com.deltax.util
Class JDK12ClassFileFinder

java.lang.Object
  com.deltax.util.JDK12ClassFileFinder

All Implemented Interfaces:

ClassFileFinder, ResourceFileFinder

Direct Known Subclasses:

DynamicJDK12ClassFileFinder

public class JDK12ClassFileFinder

extends java.lang.Object

implements ClassFileFinder, ResourceFileFinder

This class emulates JDK 1.2 behaviour for finding class, providing direct access to the files / streams.

Of course, it works only when classes are actually loaded from a filesystem.

Version:

1.4

Author:

Cristiano Sadun

Field Summary

protected java.util.HashMap	classCache Maps class names to Object[2] arrays containing file and classfile (File, byte[])
protected boolean	classCacheOn
protected java.lang.String	classPath The application class path used by this classFileFinder
protected java.util.Enumeration	classPathDirs Caches results of getClassPathDirs() If the classpath changes, it must be invalidated.
protected java.util.HashSet	missingFilesNotified

Constructor Summary

JDK12ClassFileFinder()
Creates a classfinder which looks (besides system directories) in $java.class.path

JDK12ClassFileFinder(java.lang.String classPath)
Creates a classfinder which looks (besides system directories) in the given class path

Method Summary

protected java.lang.String	classNameToEntry(java.lang.String className) Converts a fully qualified externalized java class name into a zip file entry.
protected java.lang.String	classNameToPath(java.lang.String className) Converts a fully qualified externalized java class name into a relative file path.
void	clearCorruptFiles() Empty the set of files considered corrupted since they failed to open when the finder was searching for classes, so that subsequent work will not ignore them.
java.io.File	findClassFile(java.lang.String className) This method emulates 1.2 behaviour for class finding - which means: - it first searches into the $java.home/lib/ and $java.home/lib/*.jar; - then in $java.ext.dirs/*.jar; - eventually in $java.class.path
protected java.io.File[]	findJarsInPath(java.io.File path) Find the JAR files in the given path
java.io.File	findResourceFile(java.lang.String resource) Find a resource in the filesystem.
byte[]	getBytes(java.lang.String className) Return the byte array for the class
byte[]	getClassBytes(java.lang.String className) Returns a byte array with the bytecode for the class * @param className the name of the class to find * @return byte[] the bytecode for the class * @throws IOException if a problem arises while loading the bytecode * @throws ClassNotFoundException if the class definition cannot be found
protected java.util.Enumeration	getClassPathDirs()
java.util.Set	getCorruptFiles() Return the set, possibly empty, of files which couldn't be opened when the finder was searching for classes
byte[]	getResourceBytes(java.lang.String resource) Return a byte array with the bytes for the resource, or null if the resource cannot be found
java.lang.String	getSupportedLoadingScheme() Returns the supported loading scheme
boolean	isClassCacheOn() Returns the classCacheOn.
boolean	isJar(java.io.File f) Just checks if the file ends with .jar
static void	main(java.lang.String[] args)
java.io.InputStream	openClass(java.lang.String className) Open class data.
protected java.io.InputStream	openClassInJar(java.lang.String className, java.io.File jarFile) Open class data in a JAR file
java.io.InputStream	openResource(java.lang.String resource) Return the stream associated to a resource in the filesystem, or null if such resource cannot be found.
protected java.io.File	searchJars(java.lang.String className, java.io.File[] jars) Searches jar files for a given class path
void	setClassCacheOn(boolean classCacheOn) Sets the classCacheOn.

Methods inherited from class java.lang.Object

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

Field Detail

classPath

protected java.lang.String classPath

The application class path used by this classFileFinder

classPathDirs

protected java.util.Enumeration classPathDirs

Caches results of getClassPathDirs() If the classpath changes, it must be invalidated.

missingFilesNotified

protected java.util.HashSet missingFilesNotified

classCache

protected java.util.HashMap classCache

Maps class names to Object[2] arrays containing file and classfile (File, byte[])

classCacheOn

protected boolean classCacheOn

Constructor Detail

JDK12ClassFileFinder

public JDK12ClassFileFinder(java.lang.String classPath)

Creates a classfinder which looks (besides system directories) in the given class path

Parameters:

classPath - the search class path

JDK12ClassFileFinder

public JDK12ClassFileFinder()

Creates a classfinder which looks (besides system directories) in $java.class.path

Method Detail

getSupportedLoadingScheme

public java.lang.String getSupportedLoadingScheme()

Returns the supported loading scheme

Specified by:

getSupportedLoadingScheme in interface ClassFileFinder

Returns:

a description string

openClass

public java.io.InputStream openClass(java.lang.String className)
                              throws java.io.IOException,
                                     java.lang.ClassNotFoundException

Open class data. The input stream reads exactly and only the class byte data.

