Coding tag handlers or tag files together

[Bob CHOI]

Below are my tag handler code snippets on a very-simple-nested-tags-example in "classic" style.

Hopefully you can also post yours in "simple" style or "tag file" style, so that we can learn writing tag handlers or tag files more quickly together.

[Bob CHOI]

jsp

<%@ taglib uri="http://my-tag-world.com" prefix="nested" %>
 
<nested :-o	 uter outerAttributeName="abc">
<nested:inner innerAttributeName="xyz">new text</nested:inner>
</nested :-o	 uter>
 
<nested :-o	 uter outerAttributeName="123">
<nested:inner innerAttributeName="123">new text</nested:inner>
</nested :-o	 uter>

[Bob CHOI]

tld

<?xml version="1.0" encoding="UTF-8"?>
 
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
 web-jsptaglibrary_2_0.xsd"
 version="2.0">
 
<tlib-version>1.0</tlib-version>
 
<uri>http://my-tag-world.com</uri>
 
<tag>
 
<name>outer</name>
<tag-class>p.OuterTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<name>outerAttributeName</name>
<required>true</required>
</attribute>

</tag>
 
<tag>
 
<name>inner</name>
<tag-class>p.InnerTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<name>innerAttributeName</name>
<required>true</required>
</attribute>

</tag>
 
</taglib>

[Bob CHOI]

tag handler class OuterTag

package p;
 
import java.util.*;
import java.io.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
 
public class OuterTag extends TagSupport {
 
private PageContext pc;

//Step 1
public void setPageContext(PageContext pc) {
 
this.pc = pc;
setValue("outerTextName", "default text");
 
}
 
//Step 2
public void setOuterAttributeName(String outerAttributeValue){
 
setValue("outerAttributeName", outerAttributeValue);
 
}
 
//Step 3
public int doStartTag() throws JspException {
 
return EVAL_BODY_INCLUDE;
 
}
 
//Step 8
public int doEndTag() throws JspException {
 
try
{
JspWriter jw = pc.getOut();
Object outerTextValue = getValue("outerTextName");
jw.println(outerTextValue + "<p>");
}
catch (Exception e)
{
System.out.println("OuterTag: " + e);
}

return EVAL_PAGE;
 
}

}

[Bob CHOI]

tag hanlder class InnerTag

package p;
 
import java.util.*;
import java.io.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
 
public class InnerTag extends BodyTagSupport {
 
private OuterTag ot;
private BodyContent bc;
 
//Step 4
public void setInnerAttributeName(String value) {
 
setValue("innerAttributeName", value);
 
}
 
//Step 5
public int doStartTag() throws JspException {
 
ot = (OuterTag)findAncestorWithClass(this, OuterTag.class);
                //ot = (OuterTag)getParent(); //convenience mothod to above
Object innerAttributeValue = getValue("innerAttributeName");
Object outerAttributeValue = ot.getValue("outerAttributeName");
 
if (innerAttributeValue.equals(outerAttributeValue)) 
return EVAL_BODY_BUFFERED;
else
return SKIP_BODY;
 
}
 
//Step 6
public void setBodyContent(BodyContent bc) {
 
this.bc = bc;
 
}
 
//Step 7
public int doAfterBody() throws JspException {
 
try
{
String innerTextValue = bc.getString();
ot.setValue("outerTextName", innerTextValue);
}
catch (Exception e)
{
System.out.println("InnerTag: " + e);
}
 
return SKIP_BODY;
 
}
 
}
 

[ January 12, 2007: Message edited by: Bob CHOI ]
[ January 12, 2007: Message edited by: Bob CHOI ]

[Bob CHOI]

output:

default text

new text