JAVA-620: New module core-java-io-conversions-2

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sampadawagde 2020-04-13 15:09:40 +05:30
parent a057b3af44
commit 02a4eee18c
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## Core Java IO Conversions
This module contains articles about core Java input/output(IO) conversions.
### Relevant Articles:
- [Java InputStream to String](https://www.baeldung.com/convert-input-stream-to-string)
- [Java InputStream to Byte Array and ByteBuffer](https://www.baeldung.com/convert-input-stream-to-array-of-bytes)
- [Java Write an InputStream to a File](https://www.baeldung.com/convert-input-stream-to-a-file)
- More articles: [[<-- prev]](/core-java-modules/core-java-io-conversions)

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<?xml version="1.0" encoding="UTF-8"?>
<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-io-conversions-2</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-io-conversions-2</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
</dependencies>
<build>
<finalName>core-java-io-conversions</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
</build>
</project>

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package com.baeldung.inputstreamtobytes;
import com.google.common.io.ByteSource;
import com.google.common.io.ByteStreams;
import org.apache.commons.io.IOUtils;
import org.junit.Test;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import static java.nio.channels.Channels.newChannel;
import static org.junit.Assert.assertEquals;
public class InputStreamToByteBufferUnitTest {
@Test
public void givenUsingCoreClasses_whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
byte[] input = new byte[] { 0, 1, 2 };
InputStream initialStream = new ByteArrayInputStream(input);
ByteBuffer byteBuffer = ByteBuffer.allocate(3);
while (initialStream.available() > 0) {
byteBuffer.put((byte) initialStream.read());
}
assertEquals(byteBuffer.position(), input.length);
}
@Test
public void givenUsingGuava__whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
InputStream initialStream = ByteSource
.wrap(new byte[] { 0, 1, 2 })
.openStream();
byte[] targetArray = ByteStreams.toByteArray(initialStream);
ByteBuffer bufferByte = ByteBuffer.wrap(targetArray);
while (bufferByte.hasRemaining()) {
bufferByte.get();
}
assertEquals(bufferByte.position(), targetArray.length);
}
@Test
public void givenUsingCommonsIo_whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
byte[] input = new byte[] { 0, 1, 2 };
InputStream initialStream = new ByteArrayInputStream(input);
ByteBuffer byteBuffer = ByteBuffer.allocate(3);
ReadableByteChannel channel = newChannel(initialStream);
IOUtils.readFully(channel, byteBuffer);
assertEquals(byteBuffer.position(), input.length);
}
}

