# Java 字符串到 XML – 将字符串解析为 XML DOM 示例
> 原文: [https://howtodoinjava.com/xml/parse-string-to-xml-dom/](https://howtodoinjava.com/xml/parse-string-to-xml-dom/)
在 Java 中,XML 用`org.w3c.dom.Document`对象表示。 在本 XML 教程中,我们将学习:
1. 将 XML **字符串转换为 XML** 文档
2. 将 **XML 文件内容转换为 XML 文档**
## 1)将字符串转换为 XML 文档
要将**将 XML 字符串转换为 XML Dom**,我们需要以下类:
* [`javax.xml.parsers.DocumentBuilder`](https://docs.oracle.com/javase/10/docs/api/javax/xml/parsers/DocumentBuilder.html) :定义 API,以从来自各种输入源的 XML 内容中获取 XML DOM 文档实例。 这些输入源是`InputStreams`,文件,URL 和 SAX `InputSources`。
* [`javax.xml.parsers.DocumentBuilderFactory`](https://docs.oracle.com/javase/10/docs/api/javax/xml/parsers/DocumentBuilderFactory.html) :定义一种工厂 API,使应用能够获取解析器(`DocumentBuilder`),该解析器从 XML 内容生成 DOM 对象树。
* [`org.w3c.dom.Document`](https://docs.oracle.com/javase/10/docs/api/org/w3c/dom/Document.html) :它表示整个 XML DOM。 从概念上讲,它是文档树的根,并通过工厂方法提供对文档数据的访问,甚至深入到树中。
* [`java.io.StringReader`](https://docs.oracle.com/javase/10/docs/api/java/io/StringReader.html) :根据字符串内容创建流。 `DocumentBuilder`使用此流读取 XML 内容进行解析。
```java
package com.howtodoinjava.demo;
import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
public class StringtoXMLExample
{
public static void main(String[] args)
{
final String xmlStr = "" +
" " +
" Lokesh Gupta" +
" Author" +
" " +
" " +
" Brian Lara" +
" Cricketer" +
" " +
"";
//Use method to convert XML string content to XML Document object
Document doc = convertStringToXMLDocument( xmlStr );
//Verify XML document is build correctly
System.out.println(doc.getFirstChild().getNodeName());
}
private static Document convertStringToXMLDocument(String xmlString)
{
//Parser that produces DOM object trees from XML content
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
//API to obtain DOM Document instance
DocumentBuilder builder = null;
try
{
//Create DocumentBuilder with default configuration
builder = factory.newDocumentBuilder();
//Parse the content to Document object
Document doc = builder.parse(new InputSource(new StringReader(xmlString)));
return doc;
}
catch (Exception e)
{
e.printStackTrace();
}
return null;
}
}
//Output:
employees
```
## 2)将 XML 文件转换为 XML 文档
要使**从 XML 文件**获取 XML dom,而不是将 XML 字符串传递给`DocumentBuilder`,请传递文件路径以使解析器直接读取文件内容。
我们有包含 XML 内容的`employees.xml`文件,我们将阅读以获取 XML 文档。
```java
Lokesh Gupta
Author
Brian Lara
Cricketer
```
```java
package com.howtodoinjava.demo;
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
public class StringtoXMLExample
{
public static void main(String[] args)
{
final String xmlFilePath = "employees.xml";
//Use method to convert XML string content to XML Document object
Document doc = convertXMLFileToXMLDocument( xmlFilePath );
//Verify XML document is build correctly
System.out.println(doc.getFirstChild().getNodeName());
}
private static Document convertXMLFileToXMLDocument(String filePath)
{
//Parser that produces DOM object trees from XML content
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
//API to obtain DOM Document instance
DocumentBuilder builder = null;
try
{
//Create DocumentBuilder with default configuration
builder = factory.newDocumentBuilder();
//Parse the content to Document object
Document doc = builder.parse(new File(filePath));
return doc;
}
catch (Exception e)
{
e.printStackTrace();
}
return null;
}
}
//Output:
employees
```
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