Model Part 2S2C Home « Model Part 2

In this lesson of the case study we finish writing and compiling the model code. To do this we will have to add some imports to the StockImpl class and complete the method stubs we left for this section of the case study. We will start by completing the search() method and finish the model code by updating the stocking() and unstocking() method.

Search Functionality Top

In the first part of the lesson we add imports to the StockImpl class so we can pass back a table model to our users as well as handling exceptions from our services. We then add the functionality to the search() method for passing back search results via the table model to populate the Manufacturer Panel we sketched out in View Part 1 - Designing The GUI.

Updating The StockImpl Class Top

The first thing we need to do is add a couple of imports to the top of the StockImpl class after the existing imports.


import client.ManufacturerTableModel;
import services.ServicesException;

Open the StockImpl class in your text editor and cut and paste the above imports to the top of the StockImpl class after the existing imports.

Save the StockImpl class in the   c:\_Case_Study\src\model directory.

Updating The search() Function

We also need to update the search() function stub so it now returns a ManufacturerTableModel containing all Manufacturer records pertaining to search criteria. We also need to code the method to retrieve this information.


    /**
     * Search manufacturer file via criteria entered by a user in the GUI.
     *
     * @param name The name of the Manufacturer.
     * @param location The location where the Manufacturer is based.

     * @return A ManufacturerTableModel containing all Manufacturer records pertaining to 
     *         search criteria.
     * 
     */
    public ManufacturerTableModel search(String name, String location) {
        log.entering("StockImpl", "search", 
        		new Object[]{name, location});
        ManufacturerTableModel modelStockImpl = new ManufacturerTableModel();
        long[] retrecOffsets = new long[500];

        String[] criteria = {name, location};
        // Use search criteria to return an array of record numbers (500 more than enough)
        retrecOffsets = findBySearchCriteria(criteria);
        // Now read manufacturers from cache map using returned record numbers
        try {
            for (int i = 0; i < retrecOffsets.length; i++) {
                long recOffset = retrecOffsets[i];
                // Exit loop when no more records to process 
                if (recOffset == 0) {
                    break;
                }
                Manufacturer manufacturer = getManufacturer(recOffset);
                modelStockImpl.addManufacturerRecord(manufacturer);
            }
        } catch (RecordNotFoundException e) {
            log.log(Level.SEVERE, e.getMessage(), e);
            throw new ServicesException(e);
        }
        log.exiting("ServicesImpl", "search");
        return modelStockImpl;
    }

In not already open, open the StockImpl class in your text editor and cut and paste the above search() method into the StockImpl class overwriting the existing search() method and comments. The search() method can be found at the very bottom of the StockImpl class.

Save the StockImpl class in the   c:\_Case_Study\src\model directory.

Compiling Our Source File With the -cp and -d Options

Open your command line editor:

Change to directory  cd c:\_Case_Study\src\model

Compile StockImpl.java using the java compiler with the -cp and -d options
  javac -cp ..\..\classes -d ..\..\classes StockImpl.java

The following screenshot shows that the StockImpl class compiles fine after we have made the changes.

update StockImpl class

Stock Functionalitygo to top of page Top

In this part of the lesson we finish the model code for the case study by completing the stocking() and unstocking() methods requested by Stocking Goods Limited. These methods are delegated to, via the Services singleton, whenever a user requests stocking or unstocking within the Manufacturer Application GUI.

Updating The stocking() Method Top

The stocking() method stub needs to be coded to accept a stocking amount entered in the Manufacturer GUI. We will have to update the information held in our cache map and also update the physical Manufacturer file held on disk. We must also ensure that the stock ordered hasn't been set by another user, before setting our locks and updating the information.

Open the StockImpl class in your text editor and cut and paste the following stocking() method into the StockImpl class overwriting the existing stocking() method and comments. This stock() method can be found near the bottom of the StockImpl class.


