Working with Java Memcached API

Memcached is a memory object caching system. It is used to improve the performance of web applications which is dynamic in nature.  Memcached server is an in-memory key value store for small amount of data like strings, objects from results of database calls, API calls, or page rendering.  It is very simple. Server (daemon) process written in C, providing an in-memory hashmap. Clients can be written in any language.

The below example gives very basic example to understand memcached server. 

Set memcached clinet jar file (memcached-client-2.3.jar) in your classpath.

General Usage:

Use below code to connect with memcache and push object to memcache and retrive object from memcache.

MemcachedClient c = null;

try{

c = new MemcachedClient(new InetSocketAddress("memcached_host_IP", PORT));

c.set("MyTest", 60*60*24, new Integer(20));

int fromMC = (Integer)c.get("MyTest");

System.out.println(fromMC);

} catch (Exception ex){

out.println("Exception raised when getting object from memcached; "+ex.getMessage());

} finally{

if(c != null) c.shutdown();

}

In the above code below line creates MemcachedClient with memcached ip, and port. It establishes connection to the memcache.

c = new MemcachedClient(new InetSocketAddress("memcached_host_IP", PORT));

The below line is storing Integer object into the memcache with a key "MyTest". You can get the object using this key. The object will be available in memcache for 24 hours.

c.set("MyTest", 60*60*24, new Integer(20));

The below line gets the stored object from memcache by passing key. You need to do proper typecast.

int fromMC = (Integer)c.get("MyTest");

The finally block below closes the memcache client connection.

finally{

if(c != null) c.shutdown();

}

Advaned Usage:

MemcachedClient may be processing a great deal of asynchronous messages or possibly dealing with an unreachable memcached, which may delay processing. If a memcached is disabled, for example, MemcachedConnection will continue to attempt to reconnect and replay pending operations until it comes back up. To prevent this from causing your application to hang, you can use one of the asynchronous mechanisms to time out a request and cancel the operation to the server.

Get a memcached client connected to several servers, over the binary protocol.

MemcachedClient c = new MemcachedClient(new BinaryConnectionFactory(), AddrUtil.getAddresses("server1:11211 server2:11211"));

How to create XML file using JDOM in java

This example creates xml file using JDOM apis .

import java.io.FileOutputStream;

import java.io.OutputStream;

import org.jdom.Document;

import org.jdom.Element;

import org.jdom.output.XMLOutputter;

public class CreateXML {

public static void main(String a[]){

OutputStream fos = null;

Document doc = new Document();

Element root = new Element("emps");

doc.setRootElement(root);

// create emp element

Element emp = new Element("emp");

emp.setAttribute("id", "1016");

Element name = new Element("name");

name.setText("Nataraj");

emp.addContent(name);

Element dep = new Element("dep");

dep.setText("development");

emp.addContent(dep);

//Add emp element to root element

root.addContent(emp);

Element emp1 = new Element("emp");

emp1.setAttribute("id", "1015");

Element name1 = new Element("name");

name1.setText("Nagesh");

emp1.addContent(name1);

Element dep1 = new Element("dep");

dep1.setText("accounts");

emp1.addContent(dep1);

//Add emp element to root element

root.addContent(emp1);

try{

fos = new FileOutputStream("c://test.xml");

new XMLOutputter().output(doc, fos);

} catch(Exception ex){

ex.printStackTrace();

} finally {

try{

if(fos != null) fos.close();

} catch(Exception ex){

ex.printStackTrace();

}

}

}

}

OUTPUT:

<emps><emp id="1016"><name>Nataraj</name><dep>development</dep></emp><emp id="1015"><name>Nagesh</name><dep>accounts</dep></emp></emps>

How to read XML file using JDOM in java

This article gives you an example to read xml file using JDOM api. We will read xml file and print the values on to the console:

Save below xml into emp.xml file.

<emps>
<emp id="1016">
<name>Nataraj</name>
<dep>Accounts</dep>
</emp>
<emp id="1015">
<name>Nagesh</name>
<dep>Marketing</dep>
</emp>
</emps>

Java code to read xml file:

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.List;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;

public class ParseXml {

public static void main(String a[]){

Document xmlDoc = null;
SAXBuilder builder = new SAXBuilder();
InputStream is = null;
Element root = null;
try {
is = new FileInputStream(new File("C:\\emp.xml"));
xmlDoc = builder.build(is);
if(xmlDoc != null){
root = xmlDoc.getRootElement();
System.out.println("Root element name: "+root.getName());
List empList = root.getChildren("emp");
System.out.println("Emp Size: "+empList.size());
for(Element emp:empList){
System.out.println("Id: "+emp.getAttributeValue("id"));
Element name = emp.getChild("name");
System.out.println("Name: "+name.getText());
Element dep = emp.getChild("dep");
System.out.println("Deportment: "+dep.getText());
System.out.println("<--------------------------------------->");
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}


OUTPUT:
-----------
Root element name: emps
Emp Size: 2
Id: 1016
Name: Nataraj
Deportment: Accounts
<--------------------------------------->
Id: 1015
Name: Nagesh
Deportment: Marketing
<--------------------------------------->

How to get ClassLoader or Resource in a java static method?

Follow the below steps to load property file in a java static method.

Properties prop = new Properties();

prop.load(YourClassName.class.getResourceAsStream("File path"));