跟我学EJB 分布式编程技术——SQLServer2000的BMP20实例
目录
1.1跟我学EJB 分布式编程技术——SQLServer2000的BMP20实例 (2)
1.1.1编程SQLServer2000的BMP 2.0 EJB组件 (2)
1.1.2完整的程序代码示例 (12)
1.1.3如何查看访问BMP Bean的JNDI名称 (18)
1.1.4编译该BMP 的代码以产生*.jar文件 (19)
1.1.5部署该BMP组件 (19)
1.1.6添加访问该BMP组件的客户段程序 (20)
1.1跟我学EJB 分布式编程技术——SQLServer2000的BMP20实例
1.1.1编程SQLServer2000的BMP
2.0 EJB组件
1、BMP的具体应用场合
由于CMP在某些应用场合下可能不灵活特别在复杂的查询和报表统计时,此时可以采用BMP。
2、新建一个BMP2.0的Project项目文件，名称为BMP20Bean
3、在该项目文件中添加一个EJB组件，名称为JBBMPBean20
最后生成该EJB组件的程序代码
4、在JBuilderX中引入MS SqlServer2000数据库的JDBC驱动程序
点击菜单上的“import Schema From Database”的按钮以导入数据库的结构
如果在JBuilder中已经对数据库配置过，则直接点击“Chooser Existing Connection”按钮，选择现有的连接。
访问SQLServer2000中的pubs数据库，如果没有（第一次操作时），则应该输入
在Driver栏中：com.microsoft.jdbc.sqlserver.SQLServerDriver
在URL栏中：jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=pubs
在UserName栏中：sa
在Password栏中：6407
在JNDI Name栏中：SqlServer2000JNDI（应该与在WebLogic中所配置的JDBC DataSource 的JNDI Name名称保持一致）
并且选中“All schemas”选择项目
然后点击“OK”按钮，JBuilder将开始连接数据库，然后将产生如下的数据库表的结构
5、创建BMP
（1）然后选择某一个数据库表，如：authors表。并右点击它，然后选择“Create BMP Entity Bean”（根据数据库中的数据表来生成对应的EJB组件）。
（2）设置该BMP Bean
其中Always Wrap Primary Key=true代表“复合主键”，本例设置为false，interface 类型设置为local/remote
（3）将产生如下的各个类文件
AuthorsBean.java程序代码
package bmp20bean;
import javax.ejb.*;
public class AuthorsBean implements EntityBean
{
EntityContext entityContext;
https://www.360docs.net/doc/ca12893905.html,ng.String auId;
https://www.360docs.net/doc/ca12893905.html,ng.String auLname;
https://www.360docs.net/doc/ca12893905.html,ng.String auFname;
https://www.360docs.net/doc/ca12893905.html,ng.String phone;
https://www.360docs.net/doc/ca12893905.html,ng.String address;
https://www.360docs.net/doc/ca12893905.html,ng.String city;
https://www.360docs.net/doc/ca12893905.html,ng.String state;
https://www.360docs.net/doc/ca12893905.html,ng.String zip;
https://www.360docs.net/doc/ca12893905.html,ng.Boolean contract;
public https://www.360docs.net/doc/ca12893905.html,ng.String ejbCreate(https://www.360docs.net/doc/ca12893905.html,ng.String auId) throws CreateException {
setAuId(auId);
return null;
}
public void ejbPostCreate(https://www.360docs.net/doc/ca12893905.html,ng.String auId) throws CreateException {
/**@todo Complete this method*/
}
public void ejbRemove() throws RemoveException {
/**@todo Complete this method*/
}
public void setAuId(https://www.360docs.net/doc/ca12893905.html,ng.String auId) {
this.auId = auId;
}
public void setAuLname(https://www.360docs.net/doc/ca12893905.html,ng.String auLname) {
this.auLname = auLname;
}
public void setAuFname(https://www.360docs.net/doc/ca12893905.html,ng.String auFname) {
this.auFname = auFname;
}
public void setPhone(https://www.360docs.net/doc/ca12893905.html,ng.String phone) {
this.phone = phone;
}
public void setAddress(https://www.360docs.net/doc/ca12893905.html,ng.String address) {
this.address = address;
}
public void setCity(https://www.360docs.net/doc/ca12893905.html,ng.String city) {
this.city = city;
}
public void setState(https://www.360docs.net/doc/ca12893905.html,ng.String state) {
this.state = state;
}
public void setZip(https://www.360docs.net/doc/ca12893905.html,ng.String zip) {
this.zip = zip;
}
public void setContract(https://www.360docs.net/doc/ca12893905.html,ng.Boolean contract) { this.contract = contract;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAuId() {
return auId;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAuLname() {
return auLname;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAuFname() {
return auFname;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getPhone() {
return phone;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAddress() {
return address;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getCity() {
return city;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getState() {
return state;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getZip() {
return zip;
}
public https://www.360docs.net/doc/ca12893905.html,ng.Boolean getContract() {
return contract;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String ejbFindByPrimaryKey(https://www.360docs.net/doc/ca12893905.html,ng.String auId) throws FinderException
{
/**@todo Complete this method*/
return null;
}
public void ejbLoad()
{
/**@todo Complete this method*/
}
public void ejbStore()
/**@todo Complete this method*/
}
public void ejbActivate() {
/**@todo Complete this method*/
}
public void ejbPassivate() {
/**@todo Complete this method*/
}
public void unsetEntityContext() {
this.entityContext = null;
}
public void setEntityContext(EntityContext entityContext) {
this.entityContext = entityContext;
}
}
（4）编程AuthorsBean.java程序代码以实现数据访问（本例只实现ejbFindByPrimaryKey 方法）
●加入如下的Java包的引用
import java.sql.*;
import javax.sql.DataSource;
import javax.naming.*;
●编程ejbFindByPrimaryKey()方法
public https://www.360docs.net/doc/ca12893905.html,ng.String ejbFindByPrimaryKey(https://www.360docs.net/doc/ca12893905.html,ng.String auId) throws FinderException
{
/* 具体的代码请见后面的说明
*/
return auId; //返回主键的值
private void makeConnection() throws NamingException, SQLException //提供数据库的连接方法
{
/* 具体的代码请见后面的说明
*/
}
1.1.2完整的程序代码示例
package bmp20bean;
import javax.ejb.*;
import java.sql.*;
import javax.sql.DataSource;
import javax.naming.*;
import javax.ejb.EJBException;
public class AuthorsBean implements EntityBean
{
private Connection con; //定义出一个数据库连接对象
EntityContext entityContext;
https://www.360docs.net/doc/ca12893905.html,ng.String auId;
https://www.360docs.net/doc/ca12893905.html,ng.String auLname;
https://www.360docs.net/doc/ca12893905.html,ng.String auFname;
https://www.360docs.net/doc/ca12893905.html,ng.String phone;
https://www.360docs.net/doc/ca12893905.html,ng.String address;
https://www.360docs.net/doc/ca12893905.html,ng.String city;
https://www.360docs.net/doc/ca12893905.html,ng.String state;
https://www.360docs.net/doc/ca12893905.html,ng.String zip;
https://www.360docs.net/doc/ca12893905.html,ng.Boolean contract;
public https://www.360docs.net/doc/ca12893905.html,ng.String ejbCreate(https://www.360docs.net/doc/ca12893905.html,ng.String auId) throws CreateException {
setAuId(auId);
return null;
}
public void ejbPostCreate(https://www.360docs.net/doc/ca12893905.html,ng.String auId) throws CreateException {
/**@todo Complete this method*/
}
public void ejbRemove() throws RemoveException {
/**@todo Complete this method*/
}
public void setAuId(https://www.360docs.net/doc/ca12893905.html,ng.String auId) {
this.auId = auId;
}
public void setAuLname(https://www.360docs.net/doc/ca12893905.html,ng.String auLname) {
this.auLname = auLname;
}
public void setAuFname(https://www.360docs.net/doc/ca12893905.html,ng.String auFname) {
this.auFname = auFname;
}
public void setPhone(https://www.360docs.net/doc/ca12893905.html,ng.String phone) {
this.phone = phone;
}
public void setAddress(https://www.360docs.net/doc/ca12893905.html,ng.String address) {
this.address = address;
}
public void setCity(https://www.360docs.net/doc/ca12893905.html,ng.String city) {
