#146: StickyInput

src/main/java/org/cactoos/io/StickyInput.java

@@ -0,0 +1,75 @@
+/**
+ * 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.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import org.cactoos.Input;
+import org.cactoos.Scalar;
+import org.cactoos.func.IoCheckedScalar;
+import org.cactoos.func.StickyScalar;
+
+/**
+ * Input that reads only once.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Fabricio Cabral (fabriciofx@gmail.com)
+ * @version $Id$
+ * @since 0.6
+ */
+public final class StickyInput implements Input {
+
+    /**
+     * The cache.
+     */
+    private final Scalar<InputStream> cache;
+
+    /**
+     * Ctor.
+     * @param input The input
+     */
+    public StickyInput(final Input input) {
+        this.cache = new StickyScalar<>(
+            () -> {
+                final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+                new LengthOfInput(
+                    new TeeInput(
+                        input,
+                        new OutputStreamAsOutput(baos)
+                    )
+                ).asValue();
+                return new ByteArrayInputStream(baos.toByteArray());
+            }
+        );
+    }
+
+    @Override
+    public InputStream stream() throws IOException {
+        return new IoCheckedScalar<>(this.cache).asValue();
+    }
+
+}

src/test/java/org/cactoos/io/StickyInputTest.java

@@ -0,0 +1,57 @@
+/**
+ * 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 org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+/**
+ * Test case for {@link StickyInput}.
+ * @author Yegor Bugayenko (yegor256@gmail.com)
+ * @version $Id$
+ * @since 0.6
+ * @checkstyle JavadocMethodCheck (500 lines)
+ */
+public final class StickyInputTest {
+
+    @Test
+    public void readsFileContent() throws IOException {
+        MatcherAssert.assertThat(
+            "Can't read bytes from a file",
+            new InputAsBytes(
+                new StickyInput(
+                    new UrlAsInput(
+                        this.getClass().getResource(
+                            "/org/cactoos/io/UrlAsInput.class"
+                        )
+                    )
+                )
+            ).asBytes().length,
+            Matchers.greaterThan(0)
+        );
+    }
+
+}