错误处理与异常处理

1. 异常处理的打包及自定义异常类

ACMEPort port = new ACMEPort(12);

try {
    port.open();
} catch (DeviceResponseException e) {
    reportPortError(e);
    logger.log("Device response exception", e);
} catch (ATM212UnlockedException e) {
    reportPortError(e);
    logger.log("unlock exception", e);  
} catch (GMXError e) {
    reportPortError(e);
    logger.log("Device response exception", e);
} finally {
    ...
}

重复的代码就是坏味道，为了代码结构更为清晰，有两处修改方向：

• 将重复的异常处理，打包成一个类的成员函数；

• 自定义异常类 PortDeviceFailure，其构造函数接受（DeviceResponseException、ATM212UnlockedException、GMXError 具体异常类的）父类（如 ACMEException）引用；

  LocalPort port = new LocalPort(12);
  
  try {
      port.open();
  } catch (PortDeviceFailure e) {
      reportPortError(e);
      logger.log(e.getMessage(), e);
  }
  
  
  public class LocalPort {
      private ACMEPort innerPort;
  
      public LocalPort(int portNum) {
          innerPort = new ACMEPort(portNum);
      }
  
      try {
          innerPort.open();
      } catch (DeviceResponseException e) {
          throw new PortDeviceFailure (e);
      } catch (ATM212UnlockedException e) {
          throw new PortDeviceFailure (e);
      } catch (GMXError e) {
          throw new PortDeviceFailure (e);
      }
  }
  
  public class PortDeviceFailure extends Exception {
      private ACMEException acmeExce;
      public PortDeviceFailure (ACMEException exce) {
          acmeExce = exce;
      }
      public String getMessage () {
          return ....;
      }
  }