diff --git a/core-java-io/src/test/java/com/baeldung/filechannel/FileChannelUnitTest.java b/core-java-io/src/test/java/com/baeldung/filechannel/FileChannelUnitTest.java new file mode 100644 index 0000000000..6964ba80e3 --- /dev/null +++ b/core-java-io/src/test/java/com/baeldung/filechannel/FileChannelUnitTest.java @@ -0,0 +1,165 @@ +package com.baeldung.filechannel; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertNotNull; + +import java.io.ByteArrayOutputStream; +import java.io.FileInputStream; +import java.io.FileOutputStream; +import java.io.IOException; +import java.io.RandomAccessFile; +import java.nio.ByteBuffer; +import java.nio.MappedByteBuffer; +import java.nio.channels.FileChannel; +import java.nio.channels.FileLock; +import java.nio.charset.StandardCharsets; + +import org.junit.Test; + +public class FileChannelUnitTest { + + @Test + public void givenFile_whenReadWithFileChannelUsingRandomAccessFile_thenCorrect() throws IOException { + + try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r"); + FileChannel channel = reader.getChannel(); + ByteArrayOutputStream out = new ByteArrayOutputStream();) { + + int bufferSize = 1024; + if (bufferSize > channel.size()) { + bufferSize = (int) channel.size(); + } + ByteBuffer buff = ByteBuffer.allocate(bufferSize); + + while (channel.read(buff) > 0) { + out.write(buff.array(), 0, buff.position()); + buff.clear(); + } + + String fileContent = new String(out.toByteArray(), StandardCharsets.UTF_8); + + assertEquals("Hello world", fileContent); + } + } + + @Test + public void givenFile_whenReadWithFileChannelUsingFileInputStream_thenCorrect() throws IOException { + + try (ByteArrayOutputStream out = new ByteArrayOutputStream(); + FileInputStream fin = new FileInputStream("src/test/resources/test_read.in"); + FileChannel channel = fin.getChannel();) { + + int bufferSize = 1024; + if (bufferSize > channel.size()) { + bufferSize = (int) channel.size(); + } + ByteBuffer buff = ByteBuffer.allocate(bufferSize); + + while (channel.read(buff) > 0) { + out.write(buff.array(), 0, buff.position()); + buff.clear(); + } + String fileContent = new String(out.toByteArray(), StandardCharsets.UTF_8); + + assertEquals("Hello world", fileContent); + } + } + + @Test + public void givenFile_whenReadAFileSectionIntoMemoryWithFileChannel_thenCorrect() throws IOException { + + try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r"); + FileChannel channel = reader.getChannel(); + ByteArrayOutputStream out = new ByteArrayOutputStream();) { + + MappedByteBuffer buff = channel.map(FileChannel.MapMode.READ_ONLY, 6, 5); + + if (buff.hasRemaining()) { + byte[] data = new byte[buff.remaining()]; + buff.get(data); + assertEquals("world", new String(data, StandardCharsets.UTF_8)); + } + } + } + + @Test + public void whenWriteWithFileChannelUsingRandomAccessFile_thenCorrect() throws IOException { + String file = "src/test/resources/test_write_using_filechannel.txt"; + try (RandomAccessFile writer = new RandomAccessFile(file, "rw"); + FileChannel channel = writer.getChannel();) { + ByteBuffer buff = ByteBuffer.wrap("Hello world".getBytes(StandardCharsets.UTF_8)); + + channel.write(buff); + + // now we verify whether the file was written correctly + RandomAccessFile reader = new RandomAccessFile(file, "r"); + assertEquals("Hello world", reader.readLine()); + reader.close(); + } + } + + @Test + public void givenFile_whenWriteAFileUsingLockAFileSectionWithFileChannel_thenCorrect() throws IOException { + try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "rw"); + FileChannel channel = reader.getChannel(); + FileLock fileLock = channel.tryLock(6, 5, Boolean.FALSE);) { + + assertNotNull(fileLock); + } + } + + @Test + public void givenFile_whenReadWithFileChannelGetPosition_thenCorrect() throws IOException { + + try (ByteArrayOutputStream out = new ByteArrayOutputStream(); + RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r"); + FileChannel channel = reader.getChannel();) { + + int bufferSize = 1024; + if (bufferSize > channel.size()) { + bufferSize = (int) channel.size(); + } + ByteBuffer buff = ByteBuffer.allocate(bufferSize); + + while (channel.read(buff) > 0) { + out.write(buff.array(), 0, buff.position()); + buff.clear(); + } + + // the original file is 11 bytes long, so that's where the position pointer should be + assertEquals(11, channel.position()); + + channel.position(4); + assertEquals(4, channel.position()); + } + } + + @Test + public void whenGetFileSize_thenCorrect() throws IOException { + + try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r"); + FileChannel channel = reader.getChannel();) { + + // the original file is 11 bytes long, so that's where the position pointer should be + assertEquals(11, channel.size()); + } + } + + @Test + public void whenTruncateFile_thenCorrect() throws IOException { + String input = "this is a test input"; + + FileOutputStream fout = new FileOutputStream("src/test/resources/test_truncate.txt"); + FileChannel channel = fout.getChannel(); + + ByteBuffer buff = ByteBuffer.wrap(input.getBytes()); + channel.write(buff); + buff.flip(); + + channel = channel.truncate(5); + assertEquals(5, channel.size()); + + fout.close(); + channel.close(); + } +} diff --git a/core-java-io/src/test/resources/test_truncate.txt b/core-java-io/src/test/resources/test_truncate.txt new file mode 100644 index 0000000000..26d3b38cdd --- /dev/null +++ b/core-java-io/src/test/resources/test_truncate.txt @@ -0,0 +1 @@ +this \ No newline at end of file diff --git a/core-java-io/src/test/resources/test_write_using_filechannel.txt b/core-java-io/src/test/resources/test_write_using_filechannel.txt new file mode 100644 index 0000000000..70c379b63f --- /dev/null +++ b/core-java-io/src/test/resources/test_write_using_filechannel.txt @@ -0,0 +1 @@ +Hello world \ No newline at end of file