this.city = city;
}
public void setState(https://www.360docs.net/doc/ca12893905.html,ng.String state) {
this.state = state;
}
public void setZip(https://www.360docs.net/doc/ca12893905.html,ng.String zip) {
this.zip = zip;
}
public void setContract(https://www.360docs.net/doc/ca12893905.html,ng.Boolean contract) { this.contract = contract;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAuId() {
return auId;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAuLname() {
return auLname;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAuFname() {
return auFname;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getPhone() {
return phone;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getAddress() {
return address;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getCity() {
return city;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getState() {
return state;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String getZip() {
return zip;
}
public https://www.360docs.net/doc/ca12893905.html,ng.Boolean getContract() {
return contract;
}
public https://www.360docs.net/doc/ca12893905.html,ng.String ejbFindByPrimaryKey(https://www.360docs.net/doc/ca12893905.html,ng.String auId) throws FinderException
{
PreparedStatement ps =null;
try
{
makeConnection();
}
catch (Exception ex)
{
throw new javax.ejb.EJBException ("在ejbFindByPrimaryKey方法中不能正确地连接数据库，错误为 " + ex.getMessage());
}
try
{
ps = con.prepareStatement("select * from authors where au_id =?");
ps.setString(1, auId);
ResultSet rs = ps.executeQuery();
if (rs.next())
{
this.auId=rs.getString("au_id");
this.auLname = rs.getString("au_lname");
this.auFname=rs.getString("au_fname");
this.phone = rs.getString("phone");
this.address = rs.getString("address");
this.city = rs.getString("city");
this.state=rs.getString("state");
this.zip=rs.getString("zip");
this.contract=new Boolean(rs.getBoolean("contract")); }
else
{
System.out.println("find error!");
}
}
catch(SQLException e)
{
throw new javax.ejb.EJBException ("Exception in it"+e); }
finally
{
try
{
if (ps != null)
ps.close();
if (con != null)
con.close();
}
catch (Exception ignore)
{
}
}
return auId; //返回主键的值
}
private void makeConnection() throws NamingException, SQLException //提供数据库的连接方法
{
InitialContext ic = new InitialContext();
DataSource ds = (DataSource)ic.lookup("SqlServer2000JNDI");
con = ds.getConnection();
}
public void ejbLoad() {
/**@todo Complete this method*/
}
public void ejbStore() {
/**@todo Complete this method*/
}
public void ejbActivate() {
/**@todo Complete this method*/
}
public void ejbPassivate() {
/**@todo Complete this method*/
}
/*
将数据库的连接和关闭发表放入setEntityContext和unsetEntityContext方法中，这样可以避免在各个数据的访问方法中进行数据库的连接
*/
public void unsetEntityContext() //每当容器卸载EJB Bean时将关闭数据库连接
{
this.entityContext = null;
}
public void setEntityContext(EntityContext entityContext) //每当容器加载EJB Bean时将连接数据库
{
this.entityContext = entityContext;
}
}
1.1.3如何查看访问BMP Bean的JNDI名称
查看访问BMP Bean的JNDI名称以便在客户程序中能够正确地获得它，打开weblogic-ejb-jar.xml文件
因此访问该BMP的远程接口的JNDI的名称为“AuthorsRemote”，但为了避免与CMP 中的JNDI同名称，在本例中修改它为“BMPAuthorsRemote”，local类型的JNDI名称也同时修改为“BMPAuthorsLocal”。
共享访问的问题：由于实体Bean可以由多个客户程序共享。由于多个客户程序可能修改
同一个数据，因此，为实体Bean提供事务（Transaction）支持就很重要。一般地，事务管理机制由EJB容器提供，开发者无需在Bean里面设置事务的界限。事务属性可以在Bean的部署描述器中指定。
1.1.4编译该BMP 的代码以产生*.jar文件
1.1.5部署该BMP组件
右击JBBMPBean20，然后选择“Deploy”（或者选择“Redeploy”以避免与已有的EJB的JNDI名称相同）
1.1.6添加访问该BMP组件的客户段程序
1、设计相关的程序类
类名称为AuthorsTestClient，包名称为bmp20beanclient