今天参考了一下网上Rhello示例，搞了一下RMI测试。
server端是 java8
client 段是java6
然后 运行报错：
java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.lang.ClassNotFoundException: com.sap.oms.api_order.api_invoice.rmi1.IQrCodeScanner (no security manager: RMI class loader disabled)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
at java.rmi.Naming.lookup(Unknown Source)
at com.test.rmi.QrCodeScannerClient.main(QrCodeScannerClient.java:22)
Caused by: java.lang.ClassNotFoundException: com.test.rmi1.IQrCodeScanner (no security manager: RMI class loader disabled)
at sun.rmi.server.LoaderHandler.loadProxyClass(Unknown Source)
at java.rmi.server.RMIClassLoader$2.loadProxyClass(Unknown Source)
at java.rmi.server.RMIClassLoader.loadProxyClass(Unknown Source)
at sun.rmi.server.MarshalInputStream.resolveProxyClass(Unknown Source)
at java.io.ObjectInputStream.readProxyDesc(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)
... 3 more
刚开始没有仔细查看报错，上网查了一阵，美搞后，后来发现，原来是客户端的rmi接口所在包名不对。
原来： RMI 有要求， 客户端和服务端使用的服务接口类， 包名必须一样。
再返回报错信息仔细看，客户端报错信息里面提示没有找到的类名，里面有包名全路径， 是服务端的包名字符串。大意了。