CtClass objects.
* A CtClass object must be obtained from this object.
* If get() is called on this object,
* it searches various sources represented by ClassPath
* to find a class file and then it creates a CtClass object
* representing that class file. The created object is returned to the
* caller.
*
* Memory consumption memo: * *
ClassPool objects hold all the CtClasses
* that have been created so that the consistency among modified classes
* can be guaranteed. Thus if a large number of CtClasses
* are processed, the ClassPool will consume a huge amount
* of memory. To avoid this, a ClassPool object
* should be recreated, for example, every hundred classes processed.
* Note that getDefault() is a singleton factory.
* Otherwise, detach() in CtClass should be used
* to avoid huge memory consumption.
*
*
ClassPool hierarchy:
*
*
ClassPools can make a parent-child hierarchy as
* java.lang.ClassLoaders. If a ClassPool has
* a parent pool, get() first asks the parent pool to find
* a class file. Only if the parent could not find the class file,
* get() searches the ClassPaths of
* the child ClassPool. This search order is reversed if
* ClassPath.childFirstLookup is true.
*
* @see javassist.CtClass
* @see javassist.ClassPath
*/
public class ClassPool {
/**
* Determines the search order.
*
*
If this field is true, get() first searches the
* class path associated to this ClassPool and then
* the class path associated with the parent ClassPool.
* Otherwise, the class path associated with the parent is searched
* first.
*
*
The default value is false.
*/
public boolean childFirstLookup = false;
protected ClassPoolTail source;
protected ClassPool parent;
protected Hashtable classes; // should be synchronous
/**
* Table of registered cflow variables.
*/
private Hashtable cflow = null; // should be synchronous.
private static final int INIT_HASH_SIZE = 191;
/**
* Creates a root class pool. No parent class pool is specified.
*/
public ClassPool() {
this(null);
}
/**
* Creates a class pool.
*
* @param parent the parent of this class pool. If this is a root
* class pool, this parameter must be null.
* @see javassist.ClassPool#getDefault()
*/
public ClassPool(ClassPool parent) {
this.classes = new Hashtable(INIT_HASH_SIZE);
this.source = new ClassPoolTail();
this.parent = parent;
if (parent == null) {
CtClass[] pt = CtClass.primitiveTypes;
for (int i = 0; i < pt.length; ++i)
classes.put(pt[i].getName(), pt[i]);
}
this.cflow = null;
}
/**
* Returns the default class pool.
* The returned object is always identical since this method is
* a singleton factory.
*
*
The default class pool searches the system search path,
* which usually includes the platform library, extension
* libraries, and the search path specified by the
* -classpath option or the CLASSPATH
* environment variable.
*
*
When this method is called for the first time, the default * class pool is created with the following code snippet: * *
ClassPool cp = new ClassPool();
* cp.appendSystemPath();
* If the default class pool cannot find any class files,
* try ClassClassPath and LoaderClassPath.
*
* @see ClassClassPath
* @see LoaderClassPath
*/
public static synchronized ClassPool getDefault() {
if (defaultPool == null) {
defaultPool = new ClassPool(null);
defaultPool.appendSystemPath();
}
return defaultPool;
}
private static ClassPool defaultPool = null;
/**
* Provide a hook so that subclasses can do their own
* caching of classes.
*
* @see #cacheCtClass(String,CtClass)
* @see #removeCached(String)
*/
protected CtClass getCached(String classname) {
return (CtClass)classes.get(classname);
}
/**
* Provides a hook so that subclasses can do their own
* caching of classes.
*
* @see #getCached(String)
* @see #removeCached(String,CtClass)
*/
protected void cacheCtClass(String classname, CtClass c) {
classes.put(classname, c);
}
/**
* Provide a hook so that subclasses can do their own
* caching of classes.
*
* @see #getCached(String)
* @see #cacheCtClass(String,CtClass)
*/
protected CtClass removeCached(String classname) {
return (CtClass)classes.remove(classname);
}
/**
* Returns the class search path.
*/
public String toString() {
return source.toString();
}
/**
* Records a name that never exists.
* For example, a package name can be recorded by this method.
* This would improve execution performance
* since get() does not search the class path at all
* if the given name is an invalid name recorded by this method.
* Note that searching the class path takes relatively long time.
*
* @param name a class name (separeted by dot).
*/
public void recordInvalidClassName(String name) {
source.recordInvalidClassName(name);
}
/**
* Records the $cflow variable for the field specified
* by cname and fname.