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package com.baeldung.inputstreamtostring;
import com.google.common.base.Charsets;
import com.google.common.io.ByteSource;
import com.google.common.io.ByteStreams;
import com.google.common.io.CharStreams;
import com.google.common.io.Files;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.*;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;
import java.util.Scanner;
import java.util.UUID;
import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
import static org.hamcrest.Matchers.equalTo;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;
@SuppressWarnings("unused")
public class JavaInputStreamToXUnitTest {
protected final Logger logger = LoggerFactory.getLogger(getClass());
private static final int DEFAULT_SIZE = 1500000;
// tests - InputStream to String
@Test
public final void givenUsingJava5_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
final String originalString = randomAlphabetic(DEFAULT_SIZE);
final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
final StringBuilder textBuilder = new StringBuilder();
try (Reader reader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName(StandardCharsets.UTF_8.name())))) {
int c;
while ((c = reader.read()) != -1) {
textBuilder.append((char) c);
}
}
assertEquals(textBuilder.toString(), originalString);
}
@Test
public final void givenUsingJava7_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
final String originalString = randomAlphabetic(DEFAULT_SIZE);
final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes()); // exampleString.getBytes(StandardCharsets.UTF_8);
// When
String text;
try (Scanner scanner = new Scanner(inputStream, StandardCharsets.UTF_8.name())) {
text = scanner.useDelimiter("\\A").next();
}
assertThat(text, equalTo(originalString));
}
@Test
public final void givenUsingGuava_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
final String originalString = randomAlphabetic(DEFAULT_SIZE);
final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
final ByteSource byteSource = new ByteSource() {
@Override
public final InputStream openStream() throws IOException {
return inputStream;
}
};
final String text = byteSource.asCharSource(Charsets.UTF_8).read();
assertThat(text, equalTo(originalString));
}
@Test
public final void givenUsingGuavaAndJava7_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
final String originalString = randomAlphabetic(DEFAULT_SIZE);
final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
// When
String text;
try (final Reader reader = new InputStreamReader(inputStream)) {
text = CharStreams.toString(reader);
}
assertThat(text, equalTo(originalString));
}
@Test
public final void givenUsingCommonsIo_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
final String originalString = randomAlphabetic(DEFAULT_SIZE);
final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
// When
final String text = IOUtils.toString(inputStream, StandardCharsets.UTF_8.name());
assertThat(text, equalTo(originalString));
}
@Test
public final void givenUsingCommonsIoWithCopy_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
final String originalString = randomAlphabetic(DEFAULT_SIZE);
final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
// When
final StringWriter writer = new StringWriter();
final String encoding = StandardCharsets.UTF_8.name();
IOUtils.copy(inputStream, writer, encoding);
assertThat(writer.toString(), equalTo(originalString));
}
@Test
public final void givenUsingTempFile_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
final String originalString = randomAlphabetic(DEFAULT_SIZE);
final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
// When
Path tempFile = java.nio.file.Files.createTempDirectory("").resolve(UUID.randomUUID().toString() + ".tmp");
java.nio.file.Files.copy(inputStream, tempFile, StandardCopyOption.REPLACE_EXISTING);
String result = new String(java.nio.file.Files.readAllBytes(tempFile));
assertThat(result, equalTo(originalString));
}
// tests - InputStream to byte[]
@Test
public final void givenUsingPlainJavaOnFixedSizeStream_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
final InputStream initialStream = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
final byte[] targetArray = new byte[initialStream.available()];
initialStream.read(targetArray);
}
@Test
public final void givenUsingPlainJavaOnUnknownSizeStream_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
final InputStream is = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int nRead;
final byte[] data = new byte[1024];
while ((nRead = is.read(data, 0, data.length)) != -1) {
buffer.write(data, 0, nRead);
}
buffer.flush();
final byte[] byteArray = buffer.toByteArray();
}
@Test
public final void givenUsingGuava_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
final InputStream initialStream = ByteSource.wrap(new byte[] { 0, 1, 2 }).openStream();
final byte[] targetArray = ByteStreams.toByteArray(initialStream);
}
@Test
public final void givenUsingCommonsIO_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
final InputStream initialStream = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
final byte[] targetArray = IOUtils.toByteArray(initialStream);
}
// tests - InputStream to File
@Test
public final void whenConvertingToFile_thenCorrect() throws IOException {
final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
final byte[] buffer = new byte[initialStream.available()];
initialStream.read(buffer);
final File targetFile = new File("src/test/resources/targetFile.tmp");
final OutputStream outStream = new FileOutputStream(targetFile);
outStream.write(buffer);
IOUtils.closeQuietly(initialStream);
IOUtils.closeQuietly(outStream);
}
@Test
public final void whenConvertingInProgressToFile_thenCorrect() throws IOException {
final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
final File targetFile = new File("src/test/resources/targetFile.tmp");
final OutputStream outStream = new FileOutputStream(targetFile);
final byte[] buffer = new byte[8 * 1024];
int bytesRead;
while ((bytesRead = initialStream.read(buffer)) != -1) {
outStream.write(buffer, 0, bytesRead);
}
IOUtils.closeQuietly(initialStream);
IOUtils.closeQuietly(outStream);
}
@Test
public final void whenConvertingAnInProgressInputStreamToFile_thenCorrect2() throws IOException {
final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
final File targetFile = new File("src/test/resources/targetFile.tmp");
java.nio.file.Files.copy(initialStream, targetFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
IOUtils.closeQuietly(initialStream);
}
@Test
public final void whenConvertingInputStreamToFile_thenCorrect3() throws IOException {
final InputStream initialStream = new FileInputStream(new File("src/test/resources/sample.txt"));
final byte[] buffer = new byte[initialStream.available()];
initialStream.read(buffer);
final File targetFile = new File("src/test/resources/targetFile.tmp");
Files.write(buffer, targetFile);
IOUtils.closeQuietly(initialStream);
}
@Test
public final void whenConvertingInputStreamToFile_thenCorrect4() throws IOException {
final InputStream initialStream = FileUtils.openInputStream(new File("src/test/resources/sample.txt"));
final File targetFile = new File("src/test/resources/targetFile.tmp");
FileUtils.copyInputStreamToFile(initialStream, targetFile);
}
@Test
public final void givenUsingPlainJava_whenConvertingAnInputStreamToString_thenCorrect() throws IOException {
String originalString = randomAlphabetic(8);
InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int nRead;
byte[] data = new byte[1024];
while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
buffer.write(data, 0, nRead);
}
buffer.flush();
byte[] byteArray = buffer.toByteArray();
String text = new String(byteArray, StandardCharsets.UTF_8);
assertThat(text, equalTo(originalString));
}
}

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Hello World

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Hello World