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JAVA实现MD5算法、SHA1算法和SHA256算法

MD5、SHA1和SHA256是最常见的哈希算法。JAVA中的hashCode是int类型的，占64位。

MD5计算hashCode

package utils;import org.junit.Test;import java.security.MessageDigest;public class MD5Utils {       public static String md5Code(String input) {           try {               MessageDigest digest = MessageDigest.getInstance("MD5");            byte[] hash = digest.digest(input.getBytes("UTF-8"));            StringBuilder hexString = new StringBuilder();            for (int i = 0; i < hash.length; i++) {                   String hex = Integer.toHexString(0xff & hash[i]);                if (hex.length() == 1) hexString.append('0');                hexString.append(hex);            }            return hexString.toString();        } catch (Exception e) {               throw new RuntimeException(e);        }    }    @Test    public void test() {           String str = "Welcome";        String res = md5Code(str);        System.out.println(res);    }}

SHA1计算hashCode

package utils;import org.junit.Test;import java.security.MessageDigest;public class SHA1Utils {       public static String sha1Code(String input) {           try {               MessageDigest digest = MessageDigest.getInstance("SHA1");            byte[] hash = digest.digest(input.getBytes("UTF-8"));            StringBuilder hexString = new StringBuilder();            for (int i = 0; i < hash.length; i++) {                   String hex = Integer.toHexString(0xff & hash[i]);                if (hex.length() == 1) hexString.append('0');                hexString.append(hex);            }            return hexString.toString();        } catch (Exception e) {               throw new RuntimeException(e);        }    }    @Test    public void test() {           String str = "Welcome";        String res = sha1Code(str);        System.out.println(res);    }}

SHA256计算hashCode

package utils;import org.junit.Test;import java.security.MessageDigest;public class SHA256Utils {       public static String sha256Code(String input) {           try {               MessageDigest digest = MessageDigest.getInstance("SHA-256");            byte[] hash = digest.digest(input.getBytes("UTF-8"));            StringBuffer hexString = new StringBuffer();            for (int i = 0; i < hash.length; i++) {                   String hex = Integer.toHexString(0xff & hash[i]);                if (hex.length() == 1) hexString.append('0');                hexString.append(hex);            }            return hexString.toString();        } catch (Exception e) {               throw new RuntimeException(e);        }    }    @Test    public void test() {           String value = "Welcome";        String res = sha256Code(value);        System.out.println(res);    }}

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