cuncaojin

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#SQL语法

一、Dom4j解析（需要导入Dom4j.jar）：

import java.io.FileOutputStream;
import java.io.IOException;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class Dom4jUtil {
    private static final String DEFAULT_PATH = "src/com/cuncaojin/xmlFile.xml";

    private Dom4jUtil() {
    }

    public static Document getDocument(String filePath) throws DocumentException {
        SAXReader saxReader = new SAXReader();
        filePath = filePath == null ? DEFAULT_PATH : filePath;
        return saxReader.read(filePath);
    }

    public  void write2XML(Document document, String filePath) throws IOException {
        OutputFormat format = OutputFormat.createPrettyPrint();
        format.setEncoding("UTF-8");
        filePath = filePath == null ? DEFAULT_PATH : filePath;
        XMLWriter writer = new XMLWriter(new FileOutputStream(filePath), format);
        writer.write(document);
        writer.close();
    }
}

二、XPath解析（依赖Dom4j解析技术，需要导入Dom4j.jar和jaxen-1.1-beta-6.jar包）：

import java.util.List;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
public class Demo {
    public static void main(java.lang.String[] args) throws Exception {
        String path = "myxml.xml";
        Document document = new SAXReader().read(path);
        List<Element> selectNodes = document.selectNodes("//addr[@id='addrs']");
        // List<Element> selectNodes = document.selectNodes("//addr");
        for (Node node : selectNodes) {
            System.out.println(node.getText());
        }
    }
}

1、结合Dom4j获取Document对象（XPath解析技术依赖Dom4j解析技术）
2、导入Dom4j.jar和jaxen-1.1-beta-6.jar
3、如果想使用XPATH语言，条件：只能使用node节点对象中的两个方法：
    List selectNodes(String xpathExpression);
    Node selectSingleNode(String xpathExpression);
4、xpathExpression的写法，查文档