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‎core-java-io/src/test/java/com/baeldung/filechannel/FileChannelUnitTest.java‎

Lines changed: 144 additions & 152 deletions
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@@ -12,162 +12,154 @@
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import java.nio.MappedByteBuffer;
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import java.nio.channels.FileChannel;
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import java.nio.channels.FileLock;
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import java.nio.channels.OverlappingFileLockException;
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import java.nio.charset.StandardCharsets;
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import org.junit.Test;
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public class FileChannelUnitTest {
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@Test
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public void givenFile_whenReadWithFileChannelUsingRandomAccessFile_thenCorrect() throws IOException {
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try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
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FileChannel channel = reader.getChannel();
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ByteArrayOutputStream out = new ByteArrayOutputStream();) {
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int bufferSize = 1024;
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if (bufferSize > channel.size()) {
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bufferSize = (int) channel.size();
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}
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ByteBuffer buff = ByteBuffer.allocate(bufferSize);
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while (channel.read(buff) > 0) {
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out.write(buff.array(), 0, buff.position());
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buff.clear();
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}
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assertEquals("Hello world", new String(out.toByteArray(), StandardCharsets.UTF_8));
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}
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}
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@Test
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public void givenFile_whenReadWithFileChannelUsingFileInputStream_thenCorrect() throws IOException {
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try (ByteArrayOutputStream out = new ByteArrayOutputStream();
48-
FileInputStream fin = new FileInputStream("src/test/resources/test_read.in");
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FileChannel channel = fin.getChannel();) {
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int bufferSize = 1024;
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if (bufferSize > channel.size()) {
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bufferSize = (int) channel.size();
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}
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ByteBuffer buff = ByteBuffer.allocate(bufferSize);
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while (channel.read(buff) > 0) {
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out.write(buff.array(), 0, buff.position());
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buff.clear();
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}
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assertEquals("Hello world", new String(out.toByteArray(), StandardCharsets.UTF_8));
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}
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}
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@Test
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public void givenFile_whenReadAFileSectionIntoMemoryWithFileChannel_thenCorrect() throws IOException {
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try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
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FileChannel channel = reader.getChannel();
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ByteArrayOutputStream out = new ByteArrayOutputStream();) {
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MappedByteBuffer buff = channel.map(FileChannel.MapMode.READ_ONLY, 6, 5);
75-
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if (buff.hasRemaining()) {
77-
byte[] data = new byte[buff.remaining()];
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buff.get(data);
79-
assertEquals("world", new String(data, StandardCharsets.UTF_8));
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}
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}
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}
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@Test
87-
public void whenWriteWithFileChannelUsingRandomAccessFile_thenCorrect() throws IOException {
88-
String file = "src/test/resources/test_write_using_filechannel.txt";
89-
try (RandomAccessFile writer = new RandomAccessFile(file, "rw");
90-
FileChannel channel = writer.getChannel();) {
91-
ByteBuffer buff = ByteBuffer.wrap("Hello world".getBytes(StandardCharsets.UTF_8));
92-
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if (buff.hasRemaining()) {
94-
channel.write(buff);
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}
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// verify
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RandomAccessFile reader = new RandomAccessFile(file, "r");
99-
assertEquals("Hello world", reader.readLine());
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reader.close();
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}
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}
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@Test
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public void givenFile_whenWriteAFileUsingLockAFileSectionWithFileChannel_thenCorrect() throws IOException {
106-
try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "rw");
107-
FileChannel channel = reader.getChannel();
108-
FileLock fileLock = channel.tryLock(6, 5, Boolean.FALSE);) {
109-
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assertNotNull(fileLock);
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} catch (OverlappingFileLockException | IOException ex) {
113-
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}
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}
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@Test
119-
public void givenFile_whenReadWithFileChannelGetPosition_thenCorrect() throws IOException {
