用Java的security包生成摘要

贴代码，主要备忘一下直接对文件摘要的写法。

package digest;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.security.DigestInputStream;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;public class DigestUtil {private static int BUFFERSIZE = 4096;@SuppressWarnings("unused")public static byte[] digestFile(String filepath, String algorithm)throws NoSuchAlgorithmException, FileNotFoundException, IOException {byte[] fileDigestBytes;InputStream is = new FileInputStream(new File(filepath));MessageDigest md = MessageDigest.getInstance(algorithm);DigestInputStream dis = new DigestInputStream(is, md);byte[] temp = new byte[BUFFERSIZE];int len = -1;while ((len = dis.read(temp)) > 0);fileDigestBytes = md.digest();dis.close();is.close();return fileDigestBytes;}public static byte[] digestBytes(byte[] message, String algorithm)throws NoSuchAlgorithmException {MessageDigest messagedigest = MessageDigest.getInstance(algorithm);messagedigest.update(message);return messagedigest.digest();}public static String toHexString(byte byteArr[]) {StringBuilder strBuilder = new StringBuilder();for (int i = 0; i < byteArr.length; i++) {String strHex = Integer.toHexString(byteArr[i] & 0xff);if (strHex.length() == 1) {strBuilder.append("0");}strBuilder.append(strHex);if (i < byteArr.length - 1) {strBuilder.append(":");}}return strBuilder.toString();}}

?测试

package digest;import static org.junit.Assert.*;import java.io.FileNotFoundException;import java.io.IOException;import java.security.NoSuchAlgorithmException;import org.junit.Test;public class TestDigestUtil {@Testpublic void testDigestFile() {byte[] expected = { -116, 30, 12, -4, -114, 79, -37, 99, -124, 46,-101, -75, -64, -14, -56, -117 };byte[] target = null;try {target = DigestUtil.digestFile("C:\\Android中文文档.pdf", "MD5");} catch (NoSuchAlgorithmException e) {e.printStackTrace();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}assertArrayEquals(expected, target);}@Testpublic void testDigestBytes() {byte[] byteMessage = { 77, 68, 53, 58, 32, 56, 67, 49, 69, 48, 67, 70,67, 56, 69, 52, 70, 68, 66, 54, 51, 56, 52, