package ise.library;
import java.lang.reflect.*;
/**
* a.k.a. The "ObjectMolester" <p>
*
* This class is used to access a method or field of an object no matter what
* the access modifier of the method or field. The syntax for accessing fields
* and methods is out of the ordinary because this class uses reflection to peel
* away protection. <p>
*
* Here is an example of using this to access a private member. <code>resolveName</code>
* is a private method of <code>Class</code>. <pre>
* Class c = Class.class;
* System.out.println(
* PrivilegedAccessor.invokeMethod( c,
* "resolveName",
* "/ise/library/PrivilegedAccessor" ) );
* </pre>
*
* @author Charlie Hubbard (chubbard@iss.net)
* @author Prashant Dhokte (pdhokte@iss.net)
* @author Dale Anson (danson@germane-software.com)
* @version $Revision: 1.5 $
*/
public class PrivilegedAccessor {
/**
* Gets the value of the named field and returns it as an object.
*
* @param instance the object instance
* @param fieldName the name of the field
* @return an object representing the value of
* the field
* @exception IllegalAccessException Description of Exception
* @exception NoSuchFieldException Description of Exception
*/
public static Object getValue(Object instance, String fieldName)
throws IllegalAccessException, NoSuchFieldException {
Field field = getField(instance.getClass(), fieldName);
field.setAccessible(true);
return field.get(instance);
}
/**
* Sets the value of the named field.
*
* @param instance the object instance
* @param fieldName the name of the field
* @param value the value to set for the field
* @exception IllegalAccessException Description of Exception
* @exception NoSuchFieldException Description of Exception
*/
public static void setValue(Object instance, String fieldName, Object value) throws IllegalAccessException, NoSuchFieldException {
Field field = getField(instance.getClass(), fieldName);
field.setAccessible(true);
field.set(instance, value);
}
/**
* Gets the value of the named static field and returns it as an object.
*
* @param fieldName the name of the field
* @param c
* @return an object representing the value of
* the field
* @exception IllegalAccessException Description of Exception
* @exception NoSuchFieldException Description of Exception
*/
public static Object getStaticValue(Class c, String fieldName)
throws IllegalAccessException, NoSuchFieldException {
Field field = getField(c, fieldName);
field.setAccessible(true);
return field.get(null);
}
/**
* Calls a method on the given object instance with the given argument.
*
* @param instance the object instance
* @param methodName the name of the method to invoke
* @param arg the argument to pass to the method
* @return Description of the Returned Value
* @exception NoSuchMethodException Description of Exception
* @exception IllegalAccessException Description of Exception
* @exception InvocationTargetException Description of Exception
* @see
* PrivilegedAccessor#invokeMethod(Object,String,Object[])
*/
public static Object invokeMethod(Object instance, String methodName, Object arg) throws NoSuchMethodException,
IllegalAccessException, InvocationTargetException {
Object[] args = new Object[1];
args[0] = arg;
return invokeMethod(instance, methodName, args);
}
/**
* Calls a method on the given object instance with the given arguments.
*
* @param instance the object instance
* @param methodName the name of the method to invoke
* @param args an array of objects to pass as
* arguments
* @return Description of the Returned Value
* @exception NoSuchMethodException Description of Exception
* @exception IllegalAccessException Description of Exception
* @exception InvocationTargetException Description of Exception
* @see
* PrivilegedAccessor#invokeMethod(Object,String,Object)
*/
public static Object invokeMethod(Object instance, String methodName, Object[] args) throws NoSuchMethodException,
IllegalAccessException, InvocationTargetException {
//Class[] classTypes = getClassArray( args );
//return getMethod( instance, methodName, classTypes ).invoke( instance, args );
if (args == null)
args = new Object[]{};
Class[] classTypes = getClassArray(args);
Method[] methods = instance.getClass().getDeclaredMethods();
boolean found = false;
for (int i = 0; i < methods.length; i++) {
Method method = methods[i];
Class[] paramTypes = method.getParameterTypes();
if (method.getName().equals(methodName) && compare(paramTypes, args)) {
method.setAccessible(true);
return method.invoke(instance, args);
}
}
StringBuffer sb = new StringBuffer();
sb.append("No method named ").append(methodName).append(" found in ").append(instance.getClass().getName()).append(" with parameters (");
for (int x = 0; x < classTypes.length; x++) {
sb.append(classTypes[x].getName());
if (x < classTypes.length - 1)
sb.append(", ");
}
sb.append(")");
throw new NoSuchMethodException(sb.toString());
}
/**
* Converts the object array to an array of Classes.