    /**
     * Stock the requested amount entered by a user in the GUI.
     *
     * @param name The name of the Manufacturer.
     * @param location The location where the Manufacturer is based.
     * @param stockLevel The amount of stock left.
     * @param stockOrdered The amount of stock requested.
     * 
     * @throws StockingException Stock quantity already ordered by another user. 
     * 
     */
    public void stocking(String name, String location, 
            int stockLevel, int stockOrdered) throws StockingException {
        log.entering("StockImpl", "stocking", 
                new Object[]{name, location, stockLevel, stockOrdered});
        Long lock = 0L;
        long[] retrecOffset = new long[1];
        String[] criteria = {name, location};
        boolean unlockRequired = true;
        retrecOffset = findBySearchCriteria(criteria);
        // Return the record number
        long recOffset = retrecOffset[0];

        if (recOffset == 0) {
            log.log(Level.INFO, "Problem stocking Manufacturer: " + name + ", " + location);
            String e = "Problem stocking Manufacturer: " + name + ", " + location;
            throw new ServicesException(e);
        }
        try {
            log.log(Level.FINE, "Run by: " + Thread.currentThread().getName());
            Manufacturer manufacturer = getManufacturer(recOffset);
            // Firstly make sure that stock ordered hasn't been set by another user
            if (!manufacturer.getStockOrdered().equals("")) {
                log.log(Level.INFO, "Manufacturer: " + name + ", " + location +
                            " , " + " product: " + manufacturer.getProduct() + 
                            ", stock quantity already ordered by another user.");
                unlockRequired = false;
                throw new ServicesException("Stock quantity already ordered by another user.");
            } else {
                String strStockLevel = "" + stockLevel;
                manufacturer.setStockLevel(strStockLevel);
                String strStockOrdered = "" + stockOrdered;
                manufacturer.setStockOrdered(strStockOrdered);
                String[] manufacturerData = {manufacturer.getDeletedFlag(), manufacturer.getName(), 
                        manufacturer.getLocation(), manufacturer.getProduct(), 
                        manufacturer.getPrice(), manufacturer.getStockLevel(), 
                        manufacturer.getStockOrdered()};
                //Add record number to the locking map
                lock = lockRecord(recOffset);
                //Update record with new stock totals
                updateRecord(recOffset, manufacturerData, lock);
                log.log(Level.INFO, "Manufacturer: " + name + ", " + location +
                        " product: " + manufacturer.getProduct() + 
                        " stock quantity left: " + stockLevel + 
                        ", stock quantity ordered: " + stockOrdered);
            }	
        } catch (ServicesException e) {
            log.log(Level.WARNING, e.getMessage(), e);
            throw new StockingException(e);
        } catch (ManufacturerFileAccessException e) {
            log.log(Level.SEVERE, e.getMessage(), e);
            throw new ServicesException(e);
        } catch (RecordNotFoundException e) {
            log.log(Level.SEVERE, e.getMessage(), e);
            throw new ServicesException(e);
        } catch (SecurityException e) {  
			log.log(Level.SEVERE, e.getMessage(), e);
            throw new ServicesException(e);
        } finally {  
            if (unlockRequired) {
                //Remove record number from the locking map
                unlock(recOffset, lock);
            }
        }
        log.exiting("StockImpl", "stocking");
    }

Save the StockImpl class in the   c:\_Case_Study\src\model directory.

Updating The unstocking() Method Top

The unstocking() method stub needs to be coded to accept an unstocking amount entered in the Manufacturer GUI. We will have to update the information held in our cache map and also update the physical Manufacturer file held on disk. We must also ensure that the unstocking hasn't already been done by another user, before setting our locks and updating the information.

In not already open, open the StockImpl class in your text editor and cut and paste the above unstocking() method into the StockImpl class overwriting the existing unstocking() method and comments. The unstocking() method can be found near the bottom of the StockImpl class just below the stocking() method.


