Java RandomAccessFile.skipBytes方法代码示例

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
/**
* Read Product Definition section from raf.
*
* @param raf RandomAccessFile, with pointer at start of section
* @throws java.io.IOException on I/O error
* @throws IllegalArgumentException if not a GRIB-2 record
*/
public Grib2SectionProductDefinition( RandomAccessFile raf) throws IOException {

  long startingPosition = raf.getFilePointer();

  // octets 1-4 (Length of GDS)
  int length = GribNumbers.int4(raf);

 // octet 5
  int section = raf.read();
  if (section != 4)
    throw new IllegalArgumentException("Not a GRIB-2 PDS section");

  // octets 8-9
  raf.skipBytes(2);
  templateNumber = GribNumbers.int2(raf);

  // read in whole GDS as byte[]
  rawData = new byte[length];
  raf.seek(startingPosition);
  raf.readFully(rawData);
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
static public boolean isValidFile(RandomAccessFile raf) {
	try {
		raf.seek(0);
		boolean found = raf.searchForward(matcher, maxScan); // look in first 16K
		if (!found)
			return false;
		raf.skipBytes(7); // will be positioned on byte 0 of indicator section
		int edition = raf.read(); // read at byte 8
		if (edition != 2)
			return false;

		// check ending = 7777
		long len = GribNumbers.int8(raf);
		if (len > raf.length())
			return false;
		raf.skipBytes(len - 20);
		for (int i = 0; i < 4; i++) {
			if (raf.read() != 55)
				return false;
		}
		return true;

	} catch (IOException e) {
		return false;
	}
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
/**
 * Read Grib2SectionLocalUse from raf.
 *
 * @param raf RandomAccessFile, with pointer at start od section
 * @throws java.io.IOException on I/O error
 */
public Grib2SectionLocalUse(RandomAccessFile raf) throws IOException {

  // octets 1-4 (Length of GDS)
  int length = GribNumbers.int4(raf);
  int section = raf.read();  // This is section 2

  if (section != 2) {  // no local use section
    length = 0;
    raf.skipBytes(-5);
    rawData = null;
    return;
  } else {
    rawData = new byte[length-5];
    raf.readFully(rawData);
  }
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
/**
 * Read Grib2SectionIndicator from raf.
 *
 * @param raf RandomAccessFile, with pointer at start (the "GRIB")
 * @throws java.io.IOException on I/O error
 * @throws IllegalArgumentException if not a GRIB-2 record
 */
public Grib2SectionIndicator(RandomAccessFile raf) throws IOException {
	startPos = raf.getFilePointer();
	byte[] b = new byte[4];
	raf.readFully(b);
	// 判断是不是GRIB
	for (int i = 0; i < b.length; i++) {
		if (b[i] != MAGIC[i])
			throw new IllegalArgumentException("Not a GRIB record");
	}

	raf.skipBytes(2);
	discipline = raf.read();
	int edition = raf.read();
	if (edition != 2)
		throw new IllegalArgumentException("Not a GRIB-2 record");

	messageLength = GribNumbers.int8(raf);
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
/**
 * Read Grib Definition section from raf.
 *
 * @param raf RandomAccessFile, with pointer at start of section
 * @throws java.io.IOException on I/O error
 * @throws IllegalArgumentException if not a GRIB-2 record
 */
public Grib2SectionGridDefinition(RandomAccessFile raf) throws IOException {

  startingPosition = raf.getFilePointer();

  // octets 1-4 (Length of GDS)
  int length = GribNumbers.int4(raf);

 // octet 5
  int section = raf.read();  // This is section 3
  if (section != 3)
    throw new IllegalArgumentException("Not a GRIB-2 GDS section");

  // octets 13-14
  raf.skipBytes(7);
  templateNumber = GribNumbers.uint2(raf);

  // read in whole GDS as byte[]
  rawData = new byte[length];
  raf.seek(startingPosition);
  raf.readFully(rawData);
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
static public boolean isValidFile(RandomAccessFile raf) {
  try {
    raf.seek(0);
    boolean found = raf.searchForward(matcher, maxScan); // look in first 16K
    if (!found) return false;
    raf.skipBytes(4); // will be positioned on byte 0 of indicator section
    int len = GribNumbers.uint3(raf);
    int edition = raf.read(); // read at byte 8
    if (edition != 1) return false;

    // check ending = 7777
    if (len > raf.length()) return false;
    if (allowBadIsLength) return true;

    raf.skipBytes(len-12);
    for (int i = 0; i < 4; i++) {
      if (raf.read() != 55) return false;
    }
    return true;

  } catch (IOException e) {
    return false;
  }
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
/**
 * Read Grib Definition section from raf.
 *
 * @param raf RandomAccessFile, with pointer at start of section
 * @throws java.io.IOException      on I/O error
 * @throws IllegalArgumentException if not a GRIB-2 record
 */
public Grib1SectionGridDefinition(RandomAccessFile raf) throws IOException {

  startingPosition = raf.getFilePointer();

  // octets 1-3 (Length of GDS)
  int length = GribNumbers.int3(raf);

  // octet 6
  raf.skipBytes(2);
  gridTemplate = GribNumbers.uint(raf);

  // read in whole GDS as byte[]
  rawData = new byte[length];
  raf.seek(startingPosition);
  raf.readFully(rawData);

  predefinedGridDefinition = -1;
  predefinedGridDefinitionCenter = -1;
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
/**
 * Read the bit map array.
 *
 * @param raf read from here
 * @return bit map as array of byte values
 * @throws java.io.IOException on read error
 */
public byte[] getBitmap(RandomAccessFile raf) throws IOException {
  // no bitMap
  if (bitMapIndicator == 255)
    return null;

  // LOOK: bitMapIndicator=254 == previously defined bitmap
  if (bitMapIndicator == 254)
  //  logger.debug("HEY bitMapIndicator=254 previously defined bitmap");

  if (bitMapIndicator != 0) {
    throw new UnsupportedOperationException("Grib2 Bit map section pre-defined (provided by center) = " + bitMapIndicator);
  }

  raf.seek(startingPosition);
  int length = GribNumbers.int4(raf);
  raf.skipBytes(2);

  byte[] data = new byte[length - 6];
  raf.readFully(data);

  return data;

  /* create new bit map when it is first asked for
  boolean[] bitmap = new boolean[numberOfPoints];
  int[] bitmask = {128, 64, 32, 16, 8, 4, 2, 1};
  for (int i = 0; i < bitmap.length; i++) {
    bitmap[i] = (data[i / 8] & bitmask[i % 8]) != 0;
  }
  return bitmap; */
}
 

import ucar.unidata.io.RandomAccessFile; //导入方法依赖的package包/类
/**
 * Read Product Definition section from raf.
 *
 * @param raf RandomAccessFile, with pointer at start of section
 * @throws java.io.IOException      on I/O error
 * @throws IllegalArgumentException if not a GRIB-2 record
 */
public Grib1SectionProductDefinition(RandomAccessFile raf) throws IOException {
    int length = GribNumbers.uint3(raf);
    rawData = new byte[length];
    raf.skipBytes(-3);
    raf.readFully(rawData);
}