FileTypeImpl.java

package com.opslab.util.algorithmImpl;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * 利用文件头来实现的一些文件类型的方法封装
 */
public class FileTypeImpl {

    public final static Map<String,String> FILE_TYPE_MAP = new HashMap<String,String>();

    static {
        FILE_TYPE_MAP.put("jpg", "FFD8FF"); //JPEG (jpg)
        FILE_TYPE_MAP.put("png", "89504E47");  //PNG (png)
        FILE_TYPE_MAP.put("gif", "47494638");  //GIF (gif)
        FILE_TYPE_MAP.put("tif", "49492A00");  //TIFF (tif)
        FILE_TYPE_MAP.put("bmp", "424D"); //Windows Bitmap (bmp)
        FILE_TYPE_MAP.put("dwg", "41433130"); //CAD (dwg)
        FILE_TYPE_MAP.put("html", "68746D6C3E");  //HTML (html)
        FILE_TYPE_MAP.put("rtf", "7B5C727466");  //Rich Text Format (rtf)
        FILE_TYPE_MAP.put("xml", "3C3F786D6C");
        FILE_TYPE_MAP.put("zip", "504B0304");
        FILE_TYPE_MAP.put("rar", "52617221");
        FILE_TYPE_MAP.put("psd", "38425053");  //Photoshop (psd)
        FILE_TYPE_MAP.put("eml", "44656C69766572792D646174653A");  //Email [thorough only] (eml)
        FILE_TYPE_MAP.put("dbx", "CFAD12FEC5FD746F");  //Outlook Express (dbx)
        FILE_TYPE_MAP.put("pst", "2142444E");  //Outlook (pst)
        FILE_TYPE_MAP.put("xls", "D0CF11E0");  //MS Word
        FILE_TYPE_MAP.put("doc", "D0CF11E0");  //MS Excel 注意：word 和 excel的文件头一样
        FILE_TYPE_MAP.put("mdb", "5374616E64617264204A");  //MS Access (mdb)
        FILE_TYPE_MAP.put("wpd", "FF575043"); //WordPerfect (wpd)
        FILE_TYPE_MAP.put("eps", "252150532D41646F6265");
        FILE_TYPE_MAP.put("ps", "252150532D41646F6265");
        FILE_TYPE_MAP.put("pdf", "255044462D312E");  //Adobe Acrobat (pdf)
        FILE_TYPE_MAP.put("qdf", "AC9EBD8F");  //Quicken (qdf)
        FILE_TYPE_MAP.put("pwl", "E3828596");  //Windows Password (pwl)
        FILE_TYPE_MAP.put("wav", "57415645");  //Wave (wav)
        FILE_TYPE_MAP.put("avi", "41564920");
        FILE_TYPE_MAP.put("ram", "2E7261FD");  //Real Audio (ram)
        FILE_TYPE_MAP.put("rm", "2E524D46");  //Real Media (rm)
        FILE_TYPE_MAP.put("mpg", "000001BA");  //
        FILE_TYPE_MAP.put("mov", "6D6F6F76");  //Quicktime (mov)
        FILE_TYPE_MAP.put("asf", "3026B2758E66CF11"); //Windows Media (asf)
        FILE_TYPE_MAP.put("mid", "4D546864");  //MIDI (mid)
    }

    /**
     * Created on 2010-7-1
     * <p>Discription:[getFileByFile,获取文件类型,包括图片,若格式不是已配置的,则返回null]</p>
     *
     * @param file
     * @return fileType
     * @author:[shixing_11@sina.com]
     */
    public final static String getFileType(File file) {
        String filetype = null;
        byte[] b        = new byte[50];
        try (
                InputStream is = new FileInputStream(file)
        ) {
            is.read(b);
            filetype = getFileTypeByStream(b);
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return filetype;
    }

    /**
     * Created on 2010-7-1
     * <p>Discription:[getFileTypeByStream]</p>
     *
     * @param b
     * @return fileType
     * @author:[shixing_11@sina.com]
     */
    public final static String getFileTypeByStream(byte[] b) {
        String                             filetypeHex   = String.valueOf(getFileHexString(b));
        Iterator<Map.Entry<String,String>> entryiterator = FILE_TYPE_MAP.entrySet().iterator();
        while (entryiterator.hasNext()) {
            Map.Entry<String,String> entry = entryiterator.next();
            String fileTypeHexValue = entry.getValue();
            if (filetypeHex.toUpperCase().startsWith(fileTypeHexValue)) {
                return entry.getKey();
            }
        }
        return null;
    }

    /**
     * Created on 2010-7-1
     * <p>Discription:[getFileHexString]</p>
     *
     * @param b
     * @return fileTypeHex
     * @author:[shixing_11@sina.com]
     */
    public final static String getFileHexString(byte[] b) {
        StringBuilder stringBuilder = new StringBuilder();
        if (b == null || b.length <= 0) {
            return null;
        }
        for (int i = 0; i < b.length; i++) {
            int v = b[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }
}