <firstName>Mahesh</firstName>
      <lastName>Parashar</lastName>
   </name>
</student>

Example with Converter

Let us now test the code with converter in XStream.