Introduce default method checked() for throwable functional interface

Allow throwing original checked exception instead of wrapping unchecked exception

Author: quaff

spring-core/src/main/java/org/springframework/util/function/ThrowingBiFunction.java

@@ -18,12 +18,15 @@
 
 import java.util.function.BiFunction;
 
+import static org.springframework.util.function.ThrowingFunction.throwAsUnchecked;
+
 /**
  * A {@link BiFunction} that allows invocation of code that throws a checked
  * exception.
  *
  * @author Stephane Nicoll
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  * @param <T> the type of the first argument to the function
  * @param <U> the type of the second argument to the function
@@ -96,6 +99,33 @@ public R apply(T t, U u) {
 		};
 	}
 
+	/**
+	 * Return a new {@link ThrowingBiFunction} where the {@link #apply(Object, Object)}
+	 * method will throw original checked exceptions.
+	 * @return the replacement {@link ThrowingBiFunction} instance
+	 */
+	@SuppressWarnings("NullAway")
+	default ThrowingBiFunction<T, U, R> checked() {
+		ThrowingBiFunction<T, U, R> function = this;
+		return new ThrowingBiFunction<>() {
+			@Override
+			public R applyWithException(T t, U u) throws Exception {
+				return function.applyWithException(t, u);
+			}
+
+			@Override
+			public R apply(T t, U u) {
+				try {
+					return function.applyWithException(t, u);
+				}
+				catch (Exception ex) {
+					throwAsUnchecked(ex);
+					return null; // Never happens
+				}
+			}
+		};
+	}
+
 	/**
 	 * Lambda friendly convenience method that can be used to create a
 	 * {@link ThrowingBiFunction} where the {@link #apply(Object, Object)}

spring-core/src/main/java/org/springframework/util/function/ThrowingConsumer.java

@@ -19,12 +19,15 @@
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
 
+import static org.springframework.util.function.ThrowingFunction.throwAsUnchecked;
+
 /**
  * A {@link Consumer} that allows invocation of code that throws a checked
  * exception.
  *
  * @author Stephane Nicoll
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  * @param <T> the type of the input to the operation
  */
@@ -88,6 +91,32 @@ public void accept(T t) {
 		};
 	}
 
+	/**
+	 * Return a new {@link ThrowingConsumer} where the {@link #accept(Object)}
+	 * method will throw original checked exceptions.
+	 * @return the replacement {@link ThrowingConsumer} instance
+	 */
+	@SuppressWarnings("NullAway")
+	default ThrowingConsumer<T> checked() {
+		ThrowingConsumer<T> supplier = this;
+		return new ThrowingConsumer<>() {
+			@Override
+			public void acceptWithException(T t) throws Exception {
+				supplier.acceptWithException(t);
+			}
+
+			@Override
+			public void accept(T t) {
+				try {
+					supplier.acceptWithException(t);
+				}
+				catch (Exception ex) {
+					throwAsUnchecked(ex);
+				}
+			}
+		};
+	}
+
 	/**
 	 * Lambda friendly convenience method that can be used to create a
 	 * {@link ThrowingConsumer} where the {@link #accept(Object)} method wraps

spring-core/src/main/java/org/springframework/util/function/ThrowingFunction.java

@@ -25,6 +25,7 @@
  *
  * @author Stephane Nicoll
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  * @param <T> the type of the input to the function
  * @param <R> the type of the result of the function
@@ -91,6 +92,33 @@ public R apply(T t) {
 		};
 	}
 
+	/**
+	 * Return a new {@link ThrowingFunction} where the {@link #apply(Object)}
+	 * method will throw original checked exceptions.
+	 * @return the replacement {@link ThrowingFunction} instance
+	 */
+	@SuppressWarnings("NullAway")
+	default ThrowingFunction<T, R> checked() {
+		ThrowingFunction<T, R> function = this;
+		return new ThrowingFunction<>() {
+			@Override
+			public R applyWithException(T t) throws Exception {
+				return function.applyWithException(t);
+			}
+
+			@Override
+			public R apply(T t) {
+				try {
+					return function.applyWithException(t);
+				}
+				catch (Exception ex) {
+					throwAsUnchecked(ex);
+					return null; // Never happens
+				}
+			}
+		};
+	}
+
 	/**
 	 * Lambda friendly convenience method that can be used to create a
 	 * {@link ThrowingFunction} where the {@link #apply(Object)} method wraps
@@ -135,4 +163,9 @@ static <T, R> ThrowingFunction<T, R> of(ThrowingFunction<T, R> function,
 		return function.throwing(exceptionWrapper);
 	}
 
