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BeanShell is a small, free, embeddable Java source interpreter with object scripting language features,
written in Java. BeanShell dynamically executes standard Java syntax and extends it with common scripting
conveniences such as loose types, commands, and method closures like those in Perl and JavaScript.
The newest version!
/*****************************************************************************
* *
* This file is part of the BeanShell Java Scripting distribution. *
* Documentation and updates may be found at http://www.beanshell.org/ *
* *
* Sun Public License Notice: *
* *
* The contents of this file are subject to the Sun Public License Version *
* 1.0 (the "License"); you may not use this file except in compliance with *
* the License. A copy of the License is available at http://www.sun.com *
* *
* The Original Code is BeanShell. The Initial Developer of the Original *
* Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright *
* (C) 2000. All Rights Reserved. *
* *
* GNU Public License Notice: *
* *
* Alternatively, the contents of this file may be used under the terms of *
* the GNU Lesser General Public License (the "LGPL"), in which case the *
* provisions of LGPL are applicable instead of those above. If you wish to *
* allow use of your version of this file only under the terms of the LGPL *
* and not to allow others to use your version of this file under the SPL, *
* indicate your decision by deleting the provisions above and replace *
* them with the notice and other provisions required by the LGPL. If you *
* do not delete the provisions above, a recipient may use your version of *
* this file under either the SPL or the LGPL. *
* *
* Patrick Niemeyer ([email protected]) *
* Author of Learning Java, O'Reilly & Associates *
* http://www.pat.net/~pat/ *
* *
*****************************************************************************/
package bsh;
import java.lang.reflect.*;
import java.io.*;
import java.util.Vector;
/**
All of the reflection API code lies here. It is in the form
of static utilities. Maybe this belongs in LHS.java or a generic object
wrapper class.
*/
/*
Note: This class is messy. The method and field resolution need to be
rewritten. Various methods in here catch NoSuchMethod or NoSuchField
exceptions during their searches. These should be rewritten to avoid
having to catch the exceptions. Method lookups are now cached at a high
level so they are less important, however the logic is messy.
*/
class Reflect
{
/**
Invoke method on arbitrary object.
invocation may be static (through the object instance) or dynamic.
Object may be a bsh scripted object (This type).
*/
public static Object invokeObjectMethod(
Object object, String methodName, Object[] args,
Interpreter interpreter, CallStack callstack, SimpleNode callerInfo )
throws ReflectError, EvalError, InvocationTargetException
{
// Bsh scripted object
if ( object instanceof This && !This.isExposedThisMethod( methodName) )
return ((This)object).invokeMethod(
methodName, args, interpreter, callstack, callerInfo,
false/*delcaredOnly*/ );
else
// Java object
{
// find the java method
try {
BshClassManager bcm =
interpreter == null ? null : interpreter.getClassManager();
Class clas = object.getClass();
Method method = resolveExpectedJavaMethod(
bcm, clas, object, methodName, args, false );
return invokeOnMethod( method, object, args );
} catch ( UtilEvalError e ) {
throw e.toEvalError( callerInfo, callstack );
}
}
}
/**
Invoke a method known to be static.
No object instance is needed and there is no possibility of the
method being a bsh scripted method.
*/
public static Object invokeStaticMethod(
BshClassManager bcm, Class clas, String methodName, Object [] args )
throws ReflectError, UtilEvalError, InvocationTargetException
{
Interpreter.debug("invoke static Method");
Method method = resolveExpectedJavaMethod(
bcm, clas, null, methodName, args, true );
return invokeOnMethod( method, null, args );
}
/**
Invoke the Java method on the specified object.
@param args may be null
*/
static Object invokeOnMethod(
Method method, Object object, Object[] args )
throws ReflectError, InvocationTargetException
{
if ( args == null )
args = new Object[0];
if ( Interpreter.DEBUG )
{
Interpreter.debug("Invoking method (entry): "
+method+" with args:" );
for(int i=0; i
This method performs Java method caching internally.
@param onlyStatic
The method located must be static, the object param may be null.
@return the method or null if no matching method was found.
@deprecated
*/
/*
Note: object is only used here for precondition... get rid of it?
*/
protected static Method resolveJavaMethod(
BshClassManager bcm, Class clas, Object object,
String name, Object[] args, boolean onlyStatic )
throws UtilEvalError
{
// Why is object in the args?
if ( object == Primitive.NULL )
throw new UtilTargetError( new NullPointerException(
"Attempt to invoke method " +name+" on null value" ) );
Class [] types = Types.getTypes(args);
return resolveJavaMethod( bcm, clas, name, types, onlyStatic );
}
protected static Method resolveJavaMethod(
BshClassManager bcm, Class clas, String name,
Class [] types, boolean onlyStatic )
throws UtilEvalError
{
if ( clas == null )
throw new InterpreterError("null class");
Method method = null;
if ( bcm == null )
Interpreter.debug("resolveJavaMethod UNOPTIMIZED lookup");
else {
method = bcm.getResolvedMethod( clas, name, types, onlyStatic );
if ( method != null )
return method;
}
if ( Interpreter.DEBUG )
Interpreter.debug( "Searching for method: "+
StringUtil.methodString(name, types)
+ " in '" + clas.getName() + "'" );
/*
First try for an accessible version of the exact match.
