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Posted to dev@struts.apache.org by dg...@apache.org on 2003/09/24 01:32:10 UTC
cvs commit: jakarta-struts/doc/faqs indexedprops.xml
dgraham 2003/09/23 16:32:10
Modified: doc/faqs indexedprops.xml
Log:
Replace "scriptlet" references with "JSP expression" because
<%= %> isn't technically a scriptlet. Also, added link to JSTL
homepage.
Revision Changes Path
1.4 +34 -26 jakarta-struts/doc/faqs/indexedprops.xml
Index: indexedprops.xml
===================================================================
RCS file: /home/cvs/jakarta-struts/doc/faqs/indexedprops.xml,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- indexedprops.xml 9 Sep 2003 17:49:22 -0000 1.3
+++ indexedprops.xml 23 Sep 2003 23:32:10 -0000 1.4
@@ -3,6 +3,7 @@
<document url="./indexedprops.xml">
<properties>
<author>David M. Karr</author>
+ <author>David Graham</author>
<title>Indexed Properties, Mapped Properties, and Indexed Tags</title>
</properties>
<body>
@@ -14,8 +15,7 @@
the base JSP specification actually deals with the "indexing" part. In
truth, it allows for setting "array properties", but it doesn't do much
for setting or even getting the actual values in each entry of the array,
- except in explicit scriptlet expressions (which are always allowed, but
- not recommended).
+ except with explicit JSP expressions (<%= %>).
</p>
<p>
The Struts framework provides much more powerful features related to
@@ -46,12 +46,15 @@
package org.apache.struts.webapp.exercise;
import org.apache.struts.action.ActionForm;
public class StringBean extends ActionForm {
- private String strAry[] =
- { "String 0", "String 1", "String 2", "String 3", "String 4" };
+ private String strAry[] = { "String 0", "String 1", "String 2", "String 3", "String 4" };
- public String getStringIndexed(int index) { return (strAry[index]); }
- public void setStringIndexed(int index, String value)
- { strAry[index] = value; }
+ public String getStringIndexed(int index) {
+ return strAry[index];
+ }
+
+ public void setStringIndexed(int index, String value) {
+ strAry[index] = value;
+ }
}</pre>
<p>
First note the two methods in the StringBean class, "getStringIndexed()"
@@ -83,7 +86,7 @@
<section href="listbackedprops" name="List-Backed Indexed Properties">
<p>
A variation on indexed properties are properties whose type is
- "java.util.List" or a subclass.
+ <code>java.util.List</code> or a subclass.
</p>
<p>
For instance, the first example using "StringBean.java" and
@@ -93,11 +96,11 @@
package org.apache.struts.webapp.exercise;
import org.apache.struts.action.ActionForm;
public class StringBean2 extends ActionForm {
- private String strAry[] =
- { "String 0", "String 1", "String 2", "String 3", "String 4" };
+ private String strAry[] = { "String 0", "String 1", "String 2", "String 3", "String 4" };
- public java.util.List getStringIndexed(int index)
- { return (java.util.Arrays.asList(strAry)); }
+ public java.util.List getStringIndexed(int index) {
+ return java.util.Arrays.asList(strAry);
+ }
}</pre>
<p>
Note the different implementation of the "getStringIndexed()" method,
@@ -123,8 +126,8 @@
import java.util.HashMap;
import org.apache.struts.action.ActionForm;
public class StringBean3 extends ActionForm {
- private String strAry[] =
- { "String 0", "String 1", "String 2", "String 3", "String 4" };
+ private String strAry[] = { "String 0", "String 1", "String 2", "String 3", "String 4" };
+
private HashMap map = new HashMap();
public StringBean() {
@@ -135,9 +138,13 @@
map.put("four", strAry[4]);
}
- public Object getStringMapped(String key) { return (map.get(key)); }
- public void setStringMapped(String key, Object value)
- { map.put(key, value); }
+ public Object getStringMapped(String key) {
+ return map.get(key);
+ }
+
+ public void setStringMapped(String key, Object value) {
+ map.put(key, value);
+ }
}</pre>
<p>
Note the "get" and "set" methods to represent the mapped property.
@@ -170,6 +177,7 @@
import org.apache.struts.action.ActionForm;
public class StringBean4 extends ActionForm {
private LabelValueBean[] lvbeans;
+
public StringBean() {
lvbeans = new LabelValueBean[5];
lvbeans[0] = new LabelValueBean("Zero", 0+"");
@@ -179,8 +187,9 @@
lvbeans[4] = new LabelValueBean("Four", 4+"");
}
- public LabelValueBean getLabelValue(int index)
- { return (lvbeans[index]); }
+ public LabelValueBean getLabelValue(int index) {
+ return lvbeans[index];
+ }
}</pre>
<p>
First note the use of the class "LabelValueBean". This is a simple class
@@ -236,8 +245,8 @@
</body>
</html></pre>
<p>
- That scriptlet expression for the "property" attribute is something we
- want to avoid. The syntax is somewhat messy and easy to get wrong. One
+ The JSP expression syntax for the <code>property</code> attribute is somewhat
+ messy and easy to get wrong so it's something we want to avoid. One
way to make this a little cleaner is to use "indexed tags", but there's a
wrinkle to this approach. We'll first cover the details of indexed tags,
then we'll talk about the wrinkle, and then finally an alternative to
@@ -325,18 +334,17 @@
<p>
The "indexed tags" feature was created partially because of the awkward
process for encoding the loop index into the property attribute, using a
- scriptlet expression. The creation of the JavaServer Pages Standard Tag
- Library (JSTL) eventually resulted in a solution that makes that process
- less painful.
+ JSP expression. The creation of the <a href="http://java.sun.com/products/jsp/jstl/">JSTL</a>
+ eventually resulted in a solution that makes that process less painful.
</p>
<p>
The JSTL uses a string-based expression language to evaluate attribute
- values, instead of using run-time expression scriptlets. The engine that
+ values, instead of using a run-time JSP expression. The engine that
performs these evaluations is often called just "EL" (expression language)
for short. After the JSTL was created, a derivative of the Struts tag
library called Struts-EL was created. In short, this does everything that
the Struts tag library does, but it uses the JSTL EL engine to evaluate
- attribute values, instead of the usual runtime expression scriptlets.
+ attribute values.
</p>
<p>
If you use Struts-EL, you can get back some of the flexibility of encoding
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