Java代码把字符串转化为MD5的16进制形式

Sure! Here's an example Java code that converts a string to its MD5 hash in hexadecimal form:

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class StringToMD5 {
    public static void main(String[] args) {
        String input = "Hello World";
        String md5Hex = getMD5Hex(input);
        System.out.println("MD5 Hash: " + md5Hex);
    }

    public static String getMD5Hex(String input) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] messageDigest = md.digest(input.getBytes());
            BigInteger number = new BigInteger(1, messageDigest);
            String md5Hex = number.toString(16);

            while (md5Hex.length() < 32) {
                md5Hex = "0" + md5Hex;
            }

            return md5Hex;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            return null;
        }
    }
}

In this code, we use the `MessageDigest` class from the `java.security` package to compute the MD5 hash of the input string. We convert the resulting byte array to a `BigInteger` and then convert it to a hexadecimal string using `number.toString(16)`. Finally, we add leading zeros if necessary to ensure that the resulting MD5 hash is 32 characters long.

Note: Make sure to handle the `NoSuchAlgorithmException` appropriately in your application.