Java8 Function函数式接口

以你之姓@ 2022-12-21 15:50 261阅读 0赞

### Java8 Function函数式接口 ###

*  1. 什么是函数式接口
 *  2. Java内置四大核心函数是接口
 *  3. 自定义函数式接口
 *  4. 案例

# 1. 什么是函数式接口 #

1.只包含一个抽象方法的接口，称为函数式接口。
    2.可以使用注解@FunctionalInterface注解，检查是否只包含一个接口。

# 2. Java内置四大核心函数是接口 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3NTgzNjU1_size_16_color_FFFFFF_t_70]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3NTgzNjU1_size_16_color_FFFFFF_t_70 1]

# 3. 自定义函数式接口 #

@FunctionalInterface
    public interface CalcutionFunction { 
        Integer getValue(Integer val);
    }

@FunctionalInterface
    public interface HandlerFunction<T, R> { 
    
        R getValue(T t1, T t2);
    }

# 4. 案例 #

/** * 支付对象 * * @author zrj * @date 2021/1/26 * @since 1.0 */
    @Data
    @Builder
    @NoArgsConstructor
    @AllArgsConstructor
    public class Payment { 
        public Integer id;
        public String name;
    }

/** * 支付接口 * * @author zrj * @date 2021/1/26 * @since 1.0 */
    public interface PaymentService { 
    
        int create(Payment payment);
    
        int delete(int id);
    
        int update(Payment payment);
    
        Payment get();
    
        boolean valid();
    
        void customer();
    
        void exception();
    
    }

/** * 支付实现类 * * @author zrj * @date 2021/1/26 * @since 1.0 */
    public class PaymentServiceImpl implements PaymentService { 
    
        @Override
        public int create(Payment payment) { 
            return 1;
        }
    
        @Override
        public int delete(int id) { 
            return 1;
        }
    
        @Override
        public int update(Payment payment) { 
            return 1;
        }
    
        @Override
        public Payment get() { 
            return new Payment();
        }
    
        @Override
        public boolean valid() { 
            return false;
        }
    
        @Override
        public void customer() { 
        }
    
        @Override
        public void exception() { 
            throw new RuntimeException();
        }
    }

/** * 自定义调用异常 * * @author zrj * @date 2021/1/20 * @since 1.0 **/
    public class InvokeServiceException extends RuntimeException { 
        private String code;
        private String message;
    
        public InvokeServiceException() { 
        }
    
        public InvokeServiceException(String code, String message) { 
            this.code = code;
            this.message = message;
        }
    
        public String getCode() { 
            return code;
        }
    
        public void setCode(String code) { 
            this.code = code;
        }
    
        public String getMessage() { 
            return message;
        }
    
        public void setMessage(String message) { 
            this.message = message;
        }
    }

/** * InvokeFunctionHandler * * @author zrj * @date 2021/1/26 * @since 1.0 */
    @FunctionalInterface
    public interface InvokeFunctionHandler<T> { 
        int invoke(T t) throws InvokeServiceException;
    }

/** * Represents a void of results. * no param and no result * * @author zrj * @date 2021/1/26 * @since 1.0 */
    @FunctionalInterface
    public interface InvokeConsumerHandler { 
        void invoke() throws InvokeServiceException;
    }

/** * 异常处理 * * @author zrj * @date 2021/1/26 * @since 1.0 */
    public class InvokeAdapterHandler { 
    
        /** * 校验异常处理 */
        public static boolean catchBooleanThrow(String msg, BooleanSupplier booleanSupplier) { 
            try { 
                return booleanSupplier.getAsBoolean();
            } catch (Exception ex) { 
                throw new RuntimeException(msg + ":" + ex);
            }
        }
    
        /** * 无入参无返回异常处理 */
        public static void catchConsumerThrow(String msg, InvokeConsumerHandler invokeConsumerHandler) { 
            try { 
                invokeConsumerHandler.invoke();
            } catch (Exception ex) { 
                throw new RuntimeException(msg + ":" + ex);
            }
        }
    
        /** * 无入参有返回异常处理 */
        public static <T> T catchSupplierThrow(String msg, Supplier<T> supplier) { 
            try { 
                return supplier.get();
            } catch (Exception ex) { 
                throw new RuntimeException(msg + ":" + ex);
            }
        }
    
        /** * 有入参有返回值异常处理 * 适合create，delete，update方法 * * @param msg 异常信息 * @param param 参数 * @param function 方法 * @return */
        public static Object catchFunctionThrow(String msg, Object param, Function<Object, Object> function) { 
            try { 
                return function.apply(param);
            } catch (Exception ex) { 
                throw new RuntimeException(msg + ":" + ex);
            }
        }
    
        public static int catchInvokeFunctionThrow(String msg, Object param, InvokeFunctionHandler<Object> invokeFunctionHandler) { 
            try { 
                return invokeFunctionHandler.invoke(param);
            } catch (Exception ex) { 
                throw new RuntimeException(msg + ":" + ex);
            }
        }
    }

/** * AdapterHandler测试类 * * @author zrj * @date 2021/1/26 * @since 1.0 */
    public class InvokeAdapterHandlerTest { 
        @Test
        public void invokeBooleanHandler() { 
            PaymentService paymentService = new PaymentServiceImpl();
            boolean valid = InvokeAdapterHandler.catchBooleanThrow("invokeBooleanHandler调用异常", () -> paymentService.valid());
            System.out.println("invokeBooleanHandler处理成功：" + valid);
        }
    
        @Test
        public void invokeExceptionHandler() { 
            PaymentService paymentService = new PaymentServiceImpl();
            InvokeAdapterHandler.catchConsumerThrow("invokeExceptionHandler调用异常", () -> paymentService.exception());
            System.out.println("invokeBooleanHandler处理成功");
        }
    
        @Test
        public void invokeCustomerHandler() { 
            PaymentService paymentService = new PaymentServiceImpl();
            InvokeAdapterHandler.catchConsumerThrow("invokeCustomerHandler调用异常", () -> paymentService.customer());
            System.out.println("invokeCustomerHandler处理成功");
        }
    
        @Test
        public void invokeSupplierHandler() { 
            PaymentService paymentService = new PaymentServiceImpl();
            Payment payment = InvokeAdapterHandler.catchSupplierThrow("invokeSupplierHandler调用异常", () -> paymentService.get());
            System.out.println("invokeCustomerHandler处理成功" + payment);
        }
    
        @Test
        public void invokeFunctionHandler() { 
            PaymentService paymentService = new PaymentServiceImpl();
            Payment hello = new Payment();
    
            InvokeAdapterHandler.catchInvokeFunctionThrow("invokeSupplierHandler调用异常", hello, (catchInvokeFunctionThrow) -> paymentService.create(hello));
            System.out.println("invokeCustomerHandler处理成功");
        }
    
    }

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