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JAVA实现MD5算法、SHA1算法和SHA256算法
MD5、SHA1和SHA256是常见的哈希算法。JAVA中的hashCode是int类型，占64位。MD5生成128位哈希码，SHA1生成160位哈希码，SHA256生成256位哈希码。
MD5计算hashCode
以下是一个实现MD5算法的JAVA类：
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
以下是一个实现SHA1算法的JAVA类：
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
以下是一个实现SHA256算法的JAVA类：
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); }} 以上代码均为JAVA实现MD5、SHA1和SHA256算法的示例代码，具体实现细节可根据实际需求进行调整。
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