com.google.common.io.Files.map()方法的使用及代码示例

x33g5p2x  于2022-01-18 转载在 其他  
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本文整理了Java中com.google.common.io.Files.map()方法的一些代码示例，展示了Files.map()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Files.map()方法的具体详情如下：
包路径：com.google.common.io.Files
类名称：Files
方法名：map

Files.map介绍

[英]Fully maps a file read-only in to memory as per FileChannel#map(java.nio.channels.FileChannel.MapMode,long,long).

Files are mapped from offset 0 to its length.

This only works for files ≤ Integer#MAX_VALUE bytes.
[中]按照FileChannel#map（java.nio.channels.FileChannel.MapMode，long，long）将只读文件完全映射到内存中。
文件从偏移量0映射到其长度。
这只适用于文件≤ 整数#最大值字节。

代码示例

代码示例来源：origin: google/guava

/**
 * Fully maps a file read-only in to memory as per {@link
 * FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)}.
 *
 * <p>Files are mapped from offset 0 to its length.
 *
 * <p>This only works for files ≤ {@link Integer#MAX_VALUE} bytes.
 *
 * @param file the file to map
 * @return a read-only buffer reflecting {@code file}
 * @throws FileNotFoundException if the {@code file} does not exist
 * @throws IOException if an I/O error occurs
 * @see FileChannel#map(MapMode, long, long)
 * @since 2.0
 */
public static MappedByteBuffer map(File file) throws IOException {
 checkNotNull(file);
 return map(file, MapMode.READ_ONLY);
}

代码示例来源：origin: google/j2objc

/**
 * Fully maps a file read-only in to memory as per {@link
 * FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)}.
 *
 * <p>Files are mapped from offset 0 to its length.
 *
 * <p>This only works for files ≤ {@link Integer#MAX_VALUE} bytes.
 *
 * @param file the file to map
 * @return a read-only buffer reflecting {@code file}
 * @throws FileNotFoundException if the {@code file} does not exist
 * @throws IOException if an I/O error occurs
 * @see FileChannel#map(MapMode, long, long)
 * @since 2.0
 */
public static MappedByteBuffer map(File file) throws IOException {
 checkNotNull(file);
 return map(file, MapMode.READ_ONLY);
}

代码示例来源：origin: wildfly/wildfly

/**
 * Fully maps a file read-only in to memory as per {@link
 * FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)}.
 *
 * <p>Files are mapped from offset 0 to its length.
 *
 * <p>This only works for files ≤ {@link Integer#MAX_VALUE} bytes.
 *
 * @param file the file to map
 * @return a read-only buffer reflecting {@code file}
 * @throws FileNotFoundException if the {@code file} does not exist
 * @throws IOException if an I/O error occurs
 * @see FileChannel#map(MapMode, long, long)
 * @since 2.0
 */
public static MappedByteBuffer map(File file) throws IOException {
 checkNotNull(file);
 return map(file, MapMode.READ_ONLY);
}

代码示例来源：origin: google/j2objc

/**
 * Fully maps a file in to memory as per {@link
 * FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)} using the requested {@link
 * MapMode}.
 *
 * <p>Files are mapped from offset 0 to its length.
 *
 * <p>This only works for files ≤ {@link Integer#MAX_VALUE} bytes.
 *
 * @param file the file to map
 * @param mode the mode to use when mapping {@code file}
 * @return a buffer reflecting {@code file}
 * @throws FileNotFoundException if the {@code file} does not exist
 * @throws IOException if an I/O error occurs
 * @see FileChannel#map(MapMode, long, long)
 * @since 2.0
 */
public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
 checkNotNull(file);
 checkNotNull(mode);
 if (!file.exists()) {
  throw new FileNotFoundException(file.toString());
 }
 return map(file, mode, file.length());
}

