google protobuf java.lang.NoSuchFieldError: alwaysUseFieldBuilders问题
google protobuf java.lang.NoSuchFieldError: alwaysUseFieldBuilders
报如下异常：
Exception in thread "WatcherThread" java.lang.NoSuchFieldError: alwaysUseFieldBuilders
at com.***.***.proto.message.DBACommon$DBAServerRequest.access$7(DBACommon.java:2670)
at com.***.***.proto.message.DBACommon$DBAServerRequest$Builder.maybeForceBuilderInitialization(DBACommon.java:2855)
at com.***.***.proto.message.DBACommon$DBAServerRequest$Builder.<init>(DBACommon.java:2847)
at com.***.***.proto.message.DBACommon$DBAServerRequest$Builder.create(DBACommon.java:2859)
at com.***.***.proto.message.DBACommon$DBAServerRequest$Builder.access$18(DBACommon.java:2858)
at com.***.***.proto.message.DBACommon$DBAServerRequest.newBuilder(DBACommon.java:2819)
at com.***.***.net.LogClient.getRealServerInfo(LogClientV2.java:178)
at com.***.***.net.LogClient.startMessageServer(LogClientV2.java:133)
at com.***.***.net.LogClient.access$5(LogClientV2.java:131)
at com.***.***.net.LogClient$1.onLeaderCreated(LogClientV2.java:87)
at com.***.***.cluster.ZooKeeperCluster.ClusterChanged(ZooKeeperCluster.java:352)
at com.***.***.cluster.ZooKeeperCluster.access$3(ZooKeeperCluster.java:318)
at com.***.***.cluster.ZooKeeperCluster$WatcherThread.run(ZooKeeperCluster.java:530)
原因：
是google protobuf的jar包冲突造成的。工程类路径下有protobuf-java-2.3.0.jar、protobuf-java-2.4.1.jar。该程序应该调用的是protobuf-java-2.4.1.jar，而实际上调用了protobuf-java-2.3.0.jar，造成NoSuchFieldError异常。只需要在工程类路径下去掉protobuf-java-2.3.0.jar即可。如果程序中有的地方用到protobuf-java-2.3.0.jar，而有的地方用到protobuf-java-2.4.1.jar，则统一重新生成协议类即可。
