methodutils.java

osworkflow修改版本

        Object[] args = {arg};
        return invokeExactMethod(object, methodName, args);

    }


    /**
     * <p>Invoke a method whose parameter types match exactly the object
     * types.</p>
     *
     * <p> This uses reflection to invoke the method obtained from a call to
     * {@link #getAccessibleMethod}.</p>
     *
     * @param object invoke method on this object
     * @param methodName get method with this name
     * @param args use these arguments - treat null as empty array
     *
     * @throws NoSuchMethodException if there is no such accessible method
     * @throws InvocationTargetException wraps an exception thrown by the
     *  method invoked
     * @throws IllegalAccessException if the requested method is not accessible
     *  via reflection
     */
    public static Object invokeExactMethod(
            Object object,
            String methodName,
            Object[] args)
            throws
            NoSuchMethodException,
            IllegalAccessException,
            InvocationTargetException {
        if (args == null) {
            args = emptyObjectArray;
        }
        int arguments = args.length;
        Class parameterTypes [] = new Class[arguments];
        for (int i = 0; i < arguments; i++) {
            parameterTypes[i] = args[i].getClass();
        }
        return invokeExactMethod(object, methodName, args, parameterTypes);

    }


    /**
     * <p>Invoke a method whose parameter types match exactly the parameter
     * types given.</p>
     *
     * <p>This uses reflection to invoke the method obtained from a call to
     * {@link #getAccessibleMethod}.</p>
     *
     * @param object invoke method on this object
     * @param methodName get method with this name
     * @param args use these arguments - treat null as empty array
     * @param parameterTypes match these parameters - treat null as empty array
     *
     * @throws NoSuchMethodException if there is no such accessible method
     * @throws InvocationTargetException wraps an exception thrown by the
     *  method invoked
     * @throws IllegalAccessException if the requested method is not accessible
     *  via reflection
     */
    public static Object invokeExactMethod(
            Object object,
            String methodName,
            Object[] args,
            Class[] parameterTypes)
            throws
            NoSuchMethodException,
            IllegalAccessException,
            InvocationTargetException {

        if (args == null) {
            args = emptyObjectArray;
        }

        if (parameterTypes == null) {
            parameterTypes = emptyClassArray;
        }

        Method method = getAccessibleMethod(
                object.getClass(),
                methodName,
                parameterTypes);
        if (method == null)
            throw new NoSuchMethodException("No such accessible method: " +
                    methodName + "() on object: " + object.getClass().getName());
        return method.invoke(object, args);

    }


    /**
     * <p>Return an accessible method (that is, one that can be invoked via
     * reflection) with given name and a single parameter.  If no such method
     * can be found, return <code>null</code>.
     * Basically, a convenience wrapper that constructs a <code>Class</code>
     * array for you.</p>
     *
     * @param clazz get method from this class
     * @param methodName get method with this name
     * @param parameterType taking this type of parameter
     */
    public static Method getAccessibleMethod(
            Class clazz,
            String methodName,
            Class parameterType) {

        Class[] parameterTypes = {parameterType};
        return getAccessibleMethod(clazz, methodName, parameterTypes);

    }


    /**
     * <p>Return an accessible method (that is, one that can be invoked via
     * reflection) with given name and parameters.  If no such method
     * can be found, return <code>null</code>.
     * This is just a convenient wrapper for
     * {@link #getAccessibleMethod(Method method)}.</p>
     *
     * @param clazz get method from this class
     * @param methodName get method with this name
     * @param parameterTypes with these parameters types
     */
    public static Method getAccessibleMethod(
            Class clazz,
            String methodName,
            Class[] parameterTypes) {

        try {
            MethodDescriptor md = new MethodDescriptor(clazz, methodName, parameterTypes, true);
            // Check the cache first
            Method method = (Method)cache.get(md);
            if (method != null) {
                return method;
            }

            method =  getAccessibleMethod
                    (clazz.getMethod(methodName, parameterTypes));
            cache.put(md, method);
            return method;
        } catch (NoSuchMethodException e) {
            return (null);
        }

