下面列出了java.io.RandomAccessFile#setLength ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
public void open(File outputFile) throws IOException {
outputFile.mkdirs();
if (outputFile.exists()) {
outputFile.delete();
}
outputFile.createNewFile();
outputRAF = new RandomAccessFile(outputFile, "rw");
outputRAF.setLength(mappedFileSizeBytes);
outputRAF.seek(mappedFileSizeBytes - 1);
outputRAF.writeByte(0);
outputRAF.seek(0);
outputChannel = outputRAF.getChannel();
fileBuffer = outputChannel.map(FileChannel.MapMode.READ_WRITE, 0, mappedFileSizeBytes);
}
@Override
public void truncate(final Long length) {
this.length = length;
if(temporary.exists()) {
try {
final RandomAccessFile file = random();
if(length < file.length()) {
// Truncate current
file.setLength(length);
}
}
catch(IOException e) {
log.warn(String.format("Failure truncating file %s to %d", temporary, length));
}
}
}
@Test
public void testChunkAggregatedUpload() throws IOException {
//create a random file to be uploaded.
int size = 69 * 1024;
File fname = new File(tmpFolder, "testChunkAggregatedUpload.txt");
fname.createNewFile();
RandomAccessFile randf = new RandomAccessFile(fname, "rw");
randf.setLength(size);
randf.close();
//test chunked upload
HttpURLConnection urlConn = request("/test/v1/aggregate/upload", HttpMethod.PUT);
urlConn.setChunkedStreamingMode(1024);
Files.copy(Paths.get(fname.toURI()), urlConn.getOutputStream());
assertEquals(200, urlConn.getResponseCode());
assertEquals(size, Integer.parseInt(getContent(urlConn).split(":")[1].trim()));
urlConn.disconnect();
fname.delete();
}
private CheckpointCollectionFileHeader initialize() {
CheckpointCollectionFileHeader header = null;
try {
RandomAccessFile randomAccessFile = new RandomAccessFile(fFile, "rw"); //$NON-NLS-1$
fFileChannel = randomAccessFile.getChannel();
header = createHeader();
// Reserve space for header
randomAccessFile.setLength(header.getSize());
TmfCoreTracer.traceIndexer(CheckpointCollectionFileHeader.class.getSimpleName() + " initialize " + "nbEvents: " + header.fNbEvents + " fTimeRange: " + header.fTimeRange); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
fRandomAccessFile = randomAccessFile;
} catch (IOException e) {
Activator.logError(MessageFormat.format(Messages.ErrorOpeningIndex, fFile), e);
return null;
}
return header;
}
public static POLoad createPOLoadWithSize(long size, LoadFunc loadFunc) throws Exception {
File file = File.createTempFile("tempFile", ".tmp");
file.deleteOnExit();
RandomAccessFile f = new RandomAccessFile(file, "rw");
f.setLength(size);
f.close();
loadFunc.setLocation(file.getAbsolutePath(), new org.apache.hadoop.mapreduce.Job(CONF));
FuncSpec funcSpec = new FuncSpec(loadFunc.getClass().getCanonicalName());
POLoad poLoad = new POLoad(new OperatorKey(), loadFunc);
poLoad.setLFile(new FileSpec(file.getAbsolutePath(), funcSpec));
poLoad.setPc(new PigContext());
poLoad.setUp();
return poLoad;
}
static void writeStrings(String filename, Iterable<String> strGenerator) throws IOException {
RandomAccessFile raf = new RandomAccessFile(filename, "rw");
raf.setLength(0);
ArrayList<Long> offsetttable = new ArrayList<Long>();
for(String s: strGenerator) {
offsetttable.add(raf.getFilePointer());
raf.writeUTF(s);
}
for(long offset: offsetttable)
raf.writeLong(offset);
raf.writeInt(offsetttable.size());
raf.close();
}
void copyFile( String src, String tgt ) throws IOException
{
RandomAccessFile srcFile = new RandomAccessFile( src, "r" );
RandomAccessFile tgtFile = new RandomAccessFile( tgt, "rw" );
byte[] bytes = new byte[(int) srcFile.length( )];
srcFile.read( bytes );
tgtFile.setLength( 0 );
tgtFile.write( bytes );
srcFile.close( );
tgtFile.close( );
}
public void testRecoverFromTruncatedDeltas() throws Exception {
// Create an entry with one record. Shrink the file byte by byte and ensure
// we can read it without crashing.
DeltaStore store = newDeltaStore();
WaveletDeltaRecord written = createRecord();
File deltaFile = FileDeltaCollection.deltasFile(path.getAbsolutePath(), WAVE1_WAVELET1);
long toRemove = 1;
while (true) {
// This generates the full file.
DeltasAccess wavelet = store.open(WAVE1_WAVELET1);
wavelet.append(ImmutableList.of(written));
wavelet.close();
RandomAccessFile file = new RandomAccessFile(deltaFile, "rw");
if (toRemove > file.length()) {
file.close();
break;
}
// eat the planned number of bytes
LOG.info("trying to remove " + toRemove + " bytes");
file.setLength(file.length() - toRemove);
file.close();
wavelet = store.open(WAVE1_WAVELET1);
WaveletDeltaRecord read = wavelet.getDelta(0);
assertNull("got an unexpected record " + read, read);
wavelet.close();
toRemove++;
}
}
public void save(RandomAccessFile out) throws IOException
{
// write data
if (index.offset.length > 0)
{
saveRows(out, index.getCachePos());
}
// recalc header vars
// calculate fileLength first (written in header)
if (index.offset.length > 0)
{
int filePos = 0;
if (index.cachepos == 0)
{
filePos = 100;
}
for (int j = 0; j < index.offset.length; j++)
{
// load geometry to get size
JShape tempShape = data.getShape(j + index.cachepos);
filePos += 8 + tempShape.getRecordLength();
}
header.fileLength += filePos / 2;
out.setLength(2 * header.fileLength);
// write header
out.seek(0);
header.save(out);
}
}
/**
* remove one byte from the written outputstream
* @throws IOException if there is no more buffer to unwrite from
*/
public void unwrite() throws IOException {
if (count == 0) {
throw new IOException("Pushback buffer overflow");
}
if (buf == null) {
@SuppressWarnings("resource") RandomAccessFile randomAccessFile =
new RandomAccessFile(file, "rw");
randomAccessFile.setLength(file.length() - 1);
return;
}
buf[--count] = (byte) 0;
}
@BeforeAll
public static void setUp() throws IOException
{
final RandomAccessFile file = new RandomAccessFile(PATH, "rw");
file.setLength(SIZE);
channel = file.getChannel();
}
private boolean doLock() {
if (lock != null) {
return true;
}
try {
lockFile = new RandomAccessFile(file, "rws");
lock = lockFile.getChannel().tryLock(0L, 1L, false);
if (lock != null) {
byte[] payload = ManagementFactory.getRuntimeMXBean().getName().getBytes("UTF-8");
lockFile.setLength(0);
lockFile.seek(0);
lockFile.write(payload);
}
}
catch (Exception e) {
// logging is not configured yet, so use console
System.err.println("Failed to write lock file: " + file.getAbsolutePath());
e.printStackTrace();
// handle it as null result
lock = null;
}
finally {
if (lock == null) {
release();
return false;
}
}
return true;
}
public MemoryMappedFile(final int filesize) throws IOException {
file = File.createTempFile("mmap", ".bin");
file.deleteOnExit();
randomAccessFile = new RandomAccessFile(file, "rw");
randomAccessFile.setLength(filesize);
randomAccessFile.close();
}
private TempFile createTempFile() throws IOException {
// Create temp file in temp dir or custom dir if provided
File tempFile = File.createTempFile(UUID.randomUUID().toString(),
null, spillFilesDirectory);
if (logger.isDebugEnabled()) {
logger.debug("Creating new SpillFile: " + tempFile.getAbsolutePath());
}
RandomAccessFile file = new RandomAccessFile(tempFile, "rw");
file.setLength(SPILL_FILE_SIZE);
return new TempFile(tempFile, file);
}
private File createFileWithSize(String fileName, long sizeInBytes) throws IOException {
File tmpLargeFile = new File(_localTempDir, fileName);
tmpLargeFile.createNewFile();
RandomAccessFile raf = new RandomAccessFile(tmpLargeFile, "rw");
raf.setLength(sizeInBytes);
raf.close();
return tmpLargeFile;
}
public Lobstack(File dir, String name, boolean compress, int key_step_size)
throws IOException
{
this.key_step_size = key_step_size;
this.dir = dir;