This first lookup seems redundant with below, but is apparently
needed. This whole thing is messy.
try {
method = findAccessibleMethod( clas, name, types );
} catch ( SecurityException e ) { }
*/
// If not found and there are arguments to match -
// Look for an overloaded / standard Java assignable match
// (First find the method, then find accessible version of it)
// if ( method == null && types.length > 0 )
{
Method [] methods = clas.getMethods(); // public methods
method = findMostSpecificMethod( name, types, methods );
// If found a method, make sure we have accessible version of it
if ( method != null )
{
try {
method = findAccessibleMethod(
clas, method.getName(), method.getParameterTypes() );
} catch ( SecurityException e ) { /*leave null*/ }
if ( Interpreter.DEBUG && method == null )
Interpreter.debug(
"had a method, but it wasn't accessible");
}
}
if ( method != null
&& onlyStatic && !Modifier.isStatic( method.getModifiers() )
)
throw new UtilEvalError(
"Cannot reach instance method: "
+ StringUtil.methodString(
method.getName(), method.getParameterTypes() )
+ " from static context: "+ clas.getName() );
// Succeeded. Cache the resolved method.
if ( method != null && bcm != null )
bcm.cacheResolvedMethod( clas, types, method );
return method;
}
/**
Locate a version of the method with the exact signature specified
that is accessible via a public interface or through a public
superclass or - if accessibility is on - through any interface or
superclass.
In the normal (non-accessible) case this still solves the problem that
arises when a package private class or private inner class implements a
public interface or derives from a public type.
@param onlyStatic the method located must be static.
@return null on not found
*/
static Method findAccessibleMethod(
Class clas, String name, Class [] types )
throws UtilEvalError
{
Method meth = null;
Method inaccessibleVersion = null;
Vector classQ = new Vector();
classQ.addElement( clas );
Method found = null;
while ( classQ.size() > 0 )
{
Class c = (Class)classQ.firstElement();
classQ.removeElementAt(0);
// Is this it?
// Is the class public or can we use accessibility?
if ( Modifier.isPublic( c.getModifiers() )
|| ( Capabilities.haveAccessibility() ) )
{
try
{
meth = c.getDeclaredMethod( name, types );
// Is the method public or are we in accessibility mode?
if ( ( Modifier.isPublic( meth.getModifiers() )
&& Modifier.isPublic( c.getModifiers() ) )
|| ( Capabilities.haveAccessibility()
&& ReflectManager.RMSetAccessible( meth ) ) )
{
found = meth; // Yes, it is.
break;
}
else
{
// Found at least one matching method but couldn't use
inaccessibleVersion = meth;
}
} catch ( NoSuchMethodException e ) {
// ignore and move on
}
}
// No, it is not.
// Is this a class?
if ( !c.isInterface() ) {
Class superclass = c.getSuperclass();
if ( superclass != null )
classQ.addElement((Object)superclass);
}
// search all of its interfaces breadth first
Class [] intfs = c.getInterfaces();
for( int i=0; i< intfs.length; i++ )
classQ.addElement((Object)intfs[i]);
}
if ( found != null )
return found;
if ( inaccessibleVersion != null )
throw new UtilEvalError("Found non-public method: "
+inaccessibleVersion
+". Use setAccessibility(true) to enable access to "
+" private and protected members of classes." );
return null;
}
/**
Primary object constructor
This method is simpler than those that must resolve general method
invocation because constructors are not inherited.
*/
static Object constructObject( Class clas, Object[] args )
throws ReflectError, InvocationTargetException
{
if ( clas.isInterface() )
throw new ReflectError(
"Can't create instance of an interface: "+clas);
Object obj = null;
Class[] types = Types.getTypes(args);
Constructor con = null;
/*
Find an appropriate constructor.
use declared here to see package and private as well
(there are no inherited constructors to worry about)
*/
Constructor[] constructors = clas.getDeclaredConstructors();
if ( Interpreter.DEBUG )
Interpreter.debug("Looking for most specific constructor: "+clas);
con = findMostSpecificConstructor(types, constructors);
if ( con == null )
{
if ( types.length == 0 )
throw new ReflectError(
"Can't find default constructor for: "+clas);
else
throw new ReflectError(
"Can't find constructor: "
+ StringUtil.methodString( clas.getName(), types )
+" in class: "+ clas.getName() );
}
if ( !Modifier.isPublic( con.getModifiers() )
&& Capabilities.haveAccessibility() )
try {
ReflectManager.RMSetAccessible( con );
} catch ( UtilEvalError e ) { /*ignore*/ }
args=Primitive.unwrap( args );
try {
obj = con.newInstance( args );
} catch(InstantiationException e) {
throw new ReflectError("the class is abstract ");
} catch(IllegalAccessException e) {
throw new ReflectError(
"We don't have permission to create an instance."
+"Use setAccessibility(true) to enable access." );
} catch(IllegalArgumentException e) {
throw new ReflectError("the number of arguments was wrong");
}
if (obj == null)
throw new ReflectError("couldn't construct the object");
return obj;
}
/**
Implement JLS 15.11.2 for method resolution
@return null on no match
*/
static Method findMostSpecificMethod(
String name, Class[] idealMatch, Method[] methods )
{
// Pull out the method signatures with matching names
Vector sigs = new Vector();
Vector meths = new Vector();
for(int i=0; i