XML與字符串的相互轉換

最近在做和其它系統之間的數據交換接口，有用到XML對象與字符串之間的直接轉換，在此整理一下。

一、字符串轉換爲XML對象並進行解析

 

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對象轉換爲字符串

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");

網上有的文檔中爲了解決中文亂碼的問題，在Transformer中去調用setOutputProperty方法設置encoding爲GB2312，我認爲這種方式是不可取的，XML的默認encoding都是UTF-8，在OutputStream轉String時指定encoding爲UTF-8就可以了。