You are creating a library of custom tags that mimic the HTML form tags. When the user submits a
form that fails validation, the JSP form is forwarded back to the user. The <t:textField> tag must
support the ability to re-populate the form field with the request parameters from the user’s last
request. For example, if the user entered “Samantha” in the text field called firstName, then the
form is re-populated like this:
<input type=’text’ name=’firstName’ value=’Samantha’ />
Which tag handler method will accomplish this goal?
A.
public int doStartTag() throws JspException {
JspContext ctx = getJspContext();
String value = ctx.getParameter(this.name);
if ( value == null ) value = “”;
JspWriter out = pageContext.getOut();
try {
out.write(String.format(INPUT, this.name, value));
} (Exception e) { throw new JspException(e); }
return SKIP_BODY;
}
private static String INPUT
= “<input type=’text’ name=’%s’ value=’%s’ />”;
B.
public void doTag() throws JspException {
JspContext ctx = getJspContext();
String value = ctx.getParameter(this.name);
if ( value == null ) value = “”;
JspWriter out = pageContext.getOut();
try {
out.write(String.format(INPUT, this.name, value));
} (Exception e) { throw new JspException(e); }
}
private static String INPUT
= “<input type=’text’ name=’%s’ value=’%s’ />”;
C.
public int doStartTag() throws JspException {
ServletRequet request = pageContext.getRequest();
String value = request.getParameter(this.name);
if ( value == null ) value = “”;
JspWriter out = pageContext.getOut();
try {
out.write(String.format(INPUT, this.name, value));
} (Exception e) { throw new JspException(e); }
return SKIP_BODY;
}
private static String INPUT
= “<input type=’text’ name=’%s’ value=’%s’ />”;
D.
public void doTag() throws JspException {
ServletRequet request = pageContext.getRequest();
String value = request.getParameter(this.name);
if ( value == null ) value = “”;
JspWriter out = pageContext.getOut();
try {
out.write(String.format(INPUT, this.name, value));
} (Exception e) { throw new JspException(e); }
}
private static String INPUT
= “<input type=’text’ name=’%s’ value=’%s’ />”;
Explanation: