Java里面 根据一个字符串 计算他的hash 值（工具类）md5散列的方式计算hash值

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  • 1 实现

1 实现

代码语言：javascript
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 /**
     * get hash code on 2^32 ring (md5散列的方式计算hash值)
     * 根据字符串计算hash 值
     * @param key
     * @return
     */
    private static long hash(String key) {

    // md5 byte
    MessageDigest md5;
    try {
        md5 = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException e) {
        throw new RuntimeException("MD5 not supported", e);
    }
    md5.reset();
    byte[] keyBytes = null;
    try {
        keyBytes = key.getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        throw new RuntimeException("Unknown string :" + key, e);
    }

    md5.update(keyBytes);
    byte[] digest = md5.digest();

    // hash code, Truncate to 32-bits
    long hashCode = ((long) (digest[3] & 0xFF) << 24)
            | ((long) (digest[2] & 0xFF) << 16)
            | ((long) (digest[1] & 0xFF) << 8)
            | (digest[0] & 0xFF);

    long truncateHashCode = hashCode & 0xffffffffL;
    return truncateHashCode;
}</code></pre></div></div>
#java#hash#md5