*
* @param name variable name
* @param cname class name
* @param fname field name
*/
void recordCflow(String name, String cname, String fname) {
if (cflow == null)
cflow = new Hashtable();
cflow.put(name, new Object[] { cname, fname });
}
/**
* Undocumented method. Do not use; internal-use only.
*
* @param name the name of $cflow variable
*/
public Object[] lookupCflow(String name) {
if (cflow == null)
cflow = new Hashtable();
return (Object[])cflow.get(name);
}
/**
* Reads a class file and constructs a CtClass
* object with a new name.
* This method is useful if you want to generate a new class as a copy
* of another class (except the class name). For example,
*
*
* getAndRename("Point", "Pair")
*
*
* returns a CtClass object representing Pair
* class. The definition of Pair is the same as that of
* Point class except the class name since Pair
* is defined by reading Point.class.
*
* @param orgName the original (fully-qualified) class name
* @param newName the new class name
*/
public CtClass getAndRename(String orgName, String newName)
throws NotFoundException
{
CtClass clazz = get0(orgName, false);
if (clazz == null)
throw new NotFoundException(orgName);
if (clazz instanceof CtClassType)
((CtClassType)clazz).setClassPool(this);
clazz.setName(newName); // indirectly calls
// classNameChanged() in this class
return clazz;
}
/*
* This method is invoked by CtClassType.setName(). It removes a
* CtClass object from the hash table and inserts it with the new
* name. Don't delegate to the parent.
*/
synchronized void classNameChanged(String oldname, CtClass clazz) {
CtClass c = (CtClass)getCached(oldname);
if (c == clazz) // must check this equation.
removeCached(oldname); // see getAndRename().
String newName = clazz.getName();
checkNotFrozen(newName);
cacheCtClass(newName, clazz);
}
/**
* Reads a class file from the source and returns a reference
* to the CtClass
* object representing that class file. If that class file has been
* already read, this method returns a reference to the
* CtClass created when that class file was read at the
* first time.
*
* If classname ends with "[]", then this method
* returns a CtClass object for that array type.
*
*
To obtain an inner class, use "$" instead of "." for separating
* the enclosing class name and the inner class name.
*
* @param classname a fully-qualified class name.
*/
public CtClass get(String classname) throws NotFoundException {
CtClass clazz;
if (classname == null)
clazz = null;
else
clazz = get0(classname, true);
if (clazz == null)
throw new NotFoundException(classname);
else {
clazz.incGetCounter();
return clazz;
}
}
/**
* @param useCache false if the cached CtClass must be ignored.
* @param searchParent false if the parent class pool is not searched.
* @return null if the class could not be found.
*/
protected synchronized CtClass get0(String classname, boolean useCache)
throws NotFoundException
{
CtClass clazz = null;
if (useCache) {
clazz = getCached(classname);
if (clazz != null)
return clazz;
}
if (!childFirstLookup && parent != null) {
clazz = parent.get0(classname, useCache);
if (clazz != null)
return clazz;
}
clazz = createCtClass(classname, useCache);
if (clazz != null) {
if (useCache)
cacheCtClass(classname, clazz);
return clazz;
}
if (childFirstLookup && parent != null)
clazz = parent.get0(classname, useCache);
return clazz;
}
/**
* Creates a CtClass object representing the specified class.
* It first examines whether or not the corresponding class
* file exists. If yes, it creates a CtClass object.
*
* @return null if the class file could not be found.
*/
protected CtClass createCtClass(String classname, boolean useCache) {
if (classname.endsWith("[]")) {
String base = classname.substring(0, classname.indexOf('['));
if ((!useCache || getCached(base) == null) && find(base) == null)
return null;
else
return new CtArray(classname, this);
}
else
if (find(classname) == null)
return null;
else
return new CtClassType(classname, this);
}
/**
* Searches the class path to obtain the URL of the class file
* specified by classname. It is also used to determine whether
* the class file exists.
*
* @param classname a fully-qualified class name.
* @return null if the class file could not be found.
* @see CtClass#getURL()
*/
public URL find(String classname) {
return source.find(classname);
}
/*
* Is invoked by CtClassType.setName() and methods in this class.
* This method throws an exception if the class is already frozen or
* if this class pool cannot edit the class since it is in a parent
* class pool.
