一、.pgr是什么？
.pgr文件是二进制的图像文件，可以用普通的文本文件打开，或者查看十六进制的文本信息；
读取需要了解~~~非常重要 ！！！
基本数据类型的大小端存储模式表头Header
详细信息可参考：/manual/PowerGREP.pdf
二、C++与Java存储数据差别——大小端模式
Java是大端模式，C是小端模式；
以int为类，大端模式：高位存高位，低位存地位；
小端模式：高位存地位，地位存高位
如 大端：ABCD 小端：DCBA
float，double存储为 符号位，指数位，小数位，更复杂一些；
三、Java读取小端模式数据示例代码
可以用BufferTest利用移位方法import java.nio.ByteBuffer;import java.nio.ByteOrder;/************************************** Class Name: doubleConvert* Description:〈大小端转换〉* @create /8/19* @since 1.0.0************************************/public class doubleConvert {/*** 向将bytes添加到另一个bytes结尾，并返回位置** @param buff 目标数组* @param pos 目标数组放置的起始位置* @param lens 添加的长度* @param dx 要添加的数组* @return lens添加的长度*/public static int addToBuff(byte[] buff, int pos, int lens, byte[] dx) {System.arraycopy(dx, 0, buff, pos, lens);return lens;}/*** 获得bytes的一段数据** @param buff原byte数组* @param startPos 起始位置* @param lenth 获取的长度* @return 返回获得的byte数组*/public static byte[] getFromBuff(byte[] buff, int startPos, int lenth) {byte[] bytes = new byte[lenth];System.arraycopy(buff, startPos, bytes, 0, lenth);return bytes;}/*** double转byte数组，小端模式** @param d* @return*/public static byte[] doubleToBytes_Little(double d) {long l = Double.doubleToLongBits(d);byte b[] = new byte[8];b[7] = (byte) (0xff & (l >> 56));b[6] = (byte) (0xff & (l >> 48));b[5] = (byte) (0xff & (l >> 40));b[4] = (byte) (0xff & (l >> 32));b[3] = (byte) (0xff & (l >> 24));b[2] = (byte) (0xff & (l >> 16));b[1] = (byte) (0xff & (l >> 8));b[0] = (byte) (0xff & l);return b;}/*** double转byte数组，大端模式** @param d* @return*/public static byte[] doubleToBytes_Big(double d) {long l = Double.doubleToLongBits(d);byte b[] = new byte[8];b[0] = (byte) (0xff & (l >> 56));b[1] = (byte) (0xff & (l >> 48));b[2] = (byte) (0xff & (l >> 40));b[3] = (byte) (0xff & (l >> 32));b[4] = (byte) (0xff & (l >> 24));b[5] = (byte) (0xff & (l >> 16));b[6] = (byte) (0xff & (l >> 8));b[7] = (byte) (0xff & l);return b;}/*** byte数组转double** @param bytes 8位byte数组* @param littleEndian 是否是小端模式* @return*/public static double bytesToDouble(byte[] bytes, boolean littleEndian) {ByteBuffer buffer = ByteBuffer.wrap(bytes, 0, 8);if (littleEndian) {// ByteBuffer.order(ByteOrder) 方法指定字节序,即大小端模式(BIG_ENDIAN/LITTLE_ENDIAN)// ByteBuffer 默认为大端(BIG_ENDIAN)模式buffer.order(ByteOrder.LITTLE_ENDIAN);}long l = buffer.getLong();return Double.longBitsToDouble(l);}/*** long转byte数组，小端模式** @param l* @return*/public static byte[] longToBytes_Little(long l) {byte b[] = new byte[8];b[7] = (byte) (0xff & (l >> 56));b[6] = (byte) (0xff & (l >> 48));b[5] = (byte) (0xff & (l >> 40));b[4] = (byte) (0xff & (l >> 32));b[3] = (byte) (0xff & (l >> 24));b[2] = (byte) (0xff & (l >> 16));b[1] = (byte) (0xff & (l >> 8));b[0] = (byte) (0xff & l);return b;}/*** long转byte数组，大端模式** @param l* @return*/public static byte[] longToBytes_Big(long l) {byte b[] = new byte[8];b[0] = (byte) (0xff & (l >> 56));b[1] = (byte) (0xff & (l >> 48));b[2] = (byte) (0xff & (l >> 40));b[3] = (byte) (0xff & (l >> 32));b[4] = (byte) (0xff & (l >> 24));b[5] = (byte) (0xff & (l >> 16));b[6] = (byte) (0xff & (l >> 8));b[7] = (byte) (0xff & l);return