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Modified the hack to initialize a class such that the side effect of having to create a valid object is not there anymore. 

PR: 4107


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@270780 13f79535-47bb-0310-9956-ffa450edef68
master
Magesh Umasankar 23 years ago
parent
e0155259cd
commit
3fe197c6e7
2 changed files with 108 additions and 87 deletions
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  1. +2
    -0
      WHATSNEW
  2. +106
    -87
      src/main/org/apache/tools/ant/AntClassLoader.java

+ 2
- 0
WHATSNEW View File

@@ -31,6 +31,8 @@ Changes that could break older environments:

Fixed bugs:
-----------
* Fixed bug where <java> used to sometimes invoke class constructors twice.

* Fixed bug with 4NT shell support

* Fixed bug where ant would not perform ftp without remotedir being


+ 106
- 87
src/main/org/apache/tools/ant/AntClassLoader.java View File

@@ -54,6 +54,7 @@

package org.apache.tools.ant;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.util.Enumeration;
@@ -78,6 +79,7 @@ import org.apache.tools.ant.types.Path;
*
* @author <a href="mailto:conor@cortexebusiness.com.au">Conor MacNeill</a>
* @author <a href="mailto:Jesse.Glick@netbeans.com">Jesse Glick</a>
* @author <a href="mailto:umagesh@apache.org">Magesh Umasankar</a>
*/
public class AntClassLoader extends ClassLoader implements BuildListener {

@@ -155,8 +157,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
URL url = null;
while ((pathElementsIndex < pathComponents.size()) &&
(url == null)) {
try {
File pathComponent
try {
File pathComponent
= (File)pathComponents.elementAt(pathElementsIndex);
url = getResourceURL(pathComponent, this.resourceName);
pathElementsIndex++;
@@ -173,20 +175,20 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* The size of buffers to be used in this classloader.
*/
private final static int BUFFER_SIZE = 8192;
/**
* The components of the classpath that the classloader searches for classes
*/
Vector pathComponents = new Vector();
/**
* The project to which this class loader belongs.
*/
private Project project;

/**
* Indicates whether the parent class loader should be
* consulted before trying to load with this class loader.
* Indicates whether the parent class loader should be
* consulted before trying to load with this class loader.
*/
private boolean parentFirst = true;

@@ -195,20 +197,20 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* regardless of whether the parent class loader is being searched first or not.
*/
private Vector systemPackages = new Vector();
/**
* These are the package roots that are to be loaded by this class loader
* regardless of whether the parent class loader is being searched first or not.
*/
private Vector loaderPackages = new Vector();
/**
* This flag indicates that the classloader will ignore the base
* classloader if it can't find a class.
*/
private boolean ignoreBase = false;

/**
/**
* The parent class loader, if one is given or can be determined
*/
private ClassLoader parent = null;
@@ -216,14 +218,14 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
/**
* A hashtable of zip files opened by the classloader
*/
private Hashtable zipFiles = new Hashtable();
private Hashtable zipFiles = new Hashtable();
/**
* The context loader saved when setting the thread's current context loader.
*/
private ClassLoader savedContextLoader = null;
private boolean isContextLoaderSaved = false;
private static Method getProtectionDomain = null;
private static Method defineClassProtectionDomain = null;
private static Method getContextClassLoader = null;
@@ -234,7 +236,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
Class protectionDomain = Class.forName("java.security.ProtectionDomain");
Class[] args = new Class[] {String.class, byte[].class, Integer.TYPE, Integer.TYPE, protectionDomain};
defineClassProtectionDomain = ClassLoader.class.getDeclaredMethod("defineClass", args);
getContextClassLoader = Thread.class.getMethod("getContextClassLoader", new Class[0]);
args = new Class[] {ClassLoader.class};
setContextClassLoader = Thread.class.getMethod("setContextClassLoader", args);
@@ -242,7 +244,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
catch (Exception e) {}
}

/**
* Create a classloader for the given project using the classpath given.
*
@@ -268,7 +270,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
}
}
/**
* Create a classloader for the given project using the classpath given.
*
@@ -279,7 +281,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* @param parentFirst if true indicates that the parent classloader should be consulted
* before trying to load the a class through this loader.
*/
public AntClassLoader(ClassLoader parent, Project project, Path classpath,
public AntClassLoader(ClassLoader parent, Project project, Path classpath,
boolean parentFirst) {
this(project, classpath);
if (parent != null) {
@@ -322,7 +324,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
project = null;
this.parentFirst = parentFirst;
}
/**
* Log a message through the project object if one has been provided.
*
@@ -348,7 +350,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
if (getContextClassLoader != null && setContextClassLoader != null) {
try {
savedContextLoader
savedContextLoader
= (ClassLoader)getContextClassLoader.invoke(Thread.currentThread(), new Object[0]);
Object[] args = new Object[] {this};
setContextClassLoader.invoke(Thread.currentThread(), args);
@@ -363,7 +365,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
}
}
/**
* Reset the current thread's context loader to its original value
*/
@@ -385,19 +387,19 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
}
}
/**
* Add an element to the classpath to be searched
*
*/
public void addPathElement(String pathElement) throws BuildException {
File pathComponent
File pathComponent
= project != null ? project.resolveFile(pathElement)
: new File(pathElement);
pathComponents.addElement(pathComponent);
}
/**
* The CLASSPATH this classloader will consult.
*/
@@ -426,23 +428,40 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}

