這個方法只能在有限的范圍內有效。并不是萬金油

比如

圖片類型判斷，音頻文件格式判斷，視頻文件格式判斷等這種肯定是2進制且專業性很強的文件類型判斷。

• 使用方法

  String name= FileUtils.getType("/Users/sirai/Desktop/xz_sale_interface.zip").name();
        logger.info("ssss"+name);

*FileUtils

package com.xiaozhi.xcloud.web.vo;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * Created with IntelliJ IDEA.
 * Package: com.xiaozhi.xcloud.web.vo
 * Author: sirai
 * Create Time: 17/3/3 下午2:45
 * QQ: 785716471
 * Description:
 */
public class FileUtils {
    /**
     * 將文件頭轉換成16進制字符串
     *
     * @param
     * @return 16進制字符串
     */
    private static String bytesToHexString(byte[] src){

        StringBuilder stringBuilder = new StringBuilder();
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 0; i < src.length; i++) {
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }

    private static String getFileContent(String filePath) throws IOException {

        byte[] b = new byte[28];

        InputStream inputStream = null;

        try {
            inputStream = new FileInputStream(filePath);
            inputStream.read(b, 0, 28);
        } catch (IOException e) {
            e.printStackTrace();
            throw e;
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                    throw e;
                }
            }
        }
        return bytesToHexString(b);
    }

    /**
     * 判斷文件類型
     *
     * @param filePath 文件路徑
     * @return 文件類型
     */
    public static FileType getType(String filePath) throws IOException {

        String fileHead = getFileContent(filePath);

        if (fileHead == null || fileHead.length() == 0) {
            return null;
        }

        fileHead = fileHead.toUpperCase();

        FileType[] fileTypes = FileType.values();

        for (FileType type : fileTypes) {
            if (fileHead.startsWith(type.getValue())) {
                return type;
            }
        }

        return null;
    }

}

• FileType枚舉類型

package com.xiaozhi.xcloud.web.vo;

/**
 * Created with IntelliJ IDEA.
 * Package: com.xiaozhi.xcloud.web.vo
 * Author: sirai
 * Create Time: 17/3/3 下午2:17
 * QQ: 785716471
 * Description:
 */
public enum FileType {
    /**
     * JEPG.
     */
    JPEG("FFD8FF"),

    /**
     * PNG.
     */
    PNG("89504E47"),

    /**
     * GIF.
     */
    GIF("47494638"),

    /**
     * TIFF.
     */
    TIFF("49492A00"),

    /**
     * Windows Bitmap.
     */
    BMP("424D"),

    /**
     * CAD.
     */
    DWG("41433130"),

    /**
     * Adobe Photoshop.
     */
    PSD("38425053"),

    /**
     * Rich Text Format.
     */
    RTF("7B5C727466"),

    /**
     * XML.
     */
    XML("3C3F786D6C"),

    /**
     * HTML.
     */
    HTML("68746D6C3E"),

    /**
     * Email [thorough only].
     */
    EML("44656C69766572792D646174653A"),

    /**
     * Outlook Express.
     */
    DBX("CFAD12FEC5FD746F"),

    /**
     * Outlook (pst).
     */
    PST("2142444E"),

    /**
     * MS Word/Excel.
     */
    XLS_DOC("D0CF11E0"),

    /**
     * MS Access.
     */
    MDB("5374616E64617264204A"),

    /**
     * WordPerfect.
     */
    WPD("FF575043"),

    /**
     * Postscript.
     */
    EPS("252150532D41646F6265"),

    /**
     * Adobe Acrobat.
     */
    PDF("255044462D312E"),

    /**
     * Quicken.
     */
    QDF("AC9EBD8F"),

    /**
     * Windows Password.
     */
    PWL("E3828596"),

    /**
     * ZIP Archive.
     */
    ZIP("504B0304"),

    /**
     * RAR Archive.
     */
    RAR("52617221"),

    /**
     * Wave.
     */
    WAV("57415645"),

    /**
     * AVI.
     */
    AVI("41564920"),

    /**
     * Real Audio.
     */
    RAM("2E7261FD"),

    /**
     * Real Media.
     */
    RM("2E524D46"),

    /**
     * MPEG (mpg).
     */
    MPG("000001BA"),

    /**
     * Quicktime.
     */
    MOV("6D6F6F76"),

    /**
     * Windows Media.
     */
    ASF("3026B2758E66CF11"),

    /**
     * MIDI.
     */
    MID("4D546864");

    private String value = "";

    /**
     * Constructor.
     *
     * @param type
     */
    private FileType(String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }
}