Java Code Examples for java.nio.MappedByteBuffer#clear()

/**
 * 复制文件（内存映射）
 *
 * @param   source
 *          原文件
 *
 * @param   target
 *          目标文件
 *
 * @return  true:成功 / false:失败
 *
 * @throws  IOException
 *          文件读写异常
 */
private static boolean copyByMapped(String source, String target) throws IOException {
    RandomAccessFile readFile = new RandomAccessFile(source, "r");
    RandomAccessFile writeFile = new RandomAccessFile(target, "rw");

    long fileLength = readFile.length();

    MappedByteBuffer in = readFile.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, fileLength);
    MappedByteBuffer out = writeFile.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, fileLength);

    for (int i = 0; i < fileLength; i++) {
        out.put(in.get());
    }

    readFile.close();
    writeFile.close();
    in.clear();
    out.clear();

    return true;
}
 

private void flushBuffer() throws BufferOverflowException {
    if (pagedIn) {
        MappedByteBuffer buffer;
        // Only flush if page was changed
        if (dirtyPage) {
            Collection<byte[]> values = pageMap.values();
            buffer = spillFile.getPage(pageIndex);
            buffer.clear();
            // number of elements
            buffer.putInt(values.size());
            for (byte[] value : values) {
                // element length
                buffer.putInt(value.length);
                // element
                buffer.put(value, 0, value.length);
            }
        }
        buffer = null;
        // Reset page stats
        pageMap.clear();
        totalResultSize = 0;
    }
    pagedIn = false;
    dirtyPage = false;
}
 

public void testBug53637() throws Exception {
    MappedByteBuffer mapped = (MappedByteBuffer) allocateMapped(1);
    mapped.get();
    mapped.rewind();
    mapped.get();

    mapped.rewind();
    mapped.mark();
    mapped.get();
    mapped.reset();
    mapped.get();

    mapped.rewind();
    mapped.get();
    mapped.clear();
    mapped.get();

    mapped.rewind();
    mapped.get();
    mapped.flip();
    mapped.get();
}
 

private void flushBuffer() throws BufferOverflowException {
    if (pagedIn) {
        MappedByteBuffer buffer;
        // Only flush if page was changed
        if (dirtyPage) {
            Collection<byte[]> values = pageMap.values();
            buffer = spillFile.getPage(pageIndex);
            buffer.clear();
            // number of elements
            buffer.putInt(values.size());
            for (byte[] value : values) {
                // element length
                buffer.putInt(value.length);
                // element
                buffer.put(value, 0, value.length);
            }
        }
        buffer = null;
        // Reset page stats
        pageMap.clear();
        totalResultSize = 0;
    }
    pagedIn = false;
    dirtyPage = false;
}
 

/**
 * Method to read a file
 */
public String readFile(String filePath){		
	byte[] data = null;
		try {
			java.io.FileInputStream f1;
			f1 = new java.io.FileInputStream(filePath);
		    FileChannel fc = f1.getChannel();
		    data = new byte[(int) fc.size()];
		    MappedByteBuffer b = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
		    
		    b.get(data);
		    b.clear();
		    fc.close();
		    f1.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	return new String(data);
}
 

/**
 * Method to read a file. Reads a file and returns the header and the content split in an String array
 */
public String[] readFileAndHeader(String filePath){
	byte[] data = null;
	try {
		java.io.FileInputStream f1;
		f1 = new java.io.FileInputStream(filePath);
	    FileChannel fc = f1.getChannel();
	    data = new byte[(int) fc.size()];
	    MappedByteBuffer b = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
	    
	    b.get(data);
	    b.clear();
	    fc.close();
	    f1.close();
	} catch (Exception e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	
	return new String(data).split(java.util.regex.Pattern.quote("*******************"));
}
 

/**
 * 加解密
 * 将视频文件的数据流前1000个字节中的每个字节与其下标进行异或运算。
 * 解密时只需将加密过的文件再进行一次异或运算即可。
 * @param strFile 源文件绝对路径
 * @return
 */
private boolean encrypt(String strFile) {
    int len = REVERSE_LENGTH;
    try {
        File f = new File(strFile);
        RandomAccessFile raf = new RandomAccessFile(f, "rw");
        long totalLen = raf.length();

        if (totalLen < REVERSE_LENGTH){
            len = (int) totalLen;
        }
        FileChannel channel = raf.getChannel();
        MappedByteBuffer buffer = channel.map(FileChannel.MapMode.READ_WRITE, 0, REVERSE_LENGTH);
        byte tmp;
        for (int i = 0; i < len; ++i) {
            byte rawByte = buffer.get(i);
            tmp = (byte) (rawByte ^ i);
            buffer.put(i, tmp);
        }
        buffer.force();
        buffer.clear();
        channel.close();
        raf.close();
        return true;
    } catch (Exception e) {
        e.printStackTrace();
        return false;
    }
}
 

public static void copyFile(File source, File dest) throws IOException {
    log.debug("Copy from {} to {}", source.getAbsoluteFile(), dest.getAbsoluteFile());
    FileInputStream fi = new FileInputStream(source);
    FileChannel fic = fi.getChannel();
    MappedByteBuffer mbuf = fic.map(FileChannel.MapMode.READ_ONLY, 0, source.length());
    fic.close();
    fi.close();
    fi = null;

    // ensure the destination directory exists
    if (!dest.exists()) {
        String destPath = dest.getPath();
        log.debug("Destination path: {}", destPath);
        String destDir = destPath.substring(0, destPath.lastIndexOf(File.separatorChar));
        log.debug("Destination dir: {}", destDir);
        File dir = new File(destDir);
        if (!dir.exists()) {
            if (dir.mkdirs()) {
                log.debug("Directory created");
            } else {
                log.warn("Directory not created");
            }
        }
        dir = null;
    }

    FileOutputStream fo = new FileOutputStream(dest);
    FileChannel foc = fo.getChannel();
    foc.write(mbuf);
    foc.close();
    fo.close();
    fo = null;

    mbuf.clear();
    mbuf = null;
}