this.stack_name = name;
this.compress = compress;
if (!dir.exists())
{
throw new java.io.IOException("Directory does not exist: " + dir);
}
if (!dir.isDirectory())
{
throw new java.io.IOException("Location is not a directory: " + dir);
}
data_files = new AutoCloseLRUCache<Long, FileChannel>(MAX_OPEN_FILES);
RandomAccessFile root_file = new RandomAccessFile(new File(dir, name + ".root"), MODE);
root_file_channel = root_file.getChannel();
if (root_file.length()==0)
{
root_file.setLength(16);
reset();
}
else
{
synchronized(ptr_lock)
{
root_file.seek(ROOT_ROOT_LOCATION);
current_root = root_file.readLong();
root_file.seek(ROOT_WRITE_LOCATION);
current_write_location = root_file.readLong();
}
}
showSize();
}
public static void main(String[] args) throws Exception {
int initialSize = 20480*1024;
int maximumMapSize = 16*1024*1024;
int maximumFileSize = 300000000;
File file = File.createTempFile("exp", "tmp");
file.deleteOnExit();
RandomAccessFile f = new RandomAccessFile(file, "rw");
f.setLength(initialSize);
FileChannel fc = f.getChannel();
ByteBuffer[] buffers = new ByteBuffer[128];
System.out.format("map %d -> %d\n", 0, initialSize);
buffers[0] = fc.map(FileChannel.MapMode.READ_WRITE, 0, initialSize);
int currentBuffer = 0;
int currentSize = initialSize;
int currentPosition = 0;
ArrayList<String> junk = new ArrayList<String>();
while (currentPosition+currentSize < maximumFileSize) {
int inc = Math.max(1000*1024, (currentPosition+currentSize)/8);
int size = currentPosition+currentSize+inc;
f.setLength(size);
while (currentSize+inc > maximumMapSize) {
if (currentSize < maximumMapSize) {
System.out.format("map %d -> %d\n", currentPosition,
(currentPosition + maximumMapSize));
buffers[currentBuffer] = fc.map(FileChannel.MapMode.READ_WRITE,
currentPosition, maximumMapSize);
fillBuffer(buffers[currentBuffer], currentSize);
}
currentPosition += maximumMapSize;
inc = currentSize+inc-maximumMapSize;
currentSize = 0;
currentBuffer++;
if (currentBuffer == buffers.length) {
ByteBuffer[] old = buffers;
buffers = new ByteBuffer[currentBuffer+currentBuffer/2];
System.arraycopy(old, 0, buffers, 0, currentBuffer); }
}
currentSize += inc;
if (currentSize > 0) {
System.out.format("map %d -> %d\n", currentPosition,
(currentPosition + currentSize));
buffers[currentBuffer] = fc.map(FileChannel.MapMode.READ_WRITE,
currentPosition, currentSize);
fillBuffer(buffers[currentBuffer], currentSize-inc);
}
// busy loop needed to reproduce issue
long t = System.currentTimeMillis();
while (System.currentTimeMillis() < t+500) {
junk.add(String.valueOf(t));
if (junk.size() > 100000) junk.clear();
}
}
fc.close();
// cleanup the ref to mapped buffers so they can be GCed
for (int i = 0; i < buffers.length; i++)
buffers[i] = null;
System.gc();
// Take a nap to wait for the Cleaner to cleanup those unrefed maps
Thread.sleep(1000);
System.out.println("TEST PASSED");
}
private void corruptFile(File indexFile) throws IOException {
RandomAccessFile randomAccessFile = new RandomAccessFile(indexFile, "rw");
randomAccessFile.setLength(randomAccessFile.length() - 100);
randomAccessFile.close();
}
private void requestNet() {
// (1). �����ͷ�������Դ�ļ�һ����С�Ŀ��ļ�
try {
// 1. ��ʼ��Url
URL url = new URL(path);
// 2. ͨ��Url��ȡHttp����
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
// 3. �����������������ʽ
conn.setRequestMethod("GET");
// 4. ��ȡ������ 200:�ɹ� 3xxx���� 4xxx�ͻ��˴��� 500����������
int code = conn.getResponseCode();
// 5. �õ��ӷ������˷��ص���Դ�ļ��Ĵ�С
int fileLength = conn.getContentLength();
if (code == 200) {
System.out.println("��������Դ�ļ��Ĵ�С��" + fileLength);
RandomAccessFile raf = new RandomAccessFile(getFileName(), "rw");
// ��Ҫ�����ļ��Ĵ�С
raf.setLength(fileLength);
raf.close();
}
// (2).��������߳�����
// ÿ������Ĵ�С
int blockSize = fileLength / threadCount;
