- 浏览: 467756 次
- 性别:
- 来自: 北京
文章分类
- 全部博客 (272)
- java基础 (59)
- struts (8)
- spring (8)
- 数据库 (8)
- java 网络编程 (29)
- hibernate (3)
- JavaScript (10)
- 日志管理 (2)
- jsp (4)
- servlet (7)
- xml (4)
- ajax (2)
- web service (4)
- 算法与数据结构 (13)
- java 反射机制 (11)
- java 泛型 (3)
- java I/O (8)
- java 线程 (12)
- JavaEE (6)
- java解惑 (33)
- 工具 (5)
- MyEclipse编程实践 (1)
- OSGI (2)
- 设计模式 (9)
- 正则表达式 (0)
- EJB (3)
- Ubuntu linux (6)
- Android (1)
- web前端 (2)
- 找工作 (1)
- SCA (1)
- maven (1)
- 缓存 (1)
- json (1)
- javamail (1)
- 工作笔记 (2)
最新评论
-
霜花似雪:
博主可以分享一下源码吗?
使用maven构建web项目实例 -
王庆波-行:
很好的demo!
memcache使用实例 -
surpassno:
大写的牛逼
java可视化显示内存使用情况 -
zhulin0504:
怎么访问NetEcho.html页面呀???
applet与servlet的网络通信 -
springdata:
java多线程实例demo源代码下载:http://www.z ...
java多线程例子
Q: What are the different kinds of enterprise beans?
EJB中都有哪些bean?无状态会话bean,有状态会话bean,实体bean,消息驱动bean
A: Stateless session bean- An instance of these non-persistent EJBs provides a service without storing an interaction or conversation state between methods. Any instance can be used for any client.
Stateful session bean- An instance of these non-persistent EJBs maintains state across methods and transactions. Each instance is associated with a particular client.
Entity bean- An instance of these persistent EJBs represents an object view of the data, usually rows in a database. They have a primary key as a unique identifier. Entity bean persistence can be either container-managed or bean-managed.
Message-driven bean- An instance of these EJBs is integrated with the Java Message Service (JMS) to provide the ability for message-driven beans to act as a standard JMS message consumer and perform asynchronous processing between the server and the JMS message producer.
Q: What is Session Bean?
什么是会话bean?
会话bean用于完成企业应用的业务逻辑。
A: A session bean is a non-persistent object that implements some business logic running on the server. One way to think of a session object is as a logical extension of the client program that runs on the server.
Session beans are used to manage the interactions of entity and other session beans,access resources, and generally perform tasks on behalf of the client.
There are two basic kinds of session bean: stateless and stateful.
Stateless session beans are made up of business methods that behave like procedures; they operate only on the arguments passed to them when they are invoked. Stateless beans are called stateless because they are transient; they do not maintain business state between method invocations.Each invocation of a stateless business method is independent from previous invocations. Because stateless session beans are stateless, they are easier for the EJB container to manage, so they tend to process requests faster and use less resources.
Stateful session beans encapsulate business logic and state specific to a client. Stateful beans are called "stateful" because they do maintain business state between method invocations, held in memory and not persistent. Unlike stateless session beans, clients do not share stateful beans. When a client creates a stateful bean, that bean instance is dedicated to service only that client. This makes it possible to maintain conversational state, which is business state that can be shared by methods in the same stateful bean.
Q: What is Entity Bean?
什么是实体bean?持久化bean,对应数据库中表格中的记录。
A: The entity bean is used to represent data in the database. It provides an object-oriented interface to data that would normally be accessed by the JDBC or some other back-end API. More than that, entity beans provide a component model that allows bean developers to focus their attention on the business logic of the bean, while the container takes care of managing persistence,transactions, and access control.
There are two basic kinds of entity beans: container-managed ersistence (CMP) andbean-managed persistence (BMP).
