Memcached ClassNotFound异常

所以我觉得我对memcached的工作原理有些困惑。我正在开发使用不同框架的同一个API，这些框架都包含了memcached（java版本的spymemcached）。当我在第一个框架上设置memcached时，它按预期工作。现在我试图将它合并到我使用的第二个框架中，我不断收到一个ClassNotFoundException，它试图在我使用的第一个框架中找到一个类，因此不会缓存任何内容。也许有人可以启发我去理解我的逻辑中的缺陷。这里有两个类（它们是相同的，因为我在不同的平台上构建了相同的API），core.Party类是第一个类（运行相应应用程序时起作用），pojo.PojoParty是第一个和第二个框架I使用它似乎没有连接到memcached。Memcached ClassNotFound异常

这里就是它发生在类的构造函数：

package resources; 

import health.TemplateHealthCheck; 

import java.net.InetSocketAddress; 
import java.sql.DriverManager; 
import java.sql.PreparedStatement; 
import java.sql.ResultSet; 
import java.sql.Connection; 
import java.sql.ResultSetMetaData; 
import java.util.HashMap; 

import com.codahale.metrics.Gauge; 
import com.codahale.metrics.Meter; 
import com.codahale.metrics.MetricRegistry; 
import com.codahale.metrics.Counter; 
import com.codahale.metrics.RatioGauge; 

import contextListener.MyAdminServletContextListener; 

import pojo.PartyPojo; 

import net.spy.memcached.MemcachedClient; 

    public class DBConnection { 

     public static Connection con; 
     private static ResultSet resultSet; 
     private static PreparedStatement ps; 
     private static ResultSetMetaData meta; 
     private static HashMap<String,PartyPojo> map; 
     private static DBConnection connection; 
     private static PartyPojo party; 
     private static final InetSocketAddress isa= new InetSocketAddress("atom1.cisco.com",11211); 
     private static MemcachedClient memcache; 
     private static Meter hits = MyAdminServletContextListener.registry.meter(MetricRegistry.name("Meter", 
       "get-hits")); 
     private static Meter calls = MyAdminServletContextListener.registry.meter(MetricRegistry.name("Meter", 
       "get-calls")); 
     private static Counter evictions = MyAdminServletContextListener.registry.counter(MetricRegistry.name("Counter", 
       "Memcache-Evictions")); 
     private static int getHits,getCalls; 
     private final static int MAX_MEMCACHED_EXPIRATION=2505600; 

     private DBConnection() 
     { 
      try 
      { 
       map = new HashMap<String,PartyPojo>(); 
       Class.forName("com.mysql.jdbc.Driver"); 
       con = DriverManager.getConnection(
         "jdbc:mysql://atom3.cisco.com:3306/reddb", "redteam", 
         "redteam");  
       //initialize memcache 
       memcache = new MemcachedClient(isa); //this line produces error 
       //this is just a integer variable I was using to make sure my Meters were measuring correctly 
       getHits = Integer.valueOf(DBConnection.memcache.getStats().get(DBConnection.isa). 
         get("get_hits")); 
       getCalls = Integer.valueOf(DBConnection.memcache.getStats().get(DBConnection.isa). 
         get("cmd_get")); 
       metricsRegistry();  
      } 
      catch (Exception e) 
      { 
       e.printStackTrace(); 
      } 
     }

下面是它试图达到这不是第二个框架的一部分（这是从第一框架POJO类）类：

package core; 

import java.io.Serializable; 
import java.util.HashMap; 

public class Party implements Serializable { 


    /** 
    * 
    */ 
    private static final long serialVersionUID = 1L; 
    HashMap <String,String> partyInfo = new HashMap<String,String>(); 

    public HashMap<String,String> getPartyInfo() throws Exception 
    { 
     return partyInfo; 
    } 
}

这里是相同的类，但在项目中，我试图运行

package pojo; 

import java.io.Serializable; 
import java.util.HashMap; 

import javax.xml.bind.annotation.XmlAccessType; 
import javax.xml.bind.annotation.XmlAccessorType; 
import javax.xml.bind.annotation.XmlRootElement; 
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter; 

import org.eclipse.persistence.oxm.annotations.XmlPath; 


@XmlRootElement(name="Party") 
@XmlAccessorType(XmlAccessType.FIELD) 
public class PartyPojo implements Serializable { 

    /** 
    * 
    */ 
    private static final long serialVersionUID = -4892745279086305480L; 
    /** 
    * 
    */ 
    /** 
    * 
    */ 
    @XmlPath(".") 
    @XmlJavaTypeAdapter(MapAdapter.class) 

    HashMap <String,String> partyInfo = new HashMap<String,String>(); 

    public HashMap<String,String> getPartyInfo() throws Exception 
    { 
     return partyInfo; 
    } 
}

