bankbean.java

想学习EJB的同学

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package ejb3.day4;

import java.util.List;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.LockModeType;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

/**
 *
 * @author user
 */
@Stateless(mappedName="ejb/bank")
public class BankBean implements BankRemote, BankLocal {
    @PersistenceContext
    private EntityManager em;

    
    public Account open(String name, float balance) {
        Account acc = new Account();
        acc.setName(name);
        acc.setBalance(balance);
        em.persist(acc);
        return acc;
    }

    public void deposit(Long id, float amt) {
        Account acc = em.find(Account.class, id);
        em.lock(acc, LockModeType.WRITE);
        acc.setBalance(acc.getBalance() + amt);
    }

    public float withdraw(Long id, float amt) {
        Account acc = em.find(Account.class, id);
        float balance = acc.getBalance();
        if(amt <= balance){
            acc.setBalance(balance - amt);
            return amt;
        }
        return 0.0F;
    }

    public List<Account> findAccountsByName(String name) {
        Query q = em.createNamedQuery("findByName");
        q.setParameter("name", name);
        return q.getResultList();
    }

    public List<Account> getAllAccounts() {
        Query q = em.createNamedQuery("findAll");
        return q.getResultList();
    }
}