Container-managed persistence beans are the simplest for the bean developer to create and the most difficult for the EJB server to support. This is because all the logic for synchronizing the bean's state with the database is handled automatically by the container. This means that the bean developer doesn't need to write any data access logic, while the EJB server is
supposed to take care of all the persistence needs automatically. With CMP, the container manages the persistence of the entity bean. Vendor tools are used to map the entity fields to the database and absolutely no database access code is written in the bean class.
The bean-managed persistence (BMP) enterprise bean manages synchronizing its state with the database as directed by the container. The bean uses a database API to read and write its fields to the database, but the container tells it when to do each synchronization operation and manages the transactions for the bean automatically. Bean-managed persistence gives the bean developer the flexibility to perform persistence operations that are too complicated for the container or to use a data source that is not supported by the container.
Q: What are the methods of Entity Bean?
实体bean都有哪些方法??
A: An entity bean consists of 4 groups of methods:
1. create methods: To create a new instance of a CMP entity bean, and therefore insert data into the database, the create() method on the bean's home interface must be invoked. They look like this: EntityBeanClass ejbCreateXXX(parameters), where EntityBeanClass is an Entity Bean you are trying to instantiate, ejbCreateXXX(parameters) methods are used for creating Entity Bean instances according to the parameters specified and to some programmer-defined conditions.
A bean's home interface may declare zero or more create() methods, each of which must have corresponding ejbCreate() and ejbPostCreate() methods in the bean class. These creation methods are linked at run time, so that when a create() method is invoked on the home interface, the container delegates the invocation to the corresponding ejbCreate() and ejbPostCreate() methods on the bean class.
2. finder methods: The methods in the home interface that begin with "find" are called the find methods. These are used to query the EJB server for specific entity beans, based on the name of the method and arguments passed. Unfortunately, there is no standard query language defined for find methods, so each vendor will implement the find method differently. In CMP entity beans, the find methods are not implemented with matching methods in the bean class; containers implement them when the bean is deployed in a vendor specific manner. The deployer will use vendor specific tools to tell the container how a particular find method should behave. Some vendors will use object-relational mapping tools to define the behavior of a find method while others will simply require the deployer to enter the appropriate SQL command.
There are two basic kinds of find methods: single-entity and multi-entity. Single-entity find methods return a remote reference to the one specific entity bean that matches the find request. If no entity beans are found, the method throws an ObjectNotFoundException . Every entity bean must define the single-entity find method with the method name findByPrimaryKey(), which takes the bean's primary key type as an argument.
The multi-entity find methods return a collection ( Enumeration or Collection type) of entities that match the find request. If no entities are found, the multi-entity find returns an empty collection.
3. remove methods: These methods (you may have up to 2 remove methods, or don't have them at all) allow the client to physically remove Entity beans by specifying either Handle or a Primary Key for the Entity Bean.
4. home methods: These methods are designed and implemented by a developer, and EJB specification doesn't have any requirements for them except the need to throw a RemoteException is each home method.
Q: What are the methods of Entity Bean?What is the difference between Container-Managed Persistent (CMP) bean and Bean-Managed Persistent(BMP) ?
容器管理持久化CMP和bean管理持久化BMP的区别?
A: Container-managed persistence beans are the simplest for the bean developer to create and the most difficult for the EJB server to support. This is because all the logic for synchronizing the bean's state with the database is handled automatically by the container. This means that the bean developer doesn't need to write any data access logic, while the EJB server is supposed to take care of all the persistence needs automatically. With CMP, the container manages the persistence of the entity bean. A CMP bean developer doesn't need to worry about JDBC code and transactions, because the Container performs database calls and transaction management instead of the programmer. Vendor tools are used to map the entity fields to the database and absolutely no database access code is written in the bean class. All table mapping is specified in the deployment descriptor. Otherwise, a BMP bean developer takes the load of linking an application and a database on his shoulders.
