org.bbottema.javareflection.util

Class ExternalClassLoader

java.lang.Object

java.lang.ClassLoader

org.bbottema.javareflection.util.ExternalClassLoader

public final class ExternalClassLoader
extends ClassLoader

A toolkit that can read and compile .java sourcefiles on the fly in runtime. This class loader caches loaded classes for repeated requests. Also, if a .class file already exists for a specific .java sourcefile, the classloader will compare dates and see if the .java needs recompiling.

A basepath can be specified for the classloader to look in for sourcefiles.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ExternalClassLoader.CompileException Parameterized exception used when Java's runtime compiler fails to compile a Java source file.

Constructor Summary

Constructors

Constructor and Description
ExternalClassLoader() Constructor which initializes all properties.

Method Summary

Modifier and Type	Method and Description
@Nullable Class<?>	findClass(String className) Loads a classfile from file in the following order: looks for the java source and if available, checks whether it needs to be compiled if no .java or .class file found, try to find it in the VM If the class ultimately wasn't found a ClassNotFoundException is being thrown.
@Nullable String	getBasepath()
@Nullable ExternalClassLoader.CompileException	getException()
@Nullable Class<?>	loadClass(String className) Loads a class from the classes cache if available.
void	setBasepath(@Nullable String basepath) Sets the base path this classloader will look for classes in.

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, getParent, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus

Methods inherited from class java.lang.Object

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

Constructor Detail

ExternalClassLoader

public ExternalClassLoader()

Constructor which initializes all properties.

Method Detail

loadClass

@Nullable
public final @Nullable Class<?> loadClass(String className)
                                              throws ClassNotFoundException

Loads a class from the classes cache if available. Delegates to findClass(String) otherwise.

Overrides:

loadClass in class ClassLoader

Throws:

ClassNotFoundException

See Also:

ClassLoader.loadClass(String)

findClass

@Nullable
public final @Nullable Class<?> findClass(String className)
                                              throws ClassNotFoundException

Loads a classfile from file in the following order:

1. looks for the java source and if available, checks whether it needs to be compiled
2. if no .java or .class file found, try to find it in the VM

If the class ultimately wasn't found a ClassNotFoundException is being thrown. If class was found, but an error occurred, store exception for later review and return null. This is done so because the overridden method can't throw an exception other than ClassNotFoundException.

Overrides:

findClass in class ClassLoader

Parameters:

className - The path and name to the classfile.

Returns:

The requested class reference.

Throws:

ClassNotFoundException - Thrown by ClassLoader.findSystemClass(String).

setBasepath

public void setBasepath(@Nullable
                        @Nullable String basepath)

Sets the base path this classloader will look for classes in.

Parameters:

basepath - A folder path to look for classes.

getBasepath

@Nullable
public @Nullable String getBasepath()

getException

@Nullable
public @Nullable ExternalClassLoader.CompileException getException()