代码示例来源：origin: apache/incubator-druid

/**
 * Fully maps a file read-only in to memory as per
 * {@link FileChannel#map(FileChannel.MapMode, long, long)}.
 *
 * <p>Files are mapped from offset 0 to its length.
 *
 * <p>This only works for files <= {@link Integer#MAX_VALUE} bytes.
 *
 * <p>Similar to {@link Files#map(File)}, but returns {@link MappedByteBufferHandler}, that makes it easier to unmap
 * the buffer within try-with-resources pattern:
 * <pre>{@code
 * try (MappedByteBufferHandler fileMappingHandler = FileUtils.map(file)) {
 *   ByteBuffer fileMapping = fileMappingHandler.get();
 *   // use mapped buffer
 * }}</pre>
 *
 * @param file the file to map
 *
 * @return a {@link MappedByteBufferHandler}, wrapping a read-only buffer reflecting {@code file}
 *
 * @throws FileNotFoundException if the {@code file} does not exist
 * @throws IOException           if an I/O error occurs
 * @see FileChannel#map(FileChannel.MapMode, long, long)
 */
public static MappedByteBufferHandler map(File file) throws IOException
{
 MappedByteBuffer mappedByteBuffer = Files.map(file);
 return new MappedByteBufferHandler(mappedByteBuffer);
}

代码示例来源：origin: wildfly/wildfly

/**
 * Fully maps a file in to memory as per {@link
 * FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)} using the requested {@link
 * MapMode}.
 *
 * <p>Files are mapped from offset 0 to its length.
 *
 * <p>This only works for files ≤ {@link Integer#MAX_VALUE} bytes.
 *
 * @param file the file to map
 * @param mode the mode to use when mapping {@code file}
 * @return a buffer reflecting {@code file}
 * @throws FileNotFoundException if the {@code file} does not exist
 * @throws IOException if an I/O error occurs
 * @see FileChannel#map(MapMode, long, long)
 * @since 2.0
 */
public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
 checkNotNull(file);
 checkNotNull(mode);
 if (!file.exists()) {
  throw new FileNotFoundException(file.toString());
 }
 return map(file, mode, file.length());
}

代码示例来源：origin: google/j2objc

RandomAccessFile raf =
   closer.register(new RandomAccessFile(file, mode == MapMode.READ_ONLY ? "r" : "rw"));
 return map(raf, mode, size);
} catch (Throwable e) {
 throw closer.rethrow(e);

代码示例来源：origin: apache/incubator-druid

/**
 * Returns a mapped buffer of the smooshed file with the given name. Buffer's contents from 0 to capacity() are the
 * whole mapped file contents, limit() is equal to capacity().
 */
public ByteBuffer mapFile(String name) throws IOException
{
 final Metadata metadata = internalFiles.get(name);
 if (metadata == null) {
  return null;
 }
 final int fileNum = metadata.getFileNum();
 while (buffersList.size() <= fileNum) {
  buffersList.add(null);
 }
 MappedByteBuffer mappedBuffer = buffersList.get(fileNum);
 if (mappedBuffer == null) {
  mappedBuffer = Files.map(outFiles.get(fileNum));
  buffersList.set(fileNum, mappedBuffer);
 }
 ByteBuffer retVal = mappedBuffer.duplicate();
 retVal.position(metadata.getStartOffset()).limit(metadata.getEndOffset());
 return retVal.slice();
}

代码示例来源：origin: wildfly/wildfly

RandomAccessFile raf =
   closer.register(new RandomAccessFile(file, mode == MapMode.READ_ONLY ? "r" : "rw"));
 return map(raf, mode, size);
} catch (Throwable e) {
 throw closer.rethrow(e);

代码示例来源：origin: google/guava

public void testMap_readWrite_max_value_plus_1() throws IOException {
 // Setup
 File file = createTempFile();
 // Test
 try {
  Files.map(file, MapMode.READ_WRITE, (long) Integer.MAX_VALUE + 1);
  fail("Should throw when size exceeds Integer.MAX_VALUE");
 } catch (IllegalArgumentException expected) {
 }
}

代码示例来源：origin: google/guava

public void testMap() throws IOException {
 // Test data
 int size = 1024;
 byte[] bytes = newPreFilledByteArray(size);
 // Setup
 File file = createTempFile();
 Files.write(bytes, file);
 // Test
 MappedByteBuffer actual = Files.map(file);
 // Verify
 ByteBuffer expected = ByteBuffer.wrap(bytes);
 assertTrue("ByteBuffers should be equal.", expected.equals(actual));
}

