Class Loader
- java.lang.Object
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- org.apache.logging.log4j.core.util.Loader
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public final class Loader extends java.lang.Object
Load resources (or images) from various sources.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static java.lang.ClassLoader
getClassLoader()
Returns the ClassLoader to use.static java.lang.ClassLoader
getClassLoader(java.lang.Class<?> class1, java.lang.Class<?> class2)
static java.net.URL
getResource(java.lang.String resource, java.lang.ClassLoader defaultLoader)
This method will search forresource
in different places.static java.io.InputStream
getResourceAsStream(java.lang.String resource, java.lang.ClassLoader defaultLoader)
This method will search forresource
in different places.static java.lang.ClassLoader
getThreadContextClassLoader()
Returns the ClassLoader of current thread if possible, or falls back to the system ClassLoader if none is available.static java.lang.Class<?>
initializeClass(java.lang.String className, java.lang.ClassLoader loader)
Loads and initializes a named Class using a given ClassLoader.static boolean
isClassAvailable(java.lang.String className)
Determines if a named Class can be loaded or not.static boolean
isJansiAvailable()
static java.lang.Class<?>
loadClass(java.lang.String className, java.lang.ClassLoader loader)
Loads a named Class using a given ClassLoader.static java.lang.Class<?>
loadSystemClass(java.lang.String className)
Load a Class in thejava.*
namespace by name.static <T> T
newCheckedInstanceOf(java.lang.String className, java.lang.Class<T> clazz)
Loads, instantiates, and casts a Class using the default constructor.static java.lang.Object
newInstanceOf(java.lang.String className)
Loads and instantiates a Class using the default constructor.
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Method Detail
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getClassLoader
public static java.lang.ClassLoader getClassLoader()
Returns the ClassLoader to use.- Returns:
- the ClassLoader.
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getThreadContextClassLoader
public static java.lang.ClassLoader getThreadContextClassLoader()
Returns the ClassLoader of current thread if possible, or falls back to the system ClassLoader if none is available.- Returns:
- the TCCL.
- See Also:
LoaderUtil.getThreadContextClassLoader()
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getClassLoader
public static java.lang.ClassLoader getClassLoader(java.lang.Class<?> class1, java.lang.Class<?> class2)
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getResource
public static java.net.URL getResource(java.lang.String resource, java.lang.ClassLoader defaultLoader)
This method will search forresource
in different places. The search order is as follows:- Search for
resource
using the thread context class loader under Java2. If that fails, search forresource
using the class loader that loaded this class (Loader
). Under JDK 1.1, only the the class loader that loaded this class (Loader
) is used. - Try one last time with
ClassLoader.getSystemResource(resource)
, that is is using the system class loader in JDK 1.2 and virtual machine's built-in class loader in JDK 1.1.
- Parameters:
resource
- The resource to load.defaultLoader
- The default ClassLoader.- Returns:
- A URL to the resource.
- Search for
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getResourceAsStream
public static java.io.InputStream getResourceAsStream(java.lang.String resource, java.lang.ClassLoader defaultLoader)
This method will search forresource
in different places. The search order is as follows:- Search for
resource
using the thread context class loader under Java2. If that fails, search forresource
using the class loader that loaded this class (Loader
). Under JDK 1.1, only the the class loader that loaded this class (Loader
) is used. - Try one last time with
ClassLoader.getSystemResource(resource)
, that is is using the system class loader in JDK 1.2 and virtual machine's built-in class loader in JDK 1.1.
- Parameters:
resource
- The resource to load.defaultLoader
- The default ClassLoader.- Returns:
- An InputStream to read the resouce.
- Search for
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initializeClass
public static java.lang.Class<?> initializeClass(java.lang.String className, java.lang.ClassLoader loader) throws java.lang.ClassNotFoundException
Loads and initializes a named Class using a given ClassLoader.- Parameters:
className
- The class name.loader
- The class loader.- Returns:
- The class.
- Throws:
java.lang.ClassNotFoundException
- if the class could not be found.
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loadClass
public static java.lang.Class<?> loadClass(java.lang.String className, java.lang.ClassLoader loader) throws java.lang.ClassNotFoundException
Loads a named Class using a given ClassLoader.- Parameters:
className
- The class name.loader
- The class loader.- Returns:
- The class, or null if loader is null.
- Throws:
java.lang.ClassNotFoundException
- if the class could not be found.
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loadSystemClass
public static java.lang.Class<?> loadSystemClass(java.lang.String className) throws java.lang.ClassNotFoundException
Load a Class in thejava.*
namespace by name. Useful for peculiar scenarios typically involving Google App Engine.- Parameters:
className
- The class name.- Returns:
- The Class.
- Throws:
java.lang.ClassNotFoundException
- if the Class could not be found.
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newInstanceOf
public static java.lang.Object newInstanceOf(java.lang.String className) throws java.lang.ClassNotFoundException, java.lang.IllegalAccessException, java.lang.InstantiationException, java.lang.NoSuchMethodException, java.lang.reflect.InvocationTargetException
Loads and instantiates a Class using the default constructor.- Parameters:
className
- The class name.- Returns:
- new instance of the class.
- Throws:
java.lang.ClassNotFoundException
- if the class isn't available to the usual ClassLoadersjava.lang.IllegalAccessException
- if the class can't be instantiated through a public constructorjava.lang.InstantiationException
- if there was an exception whilst instantiating the classjava.lang.NoSuchMethodException
- if there isn't a no-args constructor on the classjava.lang.reflect.InvocationTargetException
- if there was an exception whilst constructing the class
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newCheckedInstanceOf
public static <T> T newCheckedInstanceOf(java.lang.String className, java.lang.Class<T> clazz) throws java.lang.ClassNotFoundException, java.lang.NoSuchMethodException, java.lang.IllegalAccessException, java.lang.reflect.InvocationTargetException, java.lang.InstantiationException
Loads, instantiates, and casts a Class using the default constructor.- Type Parameters:
T
- The type to cast it to.- Parameters:
className
- The class name.clazz
- The class to cast it to.- Returns:
- new instance of the class cast to
T
- Throws:
java.lang.ClassNotFoundException
- if the class isn't available to the usual ClassLoadersjava.lang.IllegalAccessException
- if the class can't be instantiated through a public constructorjava.lang.InstantiationException
- if there was an exception whilst instantiating the classjava.lang.NoSuchMethodException
- if there isn't a no-args constructor on the classjava.lang.reflect.InvocationTargetException
- if there was an exception whilst constructing the classjava.lang.ClassCastException
- if the constructed object isn't type compatible withT
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isClassAvailable
public static boolean isClassAvailable(java.lang.String className)
Determines if a named Class can be loaded or not.- Parameters:
className
- The class name.- Returns:
true
if the class could be found orfalse
otherwise.
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isJansiAvailable
public static boolean isJansiAvailable()
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