Fix bug in loadJars() (#131)

Fix bug in load-jars which would not detect jars from lib/ if Path is not absolute
Add slf4j-simple logger in test scope for some logging from tests
Convert some File usage to Path

.gitignore

@@ -4,3 +4,4 @@ target/
 .settings
 .idea/
 *.iml
+demo-dist/

pf4j/pom.xml

@@ -32,6 +32,12 @@
             <artifactId>slf4j-api</artifactId>
             <version>1.7.5</version>
         </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.5</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.github.zafarkhaja</groupId>
             <artifactId>java-semver</artifactId>

pf4j/src/main/java/ro/fortsoft/pf4j/DefaultPluginDescriptorFinder.java

@@ -44,6 +44,9 @@ public class DefaultPluginDescriptorFinder extends ManifestPluginDescriptorFinde
 	@Override
     public Manifest readManifest(Path pluginPath) throws PluginException {
         // TODO it's ok with first classes root? Another idea is to specify in PluginClasspath the folder.
+        if (pluginClasspath.getClassesDirectories().size() == 0) {
+            throw new PluginException("Failed to read manifest, no classes folder in classpath");
+        }
         String classes = pluginClasspath.getClassesDirectories().get(0);
         Path manifestPath = pluginPath.resolve(Paths.get(classes,"/META-INF/MANIFEST.MF"));
         log.debug("Lookup plugin descriptor in '{}'", manifestPath);

pf4j/src/main/java/ro/fortsoft/pf4j/DefaultPluginLoader.java

@@ -69,7 +69,7 @@ public class DefaultPluginLoader implements PluginLoader {
      */
     protected void loadJars(Path pluginPath, PluginClassLoader pluginClassLoader) {
         for (String libDirectory : pluginClasspath.getLibDirectories()) {
-            File file = pluginPath.resolve(libDirectory).toFile();
+            Path file = pluginPath.resolve(libDirectory);
             List<File> jars = FileUtils.getJars(file);
             for (File jar : jars) {
                 pluginClassLoader.addFile(jar);

pf4j/src/main/java/ro/fortsoft/pf4j/util/FileUtils.java

@@ -15,13 +15,9 @@
  */
 package ro.fortsoft.pf4j.util;
 
-import java.io.BufferedReader;
-import java.io.BufferedWriter;
-import java.io.File;
-import java.io.FileFilter;
-import java.io.FileReader;
-import java.io.FileWriter;
-import java.io.IOException;
+import java.io.*;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -96,27 +92,27 @@ public class FileUtils {
 		return success;
 	}
 
-	public static List<File> getJars(File folder) {
+	public static List<File> getJars(Path folder) {
 	    List<File> bucket = new ArrayList<>();
 	    getJars(bucket, folder);
 
 	    return bucket;
     }
 
-    private static void getJars(List<File> bucket, File folder) {
+    private static void getJars(final List<File> bucket, Path folder) {
         FileFilter jarFilter = new JarFileFilter();
         FileFilter directoryFilter = new DirectoryFileFilter();
 
-        if (folder.exists() && folder.isDirectory() && folder.isAbsolute()) {
-            File[] jars = folder.listFiles(jarFilter);
+        if (Files.exists(folder) && Files.isDirectory(folder)) {
+            File[] jars = folder.toFile().listFiles(jarFilter);
             for (int i = 0; (jars != null) && (i < jars.length); ++i) {
                 bucket.add(jars[i]);
             }
 
-            File[] directories = folder.listFiles(directoryFilter);
+            File[] directories = folder.toFile().listFiles(directoryFilter);
             for (int i = 0; (directories != null) && (i < directories.length); ++i) {
                 File directory = directories[i];
-                getJars(bucket, directory);
+                getJars(bucket, directory.toPath());
             }
         }
     }