*/
void checkNotFrozen(String classname) throws RuntimeException {
CtClass clazz = getCached(classname);
if (clazz == null) {
if (!childFirstLookup && parent != null) {
try {
clazz = parent.get0(classname, true);
}
catch (NotFoundException e) {}
if (clazz != null)
throw new RuntimeException(classname
+ " is in a parent ClassPool. Use the parent.");
}
}
else
if (clazz.isFrozen())
throw new RuntimeException(classname
+ ": frozen class (cannot edit)");
}
/* for CtClassType.getClassFile2(). Don't delegate to the parent.
*/
InputStream openClassfile(String classname) throws NotFoundException {
return source.openClassfile(classname);
}
void writeClassfile(String classname, OutputStream out)
throws NotFoundException, IOException, CannotCompileException
{
source.writeClassfile(classname, out);
}
/**
* Reads class files from the source and returns an array of
* CtClass
* objects representing those class files.
*
*
If an element of classnames ends with "[]",
* then this method
* returns a CtClass object for that array type.
*
* @param classnames an array of fully-qualified class name.
*/
public CtClass[] get(String[] classnames) throws NotFoundException {
if (classnames == null)
return new CtClass[0];
int num = classnames.length;
CtClass[] result = new CtClass[num];
for (int i = 0; i < num; ++i)
result[i] = get(classnames[i]);
return result;
}
/**
* Reads a class file and obtains a compile-time method.
*
* @param classname the class name
* @param methodname the method name
* @see CtClass#getDeclaredMethod(String)
*/
public CtMethod getMethod(String classname, String methodname)
throws NotFoundException
{
CtClass c = get(classname);
return c.getDeclaredMethod(methodname);
}
/**
* Creates a new class (or interface) from the given class file.
* If there already exists a class with the same name, the new class
* overwrites that previous class.
*
*
This method is used for creating a CtClass object
* directly from a class file. The qualified class name is obtained
* from the class file; you do not have to explicitly give the name.
*
* @param classfile class file.
* @throws RuntimeException if there is a frozen class with the
* the same name.
* @see javassist.ByteArrayClassPath
*/
public CtClass makeClass(InputStream classfile)
throws IOException, RuntimeException {
classfile = new BufferedInputStream(classfile);
CtClass clazz = new CtClassType(classfile, this);
clazz.checkModify();
String classname = clazz.getName();
checkNotFrozen(classname);
cacheCtClass(classname, clazz);
return clazz;
}
/**
* Creates a new public class.
* If there already exists a class with the same name, the new class
* overwrites that previous class.
*
* @param classname a fully-qualified class name.
* @throws RuntimeException if the existing class is frozen.
*/
public CtClass makeClass(String classname) throws RuntimeException {
return makeClass(classname, null);
}
/**
* Creates a new public class.
* If there already exists a class/interface with the same name,
* the new class overwrites that previous class.
*
* @param classname a fully-qualified class name.
* @param superclass the super class.
* @throws RuntimeException if the existing class is frozen.
*/
public synchronized CtClass makeClass(String classname, CtClass superclass)
throws RuntimeException
{
checkNotFrozen(classname);
CtClass clazz = new CtNewClass(classname, this, false, superclass);
cacheCtClass(classname, clazz);
return clazz;
}
/**
* Creates a new nested class.
* This method is called by CtClassType.makeNestedClass().
*
* @param classname a fully-qualified class name.
* @return the nested class.
*/
synchronized CtClass makeNestedClass(String classname) {
checkNotFrozen(classname);
CtClass clazz = new CtNewNestedClass(classname, this, false, null);
cacheCtClass(classname, clazz);
return clazz;
}
/**
* Creates a new public interface.
* If there already exists a class/interface with the same name,
* the new interface overwrites that previous one.
*
* @param name a fully-qualified interface name.
* @throws RuntimeException if the existing interface is frozen.
*/
public CtClass makeInterface(String name) throws RuntimeException {
return makeInterface(name, null);
}
/**
* Creates a new public interface.
* If there already exists a class/interface with the same name,
* the new interface overwrites that previous one.
*
* @param name a fully-qualified interface name.
* @param superclass the super interface.
* @throws RuntimeException if the existing interface is frozen.
