htmlform.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.component.html;

import javax.faces.component.ActionSource;
import javax.faces.component.UIForm;
import javax.faces.context.FacesContext;
import javax.faces.el.MethodBinding;
import javax.faces.el.ValueBinding;
import javax.faces.event.ActionEvent;
import javax.faces.event.ActionListener;
import javax.faces.event.FacesEvent;
import javax.faces.event.PhaseId;

import org.springframework.util.Assert;

import de.mindmatters.faces.application.ViewBuilder;
import de.mindmatters.faces.el.ConstantMethodBinding;

/**
 * Represents an HTML form element. <strong>HtmlForm</strong> implements
 * {@link ActionSource} - therefore it is possible to define an action and an
 * action listener attribute. Methodbindings declared as action listener will be
 * invoked on <em>every</em> form submit <em>before</em> action listeners of
 * any nested {@link javax.faces.component.UICommand} will be executed.
 * Futhermore this form supports stateless action listeners as direct children
 * and the immediate attribute.
 * 
 * <p>
 * <strong>HtmlForm</strong> supports the <code>"method"</code> attribute.
 * Supported methods are 'POST' (default method) and 'GET'. 'GET' is
 * <strong>only</strong> supported if an appropriate {@link ViewBuilder} is
 * configured as {@link javax.faces.application.ViewHandler}.
 * </p>
 * 
 * <p>
 * By default, the rendererType property must be set to
 * <code>"de.mindmatters.faces.Form"</code>. This value can be changed by
 * calling the setRendererType() method.
 * </p>
 * 
 * @author Andreas Kuhrwahl
 */
public class HtmlForm extends javax.faces.component.html.HtmlForm implements
        ActionSource {

    /**
     * {@link MethodBinding} that delegates to an internal {@link ValueBinding}.
     * 
     * @author Andreas Kuhrwahl
     * 
     */
    private class ValueBindingToMethodBinding extends MethodBinding {

        /** The internal {@link ValueBinding}. */
        private final ValueBinding vb;

        /**
         * Creates the {@link MethodBinding}.
         * 
         * @param vb
         *            the internal {@link ValueBinding}
         */
        public ValueBindingToMethodBinding(final ValueBinding vb) {
            super();
            this.vb = vb;
        }

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

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

    }

    /** The standard renderer type for this component. */
    public static final String RENDERER_TYPE = "de.mindmatters.faces.Form";

    /** The standard component type for this component. */
    public static final String COMPONENT_TYPE = "de.mindmatters.faces.HtmlForm";

    /** The standard component type for this component. */
    public static final String COMPONENT_FAMILY = UIForm.COMPONENT_FAMILY;

    /**
     * The {@link MethodBinding} that, when invoked, yields the literal outcome
     * value.
     */
    private MethodBinding action;

    /** The immediate flag. */
    private Boolean immediate;

    /** The transient flag. */
    private Boolean isTransient;

    /** The method of this form (supports 'POST' and 'GET'). */
    private String method;

    /** The action listener {@link MethodBinding}. */
    private MethodBinding actionListener;

    /**
     * The standard constructor.
     */
    public HtmlForm() {
        super();
        setRendererType(RENDERER_TYPE);
        forceClientIdGeneration();
    }

    /**
     * Forces the generation of the client id.
     */
    private void forceClientIdGeneration() {
        FacesContext context = getFacesContext();
        if (context.getViewRoot() != null) {
            Assert.notNull(this.getClientId(getFacesContext()));
        }
    }

    /**
     * {@inheritDoc}
     */
    public MethodBinding getAction() {
        if (this.action != null) {
            return this.action;
        }
        ValueBinding vb = getValueBinding("action");
        if (vb != null) {
            return new ValueBindingToMethodBinding(vb);
        } else {
            return null;
        }
    }

    /**
     * {@inheritDoc}
     */
    public void setAction(final MethodBinding action) {
        Assert.isInstanceOf(ConstantMethodBinding.class, action);
        this.action = action;
    }

    /**
     * {@inheritDoc}
     */
    public MethodBinding getActionListener() {
        return this.actionListener;
    }

    /**
     * {@inheritDoc}
     */
    public void setActionListener(final MethodBinding actionListener) {
        this.actionListener = actionListener;
    }

    /**
     * {@inheritDoc}
     */
    public void addActionListener(final ActionListener listener) {
        addFacesListener(listener);
    }

