java.lang.ClassCastException：com.sun.proxy。在转换EJB时抛出代理 [英] java.lang.ClassCastException: com.sun.proxy.$Proxy is thrown when casting an EJB

问题描述

我无法使用远程EJB对象。 JNDI查找成功，但转换为对象，稍后使用失败。 EJB接口和实现如下：

UserViewBeanRemote.java

  package books.pointejb; 
 
 import java.util.List; 
 
 import javax.ejb.Remote; 
 
 import books.pointejb.User; 
 import books.pointejb.Book; 
 
 @Remote 
 public interface UserViewBeanRemote {
 public boolean register（User user）; 
 //用户可以删除他/她的帐号，请注意，两个用户名相同的用户名不能存在
 public void delete（User user）; 
 public boolean login（User user）; 
 public boolean logout（User user）; 
 //仅通过书名搜索
 public List< Book> search（String title）; 
} 
  

UserViewBean.java

  package books.pointejb; 
 
 
 import java.util.ArrayList; 
 import java.util.Collection; 
 import java.util.List; 
 
 import javax.ejb.Stateful; 
 import javax.management.Query; 
 import javax.persistence.EntityManager; 
 import javax.persistence.PersistenceContext; 
 
 // import javax.ejb.Remote; 
 import books.pointejb.User; 
 import books.pointejb.Book; 
 
 / ** 
 *会话Bean实现类UserView 
 * / 
 @Stateful 
 // @Remote（UserViewBeanRemote.class）
 public class UserViewBean implements UserViewBeanRemote {
 
 @PersistenceContext 
 private EntityManager entityManager; 
 / ** 
 *默认构造函数。 
 * / 
 public UserViewBean（）{
 // TODO自动生成的构造函数存根
} 
 
 public static< T>列表与LT; T> castList（Class<？extends T> clazz，Collection<？> c）{
列表< T> r = new ArrayList< T>（c.size（））; 
 for（Object o：c）
 r.add（clazz.cast（o））; 
 return r; 
} 
 
 @Override 
 public boolean register（User user）{
 //我们有一些验证这些字段的servlet，所以我们不会在这里验证任何东西b $ b //我们检查是否已经有一个具有相同用户名的用户
 Query query =（Query）entityManager.createQuery（SELECT u FROM users u WHERE u.username =：userName ）; 
（（javax.persistence.Query）query）.setParameter（userName，user.getUsername（））; 
 //我们检查每个返回的值。如果我们找到任何东西，我们不添加用户
列表< User> users = castList（User.class，（（javax.persistence.Query）query）.getResultList（））; 
 if（users.isEmpty（））{
 //用户不存在。添加此用户
 entityManager.persist（user）; 
 // returnWelcome to BooksPoint+ user.getUsername（）+！; 
返回true; 
} else {
 // return无法创建+ user.getUsername（）+。具有此名称的用户已存在; 
返回false; 
} 
 
} 
 
 @Override 
 public void delete（User user）{
 //该用户自动存在，因为用户是已经登录
查询查询=（查询）entityManager.createQuery（DELETE FROM users u WHERE u.username =：userName）; 
（（javax.persistence.Query）query）.setParameter（userName，user.getUsername（））; 
 //返回您的帐户+ user.getUsername（）+已成功删除！; 
} 
 
 @Override 
 public boolean login（User user）{
 //检查我们是否有一个有效的用户/通过对
查询查询= （Query）entityManager.createQuery（SELECT u FROM users u WHERE u.username =：userName AND u.password =：password）; 
（（javax.persistence.Query）query）.setParameter（userName，user.getUsername（））; 
（（javax.persistence.Query）query）.setParameter（password，user.getPassword（））; 
列表<用户> users = castList（User.class，（（javax.persistence.Query）query）.getResultList（））; 
 if（！users.isEmpty（））{
 // returnWelcome+ user.getUsername（）+！; 
返回true; 
} else {
 //返回用户名或密码无效; 
返回false; 
} 
} 
 
 @Override 
 public boolean logout（User user）{
 //这可以在jsp / servlet中完成。只需擦除与当前用户关联的会话变量
 return false; 
} 
 
 @Override 
 public List< Book> search（String title）{
 //检查所有条目类似于title 
的查询查询=（Query）entityManager.createQuery（SELECT * FROM books WHERE title LIKE'％：title％'） ; 
（（javax.persistence.Query）query）.setParameter（title，title）; 
列表< Book> books = castList（Book.class，（（javax.persistence.Query）query）.getResultList（））; 
 //返回书籍，剩下的就是jsp 
返回书; 
} 
} 
  

