JAVA-620: New module core-java-io-conversions-2
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core-java-modules/core-java-io-conversions-2/README.md
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core-java-modules/core-java-io-conversions-2/README.md
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## Core Java IO Conversions
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This module contains articles about core Java input/output(IO) conversions.
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### Relevant Articles:
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- [Java InputStream to String](https://www.baeldung.com/convert-input-stream-to-string)
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- [Java InputStream to Byte Array and ByteBuffer](https://www.baeldung.com/convert-input-stream-to-array-of-bytes)
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- [Java – Write an InputStream to a File](https://www.baeldung.com/convert-input-stream-to-a-file)
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- More articles: [[<-- prev]](/core-java-modules/core-java-io-conversions)
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core-java-modules/core-java-io-conversions-2/pom.xml
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core-java-modules/core-java-io-conversions-2/pom.xml
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<?xml version="1.0" encoding="UTF-8"?>
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<project
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xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<artifactId>core-java-io-conversions-2</artifactId>
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<version>0.1.0-SNAPSHOT</version>
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<name>core-java-io-conversions-2</name>
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<packaging>jar</packaging>
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<parent>
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<groupId>com.baeldung</groupId>
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<artifactId>parent-java</artifactId>
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<version>0.0.1-SNAPSHOT</version>
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<relativePath>../../parent-java</relativePath>
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</parent>
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<dependencies>
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<dependency>
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<groupId>org.apache.commons</groupId>
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<artifactId>commons-lang3</artifactId>
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<version>${commons-lang3.version}</version>
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</dependency>
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</dependencies>
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<build>
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<finalName>core-java-io-conversions</finalName>
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<resources>
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<resource>
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<directory>src/main/resources</directory>
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<filtering>true</filtering>
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</resource>
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</resources>
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</build>
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</project>
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package com.baeldung.inputstreamtobytes;
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import com.google.common.io.ByteSource;
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import com.google.common.io.ByteStreams;
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import org.apache.commons.io.IOUtils;
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import org.junit.Test;
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import java.io.ByteArrayInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.nio.ByteBuffer;
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import java.nio.channels.ReadableByteChannel;
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import static java.nio.channels.Channels.newChannel;
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import static org.junit.Assert.assertEquals;
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public class InputStreamToByteBufferUnitTest {
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@Test
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public void givenUsingCoreClasses_whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
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byte[] input = new byte[] { 0, 1, 2 };
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InputStream initialStream = new ByteArrayInputStream(input);
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ByteBuffer byteBuffer = ByteBuffer.allocate(3);
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while (initialStream.available() > 0) {
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byteBuffer.put((byte) initialStream.read());
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}
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assertEquals(byteBuffer.position(), input.length);
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}
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@Test
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public void givenUsingGuava__whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
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InputStream initialStream = ByteSource
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.wrap(new byte[] { 0, 1, 2 })
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.openStream();
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byte[] targetArray = ByteStreams.toByteArray(initialStream);
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ByteBuffer bufferByte = ByteBuffer.wrap(targetArray);
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while (bufferByte.hasRemaining()) {
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bufferByte.get();
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}
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assertEquals(bufferByte.position(), targetArray.length);
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}
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@Test
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public void givenUsingCommonsIo_whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
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byte[] input = new byte[] { 0, 1, 2 };
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InputStream initialStream = new ByteArrayInputStream(input);
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ByteBuffer byteBuffer = ByteBuffer.allocate(3);
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ReadableByteChannel channel = newChannel(initialStream);
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IOUtils.readFully(channel, byteBuffer);
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assertEquals(byteBuffer.position(), input.length);
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}
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}
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package com.baeldung.inputstreamtostring;
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import com.google.common.base.Charsets;
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import com.google.common.io.ByteSource;
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import com.google.common.io.ByteStreams;
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import com.google.common.io.CharStreams;
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import com.google.common.io.Files;
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import org.apache.commons.io.FileUtils;
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import org.apache.commons.io.IOUtils;
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import org.junit.Test;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.io.*;
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import java.nio.charset.Charset;
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import java.nio.charset.StandardCharsets;
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import java.nio.file.Path;
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import java.nio.file.StandardCopyOption;
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import java.util.Scanner;
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import java.util.UUID;
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import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
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import static org.hamcrest.Matchers.equalTo;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertThat;
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@SuppressWarnings("unused")
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public class JavaInputStreamToXUnitTest {
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protected final Logger logger = LoggerFactory.getLogger(getClass());
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private static final int DEFAULT_SIZE = 1500000;
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// tests - InputStream to String
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@Test
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public final void givenUsingJava5_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
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final String originalString = randomAlphabetic(DEFAULT_SIZE);
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final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
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final StringBuilder textBuilder = new StringBuilder();
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try (Reader reader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName(StandardCharsets.UTF_8.name())))) {
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int c;
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while ((c = reader.read()) != -1) {
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textBuilder.append((char) c);
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}
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}
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assertEquals(textBuilder.toString(), originalString);
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}
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@Test
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public final void givenUsingJava7_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
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final String originalString = randomAlphabetic(DEFAULT_SIZE);
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final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes()); // exampleString.getBytes(StandardCharsets.UTF_8);
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// When
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String text;
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try (Scanner scanner = new Scanner(inputStream, StandardCharsets.UTF_8.name())) {
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text = scanner.useDelimiter("\\A").next();
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}
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assertThat(text, equalTo(originalString));
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}
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@Test
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public final void givenUsingGuava_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
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final String originalString = randomAlphabetic(DEFAULT_SIZE);
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final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
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final ByteSource byteSource = new ByteSource() {
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@Override
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public final InputStream openStream() throws IOException {
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return inputStream;
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}
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};
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final String text = byteSource.asCharSource(Charsets.UTF_8).read();