    /**
     * {@inheritDoc}
     */
    public ActionListener[] getActionListeners() {
        return (ActionListener[]) getFacesListeners(ActionListener.class);
    }

    /**
     * {@inheritDoc}
     */
    public void removeActionListener(final ActionListener listener) {
        removeFacesListener(listener);
    }

    /**
     * {@inheritDoc}
     */
    public void setImmediate(final boolean immediate) {
        this.immediate = Boolean.valueOf(immediate);
    }

    /**
     * {@inheritDoc}
     */
    public boolean isImmediate() {
        if (this.immediate != null) {
            return this.immediate.booleanValue();
        }
        ValueBinding vb = getValueBinding("immediate");
        Boolean v = Boolean.FALSE;
        if (vb != null) {
            v = (Boolean) vb.getValue(getFacesContext());
        }
        return v.booleanValue();
    }

    /**
     * Returns the method of this form - supports 'POST' or 'GET'.
     * 
     * @return The method of this form or <code>null</code> if not set
     */
    public String getMethod() {
        if (this.method != null) {
            return this.method;
        }
        String currentMethod = null;
        ValueBinding vb = getValueBinding("method");
        if (vb != null) {
            currentMethod = (String) vb.getValue(getFacesContext());
        }
        if (currentMethod == null || !currentMethod.equalsIgnoreCase("get")) {
            currentMethod = "post";
        }
        setMethod(currentMethod);
        return getMethod();
    }

    /**
     * Sets the method of this form - supports 'POST' or 'GET'.
     * 
     * @param method
     *            The method 'POST' or 'GET'
     */
    public void setMethod(final String method) {
        this.method = method;
        if (this.method != null) {
            this.method = this.method.toLowerCase();
        }
    }

    /**
     * {@inheritDoc}
     */
    public Object saveState(final FacesContext context) {
        Object[] values = new Object[6];
        values[0] = super.saveState(context);
        values[1] = saveAttachedState(context, this.action);
        values[2] = saveAttachedState(context, this.actionListener);
        values[3] = this.immediate;
        values[4] = this.method;
        return values;
    }

    /**
     * {@inheritDoc}
     */
    public void restoreState(final FacesContext context, final Object state) {
        Object[] values = (Object[]) state;
        super.restoreState(context, values[0]);
        this.action = (MethodBinding) restoreAttachedState(context, values[1]);
        this.actionListener = (MethodBinding) restoreAttachedState(context,
                values[2]);
        this.immediate = (Boolean) values[3];
        this.method = (String) values[4];
    }

    /**
     * {@inheritDoc}
     */
    public void queueEvent(final FacesEvent e) {
        if (e instanceof ActionEvent) {
            if (isImmediate()) {
                e.setPhaseId(PhaseId.APPLY_REQUEST_VALUES);
            } else {
                e.setPhaseId(PhaseId.INVOKE_APPLICATION);
            }
        }
        super.queueEvent(e);
    }

    /**
     * {@inheritDoc}
     */
    public void broadcast(final FacesEvent event) {
        super.broadcast(event);
        if (event instanceof ActionEvent) {
            MethodBinding mb = getActionListener();
            if (mb != null) {
                mb.invoke(getFacesContext(), new Object[] { event });
            }
        }
    }

    /**
     * {@inheritDoc}
     */
    public final void setId(final String id) {
        super.setId(id);
        forceClientIdGeneration();
    }

    /**
     * {@inheritDoc}
     */
    public final boolean isTransient() {
        if (this.isTransient == null) {
            boolean calculatedTransient = false;
            if ("get".equals(getMethod())) {
                calculatedTransient = getFacesContext().getApplication()
                        .getViewHandler() instanceof ViewBuilder;
            }
            return calculatedTransient;
        } else {
            return this.isTransient.booleanValue();
        }
    }

    /**
     * {@inheritDoc}
     */
    public final void setTransient(final boolean transientFlag) {
        if (transientFlag) {
            Assert
                    .isInstanceOf(
                            ViewBuilder.class,
                            getFacesContext().getApplication().getViewHandler(),
                            "Method 'get' is not allowed with the applied ViewHandler. Use a ViewBuilder instance instead.");
        }
        this.isTransient = Boolean.valueOf(transientFlag);
    }

}