methodbindingpropertyeditor.java

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/*
 * Copyright 2002-2004 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.mindmatters.faces.el;

import java.beans.PropertyEditorSupport;

import javax.faces.FactoryFinder;
import javax.faces.application.Application;
import javax.faces.application.ApplicationFactory;
import javax.faces.context.FacesContext;
import javax.faces.el.MethodBinding;
import javax.faces.el.ReferenceSyntaxException;
import javax.faces.event.ActionEvent;

import org.springframework.util.Assert;

import de.mindmatters.faces.FacesUtils;

/**
 * Editor for {@link MethodBinding}, to directly populate a MethodBinding
 * property.
 * 
 * @author Andreas Kuhrwahl
 * 
 */
public class MethodBindingPropertyEditor extends PropertyEditorSupport {

    /**
     * MethodBinding that delegates to a binding created by the Application of
     * the underlying JSF implementation.
     * 
     * @author Andreas Kuhrwahl
     * 
     */
    private class DelegatingMethodBinding extends MethodBinding {

        /** The reference. */
        private final String ref;

        /** The internal used method binding. */
        private MethodBinding methodBinding;

        /**
         * Creates a MethodBinding based upon the given reference.
         * 
         * @param ref
         *            the reference
         */
        public DelegatingMethodBinding(final String ref) {
            super();
            this.ref = ref;
        }

        /**
         * @return the internal used MethodBinding
         */
        private MethodBinding getMethodBinding() {
            if (this.methodBinding == null) {
                try {
                    this.methodBinding = MethodBindingPropertyEditor.this.application
                            .createMethodBinding(this.ref, null);
                    Assert.isTrue(String.class.equals(this.methodBinding
                            .getType(FacesContext.getCurrentInstance())));
                } catch (Exception ex) {
                    try {
                        this.methodBinding = MethodBindingPropertyEditor.this.application
                                .createMethodBinding(this.ref,
                                        new Class[] { ActionEvent.class });
                    } catch (Exception ex2) {
                        throw new ReferenceSyntaxException(ex2);
                    }
                    if (!Void.class.equals(this.methodBinding
                            .getType(FacesContext.getCurrentInstance()))) {
                        throw new ReferenceSyntaxException("Method binding '"
                                + this.methodBinding.getExpressionString()
                                + "' not supported.");
                    }
                }
            }
            return this.methodBinding;
        }

        /**
         * {@inheritDoc}
         */
        public String getExpressionString() {
            return getMethodBinding().getExpressionString();
        }

        /**
         * {@inheritDoc}
         */
        public Class getType(final FacesContext context) {
            return getMethodBinding().getType(context);
        }

        /**
         * {@inheritDoc}
         */
        public Object invoke(final FacesContext context, final Object[] params) {
            return getMethodBinding().invoke(context, params);
        }

    }

    /** The Application of the underlying JSF implementation. */
    private final Application application;

    /**
     * Standard constructor.
     */
    public MethodBindingPropertyEditor() {
        this(((ApplicationFactory) FactoryFinder
                .getFactory(FactoryFinder.APPLICATION_FACTORY))
                .getApplication());
    }

    /**
     * Creates a MethodBindingPropertyEditor with the given {@link Application}.
     * 
     * @param application
     *            the Application of the underlying JSF implementation
     */
    public MethodBindingPropertyEditor(final Application application) {
        super();
        Assert.notNull(application);
        this.application = application;
    }

    /**
     * {@inheritDoc}
     */
    public void setAsText(final String text) {
        try {
            if (FacesUtils.isValueReference(text)) {
                setValue(new DelegatingMethodBinding(text));
            } else {
                setValue(new ConstantMethodBinding(text));
            }
        } catch (Exception ex) {
            throw new IllegalArgumentException(ex.getMessage());
        }
    }

    /**
     * {@inheritDoc}
     */
    public String getAsText() {
        MethodBinding mb = (MethodBinding) getValue();
        String result = "";
        if (mb != null) {
            result = mb.getExpressionString();
        }
        return result;
    }

}