JavaEE(19) - Web层和EJB的整合(Session Bean)

1. 通过依赖注入访问无状态Session Bean

#1. EJB注入Servlet中

#2. EJB注入JSF中

2. 通过EJB引用访问有状态Session Bean

3. 在工具类中访问Session Bean

 

1. 通过依赖注入访问无状态Session Bean

#1. EJB注入Servlet中

NetBeans创建Java Enterprise Application, di(内嵌di-ejb, di-war)。

di-ejb:

Hello.java

package org.crazyit.service;

import javax.ejb.*;

@Local
public interface Hello
{
    String hello(String name);
}

HelloBean.java

package org.crazyit.service;

import javax.ejb.*;

@Stateless(name = "hello")
public class HelloBean implements Hello {

    public String hello(String name) {
        return name + ", How are you, the time now is " + new java.util.Date();
    }
}

di-war:

HelloServlet.java

package lee;

import javax.ejb.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

import org.crazyit.service.*;

public class HelloServlet extends HttpServlet {

    //指定将内部标识名为hello的EJB注入到该Field。
    @EJB(beanName = "hello")
    private Hello hello;

    public void service(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {
        //获取请求参数
        String name = request.getParameter("name");
        if (name == null || name.equals("")) {
            name = "non-login";
        }
        //调用Session Bean的业务方法
        String resultStr = hello.hello(name);
        //创建页面输出流
        PrintStream ps = new PrintStream(response.getOutputStream());
        //将调用EJB的结果输出到客户端
        ps.println(resultStr);
    }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <servlet>
        <servlet-name>hello</servlet-name>
        <servlet-class>lee.HelloServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>hello</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>

    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

#2. EJB注入JSF中

2. 通过EJB引用访问有状态Session Bean

3. 在工具类中访问Session Bean