java计算MD5值

Posted 2020-10-16 LinuSiyu

package com.linusiyu.common;

import java.io.File;
import java.io.FileInputStream;
import java.math.BigInteger;
import java.security.MessageDigest;

public class MD5Util {
    
    public static String MD5(String content){
        byte[] result = new byte[]{};
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(content.getBytes("UTF-8"));
            result = md.digest();
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 使用StringBuilder或者BigInteger都行.
        StringBuilder sb = new StringBuilder(32);
        for (int i = 0; i < result.length; i++) {
            int val = result[i] & 0xff;
            if (val <= 0xf) {
                sb.append("0");
            }
            sb.append(Integer.toHexString(val));
        }
        return sb.toString().toLowerCase();
    }

    public static String MD5(final File file) throws Exception {
        FileInputStream fis = new FileInputStream(file);
        MessageDigest md = MessageDigest.getInstance("MD5");
        byte[] buf = new byte[1024];
        int len = -1;
        while((len = fis.read(buf, 0, 1024)) != -1){
            md.update(buf, 0, len);
        }
        fis.close();
        byte[] result = md.digest();
        return new BigInteger(1, result).toString(16).toLowerCase();
    }
}