org.apache.tools.ant.util

Class ClasspathUtils


public class ClasspathUtils
extends java.lang.Object

Offers some helper methods on the Path structure in ant.

Basic idea behind this utility class is to use it from inside the different ant objects (and user defined objects) that need classLoading for their operation. Normally those would have a setClasspathRef() {for the @classpathref} and/or a createClasspath() {for the nested <classpath>} Typically one would have in your Ant Task or DataType


 ClasspathUtils.Delegate cpDelegate;

 public void init() {
     this.cpDelegate = ClasspathUtils.getDelegate(this);
     super.init();
 }

 public void setClasspathRef(Reference r) {
     this.cpDelegate.setClasspathRef(r);
 }

 public Path createClasspath() {
     return this.cpDelegate.createClasspath();
 }

 public void setClassname(String fqcn) {
     this.cpDelegate.setClassname(fqcn);
 }
 

At execution time, when you actually need the classloading you can just:


     Object o = this.cpDelegate.newInstance();
 

Since:
Ant 1.6

Nested Class Summary

static class
ClasspathUtils.Delegate
Delegate that helps out any specific ProjectComponent that needs dynamic classloading.

Field Summary

static String
REUSE_LOADER_REF
Name of the magic property that controls classloader reuse in Ant 1.4.

Method Summary

static ClassLoader
getClassLoaderForPath(Project p, Path path, String loaderId)
Convenience overloaded version of getClassLoaderForPath(Project,Path,String,boolean).
static ClassLoader
getClassLoaderForPath(Project p, Path path, String loaderId, boolean reverseLoader)
Convenience overloaded version of getClassLoaderForPath(Project,Path,String,boolean,boolean).
static ClassLoader
getClassLoaderForPath(Project p, Path path, String loaderId, boolean reverseLoader, boolean reuseLoader)
Gets a classloader that loads classes from the classpath defined in the path argument.
static ClassLoader
getClassLoaderForPath(Project p, Reference ref)
Convenience overloaded version of getClassLoaderForPath(Project,Reference,boolean).
static ClassLoader
getClassLoaderForPath(Project p, Reference ref, boolean reverseLoader)
Convenience overloaded version of getClassLoaderForPath(Project,Path,String,boolean).
static ClasspathUtils.Delegate
getDelegate(ProjectComponent component)
Obtains a delegate that helps out with classic classpath configuration.
static ClassLoader
getUniqueClassLoaderForPath(Project p, Path path, boolean reverseLoader)
Gets a fresh, different, not used before classloader that uses the passed path as it's classpath.
static Object
newInstance(String className, ClassLoader userDefinedLoader)
Creates a fresh object instance of the specified classname.

Field Details

REUSE_LOADER_REF

public static final String REUSE_LOADER_REF
Name of the magic property that controls classloader reuse in Ant 1.4.

Method Details

getClassLoaderForPath

public static ClassLoader getClassLoaderForPath(Project p,
                                                Path path,
                                                String loaderId)
Convenience overloaded version of getClassLoaderForPath(Project,Path,String,boolean).

Assumes the logical 'false' for the reverseLoader.

Parameters:
p - current ant project
path - the path
loaderId - the loader id string

Returns:
The class loader


getClassLoaderForPath

public static ClassLoader getClassLoaderForPath(Project p,
                                                Path path,
                                                String loaderId,
                                                boolean reverseLoader)
Convenience overloaded version of getClassLoaderForPath(Project,Path,String,boolean,boolean).

Sets value for 'reuseLoader' to true if the magic property has been set.

Parameters:
p - the project
path - the path
loaderId - the loader id string
reverseLoader - if set to true this new loader will take precedence over it's parent (which is contra the regular classloader behaviour)

Returns:
The class loader


getClassLoaderForPath

public static ClassLoader getClassLoaderForPath(Project p,
                                                Path path,
                                                String loaderId,
                                                boolean reverseLoader,
                                                boolean reuseLoader)
Gets a classloader that loads classes from the classpath defined in the path argument.

Based on the setting of the magic property 'ant.reuse.loader' this will try to reuse the perviously created loader with that id, and of course store it there upon creation.

Parameters:
p - Ant Project where the handled components are living in.
path - Path object to be used as classpath for this classloader
loaderId - identification for this Loader,
reverseLoader - if set to true this new loader will take precedence over it's parent (which is contra the regular classloader behaviour)
reuseLoader - if true reuse the loader if it is found

Returns:
ClassLoader that uses the Path as its classpath.


getClassLoaderForPath

public static ClassLoader getClassLoaderForPath(Project p,
                                                Reference ref)
Convenience overloaded version of getClassLoaderForPath(Project,Reference,boolean).

Assumes the logical 'false' for the reverseLoader.

Parameters:
p - the project
ref - the reference

Returns:
The class loader


getClassLoaderForPath

public static ClassLoader getClassLoaderForPath(Project p,
                                                Reference ref,
                                                boolean reverseLoader)
Convenience overloaded version of getClassLoaderForPath(Project,Path,String,boolean).

Delegates to the other one after extracting the referenced Path from the Project This checks also that the passed Reference is pointing to a Path all right.

Parameters:
p - current ant project
ref - Reference to Path structure
reverseLoader - if set to true this new loader will take precedence over it's parent (which is contra the regular classloader behaviour)

Returns:
The class loader


getDelegate

public static ClasspathUtils.Delegate getDelegate(ProjectComponent component)
Obtains a delegate that helps out with classic classpath configuration.

Parameters:
component - your projectComponent that needs the assistence

Returns:
the helper, delegate.

See Also:
ClasspathUtils.Delegate


getUniqueClassLoaderForPath

public static ClassLoader getUniqueClassLoaderForPath(Project p,
                                                      Path path,
                                                      boolean reverseLoader)
Gets a fresh, different, not used before classloader that uses the passed path as it's classpath.

This method completely ignores the ant.reuse.loader magic property and should be used with caution.

Parameters:
p - Ant Project where the handled components are living in.
path - the classpath for this loader
reverseLoader - if set to true this new loader will take precedence over it's parent (which is contra the regular classloader behaviour)

Returns:
The fresh, different, not used before class loader.


newInstance

public static Object newInstance(String className,
                                 ClassLoader userDefinedLoader)
Creates a fresh object instance of the specified classname.

This uses the userDefinedLoader to load the specified class, and then makes an instance using the default no-argument constructor

Parameters:
className - the full qualified class name to load.
userDefinedLoader - the classloader to use.

Returns:
The fresh object instance


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