for (int threadId = 0; threadId < threadCount; threadId++) {
int startIndex = threadId * blockSize;
int endIndex = (threadId + 1) * blockSize;
// ���һ���߳�
if (threadId == threadCount - 1) {
// �����ļ�������λ��
endIndex = fileLength - 1;
}
// ��ʼ�߳�
new DownLoadThread(startIndex, endIndex, threadId).start();
}
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 下载文件并且存至tfs文件系统
*
* @param remoteFileNameTmp
* @param
* @return
*/
private Map downLoadFileToTable(String remoteFileNameTmp, FTPClientTemplate ftpClientTemplate, Map ftpItemConfigInfo) {
Map resultInfo = new HashMap();
String tfsReturnFileName = null;
long block = 10 * 1024;// 默认
if (ftpClientTemplate == null) {
resultInfo.put("SAVE_FILE_FLAG", "E");
return resultInfo;
}
String localPathName = ftpItemConfigInfo.get("localPath").toString().endsWith("/") ? ftpItemConfigInfo.get("localPath").toString()
+ ftpItemConfigInfo.get("newFileName").toString() : ftpItemConfigInfo.get("localPath").toString() + "/" + ftpItemConfigInfo.get("newFileName").toString();
ftpItemConfigInfo.put("localfilename", localPathName);// 本地带路径的文件名回写，后面读文件时使用
try {
File file = new File(localPathName);
RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");// 建立随机访问
FTPClient ftpClient = new FTPClient();
ftpClient.connect(ftpClientTemplate.getHost(), ftpClientTemplate.getPort());
if (FTPReply.isPositiveCompletion(ftpClient.getReplyCode())) {
if (!ftpClient.login(ftpClientTemplate.getUsername(), ftpClientTemplate.getPassword())) {
resultInfo.put("SAVE_FILE_FLAG", "E");
resultInfo.put("remark", "登录失败,用户名【" + ftpClientTemplate.getUsername() + "】密码【" + ftpClientTemplate.getPassword() + "】");
return resultInfo;
}
}
ftpClient.setControlEncoding("UTF-8");
ftpClient.setFileType(FTP.BINARY_FILE_TYPE); // 二进制
ftpClient.enterLocalPassiveMode(); // 被动模式
ftpClient.sendCommand("PASV");
ftpClient.sendCommand("SIZE " + remoteFileNameTmp + "\r\n");
String replystr = ftpClient.getReplyString();
String[] replystrL = replystr.split(" ");
long filelen = 0;
if (Integer.valueOf(replystrL[0]) == 213) {
filelen = Long.valueOf(replystrL[1].trim());
} else {
resultInfo.put("SAVE_FILE_FLAG", "E");
resultInfo.put("remark", "无法获取要下载的文件的大小!");
return resultInfo;
}
accessFile.setLength(filelen);
accessFile.close();
ftpClient.disconnect();
int tnum = Integer.valueOf(ftpItemConfigInfo.get("TNUM").toString());
block = (filelen + tnum - 1) / tnum;// 每个线程下载的快大小
ThreadPoolExecutor cachedThreadPool = (ThreadPoolExecutor) Executors.newCachedThreadPool();
List<Future<Map>> threadR = new ArrayList<Future<Map>>();
for (int i = 0; i < tnum; i++) {
logger.debug("发起线程：" + i);
// 保存线程日志
ftpItemConfigInfo.put("threadrunstate", "R");
ftpItemConfigInfo.put("remark", "开始下载文件");
ftpItemConfigInfo.put("data", "文件名：" + remoteFileNameTmp);
long start = i * block;
long end = (i + 1) * block - 1;
ftpItemConfigInfo.put("begin", start);
ftpItemConfigInfo.put("end", end);
saveTaskLogDetail(ftpItemConfigInfo);
Map para = new HashMap();
para.putAll(ftpItemConfigInfo);
para.put("serverfilename", remoteFileNameTmp);
para.put("filelength", filelen);
para.put("tnum", i + 0);
para.put("threadDownSize", block);
para.put("transferflag", FTPClientTemplate.TransferType.download);
FTPClientTemplate dumpThread = new FTPClientTemplate(para);
Future<Map> runresult = cachedThreadPool.submit(dumpThread);
threadR.add(runresult);
}
do {
// 等待下载完成
Thread.sleep(1000);
} while (cachedThreadPool.getCompletedTaskCount() < threadR.size());
saveDownFileData(ftpItemConfigInfo);
// 下载已经完成，多线程保存数据至表中
} catch (Exception e) {
// TODO Auto-generated catch block
logger.error("保存文件失败：", e);
resultInfo.put("SAVE_FILE_FLAG", "E");
resultInfo.put("remark", "保存文件失败：" + e);
return resultInfo;
}
resultInfo.put("SAVE_FILE_FLAG", "S");
return resultInfo;
}