The bean-managed persistence (BMP) enterprise bean manages synchronizing its state with the database as directed by the container. The bean uses a database API to read and write its fields to the database, but the container tells it when to do each synchronization operation and manages the transactions for the bean automatically. Bean-managed persistence gives the bean developer the flexibility to perform persistence operations that are too complicated for the container or to use a data source that is not supported by the container.BMP beans are not 100% database-independent, because they may contain database-specific code, but CMP beans are unable to perform complicated DML (data manipulation language) statements. EJB 2.0 specification introduced some new ways of querying database (by using the EJB QL - query language).
Q: What are the callback methods in Entity beans?
实体bean都有哪些回调函数??
A: The bean class defines create methods that match methods in the home interface and business methods that match methods in the remote interface. The bean class also implements a set of callback methods that allow the container to notify the bean of events in its life cycle. The callback methods are defined in the javax.ejb.EntityBean interface that is implemented by all entity beans.The EntityBean interface has the following definition. Notice that the bean class implements these methods.
The setEntityContext() method provides the bean with an interface to the container called the EntityContext. The EntityContext interface contains methods for obtaining information about the context under which the bean is operating at any particular moment. The EntityContext interface is used to access security information about the caller; to determine the status of the current transaction or to force a transaction rollback; or to get a reference to the bean itself, its home, or its primary key. The EntityContext is set only once in the life of an entity bean instance, so its reference should be put into one of the bean instance's fields if it will be needed later.
The unsetEntityContext() method is used at the end of the bean's life cycle before the instance is evicted from memory to dereference the EntityContext and perform any last-minute clean-up.
The ejbLoad() and ejbStore() methods in CMP entities are invoked when the entity bean's state is being synchronized with the database. The ejbLoad() is invoked just after the container has refreshed the bean container-managed fields with its state from the database. The ejbStore() method is invoked just before the container is about to write the bean container-managed fields to the database. These methods are used to modify data as it's being synchronized. This is common when the data stored in the database is different than the data used in the bean fields.
The ejbPassivate() and ejbActivate() methods are invoked on the bean by the container just before the bean is passivated and just after the bean is activated, respectively. Passivation in entity beans means that the bean instance is disassociated with its remote reference so that the container can evict it from memory or reuse it. It's a resource conservation measure the container employs to reduce the number of instances in memory. A bean might be passivated if it hasn't been used for a while or as a normal operation performed by the container to maximize reuse of resources. Some containers will evict beans from memory, while others will reuse instances for other more active remote references. The ejbPassivate() and ejbActivate() methods provide the bean with a notification as to when it's about to be passivated (disassociated with the remote reference) or activated (associated with a remote reference).
Q: What is software architecture of EJB?
EJB的软件体系结构是什么?
A: Session and Entity EJBs consist of 4 and 5 parts respetively:
1. A remote interface (a client interacts with it),
2. A home interface (used for creating objects and for declaring business methods),
3. A bean object (an object, which actually performs business logic and EJB-specific operations).
4. A deployment descriptor (an XML file containing all information required for maintaining the EJB) or a set of deployment descriptors (if you are using some container-specific features).
5.A Primary Key class - is only Entity bean specific.
Q: Can Entity Beans have no create() methods?
A: Yes. In some cases the data is inserted NOT using Java application, so you may only need to retrieve the information, perform its processing, but not create your own information of this kind.
Q: What is bean managed transaction?
A: If a developer doesn't want a Container to manage transactions, it's possible to implement all database operations manually by writing the appropriate JDBC code. This often leads to productivity increase, but it makes an Entity Bean incompatible with some databases and it enlarges the amount of code to be written. All transaction management is explicitly performed by a developer.
Q: What are transaction attributes?
A: The transaction attribute specifies how the Container must manage transactions for a method when a client invokes the method via the enterprise bean’s home or component interface or when the method is invoked as the result of the arrival of a JMS message. (Sun's EJB Specification) Below is a list of transactional attributes:
1. NotSupported - transaction context is unspecified.
2. Required - bean's method invocation is made within a transactional context. If a client is not associated with a transaction, a new transaction is invoked automatically.
3. Supports - if a transactional context exists, a Container acts like the transaction attribute is Required, else - like NotSupported.