取消注释 @Remote（UserViewBeanRemote.class） 不会更改此行为。
查找在以下文件中完成：

Lookup.java

  package books.point; 
 
 import javax.naming.Context; 
 import javax.naming.NamingException; 
 
 import books.point.clientutility.ClientUtility; 
 import books.pointejb.CartBean; 
 import books.pointejb.CartBeanRemote; 
 import books.pointejb.UserViewBean; 
 import books.pointejb.UserViewBeanRemote; 
 
 public class Lookup {
 private static final String MODULE_NAME =BooksPointEJB; 
 
 public static UserViewBean doLookupUser（）{
 Context context = null; 
 UserViewBean bean = null; 
 try {
 // 1.获取上下文
 context = ClientUtility.getInitialContext（）; 
 // 2.生成JNDI查找名称
 String lookupName = getLookupNameUser（）; 
 // 3.查找和转换
 bean =（UserViewBean）context.lookup（lookupName）; //< ==异常抛出此处
 
} catch（NamingException e）{
 e.printStackTrace（）; 
} 
返回bean; 
} 
 
 public static String getLookupNameUser（）{
 / * 
 *应用程序名称是没有.ear后缀的部署EJB的EAR名称。 
 *由于我们没有将应用程序部署为.ear，因此
 * us的应用程序名称将为空字符串
 * / 
 String appName =; 
 
 / * 
 *模块名称是没有.jar 
 *后缀的部署EJB的JAR名称。 
 * / 
 String moduleName = MODULE_NAME; 
 
 / * 
 * AS7允许每个部署具有（可选）不同的名称。如果未指定不同的名称，则
 *可以是空字符串。 
 * / 
 String distinctName =; 
 
 // EJB bean实现类名称
 String beanName = UserViewBean.class.getSimpleName（）; 
 
 //完全限定的远程接口名称
 final String interfaceName = UserViewBeanRemote.class.getName（）; 
 
 //创建一个查询字符串名称
 //在结尾的状态标志非常小心
 String name =ejb：+ appName +/+ moduleName +/+ distinctName 
 +/+ beanName +！ + interfaceName +？stateful; 
  

//用户查找名称：ejb：/ BooksPointEJB // UserViewBean！books.pointejb.UserViewBeanRemote？ stateful
System.out.println（User Lookup name is：+ name）;
返回名称;
}

  ... 
} 
  pre> 
 
 
 EJB部署日志是：
  12:10： 22,897 INFO [org.jboss.as.ejb3.deployment.processors.EjbJndiBindingsDeploymentUnitProcessor]（MSC服务线程1-5）部署单元部署中名为UserViewBean的会话bean的JNDI绑定BooksPoint.war如下：
 
 java：global / BooksPoint / UserViewBean！books.pointejb.UserViewBeanRemote 
 java：app / BooksPoint / UserViewBean！books.pointejb.UserViewBeanRemote 
 java：module / UserViewBean！books.pointejb.UserViewBeanRemote 
 java：jboss / exports / BooksPoint / UserViewBean！books.pointejb.UserViewBeanRemote 
 java：global / BooksPoint / UserViewBean 
 java：app / BooksPoint / UserViewBean 
 java：module / UserViewBean 
  
我正在使用jboss-as-7.1.1.Final。为什么会抛出这个异常？
  12：10：52,973 INFO [org.jboss.ejb.client]（http-localhost- 127.0.0.1-8080-1）JBoss EJB Client版本1.0.5.Final 
 12：10：53,043 ERROR [org.apache.catalina.core.ContainerBase。[jboss.web]。[default-host]。 [/BooksPoint].[books.point.Register]]（http-localhost-127.0.0.1-8080-1）Servlet.service（）为servlet books.point.Register抛出异常：java.lang.ClassCastException：com.sun .proxy。$ Proxy22不能被转换为books.pointejb.UserViewBean 
在books.point.Lookup.doLookupUser（Lookup.java:24）[classes：] 
 at books.point.Register.doPost（ Register.java:263）[classes：] 
在javax.servlet.http.HttpServlet.service（HttpServlet.java:754）[jboss-servlet-api_3.0_spec-1.0.0.Final.jar：1.0。 0.Final] 
 at javax.servlet.http.HttpServlet.service（HttpServlet.java:847）[jboss-servlet-api_3.0_spec-1.0.0.Final.jar：1.0.0.Final] 
在org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain .java：329）[jbossweb-7.0.13.Final.jar：] 
在org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:248）[jbossweb-7.0.13.Final.jar ：] 
在org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:275）[jbossweb-7.0.13.Final.jar：] 
在org.apache.catalina.core。 StandardContextValve.invoke（StandardContextValve.java:161）[jbossweb-7.0.13.Final.jar：] 
在org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke（WebNonTxEmCloserValve.java:50）[jboss- as-jpa-7.1.1.Final.jar：7.1.1.Final] 
在org.jboss.as.web.security.SecurityContextAssociationValve.invoke（SecurityContextAssociationValve.java:153）[jboss-as-web- 7.1.1.Final.jar：7.1.1.Final] 
在org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:155）[jbossweb-7.0.13.Final.jar：] 
在org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:102）[jbossweb-7.0.13.Final.jar：] 
在org.apache.catalina.cor e.StandardEngineValve.invoke（StandardEngineValve.java:109）[jbossweb-7.0.13.Final.jar：] 
在org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:368）[jbossweb- 7.0.13.Final.jar：] 
在org.apache.coyote.http11.Http11Processor.process（Http11Processor.java:877）[jbossweb-7.0.13.Final.jar：] 
在org .apache.coyote.http11.Http11Protocol $ Http11ConnectionHandler.process（Http11Protocol.java:671）[jbossweb-7.0.13.Final.jar：] 
在org.apache.tomcat.util.net.JIoEndpoint $ Worker。 run（JIoEndpoint.java:930）[jbossweb-7.0.13.Final.jar：] 
 java.lang.Thread.run（Unknown Source）[rt.jar：1.7.0_45] 
  
