使用 XML 工具： dom4j

Steven小于 1 分钟

开源三方件，对原生 java xml 读写做了封装。

基本用法

https://github.com/LawssssCat/blog/tree/master/code/demo-java-xml/n02-dom4j-usage/test/java/org/example/

读

XML 文件

<?xml version="1.0" encoding="utf-8" ?>
<my-content>
    <web-site>http://www.example.org</web-site>
    <owner>steven</owner>
    <description>原生 java xml 操作测试消息</description>
    <posts>
        <!-- 我是注释 -->
        <post id="P001">
            <title>文章标题01</title>
            <content>hello world 01！</content>
        </post>
        <post id="P002">
            <title>文章标题02</title>
            <content>hello world 02！</content>
        </post>
    </posts>
</my-content>

测试用例

package org.example;

import lombok.extern.slf4j.Slf4j;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@Slf4j
public class XmlDom4jReadTest {
    Document read;
    @BeforeEach
    void beforeEach() {
        SAXReader saxReader = new SAXReader();
        try {
            read = saxReader.read(getClass().getResource("/message001.xml"));
        } catch (DocumentException e) {
            throw new RuntimeException(e);
        }
    }
    @Test
    void test_elements() {
        AtomicInteger i = new AtomicInteger(0);
        printElements(1, read.getRootElement(), i);
        Assertions.assertEquals(11, i.get());
    }
    private void printElements(int deep, Element e, AtomicInteger i) {
        i.incrementAndGet();
        log.info(String.format("%"+deep+"s%s", "", e.getQualifiedName()));
        for (Element c : e.elements()) {
            printElements(deep+1, c, i);
        }
    }
    @Test
    void test_getRootElement() {
        Element rootElement = read.getRootElement();
        Assertions.assertEquals("my-content", rootElement.getQualifiedName());
        Assertions.assertEquals(2, rootElement.element("posts").elements().size());
        Assertions.assertArrayEquals(new String[] {"P001", "P002"}, rootElement.element("posts").elements().stream().map(e -> e.attribute("id").getValue()).toArray());
    }
    @Test
    void test_nodeIterator() {
        int countContentElement = 0;
        int countPostElement = 0;
        List<String> contentElementQNameList = new ArrayList<>();
        List<String> postElementIdList = new ArrayList<>();
        // test
        Element rootElement = read.getRootElement();
        Iterator<Element> contentIterator = rootElement.elementIterator();
        while (contentIterator.hasNext()) {
            countContentElement++;
            Element contentElement = contentIterator.next();
            System.out.println("contentElement = " + contentElement);
            contentElementQNameList.add(contentElement.getQualifiedName());
            if("posts".equals(contentElement.getQualifiedName())) {
                Iterator<Element> postIterator = contentElement.elementIterator();
                while (postIterator.hasNext()) {
                    countPostElement++;
                    Element post = postIterator.next();
                    System.out.println("postElement = " + post);
                    postElementIdList.add(post.attributeValue("id"));
                }
            }
        }
        Assertions.assertEquals(4, countContentElement);
        Assertions.assertEquals(2, countPostElement);
        Assertions.assertArrayEquals(new String[] {"web-site", "owner", "description", "posts"}, contentElementQNameList.toArray());
        Assertions.assertArrayEquals(new String[] {"P001", "P002"}, postElementIdList.toArray());
    }
    @Test
    void test_parseText() throws DocumentException {
        Document document = DocumentHelper.parseText(read.asXML());
        Assertions.assertEquals("my-content", document.getRootElement().getName());
    }
}

写

测试用例

package org.example;

import org.dom4j.*;
import org.dom4j.dom.DOMAttribute;
import org.dom4j.io.XMLWriter;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import utils.IOUtils;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Collections;
import java.util.List;
import java.util.Objects;

public class XmlDom4jWriteTest {
    @Test
    void test() throws IOException {
        Document document = DocumentHelper.createDocument();
        Element content = document.addElement("content");
        Element owner = content.addElement("owner");
        owner.setText("steven");
        Element posts = content.addElement("posts");
        for (int i = 0; i < 2; i++) {
            Element post = posts.addElement("post");
            List<Attribute> attributes = Collections.singletonList(new DOMAttribute(QName.get("id"), "P00" + i));
            post.setAttributes(attributes);
        }
        // write
        File file = new File(Objects.requireNonNull(getClass().getResource("/")).getFile(), getClass().getName() + ".xml");
        try (FileOutputStream fileOutputStream = new FileOutputStream(file)) {
            XMLWriter xmlWriter = new XMLWriter(fileOutputStream);
            xmlWriter.write(content);
        }
        // validate
        Assertions.assertTrue(file.exists());
        Assertions.assertEquals("<content><owner>steven</owner><posts><post id=\"P000\"/><post id=\"P001\"/></posts></content>",
                IOUtils.readFile(file));
    }
}