代码示例来源：origin: google/guava

public void testMap_noSuchFile() throws IOException {
 // Setup
 File file = createTempFile();
 boolean deleted = file.delete();
 assertTrue(deleted);
 // Test
 try {
  Files.map(file);
  fail("Should have thrown FileNotFoundException.");
 } catch (FileNotFoundException expected) {
 }
}

代码示例来源：origin: google/guava

public void testMap_readWrite() throws IOException {
 // Test data
 int size = 1024;
 byte[] expectedBytes = new byte[size];
 byte[] bytes = newPreFilledByteArray(1024);
 // Setup
 File file = createTempFile();
 Files.write(bytes, file);
 Random random = new Random();
 random.nextBytes(expectedBytes);
 // Test
 MappedByteBuffer map = Files.map(file, MapMode.READ_WRITE);
 map.put(expectedBytes);
 // Verify
 byte[] actualBytes = Files.toByteArray(file);
 assertTrue(Arrays.equals(expectedBytes, actualBytes));
}

代码示例来源：origin: apache/incubator-druid

@Test
public void testUnmapDoesntCrashJVM() throws Exception
{
 final File file = temporaryFolder.newFile("some_mmap_file");
 try (final OutputStream os = new BufferedOutputStream(new FileOutputStream(file))) {
  final byte[] data = new byte[4096];
  Arrays.fill(data, (byte) 0x5A);
  os.write(data);
 }
 final MappedByteBuffer mappedByteBuffer = Files.map(file);
 Assert.assertEquals((byte) 0x5A, mappedByteBuffer.get(0));
 ByteBufferUtils.unmap(mappedByteBuffer);
 ByteBufferUtils.unmap(mappedByteBuffer);
}

代码示例来源：origin: google/guava

public void testMap_readWrite_creates() throws IOException {
 // Test data
 int size = 1024;
 byte[] expectedBytes = newPreFilledByteArray(1024);
 // Setup
 File file = createTempFile();
 boolean deleted = file.delete();
 assertTrue(deleted);
 assertFalse(file.exists());
 // Test
 MappedByteBuffer map = Files.map(file, MapMode.READ_WRITE, size);
 map.put(expectedBytes);
 // Verify
 assertTrue(file.exists());
 assertTrue(file.isFile());
 assertEquals(size, file.length());
 byte[] actualBytes = Files.toByteArray(file);
 assertTrue(Arrays.equals(expectedBytes, actualBytes));
}

代码示例来源：origin: bedatadriven/activityinfo

private void updateHash(MessageDigest digest, String extension) throws IOException {
  File file = getFile(extension);
  if (file.exists()) {
    digest.update(Files.map(file, MapMode.READ_ONLY));
  }
}

代码示例来源：origin: com.facebook.hive/hive-dwrf-shims

public static Slice mapFileReadOnly(File file)
    throws IOException
{
  return Slice.toUnsafeSlice(Files.map(file));
}

代码示例来源：origin: zhongl/iPage

private DirectBuffer mapFrom(File file) throws IOException {
  ByteBuffer toClean = byteBuffer;
  byteBuffer = Files.map(file, PRIVATE);
  DirectByteBufferCleaner.clean(toClean);
  return this;
}

代码示例来源：origin: org.anarres.tftp/tftp-protocol

@Override
  public TftpByteBufferData load(File key) throws Exception {
    MappedByteBuffer buffer = Files.map(key, FileChannel.MapMode.READ_ONLY);
    return new TftpByteBufferData(buffer);
  }
});

代码示例来源：origin: com.google.guava/guava-tests

public void testMap_noSuchFile() throws IOException {
 // Setup
 File file = createTempFile();
 boolean deleted = file.delete();
 assertTrue(deleted);
 // Test
 try {
  Files.map(file);
  fail("Should have thrown FileNotFoundException.");
 } catch (FileNotFoundException expected) {
 }
}

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