这里的堆栈跟踪：

2013-08-05 15:54:39.810 INFO net.spy.memcached.MemcachedConnection: Added {QA sa=atom1.cisco.com/173.36.62.251:11211, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0} to connect queue 
2013-08-05 15:54:39.847 INFO net.spy.memcached.MemcachedConnection: Connection state changed for [email protected] 
2013-08-05 15:54:40.120 WARN net.spy.memcached.transcoders.SerializingTranscoder: Caught CNFE decoding 434 bytes of data 
java.lang.ClassNotFoundException: core.Party 
    at java.net.URLClassLoader$1.run(Unknown Source) 
    at java.net.URLClassLoader$1.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.net.URLClassLoader.findClass(Unknown Source) 
    at java.lang.ClassLoader.loadClass(Unknown Source) 
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) 
    at java.lang.ClassLoader.loadClass(Unknown Source) 
    at java.lang.Class.forName0(Native Method) 
    at java.lang.Class.forName(Unknown Source) 
    at java.io.ObjectInputStream.resolveClass(Unknown Source) 
    at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source) 
    at java.io.ObjectInputStream.readClassDesc(Unknown Source) 
    at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) 
    at java.io.ObjectInputStream.readObject0(Unknown Source) 
    at java.io.ObjectInputStream.readObject(Unknown Source) 
    at net.spy.memcached.transcoders.BaseSerializingTranscoder.deserialize(BaseSerializingTranscoder.java:129) 
    at net.spy.memcached.transcoders.SerializingTranscoder.decode(SerializingTranscoder.java:88) 
    at net.spy.memcached.transcoders.TranscodeService$1.call(TranscodeService.java:63) 
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) 
    at java.util.concurrent.FutureTask.run(Unknown Source) 
    at net.spy.memcached.transcoders.TranscodeService$Task.run(TranscodeService.java:110) 
    at net.spy.memcached.transcoders.TranscodeService$Task.get(TranscodeService.java:96) 
    at net.spy.memcached.internal.GetFuture.get(GetFuture.java:63) 
    at net.spy.memcached.MemcachedClient.get(MemcachedClient.java:997) 
    at net.spy.memcached.MemcachedClient.get(MemcachedClient.java:1018) 
    at resources.DBConnection.readOneParty(DBConnection.java:114) 
    at resources.OnePartyResource.getParty(OnePartyResource.java:57) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    at java.lang.reflect.Method.invoke(Unknown Source) 
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60) 
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185) 
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75) 
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288) 
    at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:134) 
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) 
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108) 
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) 
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1469) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1400) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1349) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1339) 
    at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:848) 
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:698) 
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:505) 
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:211) 
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1094) 
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:432) 
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:175) 
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1028) 
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:136) 
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) 
    at org.eclipse.jetty.server.Server.handle(Server.java:445) 
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:267) 
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:224) 
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.run(AbstractConnection.java:358) 
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:601) 
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:532) 
    at java.lang.Thread.run(Unknown Source)

来源

2013-08-05 sreya

我想通了，答案很尴尬。所以，因为我急于在不同的框架上完成代码，我基本上是将代码从一个复制到另一个。基本上发生的是它存储了第一个API罚款的值;但是，当我尝试使用其他API查询这些相同的值时，它试图将这些值存储在同一个关键位置的memcache中。因此，为什么它找不到对象，这是错误的项目！所以我基本上附加了一个程序的字符串键，以便它可以正确返回。

显然是一个令人尴尬的错误，但我会把它当成我第一次在多个程序中使用任何类型的缓存系统。

来源

2013-08-08 21:21:06 sreya

当memcached（或串行）试图从序列化形式重组的对象，它必须有获得相应的类。在反序列化方面您没有core.Party，因此memcached对于传入数据流没有Java表示。

当您谈论“不同平台”时，您似乎误解了Java库的工作原理。既然你在两边使用Java，你不应该有两个类的副本，你应该只有一个类可用。如果存在某些共享代码（例如Party），但其他代码不应该在两个发行版之间共享，请将Party放在两个项目包含的库jar中。 Maven和其他构建管理系统使这一切变得简单。

来源

2013-08-05 21:32:27 chrylis

平台有点用词不当，框架会更好。例如，我正在构建两个API，一个使用纯Servlet（仅使用泽西平台生成它）另一个使用Dropwizard。他们必须能够彼此独立运行，所以我想我的问题是，如何使memcached区分我的Dropwizard框架中的Party对象和我的PureServlet中的Party对象。我猜我认为通过单独序列化它们会使它们有区别 – sreya

答案是“不”。对通用对象使用相同的API并将它们放入共享jar中，然后在每个大型项目中包含通用组件。 – chrylis

如果它们不是同一个对象？我如何区分两者？它会自动执行吗？ – sreya

Memcached ClassNotFound异常

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