controller class

public with sharing class SearchProduct {
public list<Product2> searchResults { get; set;}
public string searchText {get;set;}

// Variables required for Sorting.
public String soql {get;set;}
public string recordid {get; set;}

public List <Product2> ProductList1 = New List <Product2>();
//public List<pProduct2> ProductList {get; set;}
public String soqlsort {get;set;}
public List <Product2> ProductList2 = New List <Product2>();

public String allchecked { get; set; }


private Set<Id> selectedproductIds;

// item in context from the page

public String contextItem{get;set;}
//private ApexPages.StandardSetController Con;

public SearchProduct()
{

}


public void doSelectItem(){

this.selectedproductIds.add(this.contextItem);

}


// handle item deselected

public void SelectAllItems()
{
//this.selectedproductIds.clear();

//List<productlistdisplay> LstProd=getproducts();
/*
for(LstProd)
{
this.selectedproductIds.add(this.ProductId);
}
*/
}
public void doDeselectItem(){

this.selectedproductIds.remove(this.contextItem);

}
public Integer getSelectedCount(){

return this.selectedproductIds.size();

}





// fired when the search button is clicked
public PageReference search()
{

//String qry = new List<Product2>(); // init the list if it is null
if(SearchText!= null)
{
String qry ='Select id,Name,ProductCode,List_Price__c,Family,Description from Product2 WHERE Name LIKE \'%'+searchText+'%\'OR ProductCode LIKE \'%'+searchText+'%\' order by Name';
this.con = new ApexPages.StandardSetController(Database.query(qry));
this.con.setPageSize(10);
this.con.setPageNumber(1);
//this.selectedproductIds= new Set<Id>();
}
else
{
this.con=null;
}

return null;

}

public PageReference show()
{
product2 products=new product2();
System.debug('-----------'+products.id);
pagereference ref= new pagereference('/'+recordid);
ref.setredirect(false);
return ref;
}


public PageReference save() {
// id oppid;
opportunity opp= [select id,Name from opportunity where id = :System.currentPageReference().getParameters().get('id')];
List<OppLineItem__c> Recordstosave = new List<OppLineItem__c>();

for(productlistdisplay Lstselected :Selectedprodlist){
OppLineItem__c OLI = new OppLineItem__c();
OLI.LineDescription__c = Lstselected.LineDes;
OLI.Pro_Quantity__c = Lstselected.Quantity;
OLI.List_Price__c = Lstselected.prod.List_Price__c;
OLI.Sales_Price__c= Lstselected.prod.List_Price__c;
//OLI.Date__c=Date.ValueOf(Opp_Date);
OLI.Product__c=Lstselected.prod.Name;
OLI.Opportunity__c=opp.id;
OLI.Product_Code__c=Lstselected.prod.ProductCode;
Recordstosave.add(OLI);

}
insert Recordstosave;
PageReference pageRef= new PageReference('https://ap1.salesforce.com/00690000009q8RY');
pageRef.setredirect(true);
return pageRef;
}






// List used in to display the table in VF page.
//public List<Product2> getProductList() {
// Passing the values of list to VF page.
//return con.getRecords();
//}

// instantiate the StandardSetController from a query locator
public ApexPages.StandardSetController con {
get {
if(con == null) {
this.selectedproductIds= new Set<Id>();
// String Query to have a list of Products for a respective End-user.
soql = 'SELECT id,Name,ProductCode,Family,List_Price__c,Description FROM Product2';

// Passing the String array to a list with Selected field sorting.
ProductList1 = Database.query(soql + ' order by ' + sortField + ' ' + sortDir );

// setting values of List in StandardSetController.
this.con = new ApexPages.StandardSetController(ProductList1);

// sets the number of records in each page set
this.con.setPageSize(10);
this.con.setPageNumber(1);
}
return con;
}
set;
}

// indicates whether there are more records after the current page set.
public Boolean hasNext {
get {
return con.getHasNext();
}
set;
}

// indicates whether there are more records before the current page set.
public Boolean hasPrevious {
get {
return con.getHasPrevious();
}
set;
}

