blocks|key|49819|text|我想你应该看看String类，有很多种方法可以做到。substring(int,int)和indexOf(int)+lastIndexOf(int)怎么样？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|49820|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/String.html^0|Q|I|19|C|1M|G|7|6|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@$9|U|A|V|1|W]]|E|$]]|$1|F|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

I think you would be look at <a href="http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/String.html" rel="nofollow">String</a> class, there are multiple ways to do it. What about <code>substring(int,int)</code> and <code>indexOf(int)</code> <code>lastIndexOf(int)</code>?

blocks|key|49826|text|做正确的XML读取，或者只是为了过日子而做一些不可靠的事情。正确的做法是使用适当的文档解析。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|49827|或者..。dodgy将使用自定义文本解析和wisuzu的响应，或者使用正则表达式和匹配器。|49828|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

There is doing XML reading right, or doing the dodgy just to get by.
Doing it right would be using proper document parsing.

Or... dodgy would be using custom text parsing with either wisuzu's response or using regular expressions with matchers.

blocks|key|5290284|text|使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5290285|String+xml+=+"<message>HELLO!</message>";
org.jdom.input.SAXBuilder+saxBuilder+=+new+SAXBuilder();
try+{
++++org.jdom.Document+doc+=+saxBuilder.build(new+StringReader(xml));
++++String+message+=+doc.getRootElement().getText();
++++System.out.println(message);
}+catch+(JDOMException+e)+{
++++//+handle+JDOMException
}+catch+(IOException+e)+{
++++//+handle+IOException
}|code-block|syntax|javascript|5290286|使用+DOMParser|offset|length|style|CODE|5290287|String+xml+=+"<message>HELLO!</message>";
DOMParser+parser+=+new+DOMParser();
try+{
++++parser.parse(new+InputSource(new+java.io.StringReader(xml)));
++++Document+doc+=+parser.getDocument();
++++String+message+=+doc.getDocumentElement().getTextContent();
++++System.out.println(message);
}+catch+(SAXException+e)+{
++++//+handle+SAXException+
}+catch+(IOException+e)+{
++++//+handle+IOException+
}|5290288|使用接口：|5290289|String+xml+=+"<message>HELLO!</message>";
DocumentBuilderFactory+dbf+=+DocumentBuilderFactory.newInstance();
DocumentBuilder+db+=+null;
try+{
++++db+=+dbf.newDocumentBuilder();
++++InputSource+is+=+new+InputSource();
++++is.setCharacterStream(new+StringReader(xml));
++++try+{
++++++++Document+doc+=+db.parse(is);
++++++++String+message+=+doc.getDocumentElement().getTextContent();
++++++++System.out.println(message);
++++}+catch+(SAXException+e)+{
++++++++//+handle+SAXException
++++}+catch+(IOException+e)+{
++++++++//+handle+IOException
++++}
}+catch+(ParserConfigurationException+e1)+{
++++//+handle+ParserConfigurationException
}|5290290|entityMap^0|0|0|3|9|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

Using <a href="http://www.jdom.org/">JDOM</a>:

<pre><code>String xml = "&lt;message&gt;HELLO!&lt;/message&gt;";
org.jdom.input.SAXBuilder saxBuilder = new SAXBuilder();
try {
 org.jdom.Document doc = saxBuilder.build(new StringReader(xml));
 String message = doc.getRootElement().getText();
 System.out.println(message);
} catch (JDOMException e) {
 // handle JDOMException
} catch (IOException e) {
 // handle IOException
}
</code></pre>

Using the <a href="http://xerces.apache.org/">Xerces</a> <code>DOMParser</code>:

<pre><code>String xml = "&lt;message&gt;HELLO!&lt;/message&gt;";
DOMParser parser = new DOMParser();
try {
 parser.parse(new InputSource(new java.io.StringReader(xml)));
 Document doc = parser.getDocument();
 String message = doc.getDocumentElement().getTextContent();
 System.out.println(message);
} catch (SAXException e) {
 // handle SAXException 
} catch (IOException e) {
 // handle IOException 
}
</code></pre>

Using the <a href="http://docs.oracle.com/javase/tutorial/jaxp/index.html">JAXP</a> interfaces:

