Apex Rest

@RestResource(urlMapping='/xxxx/*')
global with sharing class MyWLResource {
  @HttpPost
    global static void doPost(String accountid) 
    {
        Account myaccount;
        list <Opportunity> myresult;
        try
        {
            myaccount = [select website from Account where id=:accountid];
            myresult=[select id from Opportunity where website__c=:myaccount.website limit 10];

            RestContext.response.addHeader('Content-Type', 'application/json');
            RestContext.response.responseBody = Blob.valueOf(JSON.serialize(myresult));
        }
        catch (Exception e) 
        {
            RestContext.response.addHeader('Content-Type', 'text/plain');
            RestContext.response.responseBody = Blob.valueOf('Incorrect account id');
        }
    }
}