java獲取exe文件的版本信息

package util;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;


public class ExeDllFileVersion {

	public static int unpack(byte[] b) {
		int num = 0;
		for (int i = 0; i < b.length; i++) {
			num = 256 * num + (b[b.length - 1 - i] & 0xff);
		}
		return num;
	}
	public static String getExeVersion(File file) {

		String version = null;
		RandomAccessFile raf = null;
		byte[] buffer;
		String str;
		try {
			raf = new RandomAccessFile(file, "r");
			buffer = new byte[64];
			raf.read(buffer);
			str = "" + (char)buffer[0] + (char)buffer[1];
			if(!"MZ".equals(str)) {
				return version;
			}

			int peOffset = unpack(new byte[]{buffer[60], buffer[61], buffer[62], buffer[63]});
			if(peOffset < 64) {
				return version;
			}

			raf.seek(peOffset);
			buffer = new byte[24];
			raf.read(buffer);
			str = "" + (char)buffer[0] + (char)buffer[1];
			if(!"PE".equals(str)) {
				return version;
			}
			int machine = unpack(new byte[]{buffer[4], buffer[5]});
			if(machine != 332) {
				return version;
			}

			int noSections = unpack(new byte[]{buffer[6], buffer[7]});
			int optHdrSize = unpack(new byte[]{buffer[20], buffer[21]});
			raf.seek(raf.getFilePointer() + optHdrSize);
			boolean resFound = false;
			for(int i=0; i < noSections; i++) {
				buffer = new byte[40];
				raf.read(buffer);
				str = "" + (char)buffer[0] + (char)buffer[1] +
						(char)buffer[2] + (char)buffer[3] + (char)buffer[4];
				if(".rsrc".equals(str)) {
					resFound = true;
					break;
				}
			}
			if(!resFound) {
				return version;
			}

			int infoVirt = unpack(new byte[]{buffer[12], buffer[13], buffer[14], buffer[15]});
			int infoSize = unpack(new byte[]{buffer[16], buffer[17], buffer[18], buffer[19]});
			int infoOff = unpack(new byte[]{buffer[20], buffer[21], buffer[22], buffer[23]});
			raf.seek(infoOff);
			buffer = new byte[infoSize];
			raf.read(buffer);
			int nameEntries = unpack(new byte[]{buffer[12], buffer[13]});
			int idEntries = unpack(new byte[]{buffer[14], buffer[15]});
			boolean infoFound = false;
			int subOff = 0;
			for(int i=0; i < (nameEntries+idEntries); i++) {
				int type = unpack(new byte[]{buffer[i*8+16], buffer[i*8+17], buffer[i*8+18], buffer[i*8+19]});
				if(type == 16) {                          //FILEINFO resource
					infoFound = true;
					subOff = unpack(new byte[]{buffer[i*8+20], buffer[i*8+21], buffer[i*8+22], buffer[i*8+23]});
					break;
				}
			}
			if(!infoFound) {
				return version;
			}

			subOff = subOff&0x7fffffff;
			infoOff = unpack(new byte[]{buffer[subOff+20], buffer[subOff+21], buffer[subOff+22], buffer[subOff+23]}); //offset of first FILEINFO
			infoOff = infoOff&0x7fffffff;
			infoOff = unpack(new byte[]{buffer[infoOff+20], buffer[infoOff+21], buffer[infoOff+22], buffer[infoOff+23]});    //offset to data
			int dataOff = unpack(new byte[]{buffer[infoOff], buffer[infoOff+1], buffer[infoOff+2], buffer[infoOff+3]});
			dataOff = dataOff - infoVirt;

			int version1 = unpack(new byte[]{buffer[dataOff+48], buffer[dataOff+48+1]});
			int version2 = unpack(new byte[]{buffer[dataOff+48+2], buffer[dataOff+48+3]});
			int version3 = unpack(new byte[]{buffer[dataOff+48+4], buffer[dataOff+48+5]});
			int version4 = unpack(new byte[]{buffer[dataOff+48+6], buffer[dataOff+48+7]});

			version=version2 + "." + version1 + "." + version4 + "." + version3;
			return version;

		} catch (FileNotFoundException e) {
			return "獲取版本信息失敗："+version+" 原因："+e;
		} catch (IOException e) {
			return "獲取版本信息失敗："+version+" 原因："+e;
		} finally {
			if(raf != null) {
				try {
					raf.close();
				} catch (IOException e) {
				}
			}
		}


	}
}