1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
5 *
6 * Portions Copyright Apache Software Foundation.
7 *
8 * The contents of this file are subject to the terms of either the GNU
9 * General Public License Version 2 only ("GPL") or the Common Development
10 * and Distribution License("CDDL") (collectively, the "License"). You
11 * may not use this file except in compliance with the License. You can obtain
12 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
13 * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
14 * language governing permissions and limitations under the License.
15 *
16 * When distributing the software, include this License Header Notice in each
17 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
18 * Sun designates this particular file as subject to the "Classpath" exception
19 * as provided by Sun in the GPL Version 2 section of the License file that
20 * accompanied this code. If applicable, add the following below the License
21 * Header, with the fields enclosed by brackets [] replaced by your own
22 * identifying information: "Portions Copyrighted [year]
23 * [name of copyright owner]"
24 *
25 * Contributor(s):
26 *
27 * If you wish your version of this file to be governed by only the CDDL or
28 * only the GPL Version 2, indicate your decision by adding "[Contributor]
29 * elects to include this software in this distribution under the [CDDL or GPL
30 * Version 2] license." If you don't indicate a single choice of license, a
31 * recipient has the option to distribute your version of this file under
32 * either the CDDL, the GPL Version 2 or to extend the choice of license to
33 * its licensees as provided above. However, if you add GPL Version 2 code
34 * and therefore, elected the GPL Version 2 license, then the option applies
35 * only if the new code is made subject to such option by the copyright
36 * holder.
37 */
38
39 package javax.servlet.jsp.tagext;
40
41 import java.io.IOException;
42 import java.io.Writer;
43 import javax.servlet.jsp;
44
45 /**
46 * Encapsulates a portion of JSP code in an object that
47 * can be invoked as many times as needed. JSP Fragments are defined
48 * using JSP syntax as the body of a tag for an invocation to a SimpleTag
49 * handler, or as the body of a <jsp:attribute> standard action
50 * specifying the value of an attribute that is declared as a fragment,
51 * or to be of type JspFragment in the TLD.
52 * <p>
53 * The definition of the JSP fragment must only contain template
54 * text and JSP action elements. In other words, it must not contain
55 * scriptlets or scriptlet expressions. At translation time, the
56 * container generates an implementation of the JspFragment abstract class
57 * capable of executing the defined fragment.
58 * <p>
59 * A tag handler can invoke the fragment zero or more times, or
60 * pass it along to other tags, before returning. To communicate values
61 * to/from a JSP fragment, tag handlers store/retrieve values in
62 * the JspContext associated with the fragment.
63 * <p>
64 * Note that tag library developers and page authors should not generate
65 * JspFragment implementations manually.
66 * <p>
67 * <i>Implementation Note</i>: It is not necessary to generate a
68 * separate class for each fragment. One possible implementation is
69 * to generate a single helper class for each page that implements
70 * JspFragment. Upon construction, a discriminator can be passed to
71 * select which fragment that instance will execute.
72 *
73 * @since 2.0
74 */
75 public abstract class JspFragment {
76
77 /**
78 * Executes the fragment and directs all output to the given Writer,
79 * or the JspWriter returned by the getOut() method of the JspContext
80 * associated with the fragment if out is null.
81 *
82 * @param out The Writer to output the fragment to, or null if
83 * output should be sent to JspContext.getOut().
84 * @throws javax.servlet.jsp.JspException Thrown if an error occured
85 * while invoking this fragment.
86 * @throws javax.servlet.jsp.SkipPageException Thrown if the page
87 * that (either directly or indirectly) invoked the tag handler that
88 * invoked this fragment is to cease evaluation. The container
89 * must throw this exception if a Classic Tag Handler returned
90 * Tag.SKIP_PAGE or if a Simple Tag Handler threw SkipPageException.
91 * @throws java.io.IOException If there was an error writing to the
92 * stream.
93 */
94 public abstract void invoke( Writer out )
95 throws JspException, IOException;
96
97 /**
98 * Returns the JspContext that is bound to this JspFragment.
99 *
100 * @return The JspContext used by this fragment at invocation time.
101 */
102 public abstract JspContext getJspContext();
103
104 }
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