Pass data from VisualForce page to Apex Class

Question

I have a VisualForce page which displays some data from a standard controller, I would like to know how I can add a button which activates an apex class? I want to also pass data thats visible in the VF page to the apex class.

VF Page

<apex:page standardController="Opportunity" showHeader="false" sidebar="false">

    <apex:pageBlock >
        <apex:pageBlockSection title="Opportunity" columns="1">
            <apex:outputField value="{!Opportunity.Name}"/>
            <apex:pageBlockSectionItem >
            <apex:outputText value="Contacts"/>
            <apex:pageBlockTable title="Contacts" 
                                 value="{!Opportunity.Designer__r}" var="contact">
                <apex:column value="{!contact.Name}"/>
                <apex:column value="{!contact.Phone}"/>
            </apex:pageBlockTable>
            </apex:pageBlockSectionItem>
        </apex:pageBlockSection>
    </apex:pageBlock>

</apex:page>

Email Apex:

Messaging.reserveSingleEmailCapacity(1);
Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
String[] toAddresses = new String[] {'[email protected]'};
mail.setToAddresses(toAddresses);
mail.setReplyTo('[email protected]');
mail.setSenderDisplayName('John Doe');
mail.setSubject('Opportunity Request : ' + Opportunity.Id); // at the moment Opportunity ID is not linked to anything
mail.setBccSender(false);
mail.setUseSignature(false);
mail.setPlainTextBody('Your Opportunity: ' + Opportunity.Id +' request.');
Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });

Answer 1

It sounds like a controller extension is actually what you need:

<apex:page standardController='Opportunity' extensions='MyExtension'>
  <apex:form>
    <apex:inputField value="{!Opportunity.Name}" />
     <apex:commandButton value="this button" value="{!doSomething}" />
  </apex:form>
</apex:page>

Extension:

public with sharing MyExtension
{
  private Opportunity opp;

  public MyExtension(ApexPages.StandardController cont)
  {
    opp =(Opportunity) cont.getRecord();
  }

  public PageReference doSomething()
  {
    //do something here
  }
}

http://www.salesforce.com/us/developer/docs/pages/Content/pages_controller_extension.htm

Answer 2

Based on your comment I believe you need to add a controller extension to your page with a method that your custom button calls. That method can then call a static method from your other Apex Class. Or you could add the logic directly to your extension method, but if this is code you may use in other places, I would recommend keeping it its own class so you can reuse the code.

Something like this

VF

<apex:page standardController="SomeStandardObject" extensions="myCustomExtension">

    <apex:pageBlockButtons location="bottom">
        <apex:commandButton Value="Press Me" action="{!myExtensionMethod}"/>
    </apex:pageBlockButtons>

Extension

public class myCustomExtension {

    public myCustomExtension {

    }

    public void myExtensionMethod {
         MyHelperClass.Method1(param1, param2, param_x);
    }
}

Your Custom Apex Class

public class MyHelperClass {

     public static void Method1(Some_Data_Type param1, Some_Data_Type param2, Some_Data_Type param_c) {
          //YOUR CUSTOM LOGIC HERE
     }
}