Connection Pool

Use of Connection Pool - A connection pool is used to minimize the number of connections opened between application and database. It serves as a librarian, checking out connections to application code as needed. Much like a library, your application code needs to be strict about returning connections to the pool when complete, for if it does not do so, your application will run out of available connections.

Problem in Pooling : When using connection pooling, it is important to remember that a chunk of bad code that neglects to return connections can starve the rest of the application, causing it to eventually run out of connections and hang (potentially failing nowhere near the actual problem).

Avoidance of Poling: This problem can be avoided by always using a finally block to close your connection, as shown throughout this book.

What is Specialization in Java?

Specialization means Subclass is specialized version of Super Class 
like Dog is specialized version of Animal i.e  extending a class, 
which is really the opposite of generalization.

Like

class Animal
{

}

class Dog extends Animal //Dog is specialized version of animal
{

}

What is Generalization in Java

> Generalization is the process in which
> we extract common-shared behavior of two or more classes,
> and combine them into a generalized Super Class 

For example:

class dog
{
    void fourLegs()
    {
        System.out.println("four legged animal");
    }
    void bark()
    {
        System.out.println("Bark");
    }
}
class cat
{
    void fourLegs()
    {        System.out.println("four legged animal");
    }
    void Mew()
    {
        System.out.println("Bark");
    }
}



After Generalization (Shared characterstics are all together)

abstract class Animal
{
    void fourLegs()
    {        System.out.println("four legged animal");
    } 
}

class dog extends Animal
{
    void bark()
    {
        System.out.println("Bark");
    }
}
class cat extends Animal
{    void Mew()
    {
        System.out.println("Bark");
    }
}

How to delete Multiple records having same value, Using SQL

DELETE
FROM cb_entity_samples A
WHERE ROWID >
  (SELECT MIN(rowid)
  FROM cb_entity_samples B
  WHERE A.fk_specimen = B.fk_specimen
  )
 

iBatis Code FLow

JAR :  2.3.4

package mybatis;

import com.ibatis.common.resources.Resources;
import com.ibatis.sqlmap.client.SqlMapClient;
import com.ibatis.sqlmap.client.SqlMapClientBuilder;
import java.io.*;
import java.sql.SQLException;
import java.util.*;

public class IbatisRead
{
  public static void main(String[] args)
   throws IOException,SQLException{
   Reader rd = Resources.getResourceAsReader("mybatis\\SqlMapConfig.xml");
   SqlMapClient smc = SqlMapClientBuilder.buildSqlMapClient(rd);

  
    /* This would insert one record in Employee table. */
   System.out.println("Going to insert record.....");
   A_HARRY em1 = new A_HARRY("Farah", "Ali", 5000);

   smc.insert("ServiceRequestLog.insert", em1);

   System.out.println("Record Inserted Successfully ");

   System.out.println("Records Read Successfully ");

  
   /* This would read all records from the Employee table. */
   System.out.println("Going to read records.....");
   List <A_HARRY> ems = (List<A_HARRY>) smc.queryForList("ServiceRequestLog.getAll", null);
   A_HARRY em = null;
   for (A_HARRY e : ems)
   {
      System.out.print("  " + e.getId());
      System.out.print("  " + e.getFirstName());
      System.out.print("  " + e.getLastName());
      System.out.print("  " + e.getSalary());
      em = e;
      System.out.println("");
      System.out.println("");
   }   
  
   A_HARRY rec = new A_HARRY();
   rec.setId(1);
   rec.setFirstName("Roma");
   smc.update("ServiceRequestLog.update", rec );
   System.out.println("Record updated Successfully ");

   System.out.println("Going to read records.....");
   ems = (List<A_HARRY>) smc.queryForList("ServiceRequestLog.getAll", null);
   A_HARRY em2 = null;
   for (A_HARRY e : ems)
   {
      System.out.print("  " + e.getId());
      System.out.print("  " + e.getFirstName());
      System.out.print("  " + e.getLastName());
      System.out.print("  " + e.getSalary());
      em2 = e;
      System.out.println("");
      System.out.println("");
   }   
  
  
  }
} 


______________________


package mybatis;

public class A_HARRY {

    private int id;
    private String first_name;
    private String last_name;
    private int salary;

    public A_HARRY() {
    }

    public A_HARRY(String fname, String lname, int salary) {
        this.first_name = fname;
        this.last_name = lname;
        this.salary = salary;
    }


    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getFirstName() {
        return first_name;
    }

    public void setFirstName(String fname) {
        this.first_name = fname;
    }

    public String getLastName() {
        return last_name;
    }

    public void setlastName(String lname) {
        this.last_name = lname;
    }

    public int getSalary() {
        return salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }
}


_______________________________


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sqlMapConfig PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN" "http://ibatis.apache.org/dtd/sql-map-config-2.dtd">

<sqlMapConfig>
     <settings useStatementNamespaces="true"/>
     <transactionManager type="JDBC">
        <dataSource type="SIMPLE">
           
          <property name="JDBC.Driver" value="oracle.jdbc.driver.OracleDriver" />
          <property name="JDBC.ConnectionURL"
               value="jdbc:oracle:thin:@192.168.5.13:1521:veqa"/>
          <property name="JDBC.Username" value="een"/>
          <property name="JDBC.Password" value="en123"/>
        </dataSource>
      </transactionManager>
     <sqlMap resource="mybatis\ServiceRequestLog.xml"/>
</sqlMapConfig>




