This practice exam focuses on EL. For those using Head First Servlets and JSP, 2nd Edition it provides a lot of practice for the last part of chapter 8.
Archive for the ‘JSP/Servlets’ Category
Free SCWCD Mock Exam for EL
24 August 2009Free SCWCD Mock Exam for JSPs
22 August 2009This practice exam focuses on Java Server Pages.
Java Server Pages is the technology that changed the world of Web Applications. Developed on the robustness of Servlets, JSPs are the key component of the modern Web frameworks and the basis of promising new technologies like JSF.
This free practice material consists of 71 originally created questions. For those using Head First Servlets and JSP, 2nd Edition it’s a perfect companion for chapters 7-8.
Free SCWCD Mock Exam for Servlets
12 March 2009This practice exam focuses on Servlets. For those using Head First Servlets and JSP, 2nd Edition it’s a perfect companion for chapters 4-6.
Custom Tags 4 – Body manipulation of Classic Tags
19 January 2009This post explains how to manipulate the body of a classic tag.
Step 1. Write a BodyTagSupport and provide its doAfterBody() method.
package my;
public class Body extends BodyTagSupport {
public int doAfterBody() {
try {
final String body = bodyContent.getString();
final StringBuilder result = new StringBuilder();
for (int index = 0; index < body.length(); index = index + 2) {
result.append(body.charAt(index));
}
bodyContent.getEnclosingWriter().print(result.toString());
} catch (Exception e) {
e.printStackTrace();
}
return SKIP_BODY;
}
}
Step 2. Declare it in a TLD.
<taglib ...> <uri>nikojava</uri> <tag> <name>body</name> <tag-class>my.Body</tag-class> <body-content>scriptless</body-content> </tag> </taglib>
Step 3. Call it!
<%@ taglib prefix="mari" uri="nikojava" %> <html> <body> (Before) <mari:body>ABABABABABABAB</mari:body> (After) </body> </html>
Filtering the even characters of a classic tag's body
As a result, only the characters at an even position (0, 2, 4, etc.) are printed!
Explanation
BodyTagSupport IS-A TagSupport. However it offers an extra weapon: EVAL_BODY_BUFFERED. If doStartTag() returns this value, then a series of methods is invoked: setBodyContent(BodyContent), then doInitBody(), then the body is evaluated and doAfterBody() is about to execute. At this point we do have access to the actual body content.
In the above example doStartTag() is not overriden, so by default EVAL_BODY_BUFFERED is returned. The actual content is taken as a string,
final String body = bodyContent.getString();
and its even characters are selected:
for (int index = 0; index < body.length(); index = index + 2) {
result.append(body.charAt(index));
}
More examples
Color alternate letters
public int doAfterBody() {
try {
final String body = bodyContent.getString();
final StringBuilder result = new StringBuilder();
for (int index = 0; index < body.length(); index++) {
if (isOdd(index)) {
result.append("<span style='color:red'>");
result.append(body.charAt(index));
result.append("</span>");
} else {
result.append(body.charAt(index));
}
}
bodyContent.getEnclosingWriter().print(result.toString());
} catch (Exception e) {
e.printStackTrace();
}
return SKIP_BODY;
}
private boolean isOdd(int number) {
return number % 2 == 1;
}
<%@ taglib prefix="mari" uri="nikojava" %> <html> <body> (Before) <mari:body>ABABABABABABAB</mari:body> (After) </body> </html>
Coloring the even characters of a classic tag's body
Remove capital letters
public int doAfterBody() {
try {
final String body = bodyContent.getString();
final StringBuilder result = new StringBuilder();
for (int index = 0; index < body.length(); index++) {
final char current = body.charAt(index);
if (!Character.isUpperCase(current)) {
result.append(current);
}
}
bodyContent.getEnclosingWriter().print(result.toString());
} catch (Exception e) {
e.printStackTrace();
}
return SKIP_BODY;
}
<%@ taglib prefix="mari" uri="nikojava" %> <html> <body> (Before) <mari:body>Google Sun JBoss</mari:body> (After) </body> </html>
Disposing the capital letters of a custom tag's body
Have fun
public int doAfterBody() {
try {
final StringBuilder body = new StringBuilder(bodyContent.getString());
final int initialSize = body.length();
for (int index = 0; index < initialSize; index++) {
bodyContent.getEnclosingWriter().append(body);
bodyContent.getEnclosingWriter().append("<br />");
body.deleteCharAt(body.length() - 1);
}
} catch (Exception e) {
e.printStackTrace();
}
return SKIP_BODY;
}
<%@ taglib prefix="mari" uri="nikojava" %> <html> <body> <mari:body>Microsystems</mari:body> </body> </html>
Having fun with the body of a classic tag
