XML与字符串的相互转换

最近在做和其它系统之间的数据交换接口，有用到XML对象与字符串之间的直接转换，在此整理一下。

一、字符串转换为XML对象并进行解析

 

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import java.io.ByteArrayInputStream;

String strXml = "<Response><ReturnCode>1</ReturnCode></Response>";
ByteArrayInputStream stream = new ByteArrayInputStream(strXml.getBytes("UTF-8"));
try {  
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();  
    DocumentBuilder builder = factory.newDocumentBuilder();  
    Document doc = builder.parse(stream);         
    XPathFactory xfactory = XPathFactory.newInstance();  
    XPath xpath = xfactory.newXPath();  
    String value = xpath.compile("//Response//ReturnCode").evaluate(doc);  //value==1
} finally {
    stream.close();
}

二、XML对象转换为字符串

import java.io.ByteArrayOutputStream;
import org.w3c.dom.Document;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

//Document doc
TransformerFactory transFactory = TransformerFactory.newInstance();
Transformer trans = transFactory.newTransformer();
ByteArrayOutputStream output = new ByteArrayOutputStream();
trans.transform(new DOMSource(doc), new StreamResult(output));
String strXml = output.toString("UTF-8");

网上有的文档中为了解决中文乱码的问题，在Transformer中去调用setOutputProperty方法设置encoding为GB2312，我认为这种方式是不可取的，XML的默认encoding都是UTF-8，在OutputStream转String时指定encoding为UTF-8就可以了。