字符串处理类

最新推荐文章于 2025-07-16 10:20:38 发布

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最新推荐文章于 2025-07-16 10:20:38 发布

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分类专栏： java 技术集锦常用代码篇文章标签： string 加密 md5 class

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本文介绍了一个MD5加密工具类的实现细节，包括如何使用Java进行文件和字符串的MD5加密，提供了完整的代码示例，并解释了加密过程。

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import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;

/**
 * MD5加密工具类
 */
public class MD5EncoderUtil {
    private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d",
            "e", "f" };
    private static String algorithm = "MD5";

    public static String encode(String salt, String rawPass) {
        return encode(rawPass.toLowerCase() + salt);
    }

    public static String encode(String rawPass) {
        String result = null;
        try {
            MessageDigest md5 = MessageDigest.getInstance(algorithm);
            // 加密后的字符串
            result = byteArrayToHexString(md5.digest(rawPass.getBytes("utf-8")));
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return result;
    }

    public static String getFileMd5(File file) {
        FileInputStream fileInputStream = null;
        try {
            MessageDigest md5 = MessageDigest.getInstance(algorithm);
            fileInputStream = new FileInputStream(file);
            byte[] buffer = new byte[8192];
            int length;
            while ((length = fileInputStream.read(buffer)) != -1) {
                md5.update(buffer, 0, length);
            }
            return byteArrayToHexString(md5.digest());
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        } finally {
            if (fileInputStream != null) {
                try {
                    fileInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }

    }

    public static boolean isPasswordValid(String encPass, String loginName, String rawPass) {
        String pass1 = encPass;
        String pass2 = encode(loginName, rawPass);
        return pass1.toUpperCase().equals(pass2.toUpperCase());
    }

    /*
     * 转换字节数组为16进制字串
     */
    private static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
            n = 256 + n;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }
}