Android MD5算法

package com.example.myapi.md5;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import com.example.myapi.R;

import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MD5Activity extends Activity implements OnClickListener{
    private Button btn_md5;
    protected void onCreate(android.os.Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.md5);
        btn_md5 = (Button)findViewById(R.id.md5_btn);
        btn_md5.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch(v.getId()){
        case R.id.md5_btn:
            Toast.makeText(this, getMD5Str("123456"), Toast.LENGTH_LONG).show();
//            getMD5Str("123456");
            Log.e("md5", getMD5Str("123456"));
            break;
        }
    };
    /**
     * MD5加密
     * @param str 转换前的字符串
     * @return 转换后的字符串
     */
    private String getMD5Str(String str) {
          MessageDigest messageDigest = null;
          try {
              //返回实现指定摘要算法的 MessageDigest对象 例如：MD5、SHA算法
              messageDigest = MessageDigest.getInstance("MD5");
              messageDigest.reset(); //重置MessageDigest对象
              messageDigest.update(str.getBytes("UTF-8"));//指定byte数组更新
          } catch (NoSuchAlgorithmException e) {
              System.out.println("NoSuchAlgorithmException caught!");
              System.exit(-1);
          } catch (UnsupportedEncodingException e) {
              e.printStackTrace();
          }
        //完成哈希算法，完成后   MessageDigest对象被设为初始状态，而且该方法只能调用一次
          byte[] byteArray = messageDigest.digest();
          StringBuffer md5StrBuff = new StringBuffer();
          for (int i = 0; i < byteArray.length; i++) {
              if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
                  md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));
              else
                  md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
          }
        //16位加密，从第9位到25位
//          return md5StrBuff.substring(8, 24).toString().toUpperCase();
          return md5StrBuff.toString();
      }    

}