// returns the page number of the current page set
public Integer pageNumber {
get {
return con.getPageNumber();
}
set;
}

Public Integer getTotalPages(){

Decimal totalSize = this.con.getResultSize();
Decimal pageSize = this.con.getPageSize();

Decimal pages = totalSize/pageSize;

return (Integer)pages.round(System.RoundingMode.CEILING);
}

// returns the first page of records
public void first() {
con.first();
}

// returns the last page of records
public void last() {
con.last();
}

// returns the previous page of records
public void previous() {
con.previous();
}

// returns the next page of records
public void next() {
con.next();
}

// returns the PageReference of the original page, if known, or the home page.
public void cancel() {
con.cancel();
}

public PageReference AddProductToOpp()
{
PageReference pageRef= new PageReference('/apex/AddProductToOpp');
pageRef.setredirect(false);
return pageRef;
}

//Toggles the sorting of query from asc<-->desc
public void toggleSort() {
// simply toggle the direction
sortDir = sortDir.equals('asc') ? 'desc' : 'asc';

// run the query again for sorting other columns
soqlsort ='SELECT id,Name,ProductCode,Family,List_Price__c,Description FROM Product2';

// Adding String array to a List array
ProductList2 = Database.query(soqlsort + ' order by ' + sortField + ' ' + sortDir );

// Adding Caselist to Standard Pagination controller variable
con = new ApexPages.StandardSetController(ProductList2 );

// Set Page Size to 5
con.setPageSize(5);

}

// the current sort direction. defaults to asc
public String sortDir {
// To set a Direction either in ascending order or descending order.
get { if (sortDir == null) { sortDir = 'asc'; } return sortDir;}
set;
}

// the current field to sort by. defaults to last name
public String sortField {
// To set a Field for sorting.
get { if (sortField == null) {sortField = 'Name'; } return sortField; }
set;
}

// format the soql for display on the visualforce page
public String debugSoql {
get { return soql + ' order by ' + sortField + ' ' + sortDir + ' limit 20'; }
set;
}





//Wrapper Class for checkbox selection

public list<productlistdisplay> listproduct{get;set;}


public List<productlistdisplay> getproducts(){


listproduct= new List<productlistdisplay>();

for(product2 p : (List<product2>)this.Con.getRecords()){
//product2 p = (product2)pr;

productlistdisplay pd = new productlistdisplay(p);


if(this.selectedproductIds.contains(p.Id)){
pd.check=true;
}

listproduct.add(pd);
//else{
//pd.check=false;}



}

return listproduct;
}







public list<productlistdisplay> SelectedprodList{get;set;}
public list<productlistdisplay> getSelectedproducts()
{

selectedprodList = new list<productlistdisplay >();
for(productlistdisplay pCon:getproducts())
{
if(pCon.Check == true)
{
selectedprodList.add(pCon);

}

}
system.debug('#### SELETCED'+selectedprodList.size());
return selectedprodList;
}

public class productlistdisplay{
public product2 prod{get;set;}
public decimal Quantity{get;set;}
public date Opp_Date{get;set;}
public string LineDes{get;set;}
public double Sales_Price{get;set;}
public boolean check{get;set;}


public productlistdisplay( product2 p){
this.prod=p;
check=false;
}
}
}

Visual Force

<apex:page controller="SearchProduct" tabStyle="Opportunity" Sidebar="false">
<apex:sectionHeader title="Product Slection for" subtitle="Opportunity" />
<div>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Add products to this opportunity from Standard price book.
</div>

<style> .aDiff { color: red; } </style>

<!-- style class To make a button as center -->


<style>
.wrapper {
text-align: center;
}

.button {
position: absolute:
top: 50%;
}
</style>



<apex:form id="form" >
<apex:messages style="color:red"/>

<!-- function to handle checkbox selection -->
<script type="text/javascript">
function doCheckboxChange(cb,itemId){

if(cb.checked==true){
//alert('checed'+itemId);
aSelectItem(itemId);
}
else{
aDeselectItem(itemId);
}

}

function checkAll(cb,cbid)
{


var inputElem = document.getElementsByTagName("input");
for(var i=0; i<inputElem.length; i++)
{
if(inputElem[i].id.indexOf("checkedone")!=-1)
inputElem[i].checked = cb.checked;
}
}