 
 
解决方案
当您进行JNDI查找时，您将查找远程接口。 > 
 
 
所以将你的演员更改为
  bean =（UserViewBeanRemote）context.lookup lookupName）; 
  
应该做的伎俩。
 
I am having trouble using remote EJB objects. JNDI look-up succeeds but casting to an object and later usage fails. The EJB interface and implementation are as follows:

UserViewBeanRemote.java
package books.pointejb;

import java.util.List;

import javax.ejb.Remote;

import books.pointejb.User;
import books.pointejb.Book;

@Remote
public interface UserViewBeanRemote {
    public boolean register(User user);
    // A user can delete his/her account, note that two users with the same username cannot exist
    public void delete(User user);
    public boolean login(User user);
    public boolean logout(User user);
    // Search only by book titles
    public List<Book> search(String title);
}
UserViewBean.java
package books.pointejb;


import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import javax.ejb.Stateful;
import javax.management.Query;
import javax.persistence.EntityManager;  
import javax.persistence.PersistenceContext;

// import javax.ejb.Remote;
import books.pointejb.User;
import books.pointejb.Book;

/**
 * Session Bean implementation class UserView
 */
@Stateful
// @Remote(UserViewBeanRemote.class)
public class UserViewBean implements UserViewBeanRemote {

    @PersistenceContext  
     private EntityManager entityManager; 
    /**
     * Default constructor. 
     */
    public UserViewBean() {
        // TODO Auto-generated constructor stub
    }

    public static <T> List<T> castList(Class<? extends T> clazz, Collection<?> c) {
        List<T> r = new ArrayList<T>(c.size());
        for(Object o: c)
          r.add(clazz.cast(o));
        return r;
    }

    @Override
    public boolean register(User user) {
        // We have servlets that validate these fields, so we don't validate anything here
        // We check to see whether there is already a user with the same user name or not
        Query query = (Query) entityManager.createQuery("SELECT u FROM users u WHERE u.username=:userName");
        ((javax.persistence.Query) query).setParameter("userName", user.getUsername());
        // We check each returned value. If we find anything than we do not add the user
        List<User> users = castList(User.class, ((javax.persistence.Query) query).getResultList());
        if(users.isEmpty()) {
            // The user is not present. Add this user
            entityManager.persist(user);
            // return "Welcome to BooksPoint " + user.getUsername() + "!";
            return true;
        } else {
            // return "Cannot create " + user.getUsername() + ". A user with this name already exists";
            return false;
        }

    }

    @Override
    public void delete(User user) {
        // The account automatically exists since the user is already logged in
        Query query = (Query) entityManager.createQuery("DELETE FROM users u WHERE u.username=:userName");
        ((javax.persistence.Query) query).setParameter("userName", user.getUsername());
        // return "Your account " + user.getUsername() + " has been removed successfully!";
    }

    @Override
    public boolean login(User user) {
        // Check if we have a valid user/pass pair
        Query query = (Query) entityManager.createQuery("SELECT u FROM users u WHERE u.username=:userName AND u.password=:password");
        ((javax.persistence.Query) query).setParameter("userName", user.getUsername());
        ((javax.persistence.Query) query).setParameter("password", user.getPassword());
        List<User> users = castList(User.class, ((javax.persistence.Query) query).getResultList());
        if(!users.isEmpty()) {
            // return "Welcome " + user.getUsername() + "!";
            return true;
        } else {
            // return "Username or password are not valid";
            return false;
        }
    }

