https://jira.baeldung.com/browse/BAEL-8767

libraries-formatting/pom.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>libraries-formatting</artifactId>
+
+    <parent>
+        <artifactId>parent-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark</artifactId>
+            <version>${commonmark.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>21</source>
+                    <target>21</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <commonmark.version>0.28.0</commonmark.version>
+    </properties>
+
+</project>

libraries-formatting/src/main/java/com/baeldung/commonmark/CommonMarkUsage.java

@@ -0,0 +1,68 @@
+package com.baeldung.commonmark;
+
+import org.commonmark.node.Document;
+import org.commonmark.node.Heading;
+import org.commonmark.node.Node;
+import org.commonmark.node.Text;
+import org.commonmark.parser.Parser;
+import org.commonmark.renderer.html.HtmlRenderer;
+import org.commonmark.renderer.markdown.MarkdownRenderer;
+
+public class CommonMarkUsage {
+
+    public static String markDownToHtml(String markdown) {
+        Parser parser = Parser.builder()
+            .build();
+        Node node = parser.parse(markdown);
+        HtmlRenderer renderer = HtmlRenderer.builder()
+            .build();
+        return renderer.render(node);
+
+    }
+
+    public static int processParsedNode(String markdown) {
+        Parser parser = Parser.builder()
+            .build();
+        Node node = parser.parse(markdown);
+        WordCountVisitor visitor = new WordCountVisitor();
+        node.accept(visitor);
+        return visitor.wordCount;
+
+    }
+
+    public static String htmlToMarkDown(String htmlHeading) {
+        Heading heading = new Heading();
+        heading.setLevel(2);
+
+        heading.appendChild(new Text(htmlHeading));
+        Document document = new Document();
+        document.appendChild(heading);
+
+        MarkdownRenderer renderer = MarkdownRenderer.builder()
+            .build();
+        return renderer.render(document);
+    }
+
+    public static String changingHtmlAttribute(String source) {
+        Parser parser = Parser.builder()
+            .build();
+        Node node = parser.parse(source);
+        HtmlRenderer renderer = HtmlRenderer.builder()
+            .attributeProviderFactory(context -> new ImageAttributeProvider())
+            .build();
+
+        return renderer.render(node);
+    }
+
+    public static String customizingHtmlRendering(String source) {
+        Parser parser = Parser.builder()
+            .build();
+        Node node = parser.parse(source);
+        HtmlRenderer renderer = HtmlRenderer.builder()
+            .nodeRendererFactory(IndentedCodeBlockNodeRenderer::new)
+            .build();
+
+        return renderer.render(node);
+    }
+
+}

libraries-formatting/src/main/java/com/baeldung/commonmark/ImageAttributeProvider.java

@@ -0,0 +1,17 @@
+package com.baeldung.commonmark;
+
+import java.util.Map;
+
+import org.commonmark.node.Image;
+import org.commonmark.node.Node;
+import org.commonmark.renderer.html.AttributeProvider;
+
+public class ImageAttributeProvider implements AttributeProvider {
+
+    @Override
+    public void setAttributes(Node node, String tagName, Map<String, String> attributes) {
+        if (node instanceof Image) {
+            attributes.put("class", "border");
+        }
+    }
+}

libraries-formatting/src/main/java/com/baeldung/commonmark/IndentedCodeBlockNodeRenderer.java

@@ -0,0 +1,34 @@
+package com.baeldung.commonmark;
+
+import java.util.Set;
+
+import org.commonmark.node.IndentedCodeBlock;
+import org.commonmark.node.Node;
+import org.commonmark.renderer.NodeRenderer;
+import org.commonmark.renderer.html.HtmlNodeRendererContext;
+import org.commonmark.renderer.html.HtmlWriter;
+
+public class IndentedCodeBlockNodeRenderer implements NodeRenderer {
+
+    private final HtmlWriter html;
+
+    public IndentedCodeBlockNodeRenderer(HtmlNodeRendererContext context) {
+        this.html = context.getWriter();
+    }
+
+    @Override
+    public Set<Class<? extends Node>> getNodeTypes() {
+        return Set.of(IndentedCodeBlock.class);
+    }
+
+    @Override
+    public void render(Node node) {
+        IndentedCodeBlock codeBlock = (IndentedCodeBlock) node;
+        html.line();
+        html.tag("pre");
+        html.text(codeBlock.getLiteral());
+        html.tag("/pre");
+        html.line();
+
+    }
+}

libraries-formatting/src/main/java/com/baeldung/commonmark/WordCountVisitor.java

@@ -0,0 +1,18 @@
+package com.baeldung.commonmark;
+
+import org.commonmark.node.AbstractVisitor;
+import org.commonmark.node.Text;
+
+public class WordCountVisitor extends AbstractVisitor {
+
+    int wordCount = 0;
+
+    @Override
+    public void visit(Text text) {
+        wordCount += text.getLiteral().split("\\w+").length;
+        visitChildren(text);
+    }
+
+
+
+}

libraries-formatting/src/test/java/com/baeldung/commonmark/CommonMarkUsageUnitTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.commonmark;
+
+import static com.baeldung.commonmark.CommonMarkUsage.changingHtmlAttribute;
+import static com.baeldung.commonmark.CommonMarkUsage.customizingHtmlRendering;
+import static com.baeldung.commonmark.CommonMarkUsage.htmlToMarkDown;
+import static com.baeldung.commonmark.CommonMarkUsage.markDownToHtml;
+import static com.baeldung.commonmark.CommonMarkUsage.processParsedNode;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class CommonMarkUsageUnitTest {
+
+    @Test
+    void givenMarkdownInput_whenConvertingToHtml_thenReturnRenderedHtml() {
+        String html = markDownToHtml("Welcome to *Baeldung*");
+
+        assertEquals("<p>Welcome to <em>Baeldung</em></p>\n", html);
+    }
+
+    @Test
+    void givenMarkdownInput_whenProcessingParsedNode_thenReturnWordCount() {
+        int wordCount = processParsedNode("Welcome to *Baeldung*");
+
+        assertEquals(3, wordCount);
+    }
+
+    @Test
+    void givenHeadingText_whenConvertingToMarkdown_thenReturnMarkdownHeading() {
+        String markdown = htmlToMarkDown("Java Tutorial");
+
+        assertEquals("## Java Tutorial\n", markdown);
+    }
+
+    @Test
+    void givenImageMarkdown_whenRenderingHtml_thenAddCustomClassAttribute() {
+        String html = changingHtmlAttribute("![text](/url.png)");
+
+        assertEquals("<p><img src=\"/url.png\" alt=\"text\" class=\"border\" /></p>\n", html);
+    }
+
+    @Test
+    void givenIndentedCodeBlock_whenRenderingHtml_thenUseCustomNodeRenderer() {
+        String html = customizingHtmlRendering("Example:\n\n    code");
+
+        assertEquals("<p>Example:</p>\n<pre>code\n</pre>\n", html);
+    }
+}

pom.xml

@@ -719,6 +719,7 @@
                 <module>libraries-data-io-2</module>
                 <module>libraries-data-mariadb4j</module>
                 <module>libraries-files</module>
+                <module>libraries-formatting</module>
                 <module>libraries-http</module>
 		        <module>libraries-http-2</module>
 	            <module>libraries-http-3</module>
@@ -1197,6 +1198,7 @@
                 <module>libraries-data-io-2</module>
                 <module>libraries-data-mariadb4j</module>
                 <module>libraries-files</module>
+                <module>libraries-formatting</module>
                 <module>libraries-http</module>
                 <module>libraries-http-2</module>
                 <module>libraries-http-3</module>