optionstag.java

这是一个轻便的j2ee的web应用框架,是一个在多个项目中运用的实际框架,采用struts,hebinate,xml等技术,有丰富的tag,role,navigation,session,dictio

        StringBuffer sb = new StringBuffer();

        // If a collection was specified, use that mode to render options
        if (collection != null) {
            Iterator collIterator = getIterator(collection, null);
            while (collIterator.hasNext()) {

                Object bean = collIterator.next();
                Object value = null;
                Object label = null;

                try {
                    value = PropertyUtils.getProperty(bean, property);
                    if (value == null) {
                        value = "";
                    }
                } catch (IllegalAccessException e) {
                    throw new JspException(
                        messages.getMessage("getter.access", property, collection));
                } catch (InvocationTargetException e) {
                    Throwable t = e.getTargetException();
                    throw new JspException(
                        messages.getMessage("getter.result", property, t.toString()));
                } catch (NoSuchMethodException e) {
                    throw new JspException(
                        messages.getMessage("getter.method", property, collection));
                }

                try {
                    if (labelProperty != null) {
                        label = PropertyUtils.getProperty(bean, labelProperty);
                    } else {
                        label = value;
                    }

                    if (label == null) {
                        label = "";
                    }
                } catch (IllegalAccessException e) {
                    throw new JspException(
                        messages.getMessage("getter.access", labelProperty, collection));
                } catch (InvocationTargetException e) {
                    Throwable t = e.getTargetException();
                    throw new JspException(
                        messages.getMessage("getter.result", labelProperty, t.toString()));
                } catch (NoSuchMethodException e) {
                    throw new JspException(
                        messages.getMessage("getter.method", labelProperty, collection));
                }

                String stringValue = value.toString();
                addOption(sb, stringValue, label.toString(), selectTag.isMatched(stringValue));

            }

        }

        // Otherwise, use the separate iterators mode to render options
        else {

            // Construct iterators for the values and labels collections
            Iterator valuesIterator = getIterator(name, property);
            Iterator labelsIterator = null;
            if ((labelName == null) && (labelProperty == null)) {
                labelsIterator = getIterator(name, property); // Same coll.
            } else {
                labelsIterator = getIterator(labelName, labelProperty);
            }

            // Render the options tags for each element of the values coll.
            while (valuesIterator.hasNext()) {
                Object valueObject = valuesIterator.next();
                if (valueObject == null) {
                    valueObject = "";
                }
                String value = valueObject.toString();
                String label = value;
                if (labelsIterator.hasNext()) {
                    Object labelObject = labelsIterator.next();
                    if (labelObject == null) {
                        labelObject = "";
                    }
                    label = labelObject.toString();
                }
                addOption(sb, value, label, selectTag.isMatched(value));
            }
        }

        // Render this element to our writer
        ResponseUtils.write(pageContext, sb.toString());

        // Evaluate the remainder of this page
        return EVAL_PAGE;

    }

    /**
     * Release any acquired resources.
     */
    public void release() {

        super.release();
        collection = null;
        filter = true;
        labelName = null;
        labelProperty = null;
        name = null;
        property = null;
        style = null;
        styleClass = null;
    }

    // ------------------------------------------------------ Protected Methods

    /**
     * Add an option element to the specified StringBuffer based on the
     * specified parameters.
     *<p>
     * Note that this tag specifically does not support the
     * <code>styleId</code> tag attribute, which causes the HTML
     * <code>id</code> attribute to be emitted.  This is because the HTML
     * specification states that all "id" attributes in a document have to be
     * unique.  This tag will likely generate more than one <code>option</code>
     * element element, but it cannot use the same <code>id</code> value.  It's
     * conceivable some sort of mechanism to supply an array of <code>id</code>
     * values could be devised, but that doesn't seem to be worth the trouble.
     *
     * @param sb StringBuffer accumulating our results
     * @param value Value to be returned to the server for this option
     * @param label Value to be shown to the user for this option
     * @param matched Should this value be marked as selected?
     */
    protected void addOption(StringBuffer sb, String value, String label, boolean matched) {

        sb.append("<option value=\"");
        sb.append(value);
        sb.append("\"");
        if (matched) {
            sb.append(" selected=\"selected\"");
        }
        if (style != null) {
            sb.append(" style=\"");
            sb.append(style);
            sb.append("\"");
        }
        if (styleClass != null) {
            sb.append(" class=\"");
            sb.append(styleClass);
            sb.append("\"");
        }
        sb.append(">");
        if (filter) {
            sb.append(ResponseUtils.filter(label));
        } else {
            sb.append(label);
        }
        sb.append("</option>\r\n");

    }

    /**
     * Return an iterator for the option labels or values, based on our
     * configured properties.
     *
     * @param name Name of the bean attribute (if any)
     * @param property Name of the bean property (if any)
     *
     * @exception JspException if an error occurs
     */
    protected Iterator getIterator(String name, String property) throws JspException {

        // Identify the bean containing our collection
        String beanName = name;
        if (beanName == null) {
            beanName = Constants.BEAN_KEY;
        }

        Object bean = RequestUtils.lookup(pageContext, beanName, null);
        if (bean == null) {
            throw new JspException(messages.getMessage("getter.bean", beanName));
        }

        // Identify the collection itself
        Object collection = bean;
        if (property != null) {
            try {
                collection = PropertyUtils.getProperty(bean, property);
                if (collection == null) {
                    throw new JspException(messages.getMessage("getter.property", property));
                }
            } catch (IllegalAccessException e) {
                throw new JspException(messages.getMessage("getter.access", property, name));
            } catch (InvocationTargetException e) {
                Throwable t = e.getTargetException();
                throw new JspException(
                    messages.getMessage("getter.result", property, t.toString()));
            } catch (NoSuchMethodException e) {
                throw new JspException(messages.getMessage("getter.method", property, name));
            }
        }

        // Construct and return an appropriate iterator
        if (collection.getClass().isArray()) {
            collection = Arrays.asList((Object[]) collection);
        }

        if (collection instanceof Collection) {
            return (((Collection) collection).iterator());

        } else if (collection instanceof Iterator) {
            return ((Iterator) collection);

        } else if (collection instanceof Map) {
            return (((Map) collection).entrySet().iterator());

        } else if (collection instanceof Enumeration) {
            return IteratorUtils.asIterator((Enumeration) collection);

        } else {
            throw new JspException(
                messages.getMessage("optionsTag.iterator", collection.toString()));
        }
    }

}