diff --git a/src/main/java/org/cactoos/io/InputWithFallback.java b/src/main/java/org/cactoos/io/InputWithFallback.java new file mode 100644 index 0000000000..cccbae79f4 --- /dev/null +++ b/src/main/java/org/cactoos/io/InputWithFallback.java @@ -0,0 +1,95 @@ +/** + * The MIT License (MIT) + * + * Copyright (c) 2017 Yegor Bugayenko + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included + * in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ +package org.cactoos.io; + +import java.io.IOException; +import java.io.InputStream; +import org.cactoos.Func; +import org.cactoos.Input; +import org.cactoos.func.IoCheckedFunc; + +/** + * Input that returns an alternative input if the main one throws + * {@link IOException}. + * + *

There is no thread-safety guarantee. + * + * @author Yegor Bugayenko (yegor256@gmail.com) + * @version $Id$ + * @since 0.9 + */ +public final class InputWithFallback implements Input { + + /** + * The main one. + */ + private final Input main; + + /** + * The alternative one. + */ + private final IoCheckedFunc alternative; + + /** + * Ctor. + * @param input Main input + * @param alt Alternative + */ + public InputWithFallback(final Input input, final Input alt) { + this(input, error -> alt); + } + + /** + * Ctor. + * @param input Main input + * @param alt Alternative + */ + public InputWithFallback(final Input input, + final Func alt) { + this(input, new IoCheckedFunc<>(alt)); + } + + /** + * Ctor. + * @param input Main input + * @param alt Alternative + */ + public InputWithFallback(final Input input, + final IoCheckedFunc alt) { + this.main = input; + this.alternative = alt; + } + + @Override + public InputStream stream() throws IOException { + InputStream stream; + try { + stream = this.main.stream(); + } catch (final IOException ex) { + stream = this.alternative.apply(ex).stream(); + } + return stream; + } + +} diff --git a/src/test/java/org/cactoos/io/InputWithFallbackTest.java b/src/test/java/org/cactoos/io/InputWithFallbackTest.java new file mode 100644 index 0000000000..09aacb1be1 --- /dev/null +++ b/src/test/java/org/cactoos/io/InputWithFallbackTest.java @@ -0,0 +1,61 @@ +/** + * The MIT License (MIT) + * + * Copyright (c) 2017 Yegor Bugayenko + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included + * in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ +package org.cactoos.io; + +import java.io.File; +import org.cactoos.TextHasString; +import org.cactoos.text.BytesAsText; +import org.hamcrest.MatcherAssert; +import org.hamcrest.Matchers; +import org.junit.Test; + +/** + * Test case for {@link InputWithFallback}. + * + * @author Yegor Bugayenko (yegor256@gmail.com) + * @version $Id$ + * @since 0.9 + * @checkstyle JavadocMethodCheck (500 lines) + */ +public final class InputWithFallbackTest { + + @Test + public void readsAlternativeInput() { + MatcherAssert.assertThat( + "Can't read alternative source", + new BytesAsText( + new InputAsBytes( + new InputWithFallback( + new FileAsInput( + new File("/this-file-is-absent-for-sure.txt") + ), + new BytesAsInput("hello, world!") + ) + ) + ), + new TextHasString(Matchers.endsWith("world!")) + ); + } + +}