b;}/*** byte数组转long** @param bytes 8位的byte数组* @param littleEndian 是否是小端模式* @return* @throws Exception*/public static long bytesToLong(byte[] bytes, boolean littleEndian) throws Exception {if (bytes.length != 8) {throw new Exception("参数错误，无法解析。");}ByteBuffer buffer = ByteBuffer.wrap(bytes, 0, 8);if (littleEndian) {// ByteBuffer.order(ByteOrder) 方法指定字节序,即大小端模式(BIG_ENDIAN/LITTLE_ENDIAN)// ByteBuffer 默认为大端(BIG_ENDIAN)模式buffer.order(ByteOrder.LITTLE_ENDIAN);}return buffer.getLong();}/*** int转byte数组 ,小端** @param num* @return*/public static byte[] intToBytes_Little(int num) {byte[] result = new byte[4];result[0] = (byte) ((num >>> 0) & 0xff);result[1] = (byte) ((num >>> 8) & 0xff);result[2] = (byte) ((num >>> 16) & 0xff);result[3] = (byte) ((num >>> 24) & 0xff);return result;}/*** int转byte数组 ,大端** @param num* @return*/public static byte[] intToBytes_Big(int num) {byte[] result = new byte[4];result[0] = (byte) ((num >>> 24) & 0xff);result[1] = (byte) ((num >>> 16) & 0xff);result[2] = (byte) ((num >>> 8) & 0xff);result[3] = (byte) ((num >>> 0) & 0xff);return result;}/*** byte数组转int,小端** @param bytes* @return*/public static int bytesToInt_Little(byte[] bytes) {int result = 0;if (bytes.length == 4) {int a = (bytes[0] & 0xff) << 0;int b = (bytes[1] & 0xff) << 8;int c = (bytes[2] & 0xff) << 16;int d = (bytes[3] & 0xff) << 24;result = a | b | c | d;}return result;}/*** byte数组转int,大端** @param bytes* @return*/public static int bytesToInt_Big(byte[] bytes) {int result = 0;if (bytes.length == 4) {int a = (bytes[0] & 0xff) << 24;int b = (bytes[1] & 0xff) << 16;int c = (bytes[2] & 0xff) << 8;int d = (bytes[3] & 0xff) << 0;result = a | b | c | d;}return result;}/*** byte数组转十六进制** @param bytes* @return*/public static String bytesToHex(byte[] bytes) {StringBuilder buf = new StringBuilder(bytes.length * 2);for (byte b : bytes) {// 使用String的format方法进行转换buf.append(String.format("%02x", new Integer(b & 0xff)));}return buf.toString();}/*** 十六进制转byte数组** @param str* @return*/public static byte[] hexToBytes(String str) {if (str == null || str.trim().equals("")) {return new byte[0];}byte[] bytes = new byte[str.length() / 2];for (int i = 0; i < str.length() / 2; i++) {String subStr = str.substring(i * 2, i * 2 + 2);bytes[i] = (byte) Integer.parseInt(subStr, 16);}return bytes;}public static void main(String[] args) throws Exception {int num = 100;// 先将int 转小端的byte[], 小端的byte[] 再转回intSystem.out.println("intToLittle: " + bytesToInt_Little(intToBytes_Little(num)));// 先将int 转大端的byte[], 大端的byte[] 再转回intSystem.out.println("intToBig: " + bytesToInt_Big(intToBytes_Big(num)));long l = 9l;System.out.println("longToLittle: " + bytesToLong(longToBytes_Little(l), true));System.out.println("longToBig: " + bytesToLong(longToBytes_Big(l), false));double d = 9.125d;System.out.println("doubleToLittle: " + bytesToDouble(doubleToBytes_Little(d), true));System.out.println("doubleToBig: " + bytesToDouble(doubleToBytes_Big(d), false));System.out.println("doubleToLittle---Hex: " + bytesToHex(doubleToBytes_Little(d)));System.out.println("doubleToBig---Hex: " + bytesToHex(doubleToBytes_Big(d)));}}
结果如下：