/**
* Force initialization of a class in a JDK 1.1 compatible, albeit hacky
* way
* Force initialization of a class in a JDK 1.1 compatible, albeit hacky
* way
*/
public static void initializeClass(Class theClass) {
// ***HACK*** We try to create an instance to force the VM to run the
// class' static initializer. We don't care if the instance can't
// be created - we are just interested in the side effect.
try {
theClass.newInstance();
}
catch (Throwable t) {
//ignore - our work is done
// ***HACK*** We ask the VM to create an instance
// by voluntarily providing illegal arguments to force
// the VM to run the class' static initializer, while
// at the same time not running a valid constructor.

final Constructor[] cons = theClass.getDeclaredConstructors();
//At least one constructor is guaranteed to be there, but check anyway.
if (cons != null) {
if (cons.length > 0 && cons[0] != null) {
final String[] strs = new String[1024];
try {
cons[0].newInstance(strs);
// Expecting an exception to be thrown by this call:
// IllegalArgumentException: wrong number of Arguments
} catch (Throwable t) {
// Ignore - we are interested only in the side
// effect - that of getting the static initializers
// invoked. As we do not want to call a valid
// constructor to get this side effect, an
// attempt is made to call a hopefully
// invalid constructor - come on, nobody
// would have a constructor that takes in
// 1024 String arguments ;-)
}
}
}
}
/**
* Add a package root to the list of packages which must be loaded on the
* Add a package root to the list of packages which must be loaded on the
* parent loader.
*
* All subpackages are also included.
@@ -452,7 +471,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
public void addSystemPackageRoot(String packageRoot) {
systemPackages.addElement(packageRoot + ".");
}
/**
* Add a package root to the list of packages which must be loaded using
* this loader.
@@ -464,7 +483,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
public void addLoaderPackageRoot(String packageRoot) {
loaderPackages.addElement(packageRoot + ".");
}


/**
@@ -475,7 +494,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* classloader.
*
* @param classname the classname to be loaded.
*
*
* @return the required Class object
*
* @throws ClassNotFoundException if the requested class does not exist on
@@ -483,13 +502,13 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
*/
public Class forceLoadClass(String classname) throws ClassNotFoundException {
log("force loading " + classname, Project.MSG_DEBUG);
Class theClass = findLoadedClass(classname);

if (theClass == null) {
theClass = findClass(classname);
}
return theClass;
}

@@ -500,7 +519,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* which have already been loaded on the parent loader.
*
* @param classname the classname to be loaded.
*
*
* @return the required Class object
*
* @throws ClassNotFoundException if the requested class does not exist on
@@ -508,13 +527,13 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
*/
public Class forceLoadSystemClass(String classname) throws ClassNotFoundException {
log("force system loading " + classname, Project.MSG_DEBUG);
Class theClass = findLoadedClass(classname);

if (theClass == null) {
theClass = findBaseClass(classname);
}
return theClass;
}

@@ -557,17 +576,17 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
}
}
if (resourceStream == null) {
log("Couldn't load ResourceStream for " + name,
log("Couldn't load ResourceStream for " + name,
Project.MSG_DEBUG);
}

return resourceStream;
}
/**
* Get a stream to read the requested resource name from this loader.
*
@@ -577,10 +596,10 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* found on the loader's classpath.
*/
private InputStream loadResource(String name) {
// we need to search the components of the path to see if we can find the
// class we want.
// we need to search the components of the path to see if we can find the
// class we want.
InputStream stream = null;
for (Enumeration e = pathComponents.elements(); e.hasMoreElements() && stream == null; ) {
File pathComponent = (File)e.nextElement();
stream = getResourceStream(pathComponent, name);
@@ -615,11 +634,11 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
if (!file.exists()) {
return null;
}
if (file.isDirectory()) {
File resource = new File(file, resourceName);
if (resource.exists()) {
File resource = new File(file, resourceName);
if (resource.exists()) {
return new FileInputStream(resource);
}
}
@@ -628,7 +647,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
ZipFile zipFile = (ZipFile)zipFiles.get(file);
if (zipFile == null) {
zipFile = new ZipFile(file);
zipFiles.put(file, zipFile);
zipFiles.put(file, zipFile);
}
ZipEntry entry = zipFile.getEntry(resourceName);
if (entry != null) {
@@ -637,18 +656,18 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
}
catch (Exception e) {
log("Ignoring Exception " + e.getClass().getName() + ": " + e.getMessage() +
" reading resource " + resourceName + " from " + file, Project.MSG_VERBOSE);
log("Ignoring Exception " + e.getClass().getName() + ": " + e.getMessage() +
" reading resource " + resourceName + " from " + file, Project.MSG_VERBOSE);
}
return null;
return null;
}

private boolean isParentFirst(String resourceName) {
// default to the global setting and then see
// if this class belongs to a package which has been
// designated to use a specific loader first (this one or the parent one)
boolean useParentFirst = parentFirst;
boolean useParentFirst = parentFirst;

for (Enumeration e = systemPackages.elements(); e.hasMoreElements();) {
String packageName = (String)e.nextElement();
@@ -665,19 +684,19 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
break;
}
}
return useParentFirst;
}