    }


    /**
     * <p>Return an accessible method (that is, one that can be invoked via
     * reflection) that implements the specified Method.  If no such method
     * can be found, return <code>null</code>.</p>
     *
     * @param method The method that we wish to call
     */
    public static Method getAccessibleMethod(Method method) {

        // Make sure we have a method to check
        if (method == null) {
            return (null);
        }

        // If the requested method is not public we cannot call it
        if (!Modifier.isPublic(method.getModifiers())) {
            return (null);
        }

        // If the declaring class is public, we are done
        Class clazz = method.getDeclaringClass();
        if (Modifier.isPublic(clazz.getModifiers())) {
            return (method);
        }

        // Check the implemented interfaces and subinterfaces
        method =
                getAccessibleMethodFromInterfaceNest(clazz,
                        method.getName(),
                        method.getParameterTypes());
        return (method);

    }


    // -------------------------------------------------------- Private Methods

    /**
     * <p>Return an accessible method (that is, one that can be invoked via
     * reflection) that implements the specified method, by scanning through
     * all implemented interfaces and subinterfaces.  If no such method
     * can be found, return <code>null</code>.</p>
     *
     * <p> There isn't any good reason why this method must be private.
     * It is because there doesn't seem any reason why other classes should
     * call this rather than the higher level methods.</p>
     *
     * @param clazz Parent class for the interfaces to be checked
     * @param methodName Method name of the method we wish to call
     * @param parameterTypes The parameter type signatures
     */
    private static Method getAccessibleMethodFromInterfaceNest
            (Class clazz, String methodName, Class parameterTypes[]) {

        Method method = null;

        // Search up the superclass chain
        for (; clazz != null; clazz = clazz.getSuperclass()) {

            // Check the implemented interfaces of the parent class
            Class interfaces[] = clazz.getInterfaces();
            for (int i = 0; i < interfaces.length; i++) {

                // Is this interface public?
                if (!Modifier.isPublic(interfaces[i].getModifiers()))
                    continue;

                // Does the method exist on this interface?
                try {
                    method = interfaces[i].getDeclaredMethod(methodName,
                            parameterTypes);
                } catch (NoSuchMethodException e) {
                    ;
                }
                if (method != null)
                    break;

                // Recursively check our parent interfaces
                method =
                        getAccessibleMethodFromInterfaceNest(interfaces[i],
                                methodName,
                                parameterTypes);
                if (method != null)
                    break;

            }

        }

        // If we found a method return it
        if (method != null)
            return (method);

        // We did not find anything
        return (null);

    }

    /**
     * <p>Find an accessible method that matches the given name and has compatible parameters.
     * Compatible parameters mean that every method parameter is assignable from
     * the given parameters.
     * In other words, it finds a method with the given name
     * that will take the parameters given.<p>
     *
     * <p>This method is slightly undeterminstic since it loops
     * through methods names and return the first matching method.</p>
     *
     * <p>This method is used by
     * {@link
     * #invokeMethod(Object object,String methodName,Object [] args,Class[] parameterTypes)}.
     *
     * <p>This method can match primitive parameter by passing in wrapper classes.
     * For example, a <code>Boolean</code> will match a primitive <code>boolean</code>
     * parameter.
     *
     * @param clazz find method in this class
     * @param methodName find method with this name
     * @param parameterTypes find method with compatible parameters
     */
    public static Method getMatchingAccessibleMethod(
                                                Class clazz,
                                                String methodName,
                                                Class[] parameterTypes) {
        MethodDescriptor md = new MethodDescriptor(clazz, methodName, parameterTypes, false);

        // see if we can find the method directly
        // most of the time this works and it's much faster
        try {
            // Check the cache first
            Method method = (Method)cache.get(md);