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assertThat(text, equalTo(originalString));
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}
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@Test
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public final void givenUsingGuavaAndJava7_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
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final String originalString = randomAlphabetic(DEFAULT_SIZE);
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final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
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// When
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String text;
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try (final Reader reader = new InputStreamReader(inputStream)) {
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text = CharStreams.toString(reader);
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}
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assertThat(text, equalTo(originalString));
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}
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@Test
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public final void givenUsingCommonsIo_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
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final String originalString = randomAlphabetic(DEFAULT_SIZE);
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final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
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// When
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final String text = IOUtils.toString(inputStream, StandardCharsets.UTF_8.name());
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assertThat(text, equalTo(originalString));
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}
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@Test
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public final void givenUsingCommonsIoWithCopy_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
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final String originalString = randomAlphabetic(DEFAULT_SIZE);
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final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
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// When
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final StringWriter writer = new StringWriter();
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final String encoding = StandardCharsets.UTF_8.name();
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IOUtils.copy(inputStream, writer, encoding);
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assertThat(writer.toString(), equalTo(originalString));
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}
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@Test
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public final void givenUsingTempFile_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
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final String originalString = randomAlphabetic(DEFAULT_SIZE);
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final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
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// When
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Path tempFile = java.nio.file.Files.createTempDirectory("").resolve(UUID.randomUUID().toString() + ".tmp");
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java.nio.file.Files.copy(inputStream, tempFile, StandardCopyOption.REPLACE_EXISTING);
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String result = new String(java.nio.file.Files.readAllBytes(tempFile));
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assertThat(result, equalTo(originalString));
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}
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// tests - InputStream to byte[]
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@Test
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public final void givenUsingPlainJavaOnFixedSizeStream_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
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final InputStream initialStream = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
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final byte[] targetArray = new byte[initialStream.available()];
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initialStream.read(targetArray);
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}
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@Test
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public final void givenUsingPlainJavaOnUnknownSizeStream_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
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final InputStream is = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
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final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
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int nRead;
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final byte[] data = new byte[1024];
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while ((nRead = is.read(data, 0, data.length)) != -1) {
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buffer.write(data, 0, nRead);
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}
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buffer.flush();
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final byte[] byteArray = buffer.toByteArray();
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}
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@Test
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public final void givenUsingGuava_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
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final InputStream initialStream = ByteSource.wrap(new byte[] { 0, 1, 2 }).openStream();
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final byte[] targetArray = ByteStreams.toByteArray(initialStream);
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}
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@Test
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public final void givenUsingCommonsIO_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
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final InputStream initialStream = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
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final byte[] targetArray = IOUtils.toByteArray(initialStream);
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}
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// tests - InputStream to File
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@Test
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public final void whenConvertingToFile_thenCorrect() throws IOException {
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final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
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final byte[] buffer = new byte[initialStream.available()];
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initialStream.read(buffer);
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final File targetFile = new File("src/test/resources/targetFile.tmp");
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final OutputStream outStream = new FileOutputStream(targetFile);
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outStream.write(buffer);
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IOUtils.closeQuietly(initialStream);
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IOUtils.closeQuietly(outStream);
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}
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@Test
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public final void whenConvertingInProgressToFile_thenCorrect() throws IOException {
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final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
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final File targetFile = new File("src/test/resources/targetFile.tmp");
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final OutputStream outStream = new FileOutputStream(targetFile);
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final byte[] buffer = new byte[8 * 1024];
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int bytesRead;
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while ((bytesRead = initialStream.read(buffer)) != -1) {
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outStream.write(buffer, 0, bytesRead);
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}
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IOUtils.closeQuietly(initialStream);
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IOUtils.closeQuietly(outStream);
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}
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@Test
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public final void whenConvertingAnInProgressInputStreamToFile_thenCorrect2() throws IOException {
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final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
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final File targetFile = new File("src/test/resources/targetFile.tmp");
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java.nio.file.Files.copy(initialStream, targetFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
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IOUtils.closeQuietly(initialStream);
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}
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@Test
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public final void whenConvertingInputStreamToFile_thenCorrect3() throws IOException {
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final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
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final byte[] buffer = new byte[initialStream.available()];
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initialStream.read(buffer);
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final File targetFile = new File("src/test/resources/targetFile.tmp");
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Files.write(buffer, targetFile);
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IOUtils.closeQuietly(initialStream);
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}
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@Test
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public final void whenConvertingInputStreamToFile_thenCorrect4() throws IOException {
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final InputStream initialStream = FileUtils.openInputStream(new File("src/test/resources/sample.txt"));
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final File targetFile = new File("src/test/resources/targetFile.tmp");
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FileUtils.copyInputStreamToFile(initialStream, targetFile);
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}
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@Test
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public final void givenUsingPlainJava_whenConvertingAnInputStreamToString_thenCorrect() throws IOException {
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String originalString = randomAlphabetic(8);
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InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
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ByteArrayOutputStream buffer = new ByteArrayOutputStream();
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int nRead;
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byte[] data = new byte[1024];
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while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
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buffer.write(data, 0, nRead);
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}
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buffer.flush();
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byte[] byteArray = buffer.toByteArray();
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String text = new String(byteArray, StandardCharsets.UTF_8);
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assertThat(text, equalTo(originalString));
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}
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}
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Hello World
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Hello World
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