<pre><code>String xml = "&lt;message&gt;HELLO!&lt;/message&gt;";
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = null;
try {
 db = dbf.newDocumentBuilder();
 InputSource is = new InputSource();
 is.setCharacterStream(new StringReader(xml));
 try {
 Document doc = db.parse(is);
 String message = doc.getDocumentElement().getTextContent();
 System.out.println(message);
 } catch (SAXException e) {
 // handle SAXException
 } catch (IOException e) {
 // handle IOException
 }
} catch (ParserConfigurationException e1) {
 // handle ParserConfigurationException
}
</code></pre>

blocks|key|49851|text|您可以使用JAXB来实现这一点(+Java+SE+6中包含了一个实现)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|49852|import+java.io.StringReader;
import+javax.xml.bind.*;
import+javax.xml.transform.stream.StreamSource;

public+class+Demo+{

++++public+static+void+main(String[]+args)+throws+Exception+{
++++++++String+xmlString+=+"<message>HELLO!</message>+";
++++++++JAXBContext+jc+=+JAXBContext.newInstance(String.class);
++++++++Unmarshaller+unmarshaller+=+jc.createUnmarshaller();
++++++++StreamSource+xmlSource+=+new+StreamSource(new+StringReader(xmlString));
++++++++JAXBElement<String>+je+=+unmarshaller.unmarshal(xmlSource,+String.class);
++++++++System.out.println(je.getValue());
++++}

}|code-block|syntax|javascript|49853|输出|offset|length|style|BOLD|49854|HELLO!|49855|entityMap^0|0|0|0|2|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

You could do this with JAXB (an implementation is included in Java SE 6).

<pre><code>import java.io.StringReader;
import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;

public class Demo {

 public static void main(String[] args) throws Exception {
 String xmlString = "&lt;message&gt;HELLO!&lt;/message&gt; ";
 JAXBContext jc = JAXBContext.newInstance(String.class);
 Unmarshaller unmarshaller = jc.createUnmarshaller();
 StreamSource xmlSource = new StreamSource(new StringReader(xmlString));
 JAXBElement&lt;String&gt; je = unmarshaller.unmarshal(xmlSource, String.class);
 System.out.println(je.getValue());
 }

}
</code></pre>

Output

<pre><code>HELLO!
</code></pre>

blocks|key|49864|text|您还可以使用基础JRE提供的工具：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|49865|String+msg+=+"<message>HELLO!</message>";
DocumentBuilder+newDocumentBuilder+=+DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document+parse+=+newDocumentBuilder.parse(new+ByteArrayInputStream(msg.getBytes()));
System.out.println(parse.getFirstChild().getTextContent());|code-block|syntax|javascript|49866|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You could also use tools provided by the base JRE:

<pre><code>String msg = "&lt;message&gt;HELLO!&lt;/message&gt;";
DocumentBuilder newDocumentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document parse = newDocumentBuilder.parse(new ByteArrayInputStream(msg.getBytes()));
System.out.println(parse.getFirstChild().getTextContent());
</code></pre>

blocks|key|1069291|text|上面的答案之一是将XML字符串转换为不需要的字节。相反，您可以使用InputSource并为其提供StringReader。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1069292|String+xmlStr+=+"<message>HELLO!</message>";
DocumentBuilder+db+=+DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document+doc+=+db.parse(new+InputSource(new+StringReader(xmlStr)));
System.out.println(doc.getFirstChild().getNodeValue());|code-block|syntax|javascript|1069293|entityMap^0|X|B|1D|C|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

One of the above answer states to convert XML String to bytes which is not needed. Instead you can can use <code>InputSource</code> and supply it with <code>StringReader</code>.

<pre><code>String xmlStr = "&lt;message&gt;HELLO!&lt;/message&gt;";
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = db.parse(new InputSource(new StringReader(xmlStr)));
System.out.println(doc.getFirstChild().getNodeValue());
</code></pre>

I have XML in the form of a String that contains 

<pre><code>&lt;message&gt;HELLO!&lt;/message&gt; 
</code></pre>

How can I get the String "Hello!" from the XML? It should be ridiculously easy but I am lost. The XML isn't in a doc, it is simply a String.

How to parse a String containing XML in Java and retrieve the value of the root node?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个字符串形式的XML，它包含<message>HELLO!</message> 怎样才能得到字符串"Hello!“从XML？这应该是非常容易的，但是我迷路了。XML不在文档中，它只是一个字符串。

问如何在Java中解析包含XML的字符串并检索根节点的值？
EN

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问如何在Java中解析包含XML的字符串并检索根节点的值？EN