org.codehaus.janino

Class CachingJavaSourceClassLoader

public class CachingJavaSourceClassLoader extends JavaSourceClassLoader

A JavaSourceClassLoader that uses a resource storage provided by the application to cache compiled classes and thus saving unnecessary recompilations.

The application provides access to the resource storeage through a pair of a ResourceFinder and a ResourceCreator (see CachingJavaSourceClassLoader.

See (String[]) for an example how to use this class.

Notice: You must NOT rely on that this class stores some particular data in some particular resources through the given classFileCacheResourceFinder/Creator! These serve only as a means for the CachingJavaSourceClassLoader to persistently cache some data between invocations. In other words: If you want to compile .java files into .class files, then don't use this class but Compiler instead!

Constructor Summary
CachingJavaSourceClassLoader(ClassLoader parentClassLoader, File[] optionalSourcePath, String optionalCharacterEncoding, File cacheDirectory, EnumeratorSet debuggingInformation)
CachingJavaSourceClassLoader(ClassLoader parentClassLoader, ResourceFinder sourceFinder, String optionalCharacterEncoding, ResourceFinder classFileCacheResourceFinder, ResourceCreator classFileCacheResourceCreator, EnumeratorSet debuggingInformation)
Notice that this class is thread-safe if and only if the classFileCacheResourceCreator stores its data atomically, i.e. the classFileCacheResourceFinder sees the resource written by the classFileCacheResourceCreator only after the OutputStream is closed.
Method Summary
protected MapgenerateBytecodes(String className)
Override generateBytecodes to implement class file caching.

Constructor Detail

CachingJavaSourceClassLoader

public CachingJavaSourceClassLoader(ClassLoader parentClassLoader, File[] optionalSourcePath, String optionalCharacterEncoding, File cacheDirectory, EnumeratorSet debuggingInformation)
See CachingJavaSourceClassLoader.

Parameters: optionalSourcePath Directories to scan for source files cacheDirectory Directory to use for caching generated class files (see class description)

CachingJavaSourceClassLoader

public CachingJavaSourceClassLoader(ClassLoader parentClassLoader, ResourceFinder sourceFinder, String optionalCharacterEncoding, ResourceFinder classFileCacheResourceFinder, ResourceCreator classFileCacheResourceCreator, EnumeratorSet debuggingInformation)
Notice that this class is thread-safe if and only if the classFileCacheResourceCreator stores its data atomically, i.e. the classFileCacheResourceFinder sees the resource written by the classFileCacheResourceCreator only after the OutputStream is closed.

In order to make the caching scheme work, both the classFileCacheResourceFinder and the sourceFinder must support the lastModified method, so that the modification time of the source and the class files can be compared.

Parameters: parentClassLoader Attempt to load classes through this one before looking for source files sourceFinder Finds JavaTM source for class pkg.Cls in resource pkg/Cls.java optionalCharacterEncoding Encoding of JavaTM source or null for platform default encoding classFileCacheResourceFinder Finds precompiled class pkg.Cls in resource pkg/Cls.class (see class description) classFileCacheResourceCreator Stores compiled class pkg.Cls in resource pkg/Cls.class (see class description) debuggingInformation What debugging information to include into the generated class files

Method Detail

generateBytecodes

protected Map generateBytecodes(String className)
Override generateBytecodes to implement class file caching.

Returns: String name => byte[] bytecode, or null if no source code could be found

Throws: ClassNotFoundException on compilation problems or class file cache I/O problems