    /**
     * Unstock the requested amount entered by a user in the GUI.
     *
     * @param name The name of the Manufacturer.
     * @param location The location where the Manufacturer is based.
     * @param stockOrdered The amount of unstocking to do.
     * 
     */
    public void unstocking(String name, String location, int stockOrdered) {
        log.entering("StockImpl", "unstocking", 
                new Object[]{name, location, stockOrdered});
        Long lock = 0L;
        long[] retrecOffset = new long[1];
        String[] criteria = {name, location};
        boolean unlockRequired = true;
        retrecOffset = findBySearchCriteria(criteria);
        // Return the record number
        long recOffset = retrecOffset[0];

        if (recOffset == 0) {
            log.log(Level.INFO, "Problem restocking Manufacturer: " + name + ", " + location);
            String e = "Problem restocking Manufacturer: " + name + ", " + location;
            throw new ServicesException(e);
        }
        try {
            log.log(Level.FINE, "Run by: " + Thread.currentThread().getName());
            Manufacturer manufacturer = getManufacturer(recOffset);
            // Firstly make sure that ordered stock hasn't been cancelled by another user
            if (manufacturer.getStockOrdered().equals("")) {
                log.log(Level.INFO, "Manufacturer: " + name + ", " + location +
                        " , product: " + manufacturer.getProduct() + 
                        " stock quantity ordered, already reset by another user.");
                unlockRequired = false;
            } else {
                //Restock manufacturer and remove stock ordered
                int manStockLevel = 0;
                try {
                    manStockLevel = Integer.parseInt(manufacturer.getStockLevel());
                } catch (NumberFormatException e) {
                    log.log(Level.INFO, "Manufacturer: " + name + ", " + location + 
                            ", " + " stock level was non numeric");
                } finally {
                    manStockLevel = manStockLevel + stockOrdered;
                    String strStockLevel = "" + manStockLevel;
                    manufacturer.setStockLevel(strStockLevel);
                    manufacturer.setStockOrdered("");
                    String[] manufacturerData = {manufacturer.getDeletedFlag(), 
                            manufacturer.getName(), manufacturer.getLocation(), 
                            manufacturer.getProduct(), manufacturer.getPrice(), 
                            manufacturer.getStockLevel(), manufacturer.getStockOrdered()};
                    //Add record number to the locking map
                    lock = lockRecord(recOffset);
                    //Update record with new stock totals
                    updateRecord(recOffset, manufacturerData, lock);
                    log.log(Level.INFO, "Manufacturer: " + name + ", " + location +
                            ", product: " + manufacturer.getProduct() + 
                            ", new Stock Level: " + manufacturer.getStockLevel());
                }
            }
        } catch (ManufacturerFileAccessException e) {
            log.log(Level.SEVERE, e.getMessage(), e);
            throw new ServicesException(e);
        } catch (RecordNotFoundException e) {
            log.log(Level.SEVERE, e.getMessage(), e);
            throw new ServicesException(e);
        } catch (SecurityException e) {  
            log.log(Level.SEVERE, e.getMessage(), e);
            throw new ServicesException(e);
        } finally {  
            if (unlockRequired) {
                //Remove record number from the locking map
                unlock(recOffset, lock);
            }
        }
        log.exiting("StockImpl", "unstocking");
    }

Save the StockImpl class in the   c:\_Case_Study\src\model directory.

Compiling Our Source File With the -cp and -d Options

Open your command line editor:

Change to directory  cd c:\_Case_Study\src\model

Compile StockImpl.java using the java compiler with the -cp and -d options
  javac -cp ..\..\classes -d ..\..\classes StockImpl.java

The following screenshot shows that the StockImpl class compiles fine after we have made the changes.

update StockImpl class 2

Lesson 12 Complete

In this lesson we finished coding the Model elements of the MVC pattern for our case study.

Related Java Tutorials

Beginning Java - Primitive Variables
Beginning Java - Conditional Statements
Beginning Java - Loop Statements
Objects & Classes - Arrays
Objects & Classes - Class Structure and Syntax
Objects & Classes - Reference Variables
Objects & Classes - Methods
Objects & Classes - Instance Variables & Scope
Objects & Classes - Constructors
Objects & Classes - Static Members
Objects & Classes - Enumerations
OO Concepts - Encapsulation
OO Concepts - Inheritance Concepts - Using the super keyword
Swing - RMI - Serialization
Exceptions - Handling Exceptions
API Contents - Inheritance - Using the package keyword
API Contents - Inheritance - Using the import keyword
Concurrency - Synchronization - Synchronized Blocks

What's Next?

In the next section we coding the remote services Controller elements of the MVC pattern for our case study.