4. RequiresNew - a method is invoked in a new transaction context.
5. Mandatory - if a transactional context exists, a Container acts like the transaction attribute is Required, else it throws a javax.ejb.TransactionRequiredException.
6. Never - a method executes only if no transaction context is specified.
Q: What are transaction isolation levels in EJB?
A: 1. Transaction_read_uncommitted- Allows a method to read uncommitted data from a DB(fast but not wise).
2. Transaction_read_committed- Guarantees that the data you are getting has been committed.
3. Transaction_repeatable_read - Guarantees that all reads of the database will be the same during the transaction (good for read and update operations).
4. Transaction_serializable- All the transactions for resource are performed serial.
EJB中都有哪些bean?无状态会话bean,有状态会话bean,实体bean,消息驱动bean
A: Stateless session bean- An instance of these non-persistent EJBs provides a service without storing an interaction or conversation state between methods. Any instance can be used for any client.
Stateful session bean- An instance of these non-persistent EJBs maintains state across methods and transactions. Each instance is associated with a particular client.
Entity bean- An instance of these persistent EJBs represents an object view of the data, usually rows in a database. They have a primary key as a unique identifier. Entity bean persistence can be either container-managed or bean-managed.
Message-driven bean- An instance of these EJBs is integrated with the Java Message Service (JMS) to provide the ability for message-driven beans to act as a standard JMS message consumer and perform asynchronous processing between the server and the JMS message producer.
Q: What is Session Bean?
什么是会话bean?
会话bean用于完成企业应用的业务逻辑。
A: A session bean is a non-persistent object that implements some business logic running on the server. One way to think of a session object is as a logical extension of the client program that runs on the server.
Session beans are used to manage the interactions of entity and other session beans,access resources, and generally perform tasks on behalf of the client.
There are two basic kinds of session bean: stateless and stateful.
Stateless session beans are made up of business methods that behave like procedures; they operate only on the arguments passed to them when they are invoked. Stateless beans are called stateless because they are transient; they do not maintain business state between method invocations.Each invocation of a stateless business method is independent from previous invocations. Because stateless session beans are stateless, they are easier for the EJB container to manage, so they tend to process requests faster and use less resources.
Stateful session beans encapsulate business logic and state specific to a client. Stateful beans are called "stateful" because they do maintain business state between method invocations, held in memory and not persistent. Unlike stateless session beans, clients do not share stateful beans. When a client creates a stateful bean, that bean instance is dedicated to service only that client. This makes it possible to maintain conversational state, which is business state that can be shared by methods in the same stateful bean.
Q: What is Entity Bean?
什么是实体bean?持久化bean,对应数据库中表格中的记录。
A: The entity bean is used to represent data in the database. It provides an object-oriented interface to data that would normally be accessed by the JDBC or some other back-end API. More than that, entity beans provide a component model that allows bean developers to focus their attention on the business logic of the bean, while the container takes care of managing persistence,transactions, and access control.
There are two basic kinds of entity beans: container-managed ersistence (CMP) andbean-managed persistence (BMP).
Container-managed persistence beans are the simplest for the bean developer to create and the most difficult for the EJB server to support. This is because all the logic for synchronizing the bean's state with the database is handled automatically by the container. This means that the bean developer doesn't need to write any data access logic, while the EJB server is
supposed to take care of all the persistence needs automatically. With CMP, the container manages the persistence of the entity bean. Vendor tools are used to map the entity fields to the database and absolutely no database access code is written in the bean class.
The bean-managed persistence (BMP) enterprise bean manages synchronizing its state with the database as directed by the container. The bean uses a database API to read and write its fields to the database, but the container tells it when to do each synchronization operation and manages the transactions for the bean automatically. Bean-managed persistence gives the bean developer the flexibility to perform persistence operations that are too complicated for the container or to use a data source that is not supported by the container.
Q: What are the methods of Entity Bean?
实体bean都有哪些方法??
