使用 XML 工具： jdom

JDOM 是一种解析 XML 的 Java 工具包。 JDOM 是 Breet Mclaughlin 和 Jason Hunter 两大 Java 高手的创作成果，2000 年初，JDOM 作为一个开放源代码项目正式开始研发。

https://github.com/LawssssCat/blog/tree/master/code/demo-java-xml/n03-jdom-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 example;

import lombok.extern.slf4j.Slf4j;
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.JDOMException;
import org.jdom2.filter.AbstractFilter;
import org.jdom2.input.SAXBuilder;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

@Slf4j
public class XmlJDomReadTest {
    Document read;
    @BeforeEach
    void beforeEach() {
        SAXBuilder saxBuilder = new SAXBuilder();
        try {
            read = saxBuilder.build(getClass().getResource("/message001.xml"));
        } catch (JDOMException | IOException e) {
            throw new RuntimeException(e);
        }
    }
    @Test
    void test_getRootElement() {
        Element rootElement = read.getRootElement();
        Assertions.assertEquals("my-content", rootElement.getQualifiedName());
        Assertions.assertEquals(2, rootElement.getChild("posts").getChildren().size());
        Assertions.assertArrayEquals(new String[] {"P001", "P002"}, rootElement.getChild("posts").getChildren().stream().map(e -> e.getAttribute("id").getValue()).toArray());
    }

    static class ParentFilter extends AbstractFilter<Element> {
        private final Element p;
        ParentFilter(Element p) {
            this.p = p;
        }
        @Override
        public Element filter(Object content) {
            if(content instanceof Element) {
                Element e = (Element) content;
                if (p.equals(e.getParentElement())) {
                    return e;
                }
            }
            return null;
        }
    }

    @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.getDescendants(new ParentFilter(rootElement));
        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.getDescendants(new ParentFilter(contentElement));
                while (postIterator.hasNext()) {
                    countPostElement++;
                    Element post = postIterator.next();
                    System.out.println("postElement = " + post);
                    postElementIdList.add(post.getAttributeValue("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());
    }
}

写

测试用例

package example;

import org.jdom2.Attribute;
import org.jdom2.Element;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;
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.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.List;
import java.util.Objects;

public class XmlJDomWriteTest {
    private Element addContent(Element p, Element c) {
        p.addContent(c);
        return c;
    }
    @Test
    void test() throws IOException {
        Element content = new Element("content");
        Element owner = addContent(content, new Element("owner"));
        owner.setText("steven");
        Element posts = addContent(content, new Element("posts"));
        for (int i = 0; i < 2; i++) {
            Element post = addContent(posts, new Element("post"));
            List<Attribute> attributes = Collections.singletonList(new Attribute("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)) {
            XMLOutputter xmlWriter = new XMLOutputter();
            Format format = Format.getCompactFormat();
            format.setEncoding(StandardCharsets.UTF_8.name());
            xmlWriter.setFormat(format);
            xmlWriter.output(content, fileOutputStream);
        }
        // validate
        Assertions.assertTrue(file.exists());
        Assertions.assertEquals("<content><owner>steven</owner><posts><post id=\"P000\" /><post id=\"P001\" /></posts></content>",
                IOUtils.readFile(file));
    }
}

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参考：

• https://www.cnblogs.com/wordless/p/16208704.html