Specified by:

openClass in interface ClassFileFinder

Parameters:

className - the name of the class to find

Throws:

java.lang.ClassNotFoundException - if the class is not found

java.io.IOException - if an I/O Exception occurs

findClassFile

public java.io.File findClassFile(java.lang.String className)
                           throws java.io.IOException,
                                  java.lang.ClassNotFoundException

This method emulates 1.2 behaviour for class finding - which means: - it first searches into the $java.home/lib/ and $java.home/lib/*.jar; - then in $java.ext.dirs/*.jar; - eventually in $java.class.path

Specified by:

findClassFile in interface ClassFileFinder

Parameters:

className - the name of the class to find

Returns:

the File object for the class file; this can be a .class file, or a JAR file containing the class

Throws:

java.lang.ClassNotFoundException - if the class is not found

java.io.IOException - if an I/O Exception occurs

getBytes

public byte[] getBytes(java.lang.String className)
                throws java.io.IOException,
                       java.lang.ClassNotFoundException

Return the byte array for the class

Throws:

java.lang.ClassNotFoundException - if the class is not found in the JAR file

java.io.IOException - if an I/O Exception occurs

isJar

public boolean isJar(java.io.File f)

Just checks if the file ends with .jar

Parameters:

f - the file to check

Returns:

true if the file name ends with .jar

openClassInJar

protected java.io.InputStream openClassInJar(java.lang.String className,
                                             java.io.File jarFile)
                                      throws java.io.IOException,
                                             java.lang.ClassNotFoundException

Open class data in a JAR file

Returns:

an input stream to the class byte data in JAR

Throws:

java.lang.ClassNotFoundException - if the class is not found in the JAR file

java.io.IOException - if an I/O Exception occurs

java.io.FileNotFoundException - if the JAR file does not exist

searchJars

protected java.io.File searchJars(java.lang.String className,
                                  java.io.File[] jars)
                           throws java.io.IOException,
                                  java.lang.ClassNotFoundException

Searches jar files for a given class path

Parameters:

className - the name of the class to find

jars - an array of JAR file objects

Returns:

the jar file containing the class

Throws:

java.lang.ClassNotFoundException - if the class is not found

java.io.IOException - if an I/O Exception occurs

findJarsInPath

protected java.io.File[] findJarsInPath(java.io.File path)

Find the JAR files in the given path

Parameters:

path - the path to search in

Returns:

an array (may be zero-length) with the JAR file names

classNameToPath

protected java.lang.String classNameToPath(java.lang.String className)

Converts a fully qualified externalized java class name into a relative file path.

Parameters:

className - the name of the class to find

Returns:

the system-dependent path name for the class

classNameToEntry

protected java.lang.String classNameToEntry(java.lang.String className)

Converts a fully qualified externalized java class name into a zip file entry. (ZIP format uses always UNIX slash)

Parameters:

className - the name of the class to find

Returns:

the JAR entry name for the class

getClassPathDirs

protected java.util.Enumeration getClassPathDirs()

getClassBytes

public byte[] getClassBytes(java.lang.String className)
                     throws java.io.IOException,
                            java.lang.ClassNotFoundException

Description copied from interface: ClassFileFinder

Returns a byte array with the bytecode for the class * @param className the name of the class to find * @return byte[] the bytecode for the class * @throws IOException if a problem arises while loading the bytecode * @throws ClassNotFoundException if the class definition cannot be found

Specified by:

getClassBytes in interface ClassFileFinder

Throws:

java.io.IOException

java.lang.ClassNotFoundException

See Also:

ClassFileFinder.getClassBytes(java.lang.String)

openResource

public java.io.InputStream openResource(java.lang.String resource)
                                 throws java.io.IOException

Return the stream associated to a resource in the filesystem, or null if such resource cannot be found.

The returned stream is not buffered.

Specified by:

openResource in interface ResourceFileFinder

Parameters:

resource - the resource path

Returns:

a stream to the resource, or null if the resource cannot be found

Throws:

java.io.IOException - if a problem arises accessing the resource

See Also:

com.deltax.util.ResourceFileFinder#findResource(java.lang.String)

findResourceFile

public java.io.File findResourceFile(java.lang.String resource)
                              throws java.io.IOException

Find a resource in the filesystem.

This class implements findResource by operating as findClassFile() and attempting to locate the resource within directories or JAR files therein.

Resource loading from other than filesystem is not supported.

Specified by:

findResourceFile in interface ResourceFileFinder

Parameters:

resource - the resource path

Returns:

a stream to the resource, or null if the resource cannot be found

Throws:

java.io.IOException - if a problem arises accessing the resource

See Also:

com.deltax.util.ResourceFileFinder#findResource(java.lang.String)

getResourceBytes

public byte[] getResourceBytes(java.lang.String resource)
                        throws java.io.IOException

Return a byte array with the bytes for the resource, or null if the resource cannot be found. * @see com.deltax.util.ResourceFileFinder#getResourceBytes(String)

Specified by:

getResourceBytes in interface ResourceFileFinder

Throws:

java.io.IOException

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Throws:

java.lang.Exception

isClassCacheOn

public boolean isClassCacheOn()

Returns the classCacheOn.

Returns:

boolean

setClassCacheOn

public void setClassCacheOn(boolean classCacheOn)

Sets the classCacheOn. The class cache speeds up searching in jars by preserving classfile-classname-jar associations, but may lead to substantial growth of the amount of memory needed.

Parameters:

classCacheOn - The classCacheOn to set

getCorruptFiles

public java.util.Set getCorruptFiles()

Return the set, possibly empty, of files which couldn't be opened when the finder was searching for classes. * @return the set, possibly empty, of files which couldn't be opened.

clearCorruptFiles

public void clearCorruptFiles()

Empty the set of files considered corrupted since they failed to open when the finder was searching for classes, so that subsequent work will not ignore them.