umagesh 02/01/18 07:26:50
Modified: . WHATSNEW
src/main/org/apache/tools/ant AntClassLoader.java
Log:
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
Revision Changes Path
1.198 +2 -0 jakarta-ant/WHATSNEW
Index: WHATSNEW
===================================================================
RCS file: /home/cvs/jakarta-ant/WHATSNEW,v
retrieving revision 1.197
retrieving revision 1.198
diff -u -r1.197 -r1.198
--- WHATSNEW 10 Jan 2002 16:17:11 -0000 1.197
+++ WHATSNEW 18 Jan 2002 15:26:49 -0000 1.198
@@ -31,6 +31,8 @@
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
1.38 +106 -87
jakarta-ant/src/main/org/apache/tools/ant/AntClassLoader.java
Index: AntClassLoader.java
===================================================================
RCS file:
/home/cvs/jakarta-ant/src/main/org/apache/tools/ant/AntClassLoader.java,v
retrieving revision 1.37
retrieving revision 1.38
diff -u -r1.37 -r1.38
--- AntClassLoader.java 10 Jan 2002 11:21:18 -0000 1.37
+++ AntClassLoader.java 18 Jan 2002 15:26:50 -0000 1.38
@@ -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 @@
*
* @author <a href="mailto:[EMAIL PROTECTED]">Conor MacNeill</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Jesse Glick</a>
+ * @author <a href="mailto:[EMAIL PROTECTED]">Magesh Umasankar</a>
*/
public class AntClassLoader extends ClassLoader implements BuildListener {
@@ -155,8 +157,8 @@
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 @@
* 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 @@
* 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 @@
/**
* 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 @@
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 @@
catch (Exception e) {}
}
-
+
/**
* Create a classloader for the given project using the classpath given.
*
@@ -268,7 +270,7 @@
}
}
}
-
+
/**
* Create a classloader for the given project using the classpath given.
*
@@ -279,7 +281,7 @@
* @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 @@
project = null;
this.parentFirst = parentFirst;
}
-
+
/**
* Log a message through the project object if one has been provided.
*
@@ -348,7 +350,7 @@
}
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 @@
}
}
}
-
+
/**
* Reset the current thread's context loader to its original value
*/
@@ -385,19 +387,19 @@
}
}
}
-
-
+
+
/**
* 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 @@
}
/**
- * 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 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 void addLoaderPackageRoot(String packageRoot) {
loaderPackages.addElement(packageRoot + ".");
}
-
+
/**
@@ -475,7 +494,7 @@
* 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 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 @@
* 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 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 @@
}
}
}
-
+
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 @@
* 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 @@
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 @@
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 @@
}
}
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 @@
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 @@
}
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 @@
* 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 @@
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 @@
/**
* 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 @@
log("Class " + classname + " loaded from parent loader",
Project.MSG_DEBUG);
}
}
-
+
if (resolve) {
resolveClass(theClass);
}
@@ -867,16 +886,16 @@
* @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 @@
}
}
else {
- return defineClass(classname, classData, 0, classData.length);
+ return defineClass(classname, classData, 0, classData.length);
}
}
@@ -913,7 +932,7 @@
* 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 @@
* 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 @@
log("Exception reading component " + pathComponent ,
Project.MSG_VERBOSE);
}
}
-
+
throw new ClassNotFoundException(name);
}
finally {
@@ -987,7 +1006,7 @@
}
zipFiles = new Hashtable();
}
-
+
public void buildStarted(BuildEvent event) {
}
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