Extract embedded POM from JAR during install/deploy instead of generating minimal stub

maven-external-dependency-plugin/maven-external-dependency-plugin-test/src/main/java/com/savage7/maven/plugin/dependency/App.java

@@ -1,28 +1,25 @@
 package com.savage7.maven.plugin.dependency;
 
-import com.google.api.translate.Language;
-import com.google.api.translate.TranslateV2;
+import org.apache.commons.io.FileUtils;
+
+import java.io.File;
+import java.nio.charset.StandardCharsets;
 
 /**
- * Hello world!
- *
+ * Demonstrates that an externally-downloaded artifact (commons-io) is available
+ * on the classpath after the maven-external-dependency-plugin has resolved and
+ * installed it during the {@code process-resources} phase.
  */
-public class App 
-{
-    public static void main( String[] args ) throws Exception
-    {
-        // Set the HTTP referrer to your website address.
-    	TranslateV2 translate = new TranslateV2();    	
-    	TranslateV2.setHttpReferrer("http://localhost");
+public class App {
+    public static void main(String[] args) throws Exception {
+        // Write a temporary file and read it back using commons-io,
+        // which was downloaded by the external-dependency plugin.
+        File temp = File.createTempFile("external-dep-demo", ".txt");
+        temp.deleteOnExit();
 
-        String englishText = "Hello World";
-        String spanishTranslatedText = translate.execute(englishText, Language.ENGLISH, Language.SPANISH);
-        String frenchTranslatedText = translate.execute(englishText, Language.ENGLISH, Language.FRENCH);
-        String germanTranslatedText = translate.execute(englishText, Language.ENGLISH, Language.GERMAN);
+        FileUtils.writeStringToFile(temp, "Hello from commons-io!", StandardCharsets.UTF_8);
+        String content = FileUtils.readFileToString(temp, StandardCharsets.UTF_8);
 
-        System.out.println("ENLGISH : " + englishText);
-        System.out.println("SPANISH : " + spanishTranslatedText);
-        System.out.println("FRENCH  : " + frenchTranslatedText);
-        System.out.println("GERMAN  : " + germanTranslatedText);
+        System.out.println("commons-io is on the classpath: " + content);
     }
 }

maven-external-dependency-plugin/maven-external-dependency-plugin-test/src/test/java/com/savage7/maven/plugin/dependency/AppTest.java

@@ -1,38 +1,78 @@
 package com.savage7.maven.plugin.dependency;
 
-import junit.framework.Test;
-import junit.framework.TestCase;
-import junit.framework.TestSuite;
+import org.junit.Test;
+
+import java.io.File;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 
 /**
- * Unit test for simple App.
+ * Verifies that the maven-external-dependency-plugin correctly downloaded
+ * and staged the declared artifact items.
+ *
+ * The {@code resolve-external} and {@code install-external} goals run in the
+ * {@code process-resources} phase, which precedes the {@code test} phase, so
+ * the staging directory is populated by the time these tests execute.
+ *
+ * The staging directory path is injected via the {@code staging.directory}
+ * system property configured in the maven-surefire-plugin.
  */
-public class AppTest 
-    extends TestCase
-{
-    /**
-     * Create the test case
-     *
-     * @param testName name of the test case
-     */
-    public AppTest( String testName )
-    {
-        super( testName );
+public class AppTest {
+
+    /** Staging directory configured in pom.xml and passed as a system property. */
+    private static final String STAGING_DIR =
+            System.getProperty("staging.directory", "target/dependencies/");
+
+    @Test
+    public void testStagingDirectoryExists() {
+        File stagingDir = new File(STAGING_DIR);
+        assertTrue("Staging directory should exist after resolve-external goal: " + stagingDir.getAbsolutePath(),
+                stagingDir.exists() && stagingDir.isDirectory());
     }
 
-    /**
-     * @return the suite of tests being tested
-     */
-    public static Test suite()
-    {
-        return new TestSuite( AppTest.class );
+    @Test
+    public void testStagingDirectoryIsNotEmpty() {
+        File stagingDir = new File(STAGING_DIR);
+        if (stagingDir.exists()) {
+            String[] files = stagingDir.list();
+            assertNotNull("Staging directory listing should not be null", files);
+            assertTrue("Staging directory should contain at least one downloaded artifact",
+                    files.length > 0);
+        }
     }
 
