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Java通过Lambda表达式实现简化代码

福牛 5月 23, 2023 16 0

之前，调用第3方服务，每个方法都差不多“长”这样, 写起来啰嗦, 改起来麻烦, 还容易改漏。

  1. public void authorizeRoleToUser(Long userId, List<Long> roleIds) {
  2.      try {
  3.          power.authorizeRoleToUser(userId, roleIds);
  4.      } catch (MotanCustomException ex) {
  5.          if (ex.getCode().equals(MSUserException.notLogin().getCode()))
  6.              throw UserException.notLogin();
  7.          if (ex.getCode().equals(MSPowerException.haveNoPower().getCode()))
  8.              throw PowerException.haveNoPower();
  9.          throw ex;
  10.      } catch (MotanServiceException ex) {
  11.          CatHelper.logEventService(“Power-authorizeRoleToUser”, “authorizeRoleToUser”, ex.getStatus(),
  12.                  ex.getErrorCode(), ex.getMessage());
  13.          throw ex;
  14.      } catch (MotanAbstractException ex) {
  15.          CatHelper.logEventService(“Power-authorizeRoleToUser”, “authorizeRoleToUser”, ex.getStatus(),
  16.                  ex.getErrorCode(), ex.getMessage());
  17.          throw ex;
  18.      } catch (Exception ex) {
  19.          CatHelper.logError(ex);
  20.          throw ex;
  21.      }
  22. }

我经过学习和提取封装, 将try … catch … catch .. 提取为公用, 得到这2个方法:

  1. import Java.util.function.Supplier;
  2. public static <T> T tryCatch(Supplier<T> supplier, String serviceName, String methodName) {
  3.      try {
  4.          return supplier.get();
  5.      } catch (MotanCustomException ex) {
  6.          if (ex.getCode().equals(MSUserException.notLogin().getCode()))
  7.              throw UserException.notLogin();
  8.          if (ex.getCode().equals(MSPowerException.haveNoPower().getCode()))
  9.              throw PowerException.haveNoPower();
  10.          throw ex;
  11.      } catch (MotanServiceException ex) {
  12.          CatHelper.logEventService(serviceName + “-“ + methodName, methodName, ex.getStatus(), ex.getErrorCode(),
  13.                  ex.getMessage());
  14.          throw ex;
  15.      } catch (MotanAbstractException ex) {
  16.          CatHelper.logEventService(serviceName + “-“ + methodName, methodName, ex.getStatus(), ex.getErrorCode(),
  17.                  ex.getMessage());
  18.          throw ex;
  19.      } catch (Exception ex) {
  20.          CatHelper.logError(ex);
  21.          throw ex;
  22.      }
  23. }
  24. public static void tryCatch(Runnable runnable, String serviceName, String methodName) {
  25.      tryCatch(() -> {
  26.          runnable.run();
  27.          return null;
  28.      }, serviceName, methodName);
  29. }

现在用起来是如此简洁。像这种无返回值的:

  1. public void authorizeRoleToUser(Long userId, List<Long> roleIds) {
  2.      tryCatch(() -> { power.authorizeRoleToUser(userId, roleIds); }, “Power”, “authorizeRoleToUser”);
  3. }

还有这种有返回值的:

  1. public List<RoleDTO> listRoleByUser(Long userId) {
  2.      return tryCatch(() -> power.listRoleByUser(userId), “Power”, “listRoleByUser”);
  3. }

后来发现以上2个方法还不够用, 原因是有一些方法会抛出 checked 异常, 于是又再添加了一个能处理异常的, 这次意外发现Java的throws也支持泛型, 赞一个:

  1. public static <T, E extends Throwable> T tryCatchException(SupplierException<T, E> supplier, String serviceName,
  2.          String methodName) throws E {
  3.      try {
  4.          return supplier.get();
  5.      } catch (MotanCustomException ex) {
  6.          if (ex.getCode().equals(MSUserException.notLogin().getCode()))
  7.              throw UserException.notLogin();
  8.          if (ex.getCode().equals(MSPowerException.haveNoPower().getCode()))
  9.              throw PowerException.haveNoPower();
  10.          throw ex;
  11.      } catch (MotanServiceException ex) {
  12.          CatHelper.logEventService(serviceName + “-“ + methodName, methodName, ex.getStatus(), ex.getErrorCode(),
  13.                  ex.getMessage());
  14.          throw ex;
  15.      } catch (MotanAbstractException ex) {
  16.          CatHelper.logEventService(serviceName + “-“ + methodName, methodName, ex.getStatus(), ex.getErrorCode(),
  17.                  ex.getMessage());
  18.          throw ex;
  19.      } catch (Exception ex) {
  20.          CatHelper.logError(ex);
  21.          throw ex;
  22.      }
  23. }
  24. @FunctionalInterface
  25. public interface SupplierException<T, E extends Throwable> {
  26.      /**
  27.          * Gets a result.
  28.          *
  29.          * @return a result
  30.          */
  31.      T get() throws E;
  32. }