/**
* Finds the resource with the given name. A resource is
* Finds the resource with the given name. A resource is
* some data (images, audio, text, etc)
* that can be accessed by class
* code in a way that is independent of the location of the code.
*
* @param name the name of the resource for which a stream is required.
*
* @return a URL for reading the resource, or null if the resource
* @return a URL for reading the resource, or null if the resource
* could not be found or the caller
* doesn't have adequate privileges to get the resource.
*/
@@ -690,29 +709,29 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}

if (url != null) {
log("Resource " + name + " loaded from parent loader",
log("Resource " + name + " loaded from parent loader",
Project.MSG_DEBUG);

} else {
// try and load from this loader if the parent either didn't find
// try and load from this loader if the parent either didn't find
// it or wasn't consulted.
for (Enumeration e = pathComponents.elements(); e.hasMoreElements() && url == null; ) {
File pathComponent = (File)e.nextElement();
url = getResourceURL(pathComponent, name);
if (url != null) {
log("Resource " + name
+ " loaded from ant loader",
log("Resource " + name
+ " loaded from ant loader",
Project.MSG_DEBUG);
}
}
}
if (url == null && !isParentFirst(name)) {
// this loader was first but it didn't find it - try the parent
url = (parent == null) ? super.getResource(name) : parent.getResource(name);
if (url != null) {
log("Resource " + name + " loaded from parent loader",
log("Resource " + name + " loaded from parent loader",
Project.MSG_DEBUG);
}
}
@@ -740,12 +759,12 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* Get an inputstream to a given resource in the given file which may
* either be a directory or a zip file.
*
* @param file the file (directory or jar) in which to search for
* @param file the file (directory or jar) in which to search for
* the resource.
* @param resourceName the name of the resource for which a stream
* @param resourceName the name of the resource for which a stream
* is required.
*
* @return a stream to the required resource or null if the
* @return a stream to the required resource or null if the
* resource cannot be found in the given file object
*/
private URL getResourceURL(File file, String resourceName) {
@@ -769,7 +788,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
ZipFile zipFile = (ZipFile)zipFiles.get(file);
if (zipFile == null) {
zipFile = new ZipFile(file);
zipFiles.put(file, zipFile);
zipFiles.put(file, zipFile);
}

ZipEntry entry = zipFile.getEntry(resourceName);
@@ -793,14 +812,14 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
/**
* Load a class with this class loader.
*
* This method will load a class.
* This method will load a class.
*
* This class attempts to load the class firstly using the parent class loader. For
* JDK 1.1 compatability, this uses the findSystemClass method.
*
* @param classname the name of the class to be loaded.
* @param resolve true if all classes upon which this class depends are to be loaded.
*
*
* @return the required Class object
*
* @throws ClassNotFoundException if the requested class does not exist on
@@ -836,7 +855,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
log("Class " + classname + " loaded from parent loader", Project.MSG_DEBUG);
}
}
if (resolve) {
resolveClass(theClass);
}
@@ -867,16 +886,16 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* @throws IOException if there is a problem reading the class from the
* stream.
*/
private Class getClassFromStream(InputStream stream, String classname)
private Class getClassFromStream(InputStream stream, String classname)
throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int bytesRead = -1;
byte[] buffer = new byte[BUFFER_SIZE];
while ((bytesRead = stream.read(buffer, 0, BUFFER_SIZE)) != -1) {
baos.write(buffer, 0, bytesRead);
}
byte[] classData = baos.toByteArray();

// Simply put:
@@ -905,7 +924,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
}
else {
return defineClass(classname, classData, 0, classData.length);
return defineClass(classname, classData, 0, classData.length);
}
}

@@ -913,7 +932,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* Search for and load a class on the classpath of this class loader.
*
* @param name the classname to be loaded.
*
*
* @return the required Class object
*
* @throws ClassNotFoundException if the requested class does not exist on
@@ -930,8 +949,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
* Find a class on the given classpath.
*/
private Class findClassInComponents(String name) throws ClassNotFoundException {
// we need to search the components of the path to see if we can find the
// class we want.
// we need to search the components of the path to see if we can find the
// class we want.
InputStream stream = null;
String classFilename = getClassFilename(name);
try {
@@ -948,7 +967,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
log("Exception reading component " + pathComponent , Project.MSG_VERBOSE);
}
}
throw new ClassNotFoundException(name);
}
finally {
@@ -987,7 +1006,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
}
zipFiles = new Hashtable();
}
public void buildStarted(BuildEvent event) {
}



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