org.apache.flink.util

Class ClassLoaderUtil

java.lang.Object

org.apache.flink.util.ClassLoaderUtil

@Internal
public final class ClassLoaderUtil
extends Object

Utilities for information with respect to class loaders, specifically class loaders for the dynamic loading of user defined classes.

Method Summary

Modifier and Type	Method and Description
static String	formatURL(URL url) Returns the interpretation of URL in string format.
static String	getUserCodeClassLoaderInfo(ClassLoader loader) Gets information about URL class loaders.
static boolean	validateClassLoadable(ClassNotFoundException cnfe, ClassLoader cl) Checks, whether the class that was not found in the given exception, can be resolved through the given class loader.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getUserCodeClassLoaderInfo

public static String getUserCodeClassLoaderInfo(ClassLoader loader)

Gets information about URL class loaders. The returned info string contains all URLs of the class loader. For file URLs, it contains in addition whether the referenced file exists, is a valid JAR file, or is a directory.

NOTE: This method makes a best effort to provide information about the classloader, and never throws an exception.

NOTE: Passing ClassLoader.getSystemClassLoader() on Java 9+ will not return anything interesting.

Parameters:

loader - The classloader to get the info string for.

Returns:

The classloader information string.

formatURL

public static String formatURL(URL url)
                        throws IOException

Returns the interpretation of URL in string format.

If the URL is null, it returns '(null)'.

If the URL protocol is file, prepend 'file:' flag before the formatted URL. Otherwise, use 'url: ' as the prefix instead.

Also, it checks whether the object that the URL directs to exists or not. If the object exists, some additional checks should be performed in order to determine that the object is a directory or a valid/invalid jar file. If the object does not exist, a missing flag should be appended.

Parameters:

url - URL that should be formatted

Returns:

The formatted URL

Throws:

IOException - When JarFile cannot be closed

validateClassLoadable

public static boolean validateClassLoadable(ClassNotFoundException cnfe,
                                            ClassLoader cl)

Checks, whether the class that was not found in the given exception, can be resolved through the given class loader.

Parameters:

cnfe - The ClassNotFoundException that defines the name of the class.

cl - The class loader to use for the class resolution.

Returns:

True, if the class can be resolved with the given class loader, false if not.