原因：java.lang.ClassNotFoundException：日志

Question

在J2SE中進行遠程EJB查找（從JBoss 4.3中進行）時，遇到以下異常：

Exception in thread "main" java.lang.NoClassDefFoundError: LLog;
    at java.lang.Class.getDeclaredFields0(Native Method)
    at java.lang.Class.privateGetDeclaredFields(Class.java:2499)
    at java.lang.Class.getDeclaredField(Class.java:1951)
    at java.io.ObjectStreamClass.getDeclaredSUID(ObjectStreamClass.java:1659)
    at java.io.ObjectStreamClass.access$700(ObjectStreamClass.java:72)
    at java.io.ObjectStreamClass$2.run(ObjectStreamClass.java:480)
    at java.io.ObjectStreamClass$2.run(ObjectStreamClass.java:468)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.io.ObjectStreamClass.<init>(ObjectStreamClass.java:468)
    at java.io.ObjectStreamClass.lookup(ObjectStreamClass.java:365)
    at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:602)
    at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1622)
    at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1517)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1771)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1706)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1344)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
    at java.rmi.MarshalledObject.get(MarshalledObject.java:159)
    at org.jnp.interfaces.MarshalledValuePair.get(MarshalledValuePair.java:72)
    at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:737)
    at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:654)
    at javax.naming.InitialContext.lookup(InitialContext.java:411)
    at com.example.ShoppingBasketServiceClient.main(ShoppingBasketServiceClient.java:44)
Caused by: java.lang.ClassNotFoundException: Log
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    ... 32 more

這是codez，第44行是進行查找的代碼：

package com.example;

import java.util.Properties;

import javax.naming.InitialContext;
import javax.naming.NamingException;

public class ShoppingBasketServiceClient {

    public static void main(String[] args) throws NamingException {

        Properties props = new Properties();            
        props.setProperty("java.naming.factory.initial",  "org.jnp.interfaces.NamingContextFactory");
        props.setProperty("java.naming.factory.url.pkgs", "org.jboss.naming:org.jnp.interfaces");
        props.setProperty("java.naming.provider.url", "jnp://localhost:1099");
        String Lookup = "ejb/ShoppingBasketService/remote";

        try {
            InitialContext ic = new InitialContext(props);
            // ShoppingBasketServiceRemote shoppingBasketService = (ShoppingBasketServiceRemote) ic.lookup(Lookup);
            Object shoppingBasketService = (Object) ic.lookup(Lookup);

        } catch (NamingException e) {
            System.out.println("Exception:" + e);
        }
    }
}

我對於為什么要查找Log類（以及為什么異常不符合包要求）感到困惑？

ShoppingBasketServiceRemote只是一個接口，該接口導入javax.ejb.Remote批注並擴展了另一個接口-沒有對Log類進行任何引用？ 另外，您會看到我的示例僅將結果強制轉換為對象（但是如果換出服務接口，結果是相同的）？

Answer 1

ShoppingBasketServiceRemote只是一個接口，該接口導入javax.ejb.Remote批注並擴展了另一個接口-沒有對Log類進行任何引用？

• 檢查接口中引用的所有對象及其傳遞依賴項。 某些東西將指向“ Log”類。
• 同時檢查遠程服務器上是否有錯誤，也許該錯誤是在遠程服務器上
• 嘗試做一個簡單的Class.forName("ShoppingBasketServiceRemote") -您可能會看到它失敗，並顯示相同的錯誤。

另外，您會看到我的示例僅將結果強制轉換為對象（但是如果換出服務接口，結果是相同的）？

在您的jvm能夠加載ic.lookup(Lookup)返回的對象之后，才進行對象的ic.lookup(Lookup) -因此無論您是否進行轉換，都會發生錯誤。