InputRadioButtonTag.java

/* Copyright 2005-2006 Tim Fennell
 *
 * 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 net.sourceforge.stripes.tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTag;

/**
 * <p>Generates {@literal <input type="radio" value="foo"/>} HTML tags based on the attribute set
 * on the tag and the state of the form. Since a single radio button widget on a HTML page can
 * have only a single value, the value tag attribute must be a Scalar object.  The value will be
 * converted to a String using the Stripes formatting system (with appropriate defaults), or by
 * calling toString if an appropriate Formatter does not exist. Similarly since radio button sets
 * can have only a single selected value at a time the checked attribute of the tag must also be
 * a scalar value.</p>
 *
 * <p>Radio buttons perform automatic (re-)population of state.  They prefer, in order, the value
 * in the HttpServletRequest, the value in the ActionBean and lastly the value set using
 * checked="" on the page.  If the value of the current radio button matches the checked value
 * from the preferred source then the attribute checked="checked" will be written in the HTML
 * tag.</p>
 *
 * <p>The tag may include a body and if present the body is converted to a String and overrides the
 * <b>checked</b> tag attribute.</p>
 *
 * @author Tim Fennell
 */
public class InputRadioButtonTag extends InputTagSupport implements BodyTag {
    private String checked;
    private Object value;

    /** Basic constructor that sets the input tag's type attribute to "radio". */
    public InputRadioButtonTag() {
        getAttributes().put("type", "radio");
    }

    /**
     * Sets the value amongst a set of radio buttons, that should be "checked" by default.
     * @param checked the default value for a set of radio buttons
     */
    public void setChecked(String checked) { this.checked = checked; }

    /** Returns the value set with setChecked(). */
    public String getChecked() { return this.checked; }

    /** Sets the Object value of this individual checkbox. */
    public void setValue(Object value) { this.value = value; }

    /** Returns the value set with setValue() */
    public Object getValue() { return this.value; }

    /**
     * Sets the input tag type to "radio".
     * @return EVAL_BODY_BUFFERED in all cases.
     */
    @Override
    public int doStartInputTag() throws JspException {
        return EVAL_BODY_BUFFERED;
    }

    /** Does nothing. */
    public void doInitBody() throws JspException { }

    /**
     * Does nothing.
     * @return SKIP_BODY in all cases.
     */
    public int doAfterBody() throws JspException {
        return SKIP_BODY;
    }

    /**
     * Returns the body of the tag if it is present and not empty, otherwise returns
     * the value of the 'checked' attribute.
     */
    @Override
    public Object getValueOnPage() {
        String body         = getBodyContentAsString();
        if (body != null) {
            return body;
        }
        else {
            return this.checked;
        }
    }

    /**
     * Determines the state of the set of radio buttons and then writes the radio button to the
     * output stream with checked="checked" or not as appropriate.
     *
     * @return EVAL_PAGE in all cases.
     * @throws JspException if the parent form tag cannot be found, or output cannot be written.
     */
    @Override
    public int doEndInputTag() throws JspException {
        Object actualChecked = getSingleOverrideValue();

        // Now if the "checked" value matches this tags value, check it!
        if (actualChecked != null && this.value != null
                && format(this.value, false).equals(format(actualChecked, false))) {
            getAttributes().put("checked", "checked");
        }

        getAttributes().put("value", format(this.value));

        writeSingletonTag(getPageContext().getOut(), "input");

        // Restore the state of the tag to before we mucked with it
        getAttributes().remove("checked");
        getAttributes().remove("value");

        return EVAL_PAGE;
    }
}