java之MD5加密

java中用MessageDigest类，可以用来加密MD5。

首先创建一个MessageDigest对象

MessageDigest digest = MessageDigest.getInstance("MD5");

调用digest.digest(psd.getBytes());会返回一个16位的字符串，然后使用规定的模板转换为32位即可。

for (byte b : bs) {
                String hexString = Integer.toHexString(b & 0xff);
                if (hexString.length() < 2) {
                    hexString = "0" + hexString;
                }
                stringBuffer.append(hexString);
            }

完整的代码：

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Md5Util {

    /**
     * @param args
     */
    public static void main(String[] args) {
        String psd = "123";
        encoder(psd);
    }

    private static void encoder(String psd) {
        try {
            MessageDigest digest = MessageDigest.getInstance("MD5");
            byte[] bs = digest.digest(psd.getBytes());
            System.out.println(bs.length);
            StringBuffer stringBuffer = new StringBuffer();
            for (byte b : bs) {
                String hexString = Integer.toHexString(b & 0xff);
                if (hexString.length() < 2) {
                    hexString = "0" + hexString;
                }
                stringBuffer.append(hexString);
            }
            System.out.println(stringBuffer.toString());
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }

    }

}