JAVA/JSP Learning Series 7_PHP Tutorial

1. Preface (This article is translated from the Orion official website)

This article will introduce step by step how to define your own tag under Orion Application Server, then implement the function of the tag, and finally test it with a jsp example.

2. Create a label and realize the function of the label.

1. Name the package: com.acme.mytags (in order to be consistent with the original text, I will not make changes)

package com.acme.mytags;

2.import Related classes

import javax.servlet.jsp.*;

import javax.servlet.jsp.tagext.*;

3. Implement javax.servlet.jsp.tagext .Tag interface:

public class HelloWorld implements Tag

{

4. Define local variables

private PageContext pageContext;

private Tag parent;

5. Call the tag start implementation method

public int doStartTag() throws javax.servlet.jsp.JspException

{

return SKIP_BODY;

}

Note: This method returns SKIP_BODY, that is, when the body of the tag is empty, this value will be returned, otherwise it will return: EVAL_BODY_INCLUDE

6. Call Implementation method of tag end

public int doEndTag() throws javax.servlet.jsp.JspException

{

try

{

pageContext.getOut().write('Hello World!');

}

catch(java.io.IOException e)

{

throw new JspException('IO Error: ' + e.getMessage());

}

return EVAL_PAGE;

}

This will The end of the custom tag of the jsp file outputs "Hello World!"

7. Not enough, we have to write the following method:

public void release() {}

For this simple example, the above method does not require any implementation.

8. The JSP container needs to call the following method:

public void setPageContext(final javax.servlet.jsp.PageContext pageContext) {

this.pageContext=pageContext;

}

The JSP container calls the tag through the above method, and the above method is used to set the PageContext of the tag.

9. The JSP container also calls the following method ：

public void setParent(final javax.servlet.jsp.tagext.Tag parent)

{

this.parent=parent;

}

The JSP container sets the parent-Tag of the tag through the above method, because the PageContext of each tag must retain its parent tag.

10. Finally, the implementation method:

public javax.servlet.jsp.tagext.Tag getParent()

{

return parent;

}

}

11. Compile tag.

3. Description tag

Now you will write a description file to describe the tag.

1. Create a taglib.tld file,

2.taglib.tld is a text file in XML format. The XML header is as follows:


'http ://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd'>

3. Description tag library



1.0

1.1

mt http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar

My first Tag library

4. Describe tags



helloWorld

com.acme.mytags.HelloWorld

empty

A Hello world Tag



5. End



4. Packaging

The name is: mytags.jar

The directory structure is:

com/acme/mytags/HelloWorld.class

META-INF/taglib.tld

5. Use custom tags

in the jsp file to create hello.jsp As follows:





















6. Test run

In the orion directory, create the following structure, in which the tag is created by yourself, and the previous directory is the original There is.

E:oriondefault-web-app ag

Put all jar files and jsp files in this directory.

Then, visit:

http://localhost:[port]/tag/hello.jsp

The following will appear:
------ -------------------------------------------------- ----------
Hello World!
-------------------------------- ----------------------------------

7. Congratulations, you have succeeded!

Attached: mytags.jar and hello.jsp files download address of this website:

http://www.wodejia.net/softdownload/java/orion_tag01.zip (Source: viphot.com )