使用XStream将JSON转换为XML到Java对象

XStream库可以是将JSON从Java转换为XML来回转换的有效工具。
让我们逐一探究它们中的每一个，并查看使用了哪个驱动程序。

处理JSON

要将JSON转换为Java对象，您要做的就是使用适当的驱动程序初始化XStream对象，并准备将对象序列化到JSON（和从JSON序列化）。

XStream当前提供了两个用于JSON到对象ocnversion的驱动程序：

JsonHierarchicalStreamDriver：
这没有附加的依赖关系，但是只能用于编写XML
JettisonMappedXmlDriver：这是基于Jettison的，还可以再次将JSON反序列化为Java对象。

Jettison驱动程序

Jettison驱动程序使用Jettison StAX解析器读取和写入JSON格式的数据。从1.2.2版开始，它在XStream中可用，并在com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver类中实现。

为了使此工作正常，我们需要在pom中添加依赖项：

<dependencies><dependency><groupId>com.thoughtworks.xstream</groupId><artifactId>xstream</artifactId><version>1.4.7</version></dependency><dependency><groupId>org.codehaus.jettison</groupId><artifactId>jettison</artifactId><version>1.1</version></dependency></dependencies>

以及将JSON转换为对象并将对象转换为Json的代码：

XStream xstream = new XStream(new JettisonMappedXmlDriver());
xstream.toXML(xml);  //converts Object to JSON
xstream.fromXML(obj); //Converts Json to Object

将对象序列化为XML

要将对象序列化为XML XStream，请使用2个驱动程序：

StaxDriver

XStream xstream = new XStream(new StaxDriver());
xstream.toXML(xml);  //converts Object to XML
xstream.fromXML(obj); //Converts XML to Object

DomDriver

XStream xstream = new XStream(new DomDriver());
xstream.toXML(xml);  //converts Object to XML
xstream.fromXML(obj); //Converts XML to Object

最后，让我们在一个类中查看所有这些内容：

package com.anirudh;import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
import com.thoughtworks.xstream.io.xml.DomDriver;
import com.thoughtworks.xstream.io.xml.StaxDriver;/*** Created by anirudh on 15/07/14.*/
public class Transformer<T> {private static final XStream XSTREAM_INSTANCE = null;public T getObjectFromJSON(String json){return (T) getInstance().fromXML(json);}public String getJSONFromObject(T t){return getInstance().toXML(t);}private XStream getInstance(){if(XSTREAM_INSTANCE==null){return new XStream(new JettisonMappedXmlDriver());}  else {return XSTREAM_INSTANCE;}}public T getObjectFromXML(String xml){return (T)getStaxDriverInstance().fromXML(xml);}public String getXMLFromObject(T t){return getStaxDriverInstance().toXML(t);}public T getObjectFromXMLUsingDomDriver(String xml){return (T)getDomDriverInstance().fromXML(xml);}public String getXMLFromObjectUsingDomDriver(T t){return getDomDriverInstance().toXML(t);}private XStream getStaxDriverInstance(){if(XSTREAM_INSTANCE==null) {return new XStream(new StaxDriver());}else{return XSTREAM_INSTANCE;}}private XStream getDomDriverInstance(){if(XSTREAM_INSTANCE==null){return new XStream(new DomDriver());}else{return XSTREAM_INSTANCE;}}
}

编写一个JUnit类进行测试：

package com.anirudh;import com.anirudh.domain.Product;
import org.junit.Before;
import org.junit.Test;/*** Created by anirudh on 15/07/14.*/
public class TransformerTest {private Transformer<Product> productTransformer;private Product product;@Beforepublic void init(){productTransformer = new Transformer<Product>();product = new Product(123,"Banana",23.00);}@Testpublic void testJSONToObject(){String json = productTransformer.getJSONFromObject(product);System.out.println(json);Product convertedproduct = productTransformer.getObjectFromJSON(json);System.out.println(convertedproduct.getName());}@Testpublic void testXMLtoObjectForStax(){String xml = productTransformer.getXMLFromObject(product);System.out.println(xml);Product convertedproduct = productTransformer.getObjectFromXML(xml);System.out.println(convertedproduct.getName());}@Testpublic void testXMLtoObjectForDom(){String xml = productTransformer.getXMLFromObjectUsingDomDriver(product);System.out.println(xml);Product convertedproduct = productTransformer.getObjectFromXMLUsingDomDriver(xml);System.out.println(convertedproduct.getName());}}

完整的代码可以在这里看到。
在下一个博客中，我们将比较用例，探索适合的用例。