*/
public synchronized CtClass makeInterface(String name, CtClass superclass)
throws RuntimeException
{
checkNotFrozen(name);
CtClass clazz = new CtNewClass(name, this, true, superclass);
cacheCtClass(name, clazz);
return clazz;
}
/**
* Appends the system search path to the end of the
* search path. The system search path
* usually includes the platform library, extension
* libraries, and the search path specified by the
* -classpath option or the CLASSPATH
* environment variable.
*
* @return the appended class path.
*/
public ClassPath appendSystemPath() {
return source.appendSystemPath();
}
/**
* Insert a ClassPath object at the head of the
* search path.
*
* @return the inserted class path.
* @see javassist.ClassPath
* @see javassist.URLClassPath
* @see javassist.ByteArrayClassPath
*/
public ClassPath insertClassPath(ClassPath cp) {
return source.insertClassPath(cp);
}
/**
* Appends a ClassPath object to the end of the
* search path.
*
* @return the appended class path.
* @see javassist.ClassPath
* @see javassist.URLClassPath
* @see javassist.ByteArrayClassPath
*/
public ClassPath appendClassPath(ClassPath cp) {
return source.appendClassPath(cp);
}
/**
* Inserts a directory or a jar (or zip) file at the head of the
* search path.
*
* @param pathname the path name of the directory or jar file.
* It must not end with a path separator ("/").
* @return the inserted class path.
* @throws NotFoundException if the jar file is not found.
*/
public ClassPath insertClassPath(String pathname)
throws NotFoundException
{
return source.insertClassPath(pathname);
}
/**
* Appends a directory or a jar (or zip) file to the end of the
* search path.
*
* @param pathname the path name of the directory or jar file.
* It must not end with a path separator ("/").
* @return the appended class path.
* @throws NotFoundException if the jar file is not found.
*/
public ClassPath appendClassPath(String pathname)
throws NotFoundException
{
return source.appendClassPath(pathname);
}
/**
* Detatches the ClassPath object from the search path.
* The detached ClassPath object cannot be added
* to the pathagain.
*/
public void removeClassPath(ClassPath cp) {
source.removeClassPath(cp);
}
/**
* Appends directories and jar files for search.
*
*
The elements of the given path list must be separated by colons
* in Unix or semi-colons in Windows.
*
* @param pathlist a (semi)colon-separated list of
* the path names of directories and jar files.
* The directory name must not end with a path
* separator ("/").
* @throws NotFoundException if a jar file is not found.
*/
public void appendPathList(String pathlist) throws NotFoundException {
char sep = File.pathSeparatorChar;
int i = 0;
for (;;) {
int j = pathlist.indexOf(sep, i);
if (j < 0) {
appendClassPath(pathlist.substring(i));
break;
}
else {
appendClassPath(pathlist.substring(i, j));
i = j + 1;
}
}
}
/**
* Converts the given class to a java.lang.Class object.
* Once this method is called, further modifications are not
* allowed any more.
* To load the class, this method uses the context class loader
* of the current thread. If the program is running on some application
* server, the context class loader might be inappropriate to load the
* class.
*
*
This method is provided for convenience. If you need more
* complex functionality, you should write your own class loader.
*
* @see #toClass(CtClass, java.lang.ClassLoader)
*/
public Class toClass(CtClass clazz) throws CannotCompileException {
return toClass(clazz, Thread.currentThread().getContextClassLoader());
}
/**
* Converts the class to a java.lang.Class object.
* Once this method is called, further modifications are not allowed
* any more.
*
*
The class file represented by the given CtClass is
* loaded by the given class loader to construct a
* java.lang.Class object. Since a private method
* on the class loader is invoked through the reflection API,
* the caller must have permissions to do that.
*
*
This method is provided for convenience. If you need more * complex functionality, you should write your own class loader. * * @param loader the class loader used to load this class. */ public Class toClass(CtClass ct, ClassLoader loader) throws CannotCompileException { try { byte[] b = ct.toBytecode(); Class cl = Class.forName("java.lang.ClassLoader"); java.lang.reflect.Method method = cl.getDeclaredMethod("defineClass", new Class[] { String.class, byte[].class, int.class, int.class }); method.setAccessible(true); Object[] args = new Object[] { ct.getName(), b, new Integer(0), new Integer(b.length)}; Class clazz = (Class)method.invoke(loader, args); method.setAccessible(false); return clazz; } catch (RuntimeException e) { throw e; } catch (java.lang.reflect.InvocationTargetException e) { throw new CannotCompileException(e.getTargetException()); } catch (Exception e) { throw new CannotCompileException(e); } } }