tag.java

OS(OpenSymphony)的SiteMesh是一个用来在JSP中实现页面布局和装饰（layout and decoration）的框架组件

package com.opensymphony.module.sitemesh.html;

import com.opensymphony.module.sitemesh.html.util.CharArray;

/**
 * Tag returned by HTMLTagTokenizer. Allows easy access to element name and attributes.
 *
 * This interface supports read-only operations on the tag. To change a tag, use {@link CustomTag}.
 *
 * @see com.opensymphony.module.sitemesh.html.tokenizer.TokenHandler
 * @see com.opensymphony.module.sitemesh.html.tokenizer.TagTokenizer
 * @see CustomTag
 *
 * @author Joe Walnes
 */
public interface Tag {

    int OPEN = 1;
    int CLOSE = 2;
    int EMPTY = 3;
    int OPEN_MAGIC_COMMENT = 4;
    int CLOSE_MAGIC_COMMENT = 5;

    /**
     * Get the complete tag in its original form, preserving original formatting.
     *
     * This has a slight overhead in that it needs to construct a String. For improved performance, use writeTo() instead.
     *
     * @see #writeTo(com.opensymphony.module.sitemesh.html.util.CharArray)
     */
    String getContents();

    /**
     * Write out the complete tag in its original form, preserving original formatting.
     */
    void writeTo(CharArray out);

    /**
     * Name of tag (ie. element name).
     */
    String getName();

    /**
     * Type of tag: <br/>
     * &lt;blah&gt; - Tag.OPEN<br/>
     * &lt;/blah&gt; - Tag.CLOSE<br/>
     * &lt;blah/&gt; - Tag.EMPTY<br/>
     */
    int getType();

    /**
     * Number of attributes in tag.
     */
    int getAttributeCount();

    /**
     * Determine which attribute has the specified name.
     */
    int getAttributeIndex(String name, boolean caseSensitive);

    /**
     * Get name of attribute.
     */
    String getAttributeName(int index);

    /**
     * Get value of an attribute. If this is an empty attribute (i.e. just a name, without a value), null is returned.
     */
    String getAttributeValue(int index);

    /**
     * Get value of an attribute. If this is an empty attribute (i.e. just a name, without a value), null is returned.
     */
    String getAttributeValue(String name, boolean caseSensitive);

    /**
     * Determine if an attribute is present.
     */
    boolean hasAttribute(String name, boolean caseSensitive);

}