______________________________________




<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN" "http://ibatis.apache.org/dtd/sql-map-2.dtd">

<sqlMap namespace="ServiceRequestLog">
   
    <select id="getAll" resultClass="mybatis.A_HARRY">
        SELECT * FROM A_HARRY
    </select>
   
    <insert id="insert" parameterClass="mybatis.A_HARRY">
        <selectKey keyProperty="id" resultClass="int">
            SELECT EXAMPLE_ID_SEQ.NEXTVAL as val from dual
        </selectKey>
        insert into A_HARRY(id,first_name, last_name, salary)
        values (#id#,#first_name#, #last_name#, #salary#)
    </insert>
   
    <update id="update" parameterClass="mybatis.A_HARRY">
        UPDATE A_HARRY
        SET    first_name = #first_name#
        WHERE  id = #id#
    </update>
   
   
   
</sqlMap>

How to use Soap Handler Class to get Web Service Response?

import java.io.ByteArrayOutputStream;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Map;
import java.util.Set;
import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.soap.SOAPMessage;
import javax.xml.ws.handler.MessageContext;
import javax.xml.ws.handler.soap.SOAPHandler;
import javax.xml.ws.handler.soap.SOAPMessageContext;
import org.xml.sax.InputSource;

import pack.DefineStaticVariables;

import com.sun.org.apache.xml.internal.serialize.OutputFormat;
import com.sun.org.apache.xml.internal.serialize.XMLSerializer;
import org.w3c.dom.Document;

public class WebServiceResponseHandler implements SOAPHandler<SOAPMessageContext>
{
    public static String getSOAPResponse;
    public static String outputSoapMsg;
    DBCustom objDBCustom =null;
   
    public WebServiceResponseHandler()
    {
        objDBCustom = DefineStaticVariables.objDBCustom;
    }
   
    public void init(Map mapCollection)
    {
        objDBCustom.logDebugInfo("In init function..");
    }

    public boolean handleMessage(SOAPMessageContext messageContext)     {
        objDBCustom.logDebugInfo("In handleMessage() function..");
        getRequestResponse(messageContext);
        return true;
    }

    public boolean handleFault(SOAPMessageContext messageContext) {
        objDBCustom.logDebugInfo("In handleFault() function..");
        getRequestResponse(messageContext);
        return true;
    }

   
    public void close(MessageContext messageContext) {
        objDBCustom.logDebugInfo("In close() function..");
    }
   
    public void destroy() {
        objDBCustom.logDebugInfo("In destroy() function..");
    }
    public void getRequestResponse(SOAPMessageContext messageContext)
    {       
        objDBCustom.logDebugInfo("In getRequestResponse() function..");
        SOAPMessage objSOAPMessage = null;
        ByteArrayOutputStream objByteArrayOS =null;
        Boolean outboundProperty;
        Document objDocument = null;
        InputSource objInputSource =null;
        DocumentBuilderFactory documentBuilderFactory = null;
        DocumentBuilder documentBuilder =null;
        OutputFormat outFormat = null;
        Writer streamWriter = null;
        XMLSerializer serializeXML = null;
       
         try
        {
           
            objSOAPMessage = messageContext.getMessage();
           
            objByteArrayOS = new ByteArrayOutputStream();
            objSOAPMessage.writeTo(objByteArrayOS);
            outboundProperty = (Boolean) messageContext.get(MessageContext.MESSAGE_OUTBOUND_PROPERTY);
           
            if (!outboundProperty.booleanValue())
            {
                documentBuilderFactory = DocumentBuilderFactory.newInstance();
                documentBuilder = documentBuilderFactory.newDocumentBuilder();
                objInputSource = new InputSource(new StringReader(objByteArrayOS.toString()));
                objDocument = documentBuilder.parse(objInputSource);
                outFormat = new OutputFormat(objDocument);
                outFormat.setIndenting(true);
                outFormat.setIndent(2);
               
                streamWriter = new StringWriter();
                serializeXML = new XMLSerializer(streamWriter, outFormat);
                serializeXML.serialize(objDocument);
                getSOAPResponse = streamWriter.toString();
                objDBCustom.logDebugInfo("Web Service Response : " + getSOAPResponse);
               
                if(!getSOAPResponse.equals(""))
                {
                           myDBCustom.gResponseData.append(getSOAPResponse);
                }
                else
                     objDBCustom.logDebugInfo("Unable to get response Data");
            }
            else
            {
                 objDBCustom.logDebugInfo("In getRequestResponse() function: Web Service request sent");
            }
       }   
       catch (Exception errorException)
       {
            objDBCustom.logErrorInfo("Exception in logging handler: " + errorException.toString());           
       }
    }
}


Interface:  javax.xml.ws.handler.soap.SOAPMessageContext;
The interface SOAPMessageContext provides access to the SOAP message for either RPC request or response.

Implementation Class: com.sun.xml.internal.ws.handler.SOAPMessageContextImpl



In XML FILE:

<handler-chains xmlns="http://java.sun.com/xml/ns/javaee"
                xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                xsi:schemaLocation="http://java.sun.com/xml/ns/javaee">
    <handler-chain>
        <handler>
            <handler-name>WebServiceResponseHandler</handler-name>
            <handler-class>MasterProcess.WebServiceResponseHandler</handler-class>
        </handler>
    </handler-chain>
</handler-chains>

In Main Service File
@HandlerChain(file = "../Conf/ChainHandle.xml")
public class WSObjectContext extends Service
{
}

@Handler Chain, Associates the Web Service with an externally defined handler chain.