Basic Custom Tag Not Working

Question

Basic Custom Tag Not Working

1k Views Asked by Jeff Levine At 20 October 2024 at 22:31

I've been playing with this code for hours, and I can't determine why my tag appears to be doing nothing.

lab08.jspx simply outputs whatever is entered in the Set Body field in lab08J.html, seemingly ignoring the friend entry altogether. Code below.

lab08J.html

<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.w3.org/1999/xhtml
                      http://www.w3.org/2002/08/xhtml/xhtml1-strict.xsd">
  <head><title>lab08J.html</title><head>
  <body>
    <form action="lab08J.jspx">
        Set Friend:<input type="text" name="friend"/>
        <p>Set Body:<input type="text" name="body"/>
        <input type="submit"/>
    </form>
  </body>
</html>

lab08J.jspx

<html xmlns:j="http://ets.com/tags/j"
  xmlns:jsp="http://java.sun.com/JSP/Page">
  <jsp:output omit-xml-declaration="true" />
  <jsp:directive.page contentType="text/html" />
  <head><title>lab08.jspx</title></head>
  <body><j:myTag friend="${param.friend}">${param.body}</j:myTag>
  </body>
</html>

web.xml

<?xml version="1.0" ?>
<web-app version="2.4" 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    
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
</web-app>

myTags.tld

<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 
  http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd" 
  version="2.0">

  <tlib-version>1.0</tlib-version>
  <short-name>lab08Jtaglib</short-name>
  <uri>http://ets.com/tags/j</uri>
  <tag>
    <name>myTag</name>
    <tag-class>webcert.ch08.lab08J.MyTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
      <name>friend</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
</taglib>

MyTag.java

package webcert.ch08.lab08J;
import java.io.IOException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;
import javax.servlet.jsp.tagext.IterationTag;


public class MyTag extends BodyTagSupport{

private PageContext pageContext;
private BodyTagSupport parent;
private String friend;
private BodyContent bc = getBodyContent();

public void setPageContext(PageContext pageContext){
    super.setPageContext(pageContext);
    log("setPageContext()");
}
public void setParent(BodyTagSupport parent){
    super.setParent(parent);
    log("setParent()");
}
public void setFriend(String friend)throws Exception{
    this.friend = friend;
    log("setFriend() as " + friend);
    JspWriter out = pageContext.getOut();
    out.write("setFriend as " + friend);
}
public int doStartTag(){
    log("doStartTag()");
    return BodyTagSupport.EVAL_BODY_BUFFERED;

}
public void setBodyContent(BodyContent bc){
    super.setBodyContent(bc);
    log("setBodyContent()");
}
public void doInitBody(){
    log("doInitBody()");
}
public int doAfterBody(){
    log("doAfterBody()");
    try{
        bc.write("Meet my friend " + friend);
    }
    catch(IOException ioe){
        ioe.printStackTrace();
    }
    return IterationTag.EVAL_BODY_AGAIN;
}
public int doEndTag(){
    log("doEndTag()");
    try{
        bc.writeOut(bc.getEnclosingWriter());
    }
    catch(IOException ioe){
        ioe.printStackTrace();
    }
    return BodyTagSupport.EVAL_PAGE;
}
public void release(){
    System.out.println("release()");
    super.release();
}
protected void log(String s){
    try {
        bc.write(s);
    } catch (IOException e) {
        e.printStackTrace();
    }
}
}

Original Q&A

There are 1 best solutions below

**study** · Answer 1

There are some things wrong in your MyTag.java. I have tried to fix it and it should be worked.

public class MyTag extends BodyTagSupport {
    private String friend;

    @Override
    public int doAfterBody() throws JspException {
        log("doAfterBody()");

        try {
            BodyContent bodycontent = getBodyContent();
            String body = bodycontent.getString();
            JspWriter out = bodycontent.getEnclosingWriter();
            if (body != null) {
                out.print(body.toUpperCase());
            }
        } catch (IOException ioe) {
            throw new JspException("Error:" + ioe.getMessage());
        }

        log("Meet my friend " + friend);
        return BodyTagSupport.SKIP_BODY;
    }

    @Override
    public int doEndTag() {
        log("doEndTag()");
        return BodyTagSupport.EVAL_PAGE;
    }

    @Override
    public void doInitBody() {
        log("doInitBody()");
    }

    @Override
    public int doStartTag() {
        log("doStartTag()");
        return BodyTagSupport.EVAL_BODY_BUFFERED;

    }

    protected void log(String s) {
        System.out.println(s);
    }

    @Override
    public void release() {
        log("release()");
        super.release();
    }

    @Override
    public void setBodyContent(BodyContent bc) {
        super.setBodyContent(bc);
        log("setBodyContent()");
    }

    public void setFriend(String friend) throws Exception {
        this.friend = friend;
        log("setFriend() as " + friend);
        JspWriter out = pageContext.getOut();
        out.write("setFriend as " + friend);
    }

    @Override
    public void setPageContext(PageContext pageContext) {
        super.setPageContext(pageContext);
        log("setPageContext()");
    }

    public void setParent(BodyTagSupport parent) {
        super.setParent(parent);
        log("setParent()");
    }
}

Basic Custom Tag Not Working

There are 1 best solutions below

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