com.wolfram.jlink
Class JLinkClassLoader
java.lang.Object
java.lang.ClassLoader
com.wolfram.jlink.JLinkClassLoader
public class JLinkClassLoader
- extends java.lang.ClassLoader
This class loader does all the loading of classes requested via the Mathematica function LoadJavaClass[].
It also loads native libraries and resources used by classes that it loads.
The directories and files it searches for classes and other resources are provided
to it via the addLocations() method, which is called from Mathematica during every call to LoadJavaClass[]
and also by AddToClassPath[].
The JLink Mathematica code manages the class path locations, including providing a default set
of extra dirs. Directories are automatically searched for jar or zip
files they contain, so you do not have to name jar files explicitly in addLocations(), although you
can if you want to limit the search to a specific jar file in a directory.
Most uses of this class are internal to J/Link, and most programmers will never deal with it directly.
One reason to use this class is if you want to load a class in Java code that is found in the special
set of extra locations that this class loader knows about (such as Java subdirectories of Mathematica
application directories). Each KernelLink has a JLinkClassLoader instance associated with it,
which you can retrieve using the link's getClassLoader() method.
Here is an example of loading a class from a special J/Link-specific directory.
Class cls = Class.forName("Some.class.that.only.JLink.can.find", ml.getClassLoader());
You can add directories and jar files to the search path using the addLocations() method:
// This is equivalent to calling AddToClassPath["/some/dir", "/another/dir"] in Mathematica.
ml.getClassLoader().addLocations(new String[]{"/some/dir", "/another/dir"}, true);
If you using this class from a standalone Java program you should first call
the KernelLink method
enableObjectReferences() to
initialize the class loader with the special Mathematica-specific locations for Java classes.
Another advanced reason to use this class is if you need the class loader
to have a specific parent loader, because that parent loader has certain capabilities or
can load classes from certain locations that J/Link would otherwise not know about.
KernelLink ml = MathLinkFactory.createKernelLink(...);
ml.discardAnswer();
ml.setClassLoader(new JLinkClassLoader(mySpecialParentClassLoader));
ml.enableObjectReferences();
The class has some static methods that are intended to be used from Mathematica code. Here is an
example that loads a resource from a Mathematica application's Java subdirectory:
(* Mathematica code *)
LoadJavaClass["com.wolfram.jlink.JLinkClassLoader"];
JLinkClassLoader`getInstance[]@getResource["myImage.gif"];
When using the class from Java, you will always have a specific link in hand, so instead of calling
static methods you should obtain a JLinkClassLoader instance from the link using its getClassLoader()
method and then call instance methods.
- Since:
- 3.0
- See Also:
KernelLink.getClassLoader(),
KernelLink.setClassLoader(JLinkClassLoader)
|
Field Summary |
protected com.wolfram.jlink.JLinkClassLoaderHelper |
helper
|
|
Constructor Summary |
JLinkClassLoader()
Constructs a new JLinkClassLoader instance. |
JLinkClassLoader(java.lang.ClassLoader parent)
Constructs a new JLinkClassLoader instance that has the given class loader as its parent loader. |
|
Method Summary |
void |
addLocations(java.lang.String[] locations,
boolean searchForJars)
Adds URLs, directories, and jar files in which this classloader will look for classes. |
void |
addLocations(java.lang.String[] locations,
boolean searchForJars,
boolean prepend)
|
java.lang.Class |
classFromBytes(java.lang.String className,
byte[] bytes)
Converts an array of bytes into an instance of class Class. |
static java.lang.Class |
classFromName(java.lang.String name)
Loads the class with the given name using the JLinkClassLoader instance of the currently-active link. |
void |
clearAssertionStatus()
|
java.lang.String[] |
getClassPath()
Gives the set of locations in which this class loader will search for classes. |
static JLinkClassLoader |
getInstance()
Retrieves the JLinkClassLoader instance being used by the currently-active link. |
java.net.URL |
getResource(java.lang.String name)
|
java.io.InputStream |
getResourceAsStream(java.lang.String name)
|
java.lang.Class |
loadClass(java.lang.String name)
|
void |
setClassAssertionStatus(java.lang.String className,
boolean enabled)
|
void |
setDefaultAssertionStatus(boolean enabled)
|
void |
setPackageAssertionStatus(java.lang.String packageName,
boolean enabled)
|
| Methods inherited from class java.lang.ClassLoader |
defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findLibrary, findLoadedClass, findResource, findResources, findSystemClass, getPackage, getPackages, getParent, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, resolveClass, setSigners |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
helper
protected com.wolfram.jlink.JLinkClassLoaderHelper helper
JLinkClassLoader
public JLinkClassLoader()
- Constructs a new JLinkClassLoader instance. Only advanced programmers will need to use this.
