org.springframework.util.function.ThrowingSupplier Maven / Gradle / Ivy
/*
* Copyright 2002-2022 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.util.function;
import java.util.function.BiFunction;
import java.util.function.Supplier;
/**
* A {@link Supplier} that allows invocation of code that throws a checked
* exception.
*
* @author Stephane Nicoll
* @author Phillip Webb
* @since 6.0
* @param the type of results supplied by this supplier
*/
public interface ThrowingSupplier extends Supplier {
/**
* Gets a result, possibly throwing a checked exception.
* @return a result
* @throws Exception on error
*/
T getWithException() throws Exception;
/**
* Default {@link Supplier#get()} that wraps any thrown checked exceptions
* (by default in a {@link RuntimeException}).
* @see java.util.function.Supplier#get()
*/
@Override
default T get() {
return get(RuntimeException::new);
}
/**
* Gets a result, wrapping any thrown checked exceptions using the given
* {@code exceptionWrapper}.
* @param exceptionWrapper {@link BiFunction} that wraps the given message
* and checked exception into a runtime exception
* @return a result
*/
default T get(BiFunction exceptionWrapper) {
try {
return getWithException();
}
catch (RuntimeException ex) {
throw ex;
}
catch (Exception ex) {
throw exceptionWrapper.apply(ex.getMessage(), ex);
}
}
/**
* Return a new {@link ThrowingSupplier} where the {@link #get()} method
* wraps any thrown checked exceptions using the given
* {@code exceptionWrapper}.
* @param exceptionWrapper {@link BiFunction} that wraps the given message
* and checked exception into a runtime exception
* @return the replacement {@link ThrowingSupplier} instance
*/
default ThrowingSupplier throwing(BiFunction exceptionWrapper) {
return new ThrowingSupplier<>() {
@Override
public T getWithException() throws Exception {
return ThrowingSupplier.this.getWithException();
}
@Override
public T get() {
return get(exceptionWrapper);
}
};
}
/**
* Lambda friendly convenience method that can be used to create a
* {@link ThrowingSupplier} where the {@link #get()} method wraps any checked
* exception thrown by the supplied lambda expression or method reference.
* This method can be especially useful when working with method references.
* It allows you to easily convert a method that throws a checked exception
* into an instance compatible with a regular {@link Supplier}.
*
For example:
*
* optional.orElseGet(ThrowingSupplier.of(Example::methodThatCanThrowCheckedException));
*
* @param the type of results supplied by this supplier
* @param supplier the source supplier
* @return a new {@link ThrowingSupplier} instance
*/
static ThrowingSupplier of(ThrowingSupplier supplier) {
return supplier;
}
/**
* Lambda friendly convenience method that can be used to create
* {@link ThrowingSupplier} where the {@link #get()} method wraps any
* thrown checked exceptions using the given {@code exceptionWrapper}.
* This method can be especially useful when working with method references.
* It allows you to easily convert a method that throws a checked exception
* into an instance compatible with a regular {@link Supplier}.
*
For example:
*
* optional.orElseGet(ThrowingSupplier.of(Example::methodThatCanThrowCheckedException, IllegalStateException::new));
*
* @param the type of results supplied by this supplier
* @param supplier the source supplier
* @param exceptionWrapper the exception wrapper to use
* @return a new {@link ThrowingSupplier} instance
*/
static ThrowingSupplier of(ThrowingSupplier supplier,
BiFunction exceptionWrapper) {
return supplier.throwing(exceptionWrapper);
}
}