A: An entity bean consists of 4 groups of methods:
1. create methods: To create a new instance of a CMP entity bean, and therefore insert data into the database, the create() method on the bean's home interface must be invoked. They look like this: EntityBeanClass ejbCreateXXX(parameters), where EntityBeanClass is an Entity Bean you are trying to instantiate, ejbCreateXXX(parameters) methods are used for creating Entity Bean instances according to the parameters specified and to some programmer-defined conditions.
A bean's home interface may declare zero or more create() methods, each of which must have corresponding ejbCreate() and ejbPostCreate() methods in the bean class. These creation methods are linked at run time, so that when a create() method is invoked on the home interface, the container delegates the invocation to the corresponding ejbCreate() and ejbPostCreate() methods on the bean class.
2. finder methods: The methods in the home interface that begin with "find" are called the find methods. These are used to query the EJB server for specific entity beans, based on the name of the method and arguments passed. Unfortunately, there is no standard query language defined for find methods, so each vendor will implement the find method differently. In CMP entity beans, the find methods are not implemented with matching methods in the bean class; containers implement them when the bean is deployed in a vendor specific manner. The deployer will use vendor specific tools to tell the container how a particular find method should behave. Some vendors will use object-relational mapping tools to define the behavior of a find method while others will simply require the deployer to enter the appropriate SQL command.
There are two basic kinds of find methods: single-entity and multi-entity. Single-entity find methods return a remote reference to the one specific entity bean that matches the find request. If no entity beans are found, the method throws an ObjectNotFoundException . Every entity bean must define the single-entity find method with the method name findByPrimaryKey(), which takes the bean's primary key type as an argument.
The multi-entity find methods return a collection ( Enumeration or Collection type) of entities that match the find request. If no entities are found, the multi-entity find returns an empty collection.
3. remove methods: These methods (you may have up to 2 remove methods, or don't have them at all) allow the client to physically remove Entity beans by specifying either Handle or a Primary Key for the Entity Bean.
4. home methods: These methods are designed and implemented by a developer, and EJB specification doesn't have any requirements for them except the need to throw a RemoteException is each home method.
Q: What are the methods of Entity Bean?What is the difference between Container-Managed Persistent (CMP) bean and Bean-Managed Persistent(BMP) ?
容器管理持久化CMP和bean管理持久化BMP的区别?
A: Container-managed persistence beans are the simplest for the bean developer to create and the most difficult for the EJB server to support. This is because all the logic for synchronizing the bean's state with the database is handled automatically by the container. This means that the bean developer doesn't need to write any data access logic, while the EJB server is supposed to take care of all the persistence needs automatically. With CMP, the container manages the persistence of the entity bean. A CMP bean developer doesn't need to worry about JDBC code and transactions, because the Container performs database calls and transaction management instead of the programmer. Vendor tools are used to map the entity fields to the database and absolutely no database access code is written in the bean class. All table mapping is specified in the deployment descriptor. Otherwise, a BMP bean developer takes the load of linking an application and a database on his shoulders.
The bean-managed persistence (BMP) enterprise bean manages synchronizing its state with the database as directed by the container. The bean uses a database API to read and write its fields to the database, but the container tells it when to do each synchronization operation and manages the transactions for the bean automatically. Bean-managed persistence gives the bean developer the flexibility to perform persistence operations that are too complicated for the container or to use a data source that is not supported by the container.BMP beans are not 100% database-independent, because they may contain database-specific code, but CMP beans are unable to perform complicated DML (data manipulation language) statements. EJB 2.0 specification introduced some new ways of querying database (by using the EJB QL - query language).
Q: What are the callback methods in Entity beans?
实体bean都有哪些回调函数??
