| /* Statement.java |
| Copyright (C) 2004, 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.beans; |
| |
| import java.lang.reflect.Array; |
| import java.lang.reflect.Constructor; |
| import java.lang.reflect.Method; |
| |
| /** |
| * <p>A Statement captures the execution of an object method. It stores |
| * the object, the method to call, and the arguments to the method and |
| * provides the ability to execute the method on the object, using the |
| * provided arguments.</p> |
| * |
| * @author Jerry Quinn (jlquinn@optonline.net) |
| * @author Robert Schuster (robertschuster@fsfe.org) |
| * @since 1.4 |
| */ |
| public class Statement |
| { |
| private Object target; |
| private String methodName; |
| private Object[] arguments; |
| |
| /** |
| * One or the other of these will get a value after execute is |
| * called once, but not both. |
| */ |
| private transient Method method; |
| private transient Constructor ctor; |
| |
| /** |
| * <p>Constructs a statement representing the invocation of |
| * object.methodName(arg[0], arg[1], ...);</p> |
| * |
| * <p>If the argument array is null it is replaced with an |
| * array of zero length.</p> |
| * |
| * @param target The object to invoke the method on. |
| * @param methodName The object method to invoke. |
| * @param arguments An array of arguments to pass to the method. |
| */ |
| public Statement(Object target, String methodName, Object[] arguments) |
| { |
| this.target = target; |
| this.methodName = methodName; |
| this.arguments = (arguments != null) ? arguments : new Object[0]; |
| } |
| |
| /** |
| * Execute the statement. |
| * |
| * <p>Finds the specified method in the target object and calls it with |
| * the arguments given in the constructor.</p> |
| * |
| * <p>The most specific method according to the JLS(15.11) is used when |
| * there are multiple methods with the same name.</p> |
| * |
| * <p>Execute performs some special handling for methods and |
| * parameters: |
| * <ul> |
| * <li>Static methods can be executed by providing the class as a |
| * target.</li> |
| * |
| * <li>The method name new is reserved to call the constructor |
| * new() will construct an object and return it. Not useful unless |
| * an expression :-)</li> |
| * |
| * <li>If the target is an array, get and set as defined in |
| * java.util.List are recognized as valid methods and mapped to the |
| * methods of the same name in java.lang.reflect.Array.</li> |
| * |
| * <li>The native datatype wrappers Boolean, Byte, Character, Double, |
| * Float, Integer, Long, and Short will map to methods that have |
| * native datatypes as parameters, in the same way as Method.invoke. |
| * However, these wrappers also select methods that actually take |
| * the wrapper type as an argument.</li> |
| * </ul> |
| * </p> |
| * |
| * <p>The Sun spec doesn't deal with overloading between int and |
| * Integer carefully. If there are two methods, one that takes an |
| * Integer and the other taking an int, the method chosen is not |
| * specified, and can depend on the order in which the methods are |
| * declared in the source file.</p> |
| * |
| * @throws Exception if an exception occurs while locating or |
| * invoking the method. |
| */ |
| public void execute() throws Exception |
| { |
| doExecute(); |
| } |
| |
| private static Class wrappers[] = |
| { |
| Boolean.class, Byte.class, Character.class, Double.class, Float.class, |
| Integer.class, Long.class, Short.class |
| }; |
| |
| private static Class natives[] = |
| { |
| Boolean.TYPE, Byte.TYPE, Character.TYPE, Double.TYPE, Float.TYPE, |
| Integer.TYPE, Long.TYPE, Short.TYPE |
| }; |
| |
| /** Given a wrapper class, return the native class for it. |
| * <p>For example, if <code>c</code> is <code>Integer</code>, |
| * <code>Integer.TYPE</code> is returned.</p> |
| */ |
| private Class unwrap(Class c) |
| { |
| for (int i = 0; i < wrappers.length; i++) |
| if (c == wrappers[i]) |
| return natives[i]; |
| return null; |
| } |
| |
| /** Returns <code>true</code> if all args can be assigned to |
| * <code>params</code>, <code>false</code> otherwise. |
| * |
| * <p>Arrays are guaranteed to be the same length.</p> |
| */ |
| private boolean compatible(Class[] params, Class[] args) |
| { |
| for (int i = 0; i < params.length; i++) |
| { |
| // Argument types are derived from argument values. If one of them was |
| // null then we cannot deduce its type. However null can be assigned to |
| // any type. |
| if (args[i] == null) |
| continue; |
| |
| // Treat Integer like int if appropriate |
| Class nativeType = unwrap(args[i]); |
| if (nativeType != null && params[i].isPrimitive() |
| && params[i].isAssignableFrom(nativeType)) |
| continue; |
| if (params[i].isAssignableFrom(args[i])) |
| continue; |
| |
| return false; |
| } |
| return true; |
| } |
| |
| /** |
| * Returns <code>true</code> if the method arguments in first are |
| * more specific than the method arguments in second, i.e. all |
| * arguments in <code>first</code> can be assigned to those in |
| * <code>second</code>. |
| * |
| * <p>A method is more specific if all parameters can also be fed to |
| * the less specific method, because, e.g. the less specific method |
| * accepts a base class of the equivalent argument for the more |
| * specific one.</p> |
| * |
| * @param first a <code>Class[]</code> value |
| * @param second a <code>Class[]</code> value |
| * @return a <code>boolean</code> value |
| */ |
| private boolean moreSpecific(Class[] first, Class[] second) |
| { |
| for (int j=0; j < first.length; j++) |