- Since:
- 3.0
JLinkClassLoader
public JLinkClassLoader(java.lang.ClassLoader parent)
- Constructs a new JLinkClassLoader instance that has the given class loader as its parent loader.
Only advanced programmers will need to use this.
- Since:
- 3.0
clearAssertionStatus
public void clearAssertionStatus()
- Overrides:
clearAssertionStatus in class java.lang.ClassLoader
setClassAssertionStatus
public void setClassAssertionStatus(java.lang.String className,
boolean enabled)
- Overrides:
setClassAssertionStatus in class java.lang.ClassLoader
setDefaultAssertionStatus
public void setDefaultAssertionStatus(boolean enabled)
- Overrides:
setDefaultAssertionStatus in class java.lang.ClassLoader
setPackageAssertionStatus
public void setPackageAssertionStatus(java.lang.String packageName,
boolean enabled)
- Overrides:
setPackageAssertionStatus in class java.lang.ClassLoader
getResource
public java.net.URL getResource(java.lang.String name)
- Overrides:
getResource in class java.lang.ClassLoader
getResourceAsStream
public java.io.InputStream getResourceAsStream(java.lang.String name)
- Overrides:
getResourceAsStream in class java.lang.ClassLoader
loadClass
public java.lang.Class loadClass(java.lang.String name)
throws java.lang.ClassNotFoundException
- Overrides:
loadClass in class java.lang.ClassLoader
- Throws:
java.lang.ClassNotFoundException
getInstance
public static JLinkClassLoader getInstance()
- Retrieves the JLinkClassLoader instance being used by the currently-active link.
This method is intended to be called only from Mathematica, where the "active link"
is well-defined (it is the link on which the call is coming in on).
- Since:
- 3.0
classFromName
public static java.lang.Class classFromName(java.lang.String name)
throws java.lang.ClassNotFoundException
- Loads the class with the given name using the JLinkClassLoader instance of the currently-active link.
This method is intended to be called only from Mathematica, where the "active link"
is well-defined (it is the link on which the call is coming in on).
- Throws:
java.lang.ClassNotFoundException- Since:
- 3.0
addLocations
public void addLocations(java.lang.String[] locations,
boolean searchForJars)
- Adds URLs, directories, and jar files in which this classloader will look for classes.
The elements of the locations array must be full paths to directories or jar or zip files,
or http URLs.
The searchForJars parameter determines whether directories will be automatically searched
for any jar files they contain.
- Since:
- 3.0
addLocations
public void addLocations(java.lang.String[] locations,
boolean searchForJars,
boolean prepend)
getClassPath
public java.lang.String[] getClassPath()
- Gives the set of locations in which this class loader will search for classes.
Only the locations known by this loader, not its parent loader, are returned.
- Since:
- 3.0
classFromBytes
public java.lang.Class classFromBytes(java.lang.String className,
byte[] bytes)
- Converts an array of bytes into an instance of class Class.
This method is effectively a public export of the final ClassLoader method defineClass().
It exists mainly for future internal uses within J/Link applications.
- Since:
- 3.0
J/Link is Copyright (c) 1999-2008,
Wolfram Research, Inc. All rights reserved.
