使用java代码读取xml节点

Question

我连接到许多服务器的数据库以从它们检索所有数据，我使用xml文件包含每个数据库服务器[ip，port，user，passwd]的信息，然后查询在该服务器上执行。我在我的代码中读取查询作为arrayList，并逐个获取它们以进行处理。我需要的是一个清晰简单的代码，以便读取数据库服务器信息以连接到它并执行相关查询，即每次我需要在我的代码中获取数据库IP，端口，用户，密码的查询。这里是我的xml文件结构。非常感谢。

<?xml version="1.0"?> 
<Database> 
<DB> 
<ip></ip> 
<port></port> 
<user></user> 
<pass></pass> 
</DB> 
<Query> 
select date from myTable 
</Query> 
<DB> 
<ip></ip> 
<port></port> 
<user></user> 
<pass></pass> 
</DB> 
<Query> 
select time from myTable 
</Query> 
<DB> 
<ip></ip> 
<port></port> 
<user></user> 
<pass><></pass> 
</DB> 
<Query> 
select name from myTable 
</Query> 
</Database> 

Answer 1

您可以使用Java的DOM api进行xml处理和xpath。

• DOM：https://docs.oracle.com/javase/tutorial/jaxp/dom/index.html
• 的Xpath：http://www.w3schools.com/xsl/xpath_syntax.asp

下面是一些示例代码，做你想要什么部分（提取IP和端口）。您将需要修改它做休息：

import java.io.ByteArrayInputStream; 
import java.io.IOException; 
import java.io.InputStream; 

import javax.xml.parsers.DocumentBuilder; 
import javax.xml.parsers.DocumentBuilderFactory; 
import javax.xml.parsers.ParserConfigurationException; 
import javax.xml.xpath.XPath; 
import javax.xml.xpath.XPathConstants; 
import javax.xml.xpath.XPathExpression; 
import javax.xml.xpath.XPathExpressionException; 
import javax.xml.xpath.XPathFactory; 

import org.w3c.dom.Document; 
import org.w3c.dom.Element; 
import org.w3c.dom.Node; 
import org.w3c.dom.NodeList; 
import org.xml.sax.SAXException; 


public class DomTester { 


    public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, XPathExpressionException { 

     InputStream inStr = null; 
     try { 
      String xml = "<?xml version=\"1.0\"?>" 
        + "<Database>" 
        + "<DB>" 
        +  "<ip>666</ip>" 
        +  "<port>7</port>" 
        + "</DB>" 
        + "<DB>" 
        + " <ip>13</ip>" 
        +  "<port>1</port>" 
        + "</DB>" 
        + "</Database>"; 

      inStr = new ByteArrayInputStream(xml.getBytes()); 
      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 
      DocumentBuilder db = dbf.newDocumentBuilder(); 
      Document doc = db.parse(inStr); 

      XPathFactory xFactory = XPathFactory.newInstance(); 
      XPath xpath = xFactory.newXPath(); 
      XPathExpression expr = xpath.compile("/Database"); 
      Element databaseEl = (Element)expr.evaluate(doc, XPathConstants.NODE); 

      NodeList databaseNodeList = databaseEl.getChildNodes(); 
      for (int ii=0; ii<databaseNodeList.getLength(); ++ii) { 
       Node dbNode = databaseNodeList.item(ii); 
       XPathExpression ipExpr = xpath.compile("ip"); 
       Element ipElement = (Element)ipExpr.evaluate(dbNode, XPathConstants.NODE); 
       String ip = ipElement.getTextContent(); 

       XPathExpression portExpr = xpath.compile("port"); 
       Element portEl = (Element)portExpr.evaluate(dbNode, XPathConstants.NODE); 
       String port = portEl.getTextContent(); 

       System.out.println("DB node[" + ii + "] = ip: " + ip + " port: " + port); 
      } 
     } finally { 
      if (null != inStr) { 
       inStr.close(); 
      } 
     } 
    } 
} 

因为你是从文件中读取，而不是使用字符串，而不是做这样的：

inStr = new ByteArrayInputStream(xml.getBytes()); 

做到这一点：

File f = new File("your/file/path.xml"); 
inStr = new FileInputStream(f);