DPML Notify

[niclas AT hedhman.org]

Author: niclas AT hedhman.org
Date: Thu Apr 21 12:53:35 2005
New Revision: 2343

Added:
   development/planet/users/niclas/book/atm/simple/accounts/src/main/
   development/planet/users/niclas/book/atm/simple/accounts/src/main/net/
   development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/
   
development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/book/
   
development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/book/atm/
   
development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/book/atm/simple/
   
development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/book/atm/simple/accounts/
   
development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/book/atm/simple/accounts/SimpleAccountManager.java
Log:


Added: 
development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/book/atm/simple/accounts/SimpleAccountManager.java
==============================================================================
--- (empty file)
+++ 
development/planet/users/niclas/book/atm/simple/accounts/src/main/net/dpml/book/atm/simple/accounts/SimpleAccountManager.java
       Thu Apr 21 12:53:35 2005
@@ -0,0 +1,122 @@
+/* 
+ * Copyright 2005 Niclas Hedhman
+ * Licensed  under the  Apache License,  Version 2.0  (the "License");
+ * you may not use  this file  except in  compliance with the License.
+ * You may obtain a copy of the License at 
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed  under the  License is distributed on an "AS IS" BASIS,
+ * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
+ * implied.
+ * 
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package net.dpml.book.atm.simple.accounts;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.util.Properties;
+
+import net.dpml.book.atm.BackEndProvider;
+import net.dpml.book.atm.WithdrawalException;
+
+import net.dpml.parameters.ParameterException;
+import net.dpml.parameters.Parameters;
+
+/** This simple BackEndProvider implementation uses java.util.Properties
+ *  files to emulate a backend banking host.
+ *  
+ * @author <a href="mailto:niclas AT hedhman.org";>Niclas Hedhman</a>
+ * @metro.component name="simple-accountmanager" lifestyle="singleton"
+ * @metro.service type="net.dpml.book.atm.BackEndProvider"
+ */
+public class SimpleAccountManager 
+    implements BackEndProvider
+{
+    private String m_accountsFilename;
+    private Properties m_accounts;
+    private Properties m_pins;
+    
+    public SimpleAccountManager( Parameters params )
+        throws ParameterException, IOException
+    {
+        m_accountsFilename = params.getParameter( "accounts-filename" );
+        String pinsFilename = params.getParameter( "pinnumbers-filename" );
+        
+        m_accounts = loadProperties( m_accountsFilename );
+        m_pins = loadProperties( pinsFilename );
+    }
+    
+    public boolean requestWithdrawal( String account, String pin, String 
amount )
+    {
+        if( validate( account, pin ) == false )
+            return false;
+        return haveEnough( account, amount );
+    }
+
+    public void withdraw( String account, String amount )
+        throws WithdrawalException
+    {
+        synchronized( this )
+        {
+            if( haveEnough( account, amount ) == false )
+                throw new WithdrawalException( "Not enough credit for the 
account to make withdrawal of " + amount );
+            BigDecimal balance = getBalance( account );
+            BigDecimal withdrawn = convert( amount );
+            BigDecimal newBalance = balance.subtract( withdrawn );
+            m_accounts.setProperty( account, newBalance.toString() );
+            try
+            {
+                saveAccounts();
+            } catch( IOException e )
+            {
+                throw new WithdrawalException( "Withdrawal failed due to 
IOException." );
+            }
+        }
+    }
+
+    private boolean validate( String account, String pin )
+    {
+        String correct = m_pins.getProperty( account );
+        return pin.equals( correct );
+    }
+    
+    private boolean haveEnough( String account, String amount )
+    {
+        BigDecimal balance = getBalance( account );
+        BigDecimal askingFor = convert( amount );
+        return balance.subtract( askingFor ).floatValue() > 0 ;
+    }
+    
+    private BigDecimal getBalance( String account )
+    {
+        String amount = m_accounts.getProperty( account );
+        return convert( amount );
+    }
+    
+    private BigDecimal convert( String amount )
+    {
+        return new BigDecimal( amount );
+    }
+    
+    private Properties loadProperties( String filename )
+        throws IOException
+    {
+        FileInputStream in = new FileInputStream( filename );
+        Properties props = new Properties();
+        props.load( in );
+        return props;
+    }
+    
+    private void saveAccounts()
+        throws IOException
+    {
+        FileOutputStream out = new FileOutputStream( m_accountsFilename );
+        m_accounts.store( out, "Account = amount " );
+    }
+}