Class ClasspathDigger

java.lang.Object

clazzfish.monitor.internal.AbstractDigger

clazzfish.monitor.internal.ClasspathDigger

Direct Known Subclasses:

ResourcepathDigger

public class ClasspathDigger
extends AbstractDigger

This helper class digs into the classloader for information like used classpath and other things. It was extracted from ClasspathMonitor to separate the classloader specific part of it into its own class.

Originally this class was part of the PatternTesting project where it was moved into an internal package. It is not intended for external use.

Author:

oliver

Field Summary

Fields

Modifier and Type	Field	Description
static final ClasspathDigger	DEFAULT

Constructor Summary

Constructors

Constructor	Description
ClasspathDigger()	Instantiates a new classpath digger.
ClasspathDigger(ClassLoader cloader)	Instantiates a new classpath digger.

Method Summary

Modifier and Type	Method	Description
String[]	getBootClasspath()	To get the boot classpath the sytem property "sun.boot.class.path" is used to get them.
Set<String>	getClasses()	Digs into the classpath and returns the found classes.
ClassLoader	getClassLoader()	Gets the class loader.
String[]	getClasspath()	We can use the system property "java.class.path" to get the classpath.
protected static String[]	getClasspath(String key)	Gets the classpath.
protected String[]	getClasspathFromPackages()	Here we use the loaded packages to calculate the classpath.
Set<Class<?>>	getLoadedClasses()	Returns a list of classes which were loaded by the given classloader.
Package[]	getLoadedPackageArray()	Returns the packages which were loaded by the classloader.
List<String>	getLoadedResources()	Asks the classloader for the resources which it already loaded - either directly or because the corresponding package was already loaded.
String[]	getPackageArray()	Get all packages found in the classpath.
SortedSet<URI>	getResourcepathSet(Collection<String> resources)	Gets the resourcepathes which belongs to the given collection of resources.
Enumeration<URI>	getResources(String name)	Gets the resources of the given name.
static boolean	isAgentAvailable()	Checks if the ClasspathAgent is available as MBean.
boolean	isClassloaderSupported()	Checks if is classloader supported.
boolean	isLoaded(String classname)	Checks if the given classname is loaded.
String	toString()	Puts also the classloader in the toString representation.
URI	whichResource(String name)	Returns the URI of the given resource and the given classloader.

Methods inherited from class clazzfish.monitor.internal.AbstractDigger

readElementsFromNestedArchive

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT

public static final ClasspathDigger DEFAULT

Constructor Details

ClasspathDigger

public ClasspathDigger()

Instantiates a new classpath digger.

ClasspathDigger

public ClasspathDigger(ClassLoader cloader)

Instantiates a new classpath digger.

Parameters:

cloader - the cloader

Since:

1.2

Method Details

getClassLoader

public ClassLoader getClassLoader()

Gets the class loader.

Returns:

the classLoader

isClassloaderSupported

public boolean isClassloaderSupported()

Checks if is classloader supported.

Returns:

true, if is classloader supported

isAgentAvailable

public static boolean isAgentAvailable()

Checks if the ClasspathAgent is available as MBean. The ClasspathAgent is needed for classloaders which are not directly supported (e.g. IBM's classloader of their JDK).

Returns:

true, if is agent available

getBootClasspath

public String[] getBootClasspath()

To get the boot classpath the sytem property "sun.boot.class.path" is used to get them. This will work of course only for the SunVM.

Returns:

the boot classpath as String array

getClasspath

public String[] getClasspath()

We can use the system property "java.class.path" to get the classpath. But this works not inside an application server or servlet engine (e.g. inside Tomcat) because they have their own classloader to load the classes.

In the past we tried to use the private (and undocoumented) attribute "domains" of the classloader. This works for a normal application but Tomcat's WebappClassLoader listed also classes in the "domains"-Set. Now we will try to detect the different classloader to access some private and secret attributes of this classloader.

At the moment only org.apache.catalina.loader.WebappClassLoader is supported. For all other classloaders the standard approach using the system property "java.class.path" is used.

Returns:

the classpath as String array

getClasspath

protected static String[] getClasspath(String key)

Gets the classpath.

Parameters:

key - the key

Returns:

the classpath as String array

getPackageArray

public String[] getPackageArray()

Get all packages found in the classpath.

In contradiction to getLoadedPackageArray() we don't ask the classloader (e.g. by calling classLoader.getResourceAsStream("")) for the packages because the classloader would return only these packages it has already loaded.

Returns:

the packages

getLoadedPackageArray

public Package[] getLoadedPackageArray()

Returns the packages which were loaded by the classloader.

Returns:

array with the loaded packages

getClasspathFromPackages

protected String[] getClasspathFromPackages()

Here we use the loaded packages to calculate the classpath. For each loaded package we will look from which jar file or directory this package is loaded.

Returns:

the found classpath as string array

Since:

27-Jul-2009

getResources

public Enumeration<URI> getResources(String name)

Gets the resources of the given name. Normally that would only be one element but some resources (like the MANIFEST.MF file) can appear several times in the classpath.

Specified by:

getResources in class AbstractDigger

Parameters:

name - the name of the resource

Returns:

all resources with the given name

getResourcepathSet

public SortedSet<URI> getResourcepathSet(Collection<String> resources)

Gets the resourcepathes which belongs to the given collection of resources.

Parameters:

resources - the resources

Returns:

the resourcepath set

Since:

1.6.3

whichResource

public URI whichResource(String name)

Returns the URI of the given resource and the given classloader. If the resource is not found it will be tried again with/without a leading "/" and with the parent classloader.

Parameters:

name - resource name (e.g. "log4j.properties")

Returns:

URI of the given resource (or null if resource was not found)

isLoaded

public boolean isLoaded(String classname)

Checks if the given classname is loaded. Why does we use not Class as parameter here? If you would allow a parameter of type "Class" this class will be problably loaded before and this method will return always true!

Parameters:

classname - name of the class

Returns:

true if class is loaded

toString

public String toString()

Puts also the classloader in the toString representation.

Overrides:

toString in class Object

Returns:

string containing the class laoder

See Also:

• Object.toString()

getLoadedClasses

public Set<Class<?>> getLoadedClasses()

Returns a list of classes which were loaded by the given classloader.

Ok, we must do some hacks here: there is an undocumented attribute "classes" which contains the loaded classes.

HANDLE WITH CARE (it's a hack and it depends on the used classloader)

Returns:

set of classes

getLoadedResources

public List<String> getLoadedResources()

Asks the classloader for the resources which it already loaded - either directly or because the corresponding package was already loaded.

Returns:

the loaded resources

Since:

1.6.3 (15.05.2016)

getClasses

public Set<String> getClasses()

Digs into the classpath and returns the found classes.

NOTE: This logic was formerly part of the createClasspathSet(..) method of the ClasspathMonitor class.

Returns:

classes of the classpath

Since:

1.7.2