解决Java中MD5加密utf-8格式时与其他语言不同的问题

Java中MD5加密一般写法：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

public final static String MD5(String s) {         try {             byte[] btInput = s.getBytes();             MessageDigest mdInst = MessageDigest.getInstance("MD5");             mdInst.update(btInput);             byte[] md = mdInst.digest();             StringBuffer sb = new StringBuffer();             for (int i = 0; i < md.length; i++) {                 int val = ((int) md[i]) & 0xff;                 if (val < 16)                     sb.append("0");                 sb.append(Integer.toHexString(val));               }             return sb.toString();         } catch (Exception e) {             return null;         }     }

如果是给utf-8格式的字符串加密，上面的代码就会有问题。

因为Java默认编码是unicode， byte[] btInput = s.getBytes();获得的是默认的unicode的byte数组。需要将这句改为byte[] btInput = s.getBytes("utf-8");就OK啦。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

public final static String MD5Encoder(String s, String charset) {         try {             byte[] btInput = s.getBytes(charset);             MessageDigest mdInst = MessageDigest.getInstance("MD5");             mdInst.update(btInput);             byte[] md = mdInst.digest();             StringBuffer sb = new StringBuffer();             for (int i = 0; i < md.length; i++) {                 int val = ((int) md[i]) & 0xff;                 if (val < 16){                     sb.append("0");                 }                 sb.append(Integer.toHexString(val));             }             return sb.toString();         } catch (Exception e) {             return null;         }     }