Recent Notes
Displaying keyword search results 1 - 10
Created by Fang on April 16, 2012 13:18:40
Last update: April 16, 2012 13:18:40
Simply call pageContext.setAttribute() to export a variable from within a JSP custom tag:
public class MyCustomVarTag extends TagSupport {
...
The availability of the exported variable can be limited in the TLD:
<tag>
<name>setVar</name>
<tag-class...
The availability scopes are:
Value Availability
NESTED Between the start tag and the end tag.
AT_BEGIN From the start tag until the scope of any enclosing tag. If there’s no enclosing tag, then to the end of the page.
AT_END After the end tag until the scope of any enclosing tag. If there’s no enclosing tag, then to the end of the page.
Created by Fang on April 16, 2012 12:58:35
Last update: April 16, 2012 12:58:35
To implement a JSP custom tag with dynamic attributes (for example, to pass-thru arbitrary attributes not handled by the JSP tag):
Set the dynamic-attributes element to true in the TLD:
<tag>
<name>mark</name>
<tag-class>c...
The tag handler must implement javax.servlet.jsp.tagext.DynamicAttributes :
package com.example.jsp;
import java.io.*;
...
Created by magnum on January 30, 2012 18:13:52
Last update: January 30, 2012 18:13:52
There are two ways you cat get the name of a host from its ip address: getnameinfo and gethostbyaddr . The former is IPV6 compatible.
Using getnameinfo :
#include <sys/types.h>
#include <sys/socket.h>
...
Using gethostbyaddr :
#include <sys/types.h>
#include <sys/socket.h>
...
Created by Fang on January 28, 2012 13:24:09
Last update: January 28, 2012 13:31:22
This is a simple JSP custom tags library with tag body. Just like the JSF counterpart , it splits a string and repeats the body for each word, i.e., with this markup:
<%@ taglib uri="http://custom.tag.com/demo" prefix...
output:
<html>
<body>
<p>Hello Tigger!</p>
<p>H...
With Maven, this is the directory structure:
./src
./src/main
./src/main/resources
./s...
There are three files to write:
pom.xml :
<project xmlns="http://maven.apache.org/POM/4.0.0"...
src/main/java/tagdemo/IterateTag.java :
package tagdemo;
import java.io.IOException...
src/main/resources/META-INF/demotag.tld :
<?xml version="1.0" encoding="UTF-8"?>
<!DO...
Build with:
mvn clean install
To use it as a dependency in other Maven projects:
<dependency>
<groupId>tag-demo</groupId>
...
Created by Fang on December 01, 2011 18:54:54
Last update: December 01, 2011 18:54:54
Use the varStatus attribute with the ui:repeat tag to get the iteration index:
<ui:repeat varStatus="status" var="item" value="#{...
The varStatus attribute specifies the name of the exported request scoped variable for the status of the iteration.The object is a POJO with the following read-only JavaBeans properties. This scoped variable has nested visibility.
begin of type Integer
end of type Integer
index of type int
step of type Integer
even of type boolean
odd of type boolean
first of type boolean
last of type boolean
Created by Fang on November 22, 2011 10:40:16
Last update: November 22, 2011 10:40:16
This is an example that uses tag handler, UI component and renderer together to support a custom taglib. The main purpose is to show how these components play together.
The tag renders
<ui:param name="extra" value="el interpreted"/>
...
as
<h3>my:foreach</h3>
<ul class="css class" extra...
These are the files:
The tag handler ( src/main/java/com/example/ForeachTagHandler.java ):
package com.example;
import java.util.Map;
...
The UI component ( src/main/java/com/example/UIForeach.java ):
package com.example;
import java.io.IOExcep...
The renderer ( src/main/java/com/example/ForeachRenderer.java ):
package com.example;
import java.io.IOExcep...
Faces config ( src/main/resources/META-INF/faces-config.xml ):
<?xml version="1.0" encoding="UTF-8"?>
<faces-c...
Taglib config ( src/main/resources/META-INF/foreach.taglib.xml ):
<?xml version="1.0" encoding="UTF-8"?>
<facelet...
Created by Fang on November 08, 2011 20:55:00
Last update: November 21, 2011 18:19:44
In the simple taglib example , I used a tag handler class to implement a taglib. This is an example to implement a taglib with a UI component. The purpose is to use a custom tag to split a string and print each part in a separate paragraph, i.e., print
<p>john</p> <p>steve</p> <p>mike</p> with custom tag <my:foreach> : <my:foreach var="who" value="john steve mike"> ... These are the files: pom.xml <project xmlns="http://maven.apache.org/POM/4.0.0"... src/main/java/com/example/UIForeash.java : package com.example; import java.io.IOExcep... src/main/resources/META-INF/faces-config.xml : <?xml version="1.0" encoding="UTF-8"?> <faces-c... src/main/resources/META-INF/foreach.taglib.xml : <?xml version="1.0" encoding="UTF-8"?> <facelet... How to use: Put the JAR file generated by the above project in the WEB-INF/lib folder of the web app. If the web app is a Maven project, just add the taglib project as a dependency:...
Created by Dr. Xi on November 11, 2011 10:05:22
Last update: November 11, 2011 10:12:01
This is an HTML image tag filter using Java regex. It takes a string, finds the img tags, replaces the src attribute with one provided by the filter, then adds a class name to the class attribute.
import java.util.regex.*;
import java.io.*;
...
Test file:
<div id="HTML snippet">
<img src="img/big/txt-m...
Created by magnum on September 24, 2011 13:14:37
Last update: September 28, 2011 18:08:35
There are two sides to an IP socket: the local side and the remote side:
The getpeername function retrieves the peer address of the specified socket.
#include <sys/socket.h>
int getpeername(int soc...
Example:
struct sockaddr_in addr;
socklen_t socklen = si...
The getsockname function retrieves the locally-bound name of the specified socket.
#include <sys/socket.h>
int getsockname(int soc...
Example:
struct sockaddr_in addr;
socklen_t socklen = si...
Created by magnum on September 27, 2011 21:51:05
Last update: September 28, 2011 18:02:49
Client socket usually does not call bind . But I've seen code that does and it was puzzling to me what bind does to a client socket. Therefore, this little test program. It retrieves a web url and displays info about the socket. You can optionally give a bind host name/ip and port and see what it does.
Here are my test results:
$ ./client www.google.com
Local addr: 172.16.0....
This is the code:
#include <stdio.h>
#include <stdlib.h>
#incl...
