package com.oreilly.jent.rmi;
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*
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* includes the title, author, publisher, and ISBN. For example:
*
* "Java Enterprise in a Nutshell, Third Edition,
* by Jim Farley and William Crawford
* with Prakash Malani, John G. Norman, and Justin Gehtland.
* Copyright 2006 O'Reilly Media, Inc., 0-596-10142-2."
*
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import java.io.IOException;
import java.rmi.MarshalledObject;
import java.rmi.RemoteException;
import java.rmi.activation.Activatable;
import java.rmi.activation.ActivationException;
import java.rmi.activation.ActivationID;
import java.util.List;
import java.util.ListIterator;
/**
* ActivatableAccountImpl: Activatable implementation of the Account remote
* interface.
*/
public class ActivatableAccountImpl extends Activatable implements Account {
// Our current balance
private float mBalance = 0;
// Name on account
private String mName = "";
// "Regular" constructor used to create a "pre-activated" server
public ActivatableAccountImpl(String name)
throws RemoteException, ActivationException, IOException {
// Register and export object (on random open port)
// Note that we're
super(null, new MarshalledObject(new AccountState(name, 0f)), false, 0);
mName = name;
}
// Constructor called by the activation runtime to (re)activate
// and export the server
protected ActivatableAccountImpl(ActivationID id, MarshalledObject arg)
throws RemoteException, ActivationException {
// Export this object with the given activation id, on random port
super(id, 0);
System.out.println("Activating an account");
// Check incoming data (account state) passed in with activation request
try {
Object oarg = arg.get();
if (oarg instanceof AccountState) {
AccountState s = (AccountState)oarg;
// Set our name and balance based on incoming state
mName = s.name;
mBalance = s.balance;
}
else {
System.out.println("Unknown argument type received on activation: " +
oarg.getClass().getName());
}
}
catch(Exception e) {
System.out.println("Error retrieving argument to activation");
}
}
public String getName() throws RemoteException {
return mName;
}
public float getBalance() throws RemoteException {
return mBalance;
}
// Withdraw some funds
public void withdraw(float amt)
throws RemoteException, InsufficientFundsException {
if (mBalance >= amt) {
mBalance -= amt;
// Log transaction...
System.out.println("--> Withdrew " + amt + " from account " + getName());
System.out.println(" New balance: " + getBalance());
}
else {
throw new InsufficientFundsException("Withdrawal request of " + amt +
" exceeds balance of " + mBalance);
}
}
// Deposit some funds
public void deposit(float amt) throws RemoteException {
mBalance += amt;
// Log transaction...
System.out.println("--> Deposited " + amt + " into account " + getName());
System.out.println(" New balance: " + getBalance());
}
// Move some funds from another (remote) account into this one
public void transfer(float amt, Account src)
throws RemoteException, InsufficientFundsException {
if (checkTransfer(src, amt)) {
src.withdraw(amt);
this.deposit(amt);
// Log transaction...
System.out.println("--> Transferred " + amt + " from account " + getName());
System.out.println(" New balance: " + getBalance());
}
else {
throw new InsufficientFundsException("Source account balance is less " +
"than the requested transfer.");
}
}
// Make several transfers from other (remote) accounts into this one
public void transfer(List amts, List srcs)
throws RemoteException, InsufficientFundsException {
ListIterator amtCurs = amts.listIterator();
ListIterator srcCurs = srcs.listIterator();
// Iterate through the accounts and the amounts to be
// transferred from each (assumes amounts are given as Float
// objects)
while (amtCurs.hasNext() && srcCurs.hasNext()) {
Float amt = (Float)amtCurs.next();
Account src = (Account)srcCurs.next();
// Make the transaction
this.transfer(amt.floatValue(), src);
}
}
// Check to see if the transfer is possible, given the source account
private boolean checkTransfer(Account src, float amt) {
boolean approved = false;
try {
if (src.getBalance() >= amt) {
approved = true;
}
}
catch (RemoteException re) {
// If some remote exception occurred, then the transfer is still
// compromised, so return false
approved = false;
}
return approved;
}
}
// Define a structure to hold our state information in a single marshalled
// object, so that we can register it with the activation system
class AccountState {
public float balance = 0f;
public String name = null;
public AccountState(String n, float b) {
name = n;
balance = b;
}
}
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