+	@SuppressWarnings ("unchecked")
+	static <E extends Throwable> void throwAsUnchecked(Exception exception) throws E {
+		throw (E) exception;
+	}
+
 }

spring-core/src/main/java/org/springframework/util/function/ThrowingSupplier.java

@@ -19,11 +19,14 @@
 import java.util.function.BiFunction;
 import java.util.function.Supplier;
 
+import static org.springframework.util.function.ThrowingFunction.throwAsUnchecked;
+
 /**
  * A {@link Supplier} that allows invocation of code that throws a checked exception.
  *
  * @author Stephane Nicoll
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  * @param <T> the type of results supplied by this supplier
  */
@@ -86,6 +89,33 @@ public T get() {
 		};
 	}
 
+	/**
+	 * Return a new {@link ThrowingSupplier} where the {@link #get()}
+	 * method will throw original checked exceptions.
+	 * @return the replacement {@link ThrowingSupplier} instance
+	 */
+	@SuppressWarnings("NullAway")
+	default ThrowingSupplier<T> checked() {
+		ThrowingSupplier<T> supplier = this;
+		return new ThrowingSupplier<>() {
+			@Override
+			public T getWithException() throws Exception {
+				return supplier.getWithException();
+			}
+
+			@Override
+			public T get() {
+				try {
+					return supplier.getWithException();
+				}
+				catch (Exception ex) {
+					throwAsUnchecked(ex);
+					return null; // Never happens
+				}
+			}
+		};
+	}
+
 	/**
 	 * Lambda friendly convenience method that can be used to create a
 	 * {@link ThrowingSupplier} where the {@link #get()} method wraps any checked

spring-core/src/test/java/org/springframework/util/function/ThrowingBiFunctionTests.java

@@ -21,13 +21,15 @@
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIOException;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
  * Tests for {@link ThrowingBiFunction}.
  *
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  */
 class ThrowingBiFunctionTests {
@@ -76,6 +78,12 @@ void ofModifiesThrowException() {
 				() -> function.apply(this, this)).withCauseInstanceOf(IOException.class);
 	}
 
+	@Test
+	void checked() {
+		ThrowingBiFunction<Object, Object, Object> function = ThrowingBiFunction.of(this::throwIOException).checked();
+		assertThatIOException().isThrownBy(() -> function.apply(this, this));
+	}
+
 	private Object throwIOException(Object o, Object u) throws IOException {
 		throw new IOException();
 	}

spring-core/src/test/java/org/springframework/util/function/ThrowingConsumerTests.java

@@ -21,13 +21,15 @@
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIOException;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
  * Tests for {@link ThrowingConsumer}.
  *
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  */
 class ThrowingConsumerTests {
@@ -76,6 +78,12 @@ void ofModifiesThrownException() {
 				() -> consumer.accept(this)).withCauseInstanceOf(IOException.class);
 	}
 
+	@Test
+	void checked() {
+		ThrowingConsumer<Object> consumer = ThrowingConsumer.of(this::throwIOException).checked();
+		assertThatIOException().isThrownBy(() -> consumer.accept(this));
+	}
+
 	private void throwIOException(Object o) throws IOException {
 		throw new IOException();
 	}

spring-core/src/test/java/org/springframework/util/function/ThrowingFunctionTests.java

@@ -21,13 +21,15 @@
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIOException;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
  * Tests for {@link ThrowingFunction}.
  *
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  */
 class ThrowingFunctionTests {
@@ -76,6 +78,12 @@ void ofModifiesThrowException() {
 				() -> function.apply(this)).withCauseInstanceOf(IOException.class);
 	}
 
+	@Test
+	void checked() {
+		ThrowingFunction<Object, Object> function = ThrowingFunction.of(this::throwIOException).checked();
+		assertThatIOException().isThrownBy(() -> function.apply(this));
+	}
+
 	private Object throwIOException(Object o) throws IOException {
 		throw new IOException();
 	}

spring-core/src/test/java/org/springframework/util/function/ThrowingSupplierTests.java

@@ -21,13 +21,15 @@
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIOException;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
  * Tests for {@link ThrowingSupplier}.
  *
  * @author Phillip Webb
+ * @author Yanming Zhou
  * @since 6.0
  */
 class ThrowingSupplierTests {
@@ -77,6 +79,12 @@ void ofModifiesThrowException() {
 				supplier::get).withCauseInstanceOf(IOException.class);
 	}
 
+	@Test
+	void checked() {
+		ThrowingSupplier<Object> supplier = ThrowingSupplier.of(this::throwIOException).checked();
+		assertThatIOException().isThrownBy(supplier::get);
+	}
+
 	private Object throwIOException() throws IOException {
 		throw new IOException();
 	}