EJB3入门 示例
原创，转载请标明源 http://asyty.iteye.com/blog/1249495
随便贴个入门示例，贴贴代码说明一下，个人觉得网上的例子都稍显简洁，虽然我这个也不复杂，
建议搜索网上其他简单例子互相配合参考下。例如 http://blog.chinaunix.net/space.php?uid=20426042&do=blog&id=1681669
1 eclipse新建ejb项目
File --> new Project --> EJB Project
数据库中建两张表 t_users， t_roles，即用户表和权限表，字段和entity bean(entitybean在后面)里定义要一致
在src-->META-INF文件夹下新建mysql-ds.xml，配置数据库连接
<datasources> <local-tx-datasource> <jndi-name>ejbDatasource</jndi-name> <connection-url> jdbc:mysql://localhost:3306/test </connection-url> <driver-class>com.mysql.jdbc.Driver</driver-class> <user-name>root</user-name> <password></password> <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter </exception-sorter-class-name> <valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLValidConnectionChecker </valid-connection-checker-class-name> <metadata> <type-mapping>mySQL</type-mapping> </metadata> </local-tx-datasource> </datasources>
新建persistence.xml，使用Hibernate的持久化单元，也就是要需要持久化的内容，即通过JNDI指定上面定义的数据库，可以配置多个持久化单元
<?xml version="1.0" encoding="UTF-8"?> <persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> <persistence-unit name="test"> <jta-data-source>java:/ejbDatasource</jta-data-source> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" /> <property name="hibernate.hbm2ddl.auto" value="update" /> <property name="hibernate.show_sql" value="true" /> <property name="hibernate.format_sql" value="true" /> </properties> </persistence-unit> </persistence>
定义entity bean，主要是观察定义表对应的字段的annotation @id @GeneratedValue @NotNull @Colum @ManyToOne等等
Role.java
@Entity
@Table(name = "T_ROLES")
public class Role implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY) //mysql支持自增ID，uuid等类型的id
private Integer id;
@NotNull
@Column(name = "ROLE_NAME", length= 10)
private String roleName;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getRoleName() {
return roleName;
}
public void setRoleName(String roleName) {
this.roleName = roleName;
}
}
Subscriber.java
@Entity
@Table(name = "T_USERS")
public class Subscriber implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Column(name = "UUID", length = 36)
private String uuid = UUID.randomUUID().toString();
@NotNull
@Length(min = 2, max = 32)
@Column(name = "user_name", unique = true) //uuid
private String userName;
@NotNull
@Length(min = 6, max = 32)
@Column(name = "user_password")
private String password;
@Column(name = "user_email", length = 50)
private String email;
@Column(name = "user_reg_time")
@Temporal(value =TemporalType.TIMESTAMP)
private Date regTime = new Date();
@NotNull
@ManyToOne(targetEntity=Role.class) //默认lazy=false 也就是Role会被同时取出
@JoinColumn(name="role_id", referencedColumnName="id")
private Role role;
public Subscriber() {
super();
}
public String getUuid() {
return uuid;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public void setRole(Role role) {
this.role = role;
}
public Role getRole() {
return role;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public void setRegTime(Date regTime) {
this.regTime = regTime;
}
public Date getRegTime() {
return regTime;
}
}
这样，entity bean和数据库连接就定义好了
<---------------以下部分是 session bean-------------->
如果使用DAO访问数据库的话，就可以定义dao，service和action，本例中直接继承Dao模板，Dao模板中已定义增删改查等功能，可google下DAO模板。DAO,service相当于session bean，这里只写一下User的部分，role部分类似
SubscriberDao.java
@Local //@local @remote，表示这个ejb是远程调用还是本地调用
public interface SubscriberDao extends DAO<Subscriber>{
/**
* 确定是否可以登录
*/
public boolean checkUser(String username, String password);
}
SubscriberDaoImpl.java
@Stateless
public class SubscriberDaoImpl extends DaoSupport<Subscriber> implements SubscriberDao {
@Override
public boolean checkUser(String username, String password) {
long count = (Long)getEntityManager().createQuery("select count(o) from SysUser o where o.userName=?1 and o.password=?2")
.setParameter(1, username).setParameter(2, password).getSingleResult();
return count>0;
}
}
SubscriberService.java
@Local
public interface SubscriberService {
/**
* 增删改查
* @param user
*/
public void add(Subscriber user);
public void delete(String userId);
public void update(Subscriber user);
public Subscriber get(String userId);
public List<Subscriber> getAll();
public boolean checkUser(String username, String password);
}
SubscriberServiceImpl.java
@Stateless
public class SubscriberServiceImpl implements Serializable, SubscriberService {
private static final long serialVersionUID = 1L;
@EJB
private SubscriberDao subscriberDao;
@Override
public boolean checkUser(String username, String password) {
return subscriberDao.checkUser(username, password);
}
@Override
public void add(Subscriber sysUser) {
subscriberDao.save(sysUser);
}
@Override
public void delete(String userId) {
subscriberDao.delete(userId);
}
@Override
public void update(Subscriber user) {
subscriberDao.update(user);
}
@Override
public Subscriber get(String userId) {
return subscriberDao.find(userId);
}
@Override
public List<Subscriber> getAll() {
return subscriberDao.getScrollData().getResultlist();
}
}
然后在action中就可以直接调用service了。。。。。。。通过@EJB标签引入SERVICE，和service引入DAO的方式是一样的。。。。
@Named("subscriber")
@RequestScoped
public class SubscriberAction implements Action, Serializable {
private static final long serialVersionUID = 1L;
private String uuid;
private String userName;
private String password;
private Integer roleId;
private String errorMessage;
private Subscriber user;
XXXXX其他属性
@EJB
private SubscriberService subscriberService;
@EJB
private RoleService roleService;
public SubscriberAction() {
}
public String get() {
errorMessage = null;
Subscriber user =subscriberService.get(uuid);
return SUCCESS;
}
public String delete() {
errorMessage = null;
xxxxxx操作;
subscriberService.delete(uuid);
return SUCCESS;
}
public String update() {
errorMessage = null;
xxxxxx操作;
subscriberService.update(user);
return SUCCESS;
}
public String login() {
errorMessage = null;
if(!subscriberService.checkUser(userName, password)) {
errorMessage = "帐号或密码有误";
return INPUT;
}
return SUCCESS;
}
一堆getter setter。。。。。
}