Native libraries: support loading via System.loadLibrary()

(for pre-extracted native libs in NetBeans)

CHANGELOG.md

@@ -3,6 +3,11 @@ FlatLaf Change Log
 
 ## 3.0-SNAPSHOT
 
+#### New features and improvements
+
+- If value of system property `flatlaf.nativeLibraryPath` is `system`, then
+  `System.loadLibrary(String)` is used to load the native library.
+
 #### Fixed bugs
 
 - ComboBox and Spinner: Fixed missing arrow buttons if preferred height is zero.

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatSystemProperties.java

@@ -155,9 +155,19 @@ public interface FlatSystemProperties
 	String UPDATE_UI_ON_SYSTEM_FONT_CHANGE = "flatlaf.updateUIOnSystemFontChange";
 
 	/**
-	 * Specifies a directory in which the native FlatLaf library have been extracted.
+	 * Specifies a directory in which the native FlatLaf libraries have been extracted.
 	 * The path can be absolute or relative to current application working directory.
 	 * This can be used to avoid extraction of the native libraries to the temporary directory at runtime.
+	 * <p>
+	 * If the value is {@code "system"}, then {@link System#loadLibrary(String)} is
+	 * used to load the native library.
+	 * Searches for the native library in classloader of caller
+	 * (using {@link ClassLoader#findLibrary(String)}) and in paths specified
+	 * in system properties {@code sun.boot.library.path} and {@code java.library.path}.
+	 * (supported since FlatLaf 3)
+	 * <p>
+	 * If the native library can not loaded from the given path (or via {@link System#loadLibrary(String)}),
+	 * then the embedded native library is extracted to the temporary directory and loaded from there.
 	 *
 	 * @since 2
 	 */

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatNativeLibrary.java

@@ -84,11 +84,19 @@ class FlatNativeLibrary
 	private static NativeLibrary createNativeLibrary( String libraryName ) {
 		String libraryPath = System.getProperty( FlatSystemProperties.NATIVE_LIBRARY_PATH );
 		if( libraryPath != null ) {
-			File libraryFile = new File( libraryPath, System.mapLibraryName( libraryName ) );
+			if( "system".equals( libraryPath ) ) {
-			if( libraryFile.exists() )
+				NativeLibrary library = new NativeLibrary( libraryName, true );
-				return new NativeLibrary( libraryFile, true );
+				if( library.isLoaded() )
-			else
+					return library;
+
+				LoggingFacade.INSTANCE.logSevere( "Did not find library " + libraryName + " in java.library.path, using extracted library instead", null );
+			} else {
+				File libraryFile = new File( libraryPath, System.mapLibraryName( libraryName ) );
+				if( libraryFile.exists() )
+					return new NativeLibrary( libraryFile, true );
+
 				LoggingFacade.INSTANCE.logSevere( "Did not find external library " + libraryFile + ", using extracted library instead", null );
+			}
 		}
 
 		return new NativeLibrary( "com/formdev/flatlaf/natives/" + libraryName, null, true );
@@ -101,9 +109,9 @@ class FlatNativeLibrary
 			// log error only if native library jawt.dll not already loaded
 			String message = ex.getMessage();
 			if( message == null || !message.contains( "already loaded in another classloader" ) )
-				LoggingFacade.INSTANCE.logSevere( null, ex );
+				LoggingFacade.INSTANCE.logSevere( message, ex );
 		} catch( Exception ex ) {
-			LoggingFacade.INSTANCE.logSevere( null, ex );
+			LoggingFacade.INSTANCE.logSevere( ex.getMessage(), ex );
 		}
 	}
 }

flatlaf-core/src/main/java/com/formdev/flatlaf/util/NativeLibrary.java

@@ -73,6 +73,22 @@ public class NativeLibrary
 			: false;
 	}
 
+	/**
+	 * Load native library using {@link System#loadLibrary(String)}.
+	 * Searches for the library in classloader of caller
+	 * (using {@link ClassLoader#findLibrary(String)}) and in paths specified
+	 * in system properties {@code sun.boot.library.path} and {@code java.library.path}.
+	 *
+	 * @param libraryName name of the native library (without "lib" prefix and without extension)
+	 * @param supported whether the native library is supported on the current platform
+	 * @since 3
+	 */
+	public NativeLibrary( String libraryName, boolean supported ) {
+		this.loaded = supported
+			? loadLibraryFromSystem( libraryName )
+			: false;
+	}
+
 	/**
 	 * Returns whether the native library is loaded.
 	 * <p>
@@ -92,7 +108,7 @@ public class NativeLibrary
 			? classLoader.getResource( libraryName )
 			: NativeLibrary.class.getResource( "/" + libraryName );
 		if( libraryUrl == null ) {
-			log( "Library '" + libraryName + "' not found", null );
+			LoggingFacade.INSTANCE.logSevere( "Library '" + libraryName + "' not found", null );
 			return false;
 		}
 
@@ -125,7 +141,7 @@ public class NativeLibrary
 
 			return true;
 		} catch( Throwable ex ) {
-			log( null, ex );
+			LoggingFacade.INSTANCE.logSevere( ex.getMessage(), ex );
 
 			if( tempFile != null )
 				deleteOrMarkForDeletion( tempFile );
@@ -138,7 +154,24 @@ public class NativeLibrary
 			System.load( libraryFile.getAbsolutePath() );
 			return true;
 		} catch( Throwable ex ) {
-			log( ex.getMessage(), ex );
+			LoggingFacade.INSTANCE.logSevere( ex.getMessage(), ex );
+			return false;
+		}
+	}
+
+	private boolean loadLibraryFromSystem( String libraryName ) {
+		try {
+			System.loadLibrary( libraryName );
+			return true;
+		} catch( Throwable ex ) {
+			String message = ex.getMessage();
+
+			// do not log error if library was not found
+			// thrown in ClassLoader.loadLibrary(Class<?> fromClass, String name, boolean isAbsolute)
+			if( ex instanceof UnsatisfiedLinkError && message != null && message.contains( "java.library.path" ) )
+				return false;
+
+			LoggingFacade.INSTANCE.logSevere( message, ex );
 			return false;
 		}
 	}
@@ -158,10 +191,6 @@ public class NativeLibrary
 			: System.mapLibraryName( libraryName );
 	}
 
-	private static void log( String msg, Throwable thrown ) {
-		LoggingFacade.INSTANCE.logSevere( msg, thrown );
-	}
-
 	private static Path createTempFile( String libraryName ) throws IOException {
 		int sep = libraryName.lastIndexOf( '/' );
 		String name = (sep >= 0) ? libraryName.substring( sep + 1 ) : libraryName;