import org.apache.hadoop.ipc.protobuf.IpcConnectionContextProtos.UserInformationProto; //导入依赖的package包/类
public static UserGroupInformation getUgi(UserInformationProto userInfo) {
  UserGroupInformation ugi = null;
  String effectiveUser = userInfo.hasEffectiveUser() ? userInfo
      .getEffectiveUser() : null;
  String realUser = userInfo.hasRealUser() ? userInfo.getRealUser() : null;
  if (effectiveUser != null) {
    if (realUser != null) {
      UserGroupInformation realUserUgi = UserGroupInformation
          .createRemoteUser(realUser);
      ugi = UserGroupInformation
          .createProxyUser(effectiveUser, realUserUgi);
    } else {
      ugi = org.apache.hadoop.security.UserGroupInformation
          .createRemoteUser(effectiveUser);
    }
  }
  return ugi;
}
 

import org.apache.hadoop.ipc.protobuf.IpcConnectionContextProtos.UserInformationProto; //导入依赖的package包/类
/** 
 * This method creates the connection context  using exactly the same logic
 * as the old connection context as was done for writable where
 * the effective and real users are set based on the auth method.
 *
 */
public static IpcConnectionContextProto makeIpcConnectionContext(
    final String protocol,
    final UserGroupInformation ugi, final AuthMethod authMethod) {
  IpcConnectionContextProto.Builder result = IpcConnectionContextProto.newBuilder();
  if (protocol != null) {
    result.setProtocol(protocol);
  }
  UserInformationProto.Builder ugiProto =  UserInformationProto.newBuilder();
  if (ugi != null) {
    /*
     * In the connection context we send only additional user info that
     * is not derived from the authentication done during connection setup.
     */
    if (authMethod == AuthMethod.KERBEROS) {
      // Real user was established as part of the connection.
      // Send effective user only.
      ugiProto.setEffectiveUser(ugi.getUserName());
    } else if (authMethod == AuthMethod.TOKEN) {
      // With token, the connection itself establishes 
      // both real and effective user. Hence send none in header.
    } else {  // Simple authentication
      // No user info is established as part of the connection.
      // Send both effective user and real user
      ugiProto.setEffectiveUser(ugi.getUserName());
      if (ugi.getRealUser() != null) {
        ugiProto.setRealUser(ugi.getRealUser().getUserName());
      }
    }
  }   
  result.setUserInfo(ugiProto);
  return result.build();
}