A: The bean class defines create methods that match methods in the home interface and business methods that match methods in the remote interface. The bean class also implements a set of callback methods that allow the container to notify the bean of events in its life cycle. The callback methods are defined in the javax.ejb.EntityBean interface that is implemented by all entity beans.The EntityBean interface has the following definition. Notice that the bean class implements these methods.
public interface javax.ejb.EntityBean { public void setEntityContext(); public void unsetEntityContext(); public void ejbLoad(); public void ejbStore(); public void ejbActivate(); public void ejbPassivate(); public void ejbRemove(); }
The setEntityContext() method provides the bean with an interface to the container called the EntityContext. The EntityContext interface contains methods for obtaining information about the context under which the bean is operating at any particular moment. The EntityContext interface is used to access security information about the caller; to determine the status of the current transaction or to force a transaction rollback; or to get a reference to the bean itself, its home, or its primary key. The EntityContext is set only once in the life of an entity bean instance, so its reference should be put into one of the bean instance's fields if it will be needed later.
The unsetEntityContext() method is used at the end of the bean's life cycle before the instance is evicted from memory to dereference the EntityContext and perform any last-minute clean-up.
The ejbLoad() and ejbStore() methods in CMP entities are invoked when the entity bean's state is being synchronized with the database. The ejbLoad() is invoked just after the container has refreshed the bean container-managed fields with its state from the database. The ejbStore() method is invoked just before the container is about to write the bean container-managed fields to the database. These methods are used to modify data as it's being synchronized. This is common when the data stored in the database is different than the data used in the bean fields.
The ejbPassivate() and ejbActivate() methods are invoked on the bean by the container just before the bean is passivated and just after the bean is activated, respectively. Passivation in entity beans means that the bean instance is disassociated with its remote reference so that the container can evict it from memory or reuse it. It's a resource conservation measure the container employs to reduce the number of instances in memory. A bean might be passivated if it hasn't been used for a while or as a normal operation performed by the container to maximize reuse of resources. Some containers will evict beans from memory, while others will reuse instances for other more active remote references. The ejbPassivate() and ejbActivate() methods provide the bean with a notification as to when it's about to be passivated (disassociated with the remote reference) or activated (associated with a remote reference).
Q: What is software architecture of EJB?
EJB的软件体系结构是什么?
A: Session and Entity EJBs consist of 4 and 5 parts respetively:
1. A remote interface (a client interacts with it),
2. A home interface (used for creating objects and for declaring business methods),
3. A bean object (an object, which actually performs business logic and EJB-specific operations).
4. A deployment descriptor (an XML file containing all information required for maintaining the EJB) or a set of deployment descriptors (if you are using some container-specific features).
5.A Primary Key class - is only Entity bean specific.
Q: Can Entity Beans have no create() methods?
A: Yes. In some cases the data is inserted NOT using Java application, so you may only need to retrieve the information, perform its processing, but not create your own information of this kind.
Q: What is bean managed transaction?
A: If a developer doesn't want a Container to manage transactions, it's possible to implement all database operations manually by writing the appropriate JDBC code. This often leads to productivity increase, but it makes an Entity Bean incompatible with some databases and it enlarges the amount of code to be written. All transaction management is explicitly performed by a developer.
Q: What are transaction attributes?
A: The transaction attribute specifies how the Container must manage transactions for a method when a client invokes the method via the enterprise bean’s home or component interface or when the method is invoked as the result of the arrival of a JMS message. (Sun's EJB Specification) Below is a list of transactional attributes:
1. NotSupported - transaction context is unspecified.
2. Required - bean's method invocation is made within a transactional context. If a client is not associated with a transaction, a new transaction is invoked automatically.
3. Supports - if a transactional context exists, a Container acts like the transaction attribute is Required, else - like NotSupported.
4. RequiresNew - a method is invoked in a new transaction context.
5. Mandatory - if a transactional context exists, a Container acts like the transaction attribute is Required, else it throws a javax.ejb.TransactionRequiredException.
6. Never - a method executes only if no transaction context is specified.
Q: What are transaction isolation levels in EJB?
A: 1. Transaction_read_uncommitted- Allows a method to read uncommitted data from a DB(fast but not wise).
2. Transaction_read_committed- Guarantees that the data you are getting has been committed.
3. Transaction_repeatable_read - Guarantees that all reads of the database will be the same during the transaction (good for read and update operations).