namespace

XML 文件

<?xml version="1.0" encoding="utf-8" ?>
<xxx:my-content xmlns:xxx="http://example.org/xxx">
    <xxx:web-site>http://www.example.org</xxx:web-site>
    <owner>steven</owner>
    <description>原生 java xml 操作测试消息</description>
    <posts>
        <!-- 我是注释 -->
        <post id="P001">
            <title>文章标题01</title>
            <content>hello world 01！</content>
        </post>
        <post id="P002">
            <title>文章标题02</title>
            <content>hello world 02！</content>
        </post>
    </posts>
</xxx:my-content>

测试用例

package org.example;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class XmlDom4jReadNamespaceTest {
    Document read;
    @BeforeEach
    void beforeEach() {
        SAXReader saxReader = new SAXReader();
        try {
            read = saxReader.read(getClass().getResource("/message002.xml"));
        } catch (DocumentException e) {
            throw new RuntimeException(e);
        }
    }
    @Test
    void test_getName_and_getQualifiedName() {
        Element rootElement = read.getRootElement();
        Assertions.assertEquals("my-content", rootElement.getName());
        Assertions.assertEquals("xxx:my-content", rootElement.getQualifiedName());
        Assertions.assertEquals("xxx", rootElement.getNamespacePrefix());
        Assertions.assertEquals("http://example.org/xxx", rootElement.getNamespaceURI());
        Assertions.assertNull(rootElement.element("xxx:web-site"));
        Element webSite = rootElement.element("web-site");
        Assertions.assertNotNull(webSite);
        Assertions.assertEquals("web-site", webSite.getName());
        Assertions.assertEquals("xxx:web-site", webSite.getQualifiedName());
        Assertions.assertEquals("xxx", webSite.getNamespacePrefix());
        Assertions.assertEquals("http://example.org/xxx", webSite.getNamespaceURI());
    }
    @Test
    void test_XPath() {
        Element rootElement = read.getRootElement();
        Assertions.assertNull(rootElement.selectSingleNode("web-site"));
        Assertions.assertNotNull(rootElement.selectSingleNode("xxx:web-site"));
    }
}

XPath

采用 xpath 查找需要引入 jaxen-xx-xx.jar，否则会报 java.lang.NoClassDefFoundError: org/jaxen/JaxenException 异常。

<dependency>
    <groupId>jaxen</groupId>
    <artifactId>jaxen</artifactId>
</dependency>

package org.example;

import lombok.extern.slf4j.Slf4j;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import java.util.List;

@Slf4j
public class XmlDom4jXPathTest {
    Document read;
    @BeforeEach
    void beforeEach() {
        SAXReader saxReader = new SAXReader();
        try {
            read = saxReader.read(getClass().getResource("/message001.xml"));
        } catch (DocumentException e) {
            throw new RuntimeException(e);
        }
    }
    @Test
    void test_selectNodes() {
        List<Node> nodes = read.selectNodes("//posts/*");
        log.info("{}", nodes);
        Assertions.assertEquals(2, nodes.size());
        nodes.forEach(n -> {
            Assertions.assertInstanceOf(Element.class, n);
            Assertions.assertEquals("post", n.getName());
        });
    }
    @Test
    void test_selectSingleNode() {
        Node node = read.selectSingleNode("//posts/*[2]");
        Assertions.assertInstanceOf(Element.class, node);
        Assertions.assertEquals("post", node.getName());
        Element e = (Element) node;
        Assertions.assertEquals("P002", e.attribute("id").getValue());
        Assertions.assertEquals(2, e.elements().size());
    }
    @Test
    void test_Predicates() {
        Element node = (Element) read.selectSingleNode("//posts/*[@id='P002']");
        log.info("{}", node);
        Assertions.assertEquals("post", node.getQualifiedName());
        Assertions.assertEquals("文章标题02", node.element("title").getStringValue());
        Assertions.assertEquals("hello world 02！", node.element("content").getStringValue());
    }
}