    @Override
    public boolean logout(User user) {
        // This can be done in the jsp/servlet. Simply erase the session variables associated with the current user
        return false;
    }

    @Override
    public List<Book> search(String title) {
        // Check all entries for names similar to title
        Query query = (Query) entityManager.createQuery("SELECT * FROM books WHERE title LIKE '%:title%'");
        ((javax.persistence.Query) query).setParameter("title", title);
        List<Book> books = castList(Book.class, ((javax.persistence.Query) query).getResultList());
        // Return the books now leave the rest to the jsp
        return books;
    }
}
Uncommenting @Remote(UserViewBeanRemote.class) doesn't change this behavior. 
The lookup is done in the following file:

Lookup.java
package books.point;

import javax.naming.Context;
import javax.naming.NamingException;

import books.point.clientutility.ClientUtility;
import books.pointejb.CartBean;
import books.pointejb.CartBeanRemote;
import books.pointejb.UserViewBean;
import books.pointejb.UserViewBeanRemote;

public class Lookup {
    private static final String MODULE_NAME = "BooksPointEJB";

    public static UserViewBean doLookupUser() {
        Context context = null;
        UserViewBean bean = null;
        try {
            // 1. Obtaining Context
            context = ClientUtility.getInitialContext();
            // 2. Generate JNDI Lookup name
            String lookupName = getLookupNameUser();
            // 3. Lookup and cast
            bean = (UserViewBean) context.lookup(lookupName); // <== Exception is thrown here

        } catch (NamingException e) {
            e.printStackTrace();
        }
        return bean;
    }

    public static String getLookupNameUser() {
        /*
         * The app name is the EAR name of the deployed EJB without .ear suffix.
         * Since we haven't deployed the application as a .ear, the app name for
         * us will be an empty string
         */
        String appName = "";

        /*
         * The module name is the JAR name of the deployed EJB without the .jar
         * suffix.
         */
        String moduleName = MODULE_NAME;

        /*
         * AS7 allows each deployment to have an (optional) distinct name. This
         * can be an empty string if distinct name is not specified.
         */
        String distinctName = "";

        // The EJB bean implementation class name
        String beanName = UserViewBean.class.getSimpleName();

        // Fully qualified remote interface name
        final String interfaceName = UserViewBeanRemote.class.getName();

        // Create a look up string name
        // Be very careful about the stateful flag at the end
        String name = "ejb:" + appName + "/" + moduleName + "/" + distinctName
                + "/" + beanName + "!" + interfaceName + "?stateful";
// User looked up name: ejb:/BooksPointEJB//UserViewBean!books.pointejb.UserViewBeanRemote?stateful
            System.out.println("User Lookup name is: " + name);
            return name;
        }
    ...
}
The EJB deployment log is:
12:10:22,897 INFO  [org.jboss.as.ejb3.deployment.processors.EjbJndiBindingsDeploymentUnitProcessor] (MSC service thread 1-5) JNDI bindings for session bean named UserViewBean in deployment unit deployment "BooksPoint.war" are as follows:

    java:global/BooksPoint/UserViewBean!books.pointejb.UserViewBeanRemote
    java:app/BooksPoint/UserViewBean!books.pointejb.UserViewBeanRemote
    java:module/UserViewBean!books.pointejb.UserViewBeanRemote
    java:jboss/exported/BooksPoint/UserViewBean!books.pointejb.UserViewBeanRemote
    java:global/BooksPoint/UserViewBean
    java:app/BooksPoint/UserViewBean
    java:module/UserViewBean
I am using jboss-as-7.1.1.Final. Why is this exception thrown?
12:10:52,973 INFO  [org.jboss.ejb.client] (http-localhost-127.0.0.1-8080-1) JBoss EJB Client version 1.0.5.Final
12:10:53,043 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/BooksPoint].[books.point.Register]] (http-localhost-127.0.0.1-8080-1) Servlet.service() for servlet books.point.Register threw exception: java.lang.ClassCastException: com.sun.proxy.$Proxy22 cannot be cast to books.pointejb.UserViewBean
    at books.point.Lookup.doLookupUser(Lookup.java:24) [classes:]
    at books.point.Register.doPost(Register.java:263) [classes:]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:754) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.13.Final.jar:]
    at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final]
    at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.13.Final.jar:]
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.13.Final.jar:]
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.13.Final.jar:]
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.13.Final.jar:]
    at java.lang.Thread.run(Unknown Source) [rt.jar:1.7.0_45]

解决方案
When you do a JNDI lookup, you lookup the remote Interface.

so changing your cast to
bean = (UserViewBeanRemote) context.lookup(lookupName);
should do the trick.

                        
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