120-
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try (ByteArrayOutputStream out = new ByteArrayOutputStream();
122-
RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
123-
FileChannel channel = reader.getChannel();) {
124-
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int bufferSize = 1024;
126-
if (bufferSize > channel.size()) {
127-
bufferSize = (int) channel.size();
128-
}
129-
ByteBuffer buff = ByteBuffer.allocate(bufferSize);
130-
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while (channel.read(buff) > 0) {
132-
out.write(buff.array(), 0, buff.position());
133-
buff.clear();
134-
}
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assertEquals(11, channel.position());
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channel.position(4);
139-
assertEquals(4, channel.position());
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}
142-
}
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@Test
145-
public void whenGetFileSize_thenCorrect() throws IOException {
146-
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try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
148-
FileChannel channel = reader.getChannel();) {
149-
150-
long imageFileSize = channel.size();
151-
assertEquals(11, imageFileSize);
152-
}
153-
154-
}
155-
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@Test
157-
public void whenTruncateFile_thenCorrect() throws IOException {
158-
String input = "this is a test input";
159-
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FileOutputStream fout = new FileOutputStream("src/test/resources/test_truncate.txt");
161-
FileChannel channel = fout.getChannel();
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ByteBuffer buff = ByteBuffer.wrap(input.getBytes());
164-
channel.write(buff);
165-
buff.flip();
166-
167-
channel = channel.truncate(5);
168-
assertEquals(5, channel.size());
169-
170-
fout.close();
171-
channel.close();
172-
}
21+
@Test
22+
public void givenFile_whenReadWithFileChannelUsingRandomAccessFile_thenCorrect() throws IOException {
23+
24+
try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
25+
FileChannel channel = reader.getChannel();
26+
ByteArrayOutputStream out = new ByteArrayOutputStream();) {
27+
28+
int bufferSize = 1024;
29+
if (bufferSize > channel.size()) {
30+
bufferSize = (int) channel.size();
31+
}
32+
ByteBuffer buff = ByteBuffer.allocate(bufferSize);
33+
34+
while (channel.read(buff) > 0) {
35+
out.write(buff.array(), 0, buff.position());
36+
buff.clear();
37+
}
38+
39+
String fileContent = new String(out.toByteArray(), StandardCharsets.UTF_8);
40+
41+
assertEquals("Hello world", fileContent);
42+
}
43+
}
44+
45+
@Test
46+
public void givenFile_whenReadWithFileChannelUsingFileInputStream_thenCorrect() throws IOException {
47+
48+
try (ByteArrayOutputStream out = new ByteArrayOutputStream();
49+
FileInputStream fin = new FileInputStream("src/test/resources/test_read.in");
50+
FileChannel channel = fin.getChannel();) {
51+
52+
int bufferSize = 1024;
53+
if (bufferSize > channel.size()) {
54+
bufferSize = (int) channel.size();
55+
}
56+
ByteBuffer buff = ByteBuffer.allocate(bufferSize);
57+
58+
while (channel.read(buff) > 0) {
59+
out.write(buff.array(), 0, buff.position());
60+
buff.clear();
61+
}
62+
String fileContent = new String(out.toByteArray(), StandardCharsets.UTF_8);
63+
64+
assertEquals("Hello world", fileContent);
65+
}
66+
}
67+
68+
@Test
69+
public void givenFile_whenReadAFileSectionIntoMemoryWithFileChannel_thenCorrect() throws IOException {
70+
71+
try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
72+
FileChannel channel = reader.getChannel();
73+
ByteArrayOutputStream out = new ByteArrayOutputStream();) {
74+
75+
MappedByteBuffer buff = channel.map(FileChannel.MapMode.READ_ONLY, 6, 5);
76+
77+
if (buff.hasRemaining()) {
78+
byte[] data = new byte[buff.remaining()];
79+
buff.get(data);
80+
assertEquals("world", new String(data, StandardCharsets.UTF_8));
81+
}
82+
}
83+
}
84+
85+
@Test
86+
public void whenWriteWithFileChannelUsingRandomAccessFile_thenCorrect() throws IOException {
87+
String file = "src/test/resources/test_write_using_filechannel.txt";
88+
try (RandomAccessFile writer = new RandomAccessFile(file, "rw");
89+
FileChannel channel = writer.getChannel();) {
90+
ByteBuffer buff = ByteBuffer.wrap("Hello world".getBytes(StandardCharsets.UTF_8));
91+
92+
channel.write(buff);
93+
94+
// now we verify whether the file was written correctly
95+
RandomAccessFile reader = new RandomAccessFile(file, "r");
96+
assertEquals("Hello world", reader.readLine());
97+
reader.close();
98+
}
99+
}
100+
101+
@Test
102+
public void givenFile_whenWriteAFileUsingLockAFileSectionWithFileChannel_thenCorrect() throws IOException {
103+
try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "rw");
104+
FileChannel channel = reader.getChannel();
105+
FileLock fileLock = channel.tryLock(6, 5, Boolean.FALSE);) {
106+
107+
assertNotNull(fileLock);
108+
}
109+
}
110+
111+
@Test
112+
public void givenFile_whenReadWithFileChannelGetPosition_thenCorrect() throws IOException {
113+
114+
try (ByteArrayOutputStream out = new ByteArrayOutputStream();
115+
RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
116+
FileChannel channel = reader.getChannel();) {
117+
118+
int bufferSize = 1024;
119+
if (bufferSize > channel.size()) {
120+
bufferSize = (int) channel.size();
121+
}
122+
ByteBuffer buff = ByteBuffer.allocate(bufferSize);
123+
124+
while (channel.read(buff) > 0) {
125+
out.write(buff.array(), 0, buff.position());
126+
buff.clear();
127+
}
128+
129+
// the original file is 11 bytes long, so that's where the position pointer should be
130+
assertEquals(11, channel.position());
131+
132+
channel.position(4);
133+
assertEquals(4, channel.position());
134+
}
135+
}
136+
137+
@Test
138+
public void whenGetFileSize_thenCorrect() throws IOException {
139+
140+
try (RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
141+
FileChannel channel = reader.getChannel();) {
142+
143+
// the original file is 11 bytes long, so that's where the position pointer should be
144+
assertEquals(11, channel.size());
145+
}
146+
}
147+
148+
@Test
149+
public void whenTruncateFile_thenCorrect() throws IOException {
150+
String input = "this is a test input";
151+
152+
FileOutputStream fout = new FileOutputStream("src/test/resources/test_truncate.txt");
153+
FileChannel channel = fout.getChannel();
154+
155+
ByteBuffer buff = ByteBuffer.wrap(input.getBytes());
156+
channel.write(buff);
157+
buff.flip();
158+
159+
channel = channel.truncate(5);
160+
assertEquals(5, channel.size());
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162+
fout.close();
163+
channel.close();
164+
}
173165
}

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