如何从客户端创建远程会话 EJB [英] how to create a remote session EJB from a client
本文介绍了如何从客户端创建远程会话 EJB的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
根据 关于 EJB 客户端应用程序的 Netbeans 教程,我似乎无法调用方法:
As per the Netbeans Tutorial on EJB Client applications, I cannot seem to invoke the method:
编译错误:
-do-compile:
[mkdir] Created dir: /home/thufir/NetBeansProjects/EntAppClient/build/empty
[mkdir] Created dir: /home/thufir/NetBeansProjects/EntAppClient/build/generated-sources/ap-source-output
[javac] Compiling 1 source file to /home/thufir/NetBeansProjects/EntAppClient/build/jar
[javac] /home/thufir/NetBeansProjects/EntAppClient/src/java/entappclient/Main.java:16: error: cannot find symbol
[javac] System.err.println("result = " + mySession.getResult());
[javac] ^
[javac] symbol: method getResult()
[javac] location: variable mySession of type MySessionRemote
[javac] 1 error
BUILD FAILED
客户:
package entappclient;
import ejb.MySessionRemote;
import javax.ejb.EJB;
public class Main {
@EJB
private static MySessionRemote mySession;
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
System.err.println("result = " + mySession.getResult());
}
}
ejb:
package ejb;
import javax.ejb.Stateless;
@Stateless
public class MySession implements MySessionRemote {
public String getResult() {
return "This is My Session Bean";
}
}
远程接口:
package ejb;
import javax.ejb.Remote;
@Remote
public interface MySessionRemote {
}
现在,如果界面被修改:
now, if the interface is modified:
package ejb;
import javax.ejb.Remote;
@Remote
public interface MySessionRemote {
public String getResult();
}
bean 现在可以@Override
方法:
the bean can now @Override
the method:
package ejb;
import javax.ejb.Stateless;
@Stateless
public class MySession implements MySessionRemote {
@Override
public String getResult() {
return "This is My Session Bean";
}
}
但是,有一个 NPE:
however, there's a NPE:
-run:
[java] java.lang.reflect.InvocationTargetException
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[java] at java.lang.reflect.Method.invoke(Method.java:606)
[java] at org.glassfish.appclient.client.acc.AppClientContainer.launch(AppClientContainer.java:446)
[java] at org.glassfish.appclient.client.AppClientFacade.main(AppClientFacade.java:166)
[java] Caused by: java.lang.NullPointerException
[java] at entappclient.Main.main(Main.java:16)
[java] ... 6 more
[java] Java Result: 1
run:
BUILD SUCCESSFUL
Total time: 18 seconds
thufir@dur:~/NetBeansProjects/EntAppClient$
如何正确调用该方法?EJB 没有实例化?
How can I invoke the method correctly? The EJB isn't instantiated?
推荐答案
我从头开始.我能想到的唯一区别是,我没有制作 EJB 应用程序,而是为 bean 制作了一个 EJB 模块.否则,我认为是一样的.
I started from scratch. The only difference I can think of is that instead of making an EJB application, I just made an EJB module for the bean. Otherwise, I think it's the same.
结构:
thufir@dur:~/NetBeansProjects$
thufir@dur:~/NetBeansProjects$ tree HelloLibrary/
HelloLibrary/
├── build.xml
├── nbproject
│ ├── build-impl.xml
│ ├── genfiles.properties
│ ├── private
│ │ └── private.properties
│ ├── project.properties
│ └── project.xml
└── src
└── hello
└── HelloBeanRemote.java
4 directories, 7 files
thufir@dur:~/NetBeansProjects$
thufir@dur:~/NetBeansProjects$ tree HelloEJB/
HelloEJB/
├── build.xml
├── nbproject
│ ├── ant-deploy.xml
│ ├── build-impl.xml
│ ├── genfiles.properties
│ ├── private
│ │ └── private.properties
│ ├── project.properties
│ └── project.xml
└── src
├── conf
│ └── MANIFEST.MF
└── java
└── hello
└── HelloBean.java
6 directories, 9 files
thufir@dur:~/NetBeansProjects$
thufir@dur:~/NetBeansProjects$ tree HelloClient/
HelloClient/
├── build.xml
├── nbproject
│ ├── ant-deploy.xml
│ ├── build-impl.xml
│ ├── genfiles.properties
│ ├── private
│ │ └── private.properties
│ ├── project.properties
│ └── project.xml
├── src
│ ├── conf
│ │ ├── application-client.xml
│ │ └── MANIFEST.MF
│ └── java
│ └── helloclient
│ └── Main.java
└── test
7 directories, 10 files
thufir@dur:~/NetBeansProjects$
thufir@dur:~/NetBeansProjects$
客户端代码:
package helloclient;
import hello.HelloBeanRemote;
import javax.ejb.EJB;
public class Main {
@EJB
private static HelloBeanRemote helloBean;
public static void main(String... args) {
System.out.println(helloBean.Hi());
}
}
豆:
package hello;
import javax.ejb.Stateless;
@Stateless
public class HelloBean implements HelloBeanRemote {
@Override
public String Hi() {
return "hello world";
}
@Override
public String Bye() {
return "goodbye";
}
}
远程接口:
package hello;
import javax.ejb.Remote;
@Remote
public interface HelloBeanRemote {
public String Hi();
public String Bye();
}
这篇关于如何从客户端创建远程会话 EJB的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
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