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Jboss Ejb3.0 Entity Bean
















 
 




Order.java



package org.jboss.tutorial.entity.bean;




 


import javax.persistence.CascadeType;



import javax.persistence.Entity;



import javax.persistence.FetchType;



import javax.persistence.GeneratorType;



import javax.persistence.Id;



import javax.persistence.OneToMany;



import javax.persistence.Table;



import javax.persistence.Id;



import javax.persistence.CascadeType;



import javax.persistence.FetchType;



import java.util.ArrayList;



import java.util.Collection;




 


@Entity



@Table(name = "PURCHASE_ORDER")



//If the table name isn't specified it defaults to the bean name



//of the class. For instance, the LineItem EJB would be mapped to



//the LINEITEM table



public class Order implements java.io.Serializable



{



   private int id;



   private double total;



   private Collection<LineItem> lineItems;




 


   @Id(generate = GeneratorType.AUTO)



   public int getId()



   {



      return id;



   }




 


   public void setId(int id)



   {



      this.id = id;



   }




 


   public double getTotal()



   {



      return total;



   }




 


   public void setTotal(double total)



   {



      this.total = total;



   }




 


   public void addPurchase(String product, int quantity, double price)



   {



      if (lineItems == null) lineItems = new ArrayList<LineItem>();



      LineItem item = new LineItem();



      item.setOrder(this);



      item.setProduct(product);



      item.setQuantity(quantity);



      item.setSubtotal(quantity * price);



      lineItems.add(item);



      total += quantity * price;



   }




 


   //CascadeType.ALL specifies that when an Order is created,



   //any LineItems held in the lineItems collection will be created



   //as well (CascadeType.PERSIST). If the Order is delete from



   //persistence storage, all related LineItems will be



   //deleted (CascadeType.REMOVE). If an Order instance is



   //reattached to persistence storage, any changes to the



   //LineItems collection will be merged with persistence



   //storage (CascadeType.MERGE).



   //FetchType.EAGER specifies that when the Order is loaded



   //whether or not to prefetch the relationship as well.



   //If you want the LineItems to be loaded on demand, then specify FetchType.LAZY.



   //   The mappedBy attribute specifies that this is a bi-directional



   //relationship that is managed by the order property on the LineItem entity bean.



   @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy="order")



   public Collection<LineItem> getLineItems()



   {



      return lineItems;



   }




 


   public void setLineItems(Collection<LineItem> lineItems)



   {



      this.lineItems = lineItems;



   }



}




 


加了不少英文注释,希望能看得懂。



@Table(name = "PURCHASE_ORDER")



指名数据库(jboss的数据库为hsqldb)中对应得表的名字,默认为class的名字,比如下面的LineItem就没有@table。(order.java , LineItem.java都为o/r映射,值得互相对照)



@Id(generate = GeneratorType.AUTO)



递增,同数据库里的相同。必须在getter方法上标注。



@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy="order")



关系:order和LineItem为1对多的关系。在这里CascadeType.ALL是指明当建立一个Order被实例化后,都应该同时同时建立LineItem。注释里的就是根据两者建立时间的不同,定义了不同的CascadeType。




 



 


LineItem.java



package org.jboss.tutorial.entity.bean;




 


import javax.persistence.Entity;



import javax.persistence.GeneratorType;



import javax.persistence.Id;



import javax.persistence.JoinColumn;



import javax.persistence.ManyToOne;



import javax.persistence.Entity;




 


@Entity



public class LineItem implements java.io.Serializable



{



   private int id;



   private double subtotal;



   private int quantity;



   private String product;



   private Order order;




 


   @Id(generate = GeneratorType.AUTO)



   public int getId()



   {



      return id;



   }




 


   public void setId(int id)



   {



      this.id = id;



   }




 


   public double getSubtotal()



   {



      return subtotal;



   }




 


   public void setSubtotal(double subtotal)



   {



      this.subtotal = subtotal;



   }




 


   public int getQuantity()



   {



      return quantity;



   }




 


   public void setQuantity(int quantity)



   {



      this.quantity = quantity;



   }




 


   public String getProduct()



   {



      return product;



   }




 


   public void setProduct(String product)



   {



      this.product = product;



   }




 


   //The @JoinColumn specifies the foreign key column within the LineItem table.