4. Transaction_serializable- All the transactions for resource are performed serial.
发表评论
-
数据库及struts面试题
2011-06-22 11:07 1060数据库部分 Q: What is SQL? ... -
java中的servlet面试题
2011-06-22 10:43 1110Q: Explain the life cycle metho ... -
java中JSP的面试题
2011-06-22 10:22 1544Q: What is a output comment? (可 ... -
java中的集合面试题
2011-06-22 10:12 721Q: What is the Collections API? ... -
彻底搞清楚java的内部类
2011-06-15 10:47 1507内部类允许在一个类中 ... -
细说java(java中的浮点数十六进制表示)
2011-06-12 16:48 3566java中浮点数不能用八进制表示,但可以用十六进制表示,只能用 ... -
SCJP试题
2011-06-09 16:14 1179package scjp; public class T ... -
java面试题解惑 之 继承、多态、重载、重写
2011-06-03 09:36 1301继承、多态、重载、重写 继承 java中有三种类:类,抽象类, ... -
java面试题解惑 之 多线程
2011-06-02 17:24 9921,多线程 线程或者说 ... -
java面试题解惑 之变量初始顺序,变量覆盖,字符串池,final,finally区别
2011-06-02 16:26 7991,变量初始化顺序 package com.qdu.sun; ... -
java解惑(Map的使用,静态导入方法,线程中断interrupted与线程死锁)
2011-05-17 12:38 1397Map的使用 package other; import ... -
java 继承的一个问题(想不明白)
2011-04-13 17:03 916java中的继承问题,以为是学会了java,结果最简单的一个j ... -
java解惑(谜题76。。)
2011-03-09 11:22 1221谜题76:乒乓public class PingPong { ... -
java解惑(谜题60,65)
2011-03-08 15:52 919一行以毙之 1,编写一个 ... -
java解惑(谜题66。。。)
2011-02-28 20:54 956谜题66:一件私事 class Base{ public ... -
java解惑(谜题61。。。)
2011-02-28 20:17 916谜题61:日期游戏 import java.util.Cal ... -
java解惑(谜题56到。。库之谜)
2011-02-28 19:41 860谜题56:大问题 import jav ... -
java解惑(谜题49。。)
2011-02-27 10:52 954谜题49:比生命更大 import java.util.Cal ... -
java解惑(谜题41到谜题)
2011-02-27 10:18 922谜题41:域和流 下面的 ... -
谜题36-谜题
2011-02-25 10:55 902谜题36:优柔寡断 public ...
相关推荐
【EJB面试题详解】 EJB(Enterprise JavaBeans)是Java EE平台中用于构建企业级应用的核心组件。在面试中,EJB相关的题目通常涉及到EJB的版本差异、功能、与Java Bean的区别以及其实现机制。 1. **EJB2.0与EJB1.1...
2. **EJB面试题**: - EJB的作用是什么?有哪些类型的EJB? - Session Beans(会话bean):表示业务逻辑,分为Stateful(有状态)和Stateless(无状态)。 - Entity Beans(实体bean):持久化对象,代表数据库中...
### EJB面试题汇总知识点详解 #### 一、EJB基本概念及架构 **1.1 EJB(Enterprise JavaBeans)定义** EJB是服务器端组件开发架构,它提供了构建分布式应用的一种方式,使得开发者能够将业务逻辑封装到组件中,并在...
在面试中,EJB相关的问题常常被用来测试候选人在企业级Java开发领域的专业素养。 94、EJB 2.0的内容和场合: EJB 2.0规范包括Bean提供者、应用程序装配者、EJB容器、EJB配置工具、EJB服务提供者以及系统管理员。...
以下是一些EJB面试的关键知识点: Q1: 企业豆有哪些不同类型? A: EJB分为四种主要类型: 1. 无状态会话bean(Stateless Session Bean):这类非持久性的EJB在方法之间不保存交互或对话状态。任何实例都可以为任何...
