```
package com.test;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class Test {
    public static void main(String[] args) {
        System.out.println(getSafeUrl("txrtmp", "11212122", 1469762325L));
    }
    private static final char[] DIGITS_LOWER =
        {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
    /*
    * KEY+ streamName + txTime
    */
    private static String getSafeUrl(String key, String streamName, long txTime) {
        String input = new StringBuilder().
                            append(key).
                            append(streamName).
                            append(Long.toHexString(txTime).toUpperCase()).toString();
        String txSecret = null;
        try {
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            txSecret  = byteArrayToHexString(
                        messageDigest.digest(input.getBytes("UTF-8")));
        } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
        }
        return txSecret == null ? "" :
                           new StringBuilder().
                           append("txSecret=").
                           append(txSecret).
                           append("&").
                           append("txTime=").
                           append(Long.toHexString(txTime).toUpperCase()).
                           toString();
        }
    private static String byteArrayToHexString(byte[] data) {
        char[] out = new char[data.length << 1];
        for (int i = 0, j = 0; i < data.length; i++) {
                out[j++] = DIGITS_LOWER[(0xF0 & data[i]) >>> 4];
                out[j++] = DIGITS_LOWER[0x0F & data[i]];
        }
        return new String(out);
    }
}
```