   @ManyToOne



   @JoinColumn(name = "order_id")



   public Order getOrder()



   {



      return order;



   }




 


   public void setOrder(Order order)



   {



      this.order = order;



   }



}




 



 



 


ShoppingCart.java



package org.jboss.tutorial.entity.bean;




 


import javax.ejb.Remote;



import javax.ejb.Remove;




 


@Remote



public interface ShoppingCart



{



   void buy(String product, int quantity, double price);




 


   Order getOrder();




 


   @Remove void checkout();



}




 



 



 


ShoppingCartBean.java



package org.jboss.tutorial.entity.bean;




 


import javax.persistence.EntityManager;



import javax.ejb.Inject;



import javax.ejb.Remove;



import javax.ejb.Stateful;




 



 


@Stateful



public class ShoppingCartBean implements ShoppingCart



{



   @Inject



   private EntityManager manager;       //The EntityManager is used to do querying,



//creating, find by primary key, and removal of entity beans.



   private Order order;




 


   public void buy(String product, int quantity, double price)



   {



      if (order == null) order = new Order();



      order.addPurchase(product, quantity, price);



   }




 


   public Order getOrder()



   {



      return order;



   }




 


   @Remove



   public void checkout()



   {



      manager.persist(order);



   }



}




 


EntityManager的作用可大了,可以用于查询,创建,删除实体Bean,这里插入个EntityManager,主要是在最后用户离开时,在数据库里保存数据,相当于保存个object。运行完Client.java后就可以在hsqldb上看到有purchase_order 和 LineItem 的两张表。HypersonicDatabase ,找到startDatabaseManager然后下面有个invoke,点击就可以访问hsqldb了。




 



 


Client.java



package org.jboss.tutorial.entity.client;




 



 


import org.jboss.tutorial.entity.bean.LineItem;



import org.jboss.tutorial.entity.bean.Order;



import org.jboss.tutorial.entity.bean.ShoppingCart;




 


import javax.naming.InitialContext;




 


public class Client



{



   public static void main(String[] args) throws Exception



   {



      InitialContext ctx = new InitialContext();



      ShoppingCart cart = (ShoppingCart) ctx.lookup(ShoppingCart.class.getName());




 


      System.out.println("Buying 2 memory sticks");



      cart.buy("Memory stick", 2, 500.00);



      System.out.println("Buying a laptop");



      cart.buy("Laptop", 1, 2000.00);




 


      System.out.println("Print cart:");



      Order order = cart.getOrder();



      System.out.println("Total: $" + order.getTotal());



      for (LineItem item : order.getLineItems())



      {



         System.out.println(item.getQuantity() + "     " + item.getProduct() + "     " + item.getSubtotal());



      }




 


      System.out.println("Checkout");



      cart.checkout();



   }



}




 



 


这里附上log4j.properties 在jboss-EJB-3.0_Preview_5.zip 里面没有这个老是显示缺少appender。有了这个将在该目录下生成个record.log日志文件。




 


log4j.properties



log4j.appender.R=org.apache.log4j.RollingFileAppender



log4j.appender.R.File=record.log



log4j.appender.R.layout=org.apache.log4j.PatternLayout



log4j.appender.R.layout.ConversionPattern=%p  %d{hh:mm:ss} %t %c{1} -%m%n



log4j.appender.R.MaxBackupIndex=1



log4j.appender.R.MaxFileSize=100KB



log4j.appender.stdout.layout=org.apache.log4j.PatternLayout



log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) -%m%n



log4j.appender.stdout=org.apache.log4j.ConsoleAppender



log4j.rootLogger=stdout,R




 



 



 


运行:参考installing.html



Windows下



打开命令提示符cmd,到  jboss_home/bin



 Run.bat –c all



用ant



先build后run 就行了。




 


 




 


 



 


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