MD5.java

//MD5
import java.security.MessageDigest;

public class MD5 { 
  public static String hash(String plainText) {
    MessageDigest cry = null;
    
    try {
      cry = MessageDigest.getInstance("MD5");
    } catch (Exception e) {
    }

    cry.reset(); // Resets the digest for further use.

    return stringify(cry.digest(plainText.getBytes()));
  }

  /**
  * 計算MD5
  * @param buf
  * @return
  */
  private static String stringify(byte buf[]) {
    StringBuffer sb = new StringBuffer(2 * buf.length);
    
    for (int i = 0; i < buf.length; i++) {
      int h = (buf[i] & 0xf0) >> 4;
      int l = (buf[i] & 0x0f);
      sb.append(new Character((char) ((h > 9) ? 'a' + h - 10 : '0' + h)));
      sb.append(new Character((char) ((l > 9) ? 'a' + l - 10 : '0' + l)));
    }
    
      return sb.toString();
    }
  }

  
  public static void main(String[] args){
    String plainText;
    String chsm = MD5.hash(plainText);
  }