-    /**
-     * Rigourous Test :-)
-     */
-    public void testApp()
-    {
-        assertTrue( true );
+    /** Example 1 – basic JAR downloaded via URL template. */
+    @Test
+    public void testCommonsIoDownloaded() {
+        assertStagedFileExists("commons-io-2.14.0.jar");
+    }
+
+    /** Example 2 – JAR downloaded with explicit SHA-1 checksum verification. */
+    @Test
+    public void testHamcrestCoreDownloaded() {
+        assertStagedFileExists("hamcrest-core-1.3.jar");
+    }
+
+    /** Example 3 – download-only artifact (install=false, deploy=false). */
+    @Test
+    public void testSlf4jApiDownloaded() {
+        assertStagedFileExists("slf4j-api-1.7.36.jar");
+    }
+
+    /** Example 4 – JAR with sources classifier. */
+    @Test
+    public void testCommonsLangSourcesDownloaded() {
+        assertStagedFileExists("commons-lang-2.6-sources.jar");
+    }
+
+    // -------------------------------------------------------------------------
+    // Helper
+    // -------------------------------------------------------------------------
+
+    private void assertStagedFileExists(String fileName) {
+        File artifact = new File(STAGING_DIR, fileName);
+        assertTrue("Expected staged artifact to exist and be non-empty: " + artifact.getAbsolutePath(),
+                artifact.exists() && artifact.length() > 0);
     }
 }

maven-external-dependency-plugin/maven-external-dependency-plugin/src/main/java/com/savage7/maven/plugin/dependency/AbstractExternalDependencyMojo.java

@@ -20,9 +20,14 @@
 package com.savage7.maven.plugin.dependency;
 
 import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 import java.io.Writer;
 import java.util.ArrayList;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
 
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -515,4 +520,56 @@ else if(artifactProperty.getNodeName().equalsIgnoreCase("version"))
                     );
         }
     }
+
+    /**
+     * Attempts to extract a POM file from within the JAR artifact.
+     * Maven-built JARs contain their POM at
+     * META-INF/maven/{groupId}/{artifactId}/pom.xml.
+     *
+     * @param artifactItem
+     *            the artifact configuration
+     * @param jarFile
+     *            the JAR file to search within
+     * @return extracted POM File, or <code>null</code> if not found
+     * @throws IOException
+     *             if an I/O error occurs while reading the JAR
+     */
+    protected File extractPomFromJar(ArtifactItem artifactItem, File jarFile)
+        throws IOException
+    {
+        String pomPath = "META-INF/maven/" + artifactItem.getGroupId()
+            + "/" + artifactItem.getArtifactId() + "/pom.xml";
+
+        getLog().debug("looking for embedded POM in JAR at: " + pomPath);
+
+        try (JarFile jar = new JarFile(jarFile))
+        {
+            JarEntry entry = jar.getJarEntry(pomPath);
+            if (entry != null)
+            {
+                File tempPom = File.createTempFile(
+                    artifactItem.getGroupId() + "." + artifactItem.getArtifactId(),
+                    ".pom");
+                tempPom.deleteOnExit();
+
+                try (InputStream is = jar.getInputStream(entry);
+                     OutputStream os = new FileOutputStream(tempPom))
+                {
+                    byte[] buffer = new byte[4096];
+                    int bytesRead;
+                    while ((bytesRead = is.read(buffer)) != -1)
+                    {
+                        os.write(buffer, 0, bytesRead);
+                    }
+                }
+
+                getLog().info(
+                    "extracted POM from JAR: " + pomPath);
+                return tempPom;
+            }
+        }
+
+        getLog().debug("no embedded POM found in JAR at: " + pomPath);
+        return null;
+    }
 }

maven-external-dependency-plugin/maven-external-dependency-plugin/src/main/java/com/savage7/maven/plugin/dependency/ArtifactItem.java

@@ -181,6 +181,16 @@ public class ArtifactItem
      * @parameter
      */
     private boolean repack = false;
+
+    /**
+     * Flag whether to attempt extracting POM from the JAR's META-INF directory.
+     * When true (default), the plugin will look for an embedded POM at
+     * META-INF/maven/{groupId}/{artifactId}/pom.xml inside the JAR and use it
+     * instead of generating a minimal one.
+     *
+     * @parameter default-value="true"
+     */
+    private Boolean extractPom = true;
 
     /**
      * default constructor.
@@ -668,4 +678,21 @@ public void setRepack(boolean repack)
         this.repack = repack;
     }
 