| { |
| if (second[j].isAssignableFrom(first[j])) |
| continue; |
| return false; |
| } |
| return true; |
| } |
| |
| final Object doExecute() throws Exception |
| { |
| Class klazz = (target instanceof Class) |
| ? (Class) target : target.getClass(); |
| Object args[] = (arguments == null) ? new Object[0] : arguments; |
| Class argTypes[] = new Class[args.length]; |
| |
| // Retrieve type or use null if the argument is null. The null argument |
| // type is later used in compatible(). |
| for (int i = 0; i < args.length; i++) |
| argTypes[i] = (args[i] != null) ? args[i].getClass() : null; |
| |
| if (target.getClass().isArray()) |
| { |
| // FIXME: invoke may have to be used. For now, cast to Number |
| // and hope for the best. If caller didn't behave, we go boom |
| // and throw the exception. |
| if (methodName.equals("get") && argTypes.length == 1) |
| return Array.get(target, ((Number)args[0]).intValue()); |
| if (methodName.equals("set") && argTypes.length == 2) |
| { |
| Object obj = Array.get(target, ((Number)args[0]).intValue()); |
| Array.set(target, ((Number)args[0]).intValue(), args[1]); |
| return obj; |
| } |
| throw new NoSuchMethodException("No matching method for statement " + toString()); |
| } |
| |
| // If we already cached the method, just use it. |
| if (method != null) |
| return method.invoke(target, args); |
| else if (ctor != null) |
| return ctor.newInstance(args); |
| |
| // Find a matching method to call. JDK seems to go through all |
| // this to find the method to call. |
| |
| // if method name or length don't match, skip |
| // Need to go through each arg |
| // If arg is wrapper - check if method arg is matchable builtin |
| // or same type or super |
| // - check that method arg is same or super |
| |
| if (methodName.equals("new") && target instanceof Class) |
| { |
| Constructor ctors[] = klazz.getConstructors(); |
| for (int i = 0; i < ctors.length; i++) |
| { |
| // Skip methods with wrong number of args. |
| Class ptypes[] = ctors[i].getParameterTypes(); |
| |
| if (ptypes.length != args.length) |
| continue; |
| |
| // Check if method matches |
| if (!compatible(ptypes, argTypes)) |
| continue; |
| |
| // Use method[i] if it is more specific. |
| // FIXME: should this check both directions and throw if |
| // neither is more specific? |
| if (ctor == null) |
| { |
| ctor = ctors[i]; |
| continue; |
| } |
| Class mptypes[] = ctor.getParameterTypes(); |
| if (moreSpecific(ptypes, mptypes)) |
| ctor = ctors[i]; |
| } |
| if (ctor == null) |
| throw new InstantiationException("No matching constructor for statement " + toString()); |
| return ctor.newInstance(args); |
| } |
| |
| Method methods[] = klazz.getMethods(); |
| |
| for (int i = 0; i < methods.length; i++) |
| { |
| // Skip methods with wrong name or number of args. |
| if (!methods[i].getName().equals(methodName)) |
| continue; |
| Class ptypes[] = methods[i].getParameterTypes(); |
| if (ptypes.length != args.length) |
| continue; |
| |
| // Check if method matches |
| if (!compatible(ptypes, argTypes)) |
| continue; |
| |
| // Use method[i] if it is more specific. |
| // FIXME: should this check both directions and throw if |
| // neither is more specific? |
| if (method == null) |
| { |
| method = methods[i]; |
| continue; |
| } |
| Class mptypes[] = method.getParameterTypes(); |
| if (moreSpecific(ptypes, mptypes)) |
| method = methods[i]; |
| } |
| if (method == null) |
| throw new NoSuchMethodException("No matching method for statement " + toString()); |
| |
| // If we were calling Class.forName(String) we intercept and call the |
| // forName-variant that allows a ClassLoader argument. We take the |
| // system classloader (aka application classloader) here to make sure |
| // that application defined classes can be resolved. If we would not |
| // do that the Class.forName implementation would use the class loader |
| // of java.beans.Statement which is <null> and cannot resolve application |
| // defined classes. |
| if (method.equals( |
| Class.class.getMethod("forName", new Class[] { String.class }))) |
| return Class.forName( |
| (String) args[0], true, ClassLoader.getSystemClassLoader()); |
| |
| try { |
| return method.invoke(target, args); |
| } catch(IllegalArgumentException iae){ |
| System.err.println("method: " + method); |
| |
| for(int i=0;i<args.length;i++){ |
| System.err.println("args[" + i + "]: " + args[i]); |
| } |
| throw iae; |
| } |
| } |
| |
| |
| |
| /** Return the statement arguments. */ |
| public Object[] getArguments() { return arguments; } |
| |
| /** Return the statement method name. */ |
| public String getMethodName() { return methodName; } |
| |
| /** Return the statement object. */ |
| public Object getTarget() { return target; } |
| |
| /** Return a string representation. */ |
| public String toString() |
| { |
| StringBuffer result = new StringBuffer(); |
| |
| String targetName = target.getClass().getName(); |
| if ( targetName.startsWith("java")) |
| { |
| targetName = targetName.substring(targetName.lastIndexOf('.') + 1); |
| } |
| |
| result.append(targetName); |
| result.append("."); |
| result.append(methodName); |
| result.append("("); |
| |
| String sep = ""; |
| for (int i = 0; i < arguments.length; i++) |
| { |
| result.append(sep); |
| result.append( |
| ( arguments[i] == null ) ? "null" : |
| ( arguments[i] instanceof String ) ? "\"" + arguments[i] + "\"" : |
| arguments[i].getClass().getName()); |
| sep = ", "; |
| } |
| result.append(")"); |
| |
| return result.toString(); |
| } |
| |
| } |