001: /*
002: * Copyright (c) 1998-2003 Caucho Technology -- all rights reserved
003: *
004: * This file is part of Resin(R) Open Source
005: *
006: * Each copy or derived work must preserve the copyright notice and this
007: * notice unmodified.
008: *
009: * Resin Open Source is free software; you can redistribute it and/or modify
010: * it under the terms of the GNU General Public License as published by
011: * the Free Software Foundation; either version 2 of the License, or
012: * (at your option) any later version.
013: *
014: * Resin Open Source is distributed in the hope that it will be useful,
015: * but WITHOUT ANY WARRANTY; without even the implied warranty of
016: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
017: * of NON-INFRINGEMENT. See the GNU General Public License for more
018: * details.
019: *
020: * You should have received a copy of the GNU General Public License
021: * along with Resin Open Source; if not, write to the
022: * Free SoftwareFoundation, Inc.
023: * 59 Temple Place, Suite 330
024: * Boston, MA 02111-1307 USA
025: *
026: * @author Scott Ferguson
027: */
028:
029: package javax.servlet.jsp.tagext;
030:
031: import javax.servlet.jsp.JspException;
032: import javax.servlet.jsp.PageContext;
033:
034: /**
035: * Tags are Java classes implementing JSP Tag extensions. The class must
036: * have a null argument public constructor and implement the tag attribute
037: * as setXXX methods, following the Beans spec.
038: *
039: * <pre><code>
040: * MyTag tag = new MyTag();
041: *
042: * tag.setPageContext(page);
043: * tag.setParent(...);
044: * tag.setFoo(...);
045: * tag.setBar(...);
046: * if (tag.doStartTag() == EVAL_BODY_INCLUDE) {
047: * ...
048: * }
049: * if (tag.doEndTag() == SKIP_PAGE)
050: * return;
051: * ...
052: * tag.setParent(...);
053: * tag.setFoo(...);
054: * if (tag.doStartTag() == EVAL_BODY_INCLUDE) {
055: * ...
056: * }
057: * if (tag.doEndTag() == SKIP_PAGE)
058: * return;
059: * ...
060: * tag.release();
061: * </code><pre>
062: */
063: public interface Tag extends JspTag {
064: public final static int SKIP_BODY = 0;
065: public final static int EVAL_BODY_INCLUDE = 1;
066:
067: public final static int SKIP_PAGE = 5;
068: public final static int EVAL_PAGE = 6;
069:
070: /**
071: * Sets the page context of this page.
072: */
073: public void setPageContext(PageContext page);
074:
075: /**
076: * Sets the containing tag.
077: */
078: public void setParent(Tag t);
079:
080: /**
081: * Returns the containing tag.
082: */
083: public Tag getParent();
084:
085: /**
086: * Callback to handle the start of a tag.
087: *
088: * <p>doStartTag can assume <code>setPageContext</code>,
089: * <code>setParent</code>, and all tag attribute properties have
090: * been called.
091: *
092: * @return SKIP_BODY to ignore the body and EVAL_BODY_INCLUDE
093: * to evaluate the body.
094: */
095: public int doStartTag() throws JspException;
096:
097: /**
098: * Callback to handle the end of a tag.
099: * @return SKIP_PAGE to skip the rest of the page and
100: * EVAL_PAGE to continue with the rest of the page.
101: */
102: public int doEndTag() throws JspException;
103:
104: /**
105: * Cleans up the tag at the end of the page. The same tag instance
106: * might be reused for multiple tags in the page.
107: */
108: public void release();
109: }
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