</script>

<apex:pageBlock id="Select" tabStyle="Opportunity">
<div class="wrapper">

<apex:commandButton action="{!AddProductToOpp}" value="Select"/>
<apex:commandButton action="{!cancel}" value="Cancel"/>
</div>
</apex:pageBlock>
<apex:pageBlock Title="Find Products" mode="edit" id="block" >
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Enter your Product Code or Product Name, then click Search to begin your search. Search results include all records based on your keyword.</p><br> </br>
<apex:outputPanel >
<apex:outputLabel for="searchText">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<h3>By Keyword</h3></apex:outputLabel><br></br>

&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<apex:inputText id="searchText" value="{!searchText}"/><br></br>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<apex:commandButton value="Search" action="{!search}" rerender="ProductTable" status="status"/>
<apex:actionStatus id="status" startText="Searching... please wait..."/>
</apex:outputPanel>



</apex:pageBlock>




<apex:pageBlock >


<apex:actionFunction name="aSelectItem" action="{!doSelectItem}" rerender="refresh">

<apex:param name="contextItem" value="" assignTo="{!contextItem}"/>
</apex:actionFunction>
<apex:actionFunction name="aSelectAllItems" action="{!SelectAllItems}" rerender="refresh"/>
<!-- handle deselected item -->
<apex:actionFunction name="aDeselectItem" action="{!doDeselectItem}">
<apex:param name="contextItem" value="" assignTo="{!contextItem}"/>
</apex:actionFunction>



<apex:pageBlockTable value="{!products}" var="ProList" align="centre" id="ProductTable" columns="10">
<apex:column >
<apex:facet name="header">
<apex:inputCheckbox value="{!ProList.check}" onclick="checkAll(this,'checkedone')" style="background-color:lightblue;" />
</apex:facet>
<apex:inputCheckbox value="{!ProList.check}" id="checkedone" onchange="doCheckboxChange(this,'{!ProList.prod.Id}')" />
</apex:column>

<apex:column >

<apex:facet name="header" >
<apex:commandLink action="{!toggleSort}" rerender="ProductTable">
<apex:outputText value="Product Name" />
<apex:outputText escape="false" rendered="{!sortField =='Name'&&sortDir=='asc'}">
<img src="/s.gif" alt="Sorted Ascending" class="sortAsc" title="Sorted Ascending" />
</apex:outputText>
<apex:outputText escape="false" rendered="{!sortField =='Name'&&sortDir=='desc'}">
<img src="/s.gif" alt="Sorted Descending" class="sortDesc" title="Sorted Descending" />
</apex:outputText>
<apex:param value="Name" name="column" assignTo="{!sortField }" />
<apex:param value="{!IF(sortDir=='asc'&&sortField =='Name', 'asc', 'desc')}" name="direction" assignTo="{!sortDir}" />
</apex:commandLink>

</apex:facet>
<apex:commandlink value="{!ProList.prod.Name}" action="{!show}" rerender="ProductTable" >
<apex:param value="{!ProList.prod.id}" assignTo="{!recordid}" name="recordid"/>
</apex:commandLink>
</apex:column>

<apex:column >
<apex:facet name="header" >
<apex:commandLink action="{!toggleSort}" rerender="ProductTable">
<apex:outputText value="Product Code" />
<apex:outputText escape="false" rendered="{!sortField =='ProductCode'&&sortDir=='asc'}">
<img src="/s.gif" alt="Sorted Ascending" class="sortAsc" title="Sorted Ascending" />
</apex:outputText>
<apex:outputText escape="false" rendered="{!sortField =='ProductCode'&&sortDir=='desc'}">
<img src="/s.gif" alt="Sorted Descending" class="sortDesc" title="Sorted Descending" />
</apex:outputText>
<apex:param value="ProductCode" name="column" assignTo="{!sortField }" />
<apex:param value="{!IF(sortDir=='asc'&&sortField =='ProductCode', 'asc', 'desc')}" name="direction" assignTo="{!sortDir}" />
</apex:commandLink>