*
* @param args the object array to convert
* @return a Class array
*/
private static Class[] getClassArray(Object[] args) {
Class[] classTypes = null;
if (args != null) {
classTypes = new Class[args.length];
for (int i = 0; i < args.length; i++) {
if (args[i] != null)
classTypes[i] = args[i].getClass();
}
}
return classTypes;
}
/**
* @param instance the object instance
* @param methodName the
* @param classTypes
* @return The method value
* @exception NoSuchMethodException Description of Exception
*/
public static Method getMethod(Object instance, String methodName, Class[] classTypes) throws NoSuchMethodException {
Method accessMethod = getMethod(instance.getClass(), methodName, classTypes);
accessMethod.setAccessible(true);
return accessMethod;
}
/**
* Return the named field from the given class.
*
* @param thisClass
* @param fieldName
* @return The field value
* @exception NoSuchFieldException Description of Exception
*/
public static Field getField(Class thisClass, String fieldName) throws NoSuchFieldException {
if (thisClass == null)
throw new NoSuchFieldException("Invalid field : " + fieldName);
try {
return thisClass.getDeclaredField(fieldName);
}
catch (NoSuchFieldException e) {
return getField(thisClass.getSuperclass(), fieldName);
}
}
/**
* Return the named method with a method signature matching classTypes from
* the given class.
*
* @param thisClass
* @param methodName
* @param classTypes
* @return The method value
* @exception NoSuchMethodException Description of Exception
*/
public static Method getMethod(Class thisClass, String methodName, Class[] classTypes) throws NoSuchMethodException {
if (thisClass == null)
throw new NoSuchMethodException("Invalid method : " + methodName);
try {
return thisClass.getDeclaredMethod(methodName, classTypes);
}
catch (NoSuchMethodException e) {
return getMethod(thisClass.getSuperclass(), methodName, classTypes);
}
}
/**
* Description of the Method
*
* @param c
* @param args
* @return Description of the Returned Value
*/
private static boolean compare(Class[] c, Object[] args) {
if (c.length != args.length) {
return false;
}
if (c.length == 0)
return true;
for (int i = 0; i < args.length; i++) {
if (!c[i].isInstance(args[i])) {
return false;
}
}
return true;
}
/**
* Creates a new instance of the named class initialized with the given
* arguments.
*
* @param classname the name of the class to
* instantiate.
* @param args the arguments to pass as parameters
* to the constructor of the class.
* @return the instantiated object
* @exception ClassNotFoundException Description of Exception
* @exception InstantiationException Description of Exception
* @exception NoSuchMethodException Description of Exception
* @exception IllegalAccessException Description of Exception
* @exception InvocationTargetException Description of Exception
*/
public static Object getNewInstance(String classname, Object[] args)
throws ClassNotFoundException, InstantiationException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {
if (classname == null)
throw new ClassNotFoundException();
return getNewInstance(Class.forName(classname), args);
}
/**
* Gets the newInstance attribute of the PrivilegedAccessor class
*
* @param c
* @param args
* @return The newInstance value
* @exception ClassNotFoundException Description of Exception
* @exception InstantiationException Description of Exception
* @exception NoSuchMethodException Description of Exception
* @exception IllegalAccessException Description of Exception
* @exception InvocationTargetException Description of Exception
*/
public static Object getNewInstance(Class c, Object[] args)
throws ClassNotFoundException, InstantiationException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {
if (c == null)
throw new ClassNotFoundException();
if (args == null)
args = new Object[]{};
Class[] classTypes = getClassArray(args);
Constructor[] constructors = c.getConstructors();
for (int i = 0; i < constructors.length; i++) {
Constructor constructor = constructors[i];
Class[] paramTypes = constructor.getParameterTypes();
if (compare(paramTypes, args)) {
return constructor.newInstance(args);
}
}
StringBuffer sb = new StringBuffer();
sb.append("No constructor found for ").append(c.getName()).append(" with parameters (");
for (int x = 0; x < classTypes.length; x++) {
sb.append(classTypes[x].getName());
if (x < classTypes.length - 1)
sb.append(", ");
}
sb.append(")");
throw new NoSuchMethodException(sb.toString());
}
}