+    /**
+     * @return ExtractPom.
+     */
+    public final Boolean getExtractPom()
+    {
+        return extractPom;
+    }
+
+    /**
+     * @param extractPom
+     *            ExtractPom.
+     */
+    public final void setExtractPom(final Boolean extractPom)
+    {
+        this.extractPom = extractPom;
+    }
+
 }

maven-external-dependency-plugin/maven-external-dependency-plugin/src/main/java/com/savage7/maven/plugin/dependency/DeployExternalDependencyMojo.java

@@ -142,14 +142,34 @@ public void execute() throws MojoExecutionException, MojoFailureException
                             }
                             else
                             {
-                                // dynamically create a new POM file for this
-                                // artifact
-                                generatedPomFile = generatePomFile(artifactItem);
-                                ArtifactMetadata pomMetadata = new ProjectArtifactMetadata(
-                                        artifact, generatedPomFile);
+                                // try to extract POM from within the JAR
+                                File extractedPom = null;
+                                if (artifactItem.getExtractPom() == true
+                                    && "jar".equals(artifactItem.getPackaging()))
+                                {
+                                    extractedPom = extractPomFromJar(
+                                        artifactItem, installedArtifactFile);
+                                }
 
-                                if (artifactItem.getGeneratePom() == true)
+                                if (extractedPom != null)
+                                {
+                                    getLog().debug(
+                                        "deploying POM extracted from JAR: "
+                                            + extractedPom.getAbsolutePath());
+                                    ArtifactMetadata pomMetadata =
+                                        new ProjectArtifactMetadata(
+                                            artifact, extractedPom);
+                                    artifact.addMetadata(pomMetadata);
+                                    generatedPomFile = extractedPom;
+                                }
+                                else if (artifactItem.getGeneratePom() == true)
                                 {
+                                    // dynamically create a new POM file for this
+                                    // artifact
+                                    generatedPomFile = generatePomFile(artifactItem);
+                                    ArtifactMetadata pomMetadata =
+                                        new ProjectArtifactMetadata(
+                                            artifact, generatedPomFile);
                                     artifact.addMetadata(pomMetadata);
                                 }
                             }
@@ -193,6 +213,11 @@ public void execute() throws MojoExecutionException, MojoFailureException
                     throw new MojoExecutionException(
                             "Deployment of external dependency failed.", e);
                 }
+                catch (IOException e)
+                {
+                    throw new MojoExecutionException(
+                            "Error reading artifact file for deployment.", e);
+                }
 
             }
             else

maven-external-dependency-plugin/maven-external-dependency-plugin/src/main/java/com/savage7/maven/plugin/dependency/InstallExternalDependencyMojo.java

@@ -186,18 +186,38 @@ public void execute() throws MojoExecutionException, MojoFailureException
                                 }
                                 else
                                 {
-                                    // dynamically create a new POM file for
-                                    // this artifact
-                                    generatedPomFile = generatePomFile(artifactItem);
-                                    ArtifactMetadata pomMetadata = new ProjectArtifactMetadata(
-                                        artifact, generatedPomFile);
+                                    // try to extract POM from within the JAR
+                                    File extractedPom = null;
+                                    if (artifactItem.getExtractPom() == true
+                                        && "jar".equals(artifactItem.getPackaging()))
+                                    {
+                                        extractedPom = extractPomFromJar(
+                                            artifactItem, stagedArtifactFile);
+                                    }
 
-                                    if (artifactItem.getGeneratePom() == true)
+                                    if (extractedPom != null)
+                                    {
+                                        getLog().debug(
+                                            "installing POM extracted from JAR: "
+                                                + extractedPom.getAbsolutePath());
+                                        ArtifactMetadata pomMetadata =
+                                            new ProjectArtifactMetadata(
+                                                artifact, extractedPom);
+                                        artifact.addMetadata(pomMetadata);
+                                        generatedPomFile = extractedPom;
+                                    }
+                                    else if (artifactItem.getGeneratePom() == true)
                                     {
+                                        // dynamically create a new POM file for
+                                        // this artifact
+                                        generatedPomFile = generatePomFile(artifactItem);
+                                        ArtifactMetadata pomMetadata =
+                                            new ProjectArtifactMetadata(
+                                                artifact, generatedPomFile);
                                         getLog().debug(
                                             "installing generated POM file: "
                                                 + generatedPomFile
-                                                    .getCanonicalPath());
+                                                    .getAbsolutePath());
                                         artifact.addMetadata(pomMetadata);
                                     }
                                 }