</apex:facet>
<apex:commandlink value="{!ProList.prod.ProductCode}" action="{!show}" rerender="ProductTable">
<apex:param value="{!ProList.prod.id}" assignTo="{!recordid}" name="recordid"/>
</apex:commandLink>
</apex:column>

<apex:column >
<apex:facet name="header" >
<apex:commandLink action="{!toggleSort}" rerender="ProductTable">
<apex:outputText value="List Price" />
<apex:outputText escape="false" rendered="{!sortField =='List_Price__c '&&sortDir=='asc'}">
<img src="/s.gif" alt="Sorted Ascending" class="sortAsc" title="Sorted Ascending" />
</apex:outputText>
<apex:outputText escape="false" rendered="{!sortField =='List_Price__c '&&sortDir=='desc'}">
<img src="/s.gif" alt="Sorted Descending" class="sortDesc" title="Sorted Descending" />
</apex:outputText>
<apex:param value="List_Price__c " name="column" assignTo="{!sortField }" />
<apex:param value="{!IF(sortDir=='asc'&&sortField =='List_Price__c ', 'asc', 'desc')}" name="direction" assignTo="{!sortDir}" />
</apex:commandLink>

</apex:facet>
<apex:outputField value="{!ProList.prod.List_Price__c }"/>
</apex:column>

<apex:column >
<apex:facet name="header" >
<apex:commandLink action="{!toggleSort}" rerender="ProductTable">
<apex:outputText value="Product Family" />
<apex:outputText escape="false" rendered="{!sortField =='Family'&&sortDir=='asc'}">
<img src="/s.gif" alt="Sorted Ascending" class="sortAsc" title="Sorted Ascending" />
</apex:outputText>
<apex:outputText escape="false" rendered="{!sortField =='Family'&&sortDir=='desc'}">
<img src="/s.gif" alt="Sorted Descending" class="sortDesc" title="Sorted Descending" />
</apex:outputText>
<apex:param value="Family" name="column" assignTo="{!sortField }" />
<apex:param value="{!IF(sortDir=='asc'&&sortField =='Family', 'asc', 'desc')}" name="direction" assignTo="{!sortDir}" />
</apex:commandLink>

</apex:facet>
<apex:outputField value="{!ProList.prod.Family}"/>
</apex:column>
<apex:column >
<apex:facet name="header" >
<apex:commandLink action="{!toggleSort}" rerender="ProductTable">
<apex:outputText value="Product Description" />
<apex:outputText escape="false" rendered="{!sortField =='Description'&&sortDir=='asc'}">
<img src="/s.gif" alt="Sorted Ascending" class="sortAsc" title="Sorted Ascending" />
</apex:outputText>
<apex:outputText escape="false" rendered="{!sortField =='Description'&&sortDir=='desc'}">
<img src="/s.gif" alt="Sorted Descending" class="sortDesc" title="Sorted Descending" />
</apex:outputText>
<apex:param value="Description" name="column" assignTo="{!sortField }" />
<apex:param value="{!IF(sortDir=='asc'&&sortField =='Description', 'asc', 'desc')}" name="direction" assignTo="{!sortDir}" />
</apex:commandLink>

</apex:facet>
<apex:outputField value="{!ProList.prod.Description}"/>
</apex:column>

</apex:pageBlockTable>





<apex:panelGrid columns="6" id="refresh">
<apex:outputLabel value="[{!selectedCount} records selected]" />
<apex:commandLink action="{!first}">First</apex:commandlink>
<apex:commandLink action="{!previous}" rendered="{!hasPrevious}">Previous</apex:commandlink>
<apex:commandLink action="{!next}" rendered="{!hasNext}">Next</apex:commandlink>
<apex:commandLink action="{!last}">Last</apex:commandlink>

<apex:outputLabel value="(page {!pageNumber} of {!totalPages})" styleClass="aDiff"/>
</apex:panelGrid>




</apex:pageBlock>

<apex:pageBlock title="Debug - SOQL" id="debug">
<apex:outputText value="{!debugSoql}" />
</apex:pageBlock>



</apex:form>
</apex:page>