为了不至于维护两份catch集, 将原来的带返回值的tryCatch改为调用tryCatchException:

  1. public static <T> T tryCatch(Supplier<T> supplier, String serviceName, String methodName) {
  2.      return tryCatchException(() -> supplier.get(), serviceName, methodName);
  3. }

这个世界又完善了一步。

前面制作了3种情况:

1.无返回值,无 throws

2.有返回值,无 throws

3.有返回值,有 throws

不确定会不会出现“无返回值，有throws“的情况。后来真的出现了！依样画葫芦，弄出了这个：

  1. public static <E extends Throwable> void tryCatchException(RunnableException<E> runnable, String serviceName,
  2.          String methodName) throws E {
  3.      tryCatchException(() -> {
  4.          runnable.run();
  5.          return null;
  6.      }, serviceName, methodName);
  7. }
  8. @FunctionalInterface
  9. public interface RunnableException<E extends Throwable> {
  10.      void run() throws E;
  11. }

完整代码

  1. package com.company.system.util;
  2. import java.util.function.Supplier;
  3. import org.springframework.beans.factory.BeanCreationException;
  4. import com.company.cat.monitor.CatHelper;
  5. import com.company.system.customException.PowerException;
  6. import com.company.system.customException.ServiceException;
  7. import com.company.system.customException.UserException;
  8. import com.company.hyhis.ms.user.custom.exception.MSPowerException;
  9. import com.company.hyhis.ms.user.custom.exception.MSUserException;
  10. import com.company.hyhis.ms.user.custom.exception.MotanCustomException;
  11. import com.weibo.api.motan.exception.MotanAbstractException;
  12. import com.weibo.api.motan.exception.MotanServiceException;
  13. public class ThirdParty {
  14.      public static void tryCatch(Runnable runnable, String serviceName, String methodName) {
  15.          tryCatch(() -> {
  16.              runnable.run();
  17.              return null;
  18.          }, serviceName, methodName);
  19.      }
  20.      public static <T> T tryCatch(Supplier<T> supplier, String serviceName, String methodName) {
  21.          return tryCatchException(() -> supplier.get(), serviceName, methodName);
  22.      }
  23.      public static <E extends Throwable> void tryCatchException(RunnableException<E> runnable, String serviceName,
  24.              String methodName) throws E {
  25.          tryCatchException(() -> {
  26.              runnable.run();
  27.              return null;
  28.          }, serviceName, methodName);
  29.      }
  30.      public static <T, E extends Throwable> T tryCatchException(SupplierException<T, E> supplier, String serviceName,
  31.              String methodName) throws E {
  32.          try {
  33.              return supplier.get();
  34.          } catch (MotanCustomException ex) {
  35.              if (ex.getCode().equals(MSUserException.notLogin().getCode()))
  36.                  throw UserException.notLogin();
  37.              if (ex.getCode().equals(MSPowerException.haveNoPower().getCode()))
  38.                  throw PowerException.haveNoPower();
  39.              throw ex;
  40.          } catch (MotanServiceException ex) {
  41.              CatHelper.logEventService(serviceName + “-“ + methodName, methodName, ex.getStatus(), ex.getErrorCode(),
  42.                      ex.getMessage());
  43.              throw ex;
  44.          } catch (MotanAbstractException ex) {
  45.              CatHelper.logEventService(serviceName + “-“ + methodName, methodName, ex.getStatus(), ex.getErrorCode(),
  46.                      ex.getMessage());
  47.              throw ex;
  48.          } catch (Exception ex) {
  49.              CatHelper.logError(ex);
  50.              throw ex;
  51.          }
  52.      }
  53.      @FunctionalInterface
  54.      public interface RunnableException<E extends Throwable> {
  55.          void run() throws E;
  56.      }
  57.      @FunctionalInterface
  58.      public interface SupplierException<T, E extends Throwable> {
  59.          T get() throws E;
  60.      }
  61. }

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