【EJB(Enterprise JavaBean)概述】 EJB(Enterprise JavaBean)是Java 企业级应用开发的核心组成部分,属于Java 2 Platform, Enterprise Edition (J2EE)的一部分。它定义了一套标准,用于创建可扩展、分布式、...
**EJB(Enterprise JavaBean)**是Java 2 Platform, Enterprise Edition (J2EE)的重要组成部分,主要用于构建可扩展、分布式、事务处理、持久化和安全的企业级应用程序。EJB定义了一种标准,使得开发者可以专注于...
软件测试面试题,Python面试题,Oracle面试题,MySql面试题,Web开发面试题,Unix面试题,程序员面试,网络技术面试题,网络安全面试题,Linux面试题,Hibernate面试题,Spring面试题,SQL Server面试题,Struts面试题,EJB面试题 ...
**EJB(Enterprise JavaBean)**是Java 2 Platform, Enterprise Edition (J2EE)框架中的核心组件,它为开发可扩展、分布式、事务处理、持久性和安全的服务器端应用程序提供了一种标准方法。EJB规范定义了一系列API,...
**EJB(Enterprise JavaBean)**是Java 2 Platform, Enterprise Edition (J2EE) 的核心组成部分,主要用于构建可扩展、分布式、事务处理、持久化和安全的企业级应用组件。EJB规范定义了一套API,使得开发者能够专注...
软件测试面试题,Python面试题,Oracle面试题,MySql面试题,Web开发面试题,Unix面试题,程序员面试,网络技术面试题,网络安全面试题,Linux面试题,Hibernate面试题,Spring面试题,SQL Server面试题,Struts面试题,EJB面试题 ...
内含最全最新IT技术面试合集,含有: Java面试题,J2EE面试题,.net面试题,PHP面试题,数据库面试题,英语面试,外企面试,软件测试面试题,Python...Hibernate面试题,Spring面试题,SQL Server面试题,Struts面试题,EJB面试题
理解EJB的生命周期、事务管理、安全性以及容器提供的服务(如依赖注入、状态管理和并发控制)是EJB面试的关键。 在面试中,可能会问到关于EJB的版本差异,比如EJB 2.x和3.x的主要改进。EJB 3.x引入了注解,大大简化...
这里我们将深入探讨Java笔试题集中的重点,包括J2EE面试题、Struts2权限拦截器以及JAVA工程师对EJB面试题集的相关内容。 首先,让我们来看看J2EE面试题。J2EE(Java Platform, Enterprise Edition)是Java平台上...
java企业面试题大全(包括18个文档)。1、15个经典面试题.pdf。2、120个Java经典面试题和答案(上).pdf。3、120个Java经典面试题和答案(下).pdf。4、EJB方面.pdf。5、java web面试题.pdf。6、Java基础方面.pdf。7...
【EJB概述】 EJB(Enterprise JavaBeans)是Java平台上的企业级开发组件,主要用于构建分布式、事务处理和安全的企业级应用。EJB规范定义了一种标准,使得开发者可以创建可部署在Java应用服务器上的服务器端组件,...
金蝶公司面试题及试题简答涵盖了多个IT相关领域的知识点,包括Java基础、XML、数据库、软件设计模式、EJB等。 首先,让我们来看一下Java基础部分。在Java基础部分中,提到了Integer和Long的比较、equals()方法的...
│ C++面试题大全.doc │ c与c++面试题汇总.doc │ java面试题集.txt │ ├─C++笔试题 │ (1)C,C++经典问题,及面试笔试题 .txt │ (2)cc++.txt │ (3)笔试题2.doc │ (4)笔试题.doc │ (5)想成为嵌入式程序员应...
这是我找java软件工程师时候,收集的java面试题,汇集了主要的试题,实际我在笔试中有80%的内容和这里面的是重复的.希望能帮助找java工作的您. EJB方面.doc java.doc Java中文问题详解(高手必读).txt Java中文问题...