manufacturehelper.java

ORACLE AQ sample 演示的如何出列

    p_productList.put(p_updatedProductInfo.getProductID(), p_updatedProductInfo);

    return p_productList;
  }

  /**
   * This method is called when the manufacturer wants to
   * delete few products from his database. The basic functionality
   * of this method is to construct one query for each of the
   * product selected for deletion and send it to DBConnect.java
   * to be executed, then send the details of all the products
   * deleted to ENqueuePrdHelper to be enqueued and sent to
   * Retail manager through message propagation. If everything goes
   * on successfully then all the details are deleted from the
   * products hash and returned to the calling method in the
   * respective manager class.
   *
   * @param p_user Type of the user
   * @param p_productList List of all the products the manufacturer has
   * @param p_productsToBeDeleted Details of the products to be deleted
   * @exception Exception Incase of some error or unreported Exception
   * @return Details of the products the manufacturer currently has after
   *     deleting the product details sent.
   * @see Product.java
   * @see EnqueuePrdHelper.java
   * @see DBConnect.java
   */
  public static Hashtable deleteProducts(String p_user, Hashtable p_productList,
                          Product[] p_productsToBeDeleted) throws Exception{
    // Get DBConnect Instance to execute query
    DBConnect dbInstance = DBConnect.getInstance();

    // Store the number of products to be deleted.
    int noOfPrds=p_productsToBeDeleted.length;
    String[] queriesArr=new String[noOfPrds];
    for(int i=0;i<noOfPrds;i++){
      // Construct array of queries for all the products to be deleted.
      queriesArr[i] = new StringBuffer("DELETE PRODUCT_MASTER WHERE product_id='")
                        .append(p_productsToBeDeleted[i].getProductID())
                        .append("' AND manufacturer_id ='")
                        .append(p_productsToBeDeleted[i].getManufactureID())
                        .append("'").toString();
    }

    // Execute the query using the DBConnect instance retrieved.
    int arr[]=dbInstance.executeUpdate(queriesArr, p_user);

    // Add the product details into Queue.
    EnqueuePrdHelper.addPrdToQueue(p_productsToBeDeleted,p_user,"DELETE");

    // Delete all the details of the product from the hash table using their
    // product id.
    for(int i=0;i<noOfPrds;i++){
      p_productList.remove(p_productsToBeDeleted[i].getProductID());
    }
    return p_productList;
  }

  /**
   * This method is called by addProduct method. The basic
   * functionality of this method is to construct a query
   * to retrieve the next product ID from the sequence,
   * convert it into product Id by appending the alphabet
   * 'P' in front and return it.
   *
   * @param p_user Type of the user
   * @exception Exception Incase of some error or unreported Exception
   * @return The product id of the product to be added
   */
  private static String getProductId(String p_user) throws Exception{
    // Get DBConnect Instance to execute query
    DBConnect dbInstance = DBConnect.getInstance();

    // Construct the query
    String query="SELECT Product_Id_Seq.NEXTVAL FROM DUAL";

    // Execute the query using the instance retrieved.
    Vector productIdVec=dbInstance.executeQuery(query, p_user);
    
    String productId="";

    // The Vector retrieved will contain one value in one row retrieved from
    // the sequence.
    for(int i=0;i<productIdVec.size();i++){
      // Get the next sequence from the Vector
      String[] resultArr=(String[])productIdVec.elementAt(i);

      // Append the alphabet 'P' to it to form the product id.
      productId=new StringBuffer().append("P").append(resultArr[0]).toString();
      
      break;
    }
    return productId;
  }

  /**
   * This method is called by addProduct method. The basic
   * functionality of this method is to construct a query
   * to retrieve the manufacturer ID from the Manufacturer master table,
   * and return it to the function.
   *
   * @param p_user Type of the user
   * @exception Exception Incase of some error or unreported Exception
   * @return The manufacturer id of the product to be added
   */
  private static String getManufacturerId(String p_user) throws Exception{
    // Get DBConnect Instance to execute query
    DBConnect dbInstance = DBConnect.getInstance();

    // Construct the query
    String query="SELECT manufacturer_id FROM Manufacturer_Master";

    // Execute the query using the instance retrieved.
    Vector manufacturerIdVec=dbInstance.executeQuery(query, p_user);
    
    // The manufacturer table contains only one row which contains the id of the
    // manufacturer. So the query returned contains only the manufacturer id in 
    // the string array as the only element in the vector.
    return (((String[])manufacturerIdVec.elementAt(0))[0]);

  }
  /**
   * This method converts the List of products stored in the vector as an
   * array of string into a Hash table. The key of the Hash table is productId
   * and value is object of the class Product.
   *
   * @exception Exception Incase of some error or unreported Exception
   * @param productsVector Details of all the products stored as an array of
   *     strings in the Vector.
   * @return Details of all the products the manufacturer has in the form of
   *      Hash table
   * @see DBConnect.java
   */
  private static Hashtable storePrdsInHash(Vector p_productsVector)
                                            throws Exception {
    Hashtable productHash = new Hashtable();
    int noOfProducts      = p_productsVector.size();
    Product productObj    = null;
    String[] productArr;
    for(int i=0;i<noOfProducts;i++){
      // The information about the product is stored as an array of String in
      // the Vector.
      productArr  = (String [])p_productsVector.elementAt(i);

      // Store the details of the product present in the array in Product object.
      productObj  = storeProductDetails(productArr);

      // ProductId is used as key for the hash table.
      productHash.put(productArr[0], productObj);
    }
    return productHash;
  }

  /**
   * Retrieves the product details stored as string array in Vector
   * and assigns it to the corresponding element in the object of
   * Product using the set methods provided in the class.
   *
   * @param productArr Details of the product
   * @exception Exception Incase of some error or unreported Exception
   * @return Object of the class Product containing the details of the product
   *      sent in vector
   * @see Product.java
   */
  private static Product storeProductDetails(String[] p_productArr)
                                          throws Exception{
     Product product = new Product();
     product.setProductID(p_productArr[0]);
     product.setProductName(p_productArr[1]);
     product.setProductDesc(p_productArr[2]);
     product.setManufactureID(p_productArr[3]);
     product.setCategoryDesc(p_productArr[5]);
     product.setProductPrice(p_productArr[4]);
     product.setQuantityOnHand(p_productArr[6]);
     return product;
  }
}