关于java中MD5加密（可直接使用）

本文转自：http://www.cnblogs.com/solove/archive/2011/10/18/2216715.html

上部分是转载的关于字符串的加密，后半部分则比较全，包括字符串、文件、字节数组、等

1. package util; 
2.  
3. import java.security.MessageDigest; 
4.  
5. public class Encript { 
6.     //十六进制下数字到字符的映射数组 
7.     private final static String[] hexDigits = {"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"}; 
8.  
9.     /**把inputString加密*/ 
10.     public static String md5(String inputStr){ 
11.         return encodeByMD5(inputStr); 
12.     } 
13.  
14.     /** 
15.     * 验证输入的密码是否正确 
16.     * @param password 真正的密码（加密后的真密码） 
17.     * @param inputString 输入的字符串 
18.     * @return 验证结果，boolean类型 
19.     */ 
20.     public static boolean authenticatePassword(String password,String inputString){ 
21.         if(password.equals(encodeByMD5(inputString))){ 
22.             return true; 
23.         }else{ 
24.             return false; 
25.         } 
26.     } 
27.  
28.     /**对字符串进行MD5编码*/ 
29.     private static String encodeByMD5(String originString){ 
30.         if (originString!=null) { 
31.             try { 
32.                 //创建具有指定算法名称的信息摘要 
33.                 MessageDigest md5 = MessageDigest.getInstance("MD5"); 
34.                 //使用指定的字节数组对摘要进行最后更新，然后完成摘要计算 
35.                 byte[] results = md5.digest(originString.getBytes()); 
36.                 //将得到的字节数组变成字符串返回  
37.                 String result = byteArrayToHexString(results); 
38.                 return result; 
39.             } catch (Exception e) { 
40.                 e.printStackTrace(); 
41.             } 
42.         } 
43.         return null; 
44.     } 
45.  
46.     /** 
47.     * 轮换字节数组为十六进制字符串 
48.     * @param b 字节数组 
49.     * @return 十六进制字符串 
50.     */ 
51.     private static String byteArrayToHexString(byte[] b){ 
52.         StringBuffer resultSb = new StringBuffer(); 
53.         for(int i=0;i<b.length;i++){ 
54.             resultSb.append(byteToHexString(b[i])); 
55.         } 
56.         return resultSb.toString(); 
57.     } 
58.  
59.     //将一个字节转化成十六进制形式的字符串 
60.     private static String byteToHexString(byte b){ 
61.         int n = b; 
62.         if(n<0) 
63.         n=256+n; 
64.         int d1 = n/16; 
65.         int d2 = n%16; 
66.         return hexDigits[d1] + hexDigits[d2]; 
67.     } 
68. } 
69. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

70. package com.angsentech.ssm.util;

    import java.io.File;
    import java.io.FileInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.UnsupportedEncodingException;
    import java.security.MessageDigest;
    import java.security.NoSuchAlgorithmException;

    /**
    * MD5加密处理工具类
    * @author Administrator
    *
    */

    public class MD5Utils {
    /**
    * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,apache校验下载的文件的正确性用的就是默认的这个组合
    */
    protected static char hexDigits[] = { ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘,
    ‘7‘, ‘8‘, ‘9‘, ‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘ };

    protected static MessageDigest messagedigest = null;
    static {
    try {
    messagedigest = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException nsaex) {
    System.err.println(MD5Utils.class.getName()
    + "初始化失败，MessageDigest不支持MD5Util。");
    nsaex.printStackTrace();
    }
    }

    /**
    * 生成字符串的md5校验值
    *
    * @param s
    * @return
    */
    public static String getMD5String(String s) {
    return getMD5String(s.getBytes());
    }

    /**
    * 判断字符串的md5校验码是否与一个已知的md5码相匹配
    *
    * @param password
    * 要校验的字符串
    * @param md5PwdStr
    * 已知的md5校验码
    * @return
    */
    public static boolean isEqualsToMd5(String password, String md5PwdStr) {
    String s = getMD5String(password);
    return s.equals(md5PwdStr);
    }

    /**
    * 生成文件的md5校验值
    *
    * @param file
    * @return
    * @throws IOException
    */
    public static String getFileMD5String(File file) throws IOException {
    InputStream fis;
    fis = new FileInputStream(file);
    byte[] buffer = new byte[1024];
    int numRead = 0;
    while ((numRead = fis.read(buffer)) > 0) {
    messagedigest.update(buffer, 0, numRead);
    }
    fis.close();
    return bufferToHex(messagedigest.digest());
    }

    /**
    * 生成字节数组的md5校验值
    *
    * @param s
    * @return
    */
    public static String getMD5String(byte[] bytes) {
    messagedigest.update(bytes);
    return bufferToHex(messagedigest.digest());
    }

    private static String bufferToHex(byte bytes[]) {
    return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte bytes[], int m, int n) {
    StringBuffer stringbuffer = new StringBuffer(2 * n);
    int k = m + n;
    for (int l = m; l < k; l++) {
    appendHexPair(bytes[l], stringbuffer);
    }
    return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
    char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换, >>>
    // 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同
    char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换
    stringbuffer.append(c0);
    stringbuffer.append(c1);
    }
    
    /**
    * 将源字符串使用MD5加密为字节数组
    * @param source
    * @return
    */
    public static byte[] encode2bytes(String source) {
    byte[] result = null;
    try {
    MessageDigest md = MessageDigest.getInstance("MD5");
    md.reset();
    md.update(source.getBytes("UTF-8"));
    result = md.digest();
    } catch (NoSuchAlgorithmException e) {
    e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
    e.printStackTrace();
    }

    return result;
    }

    /**
    * 将源字符串使用MD5加密为32位16进制数
    * @param source
    * @return
    */
    public static String encode2hex(String source) {
    byte[] data = encode2bytes(source);
    StringBuffer hexString = new StringBuffer();
    for (int i = 0; i < data.length; i++) {
    String hex = Integer.toHexString(0xff & data[i]);

    if (hex.length() == 1) {
    hexString.append(‘0‘);
    }

    hexString.append(hex);
    }

    return hexString.toString();
    }

    /**
    * 验证字符串是否匹配
    * @param unknown 待验证的字符串
    * @param okHex 使用MD5加密过的16进制字符串
    * @return 匹配返回true，不匹配返回false
    */
    public static boolean validate(String unknown , String okHex) {
    return okHex.equals(encode2hex(unknown));
    }
    }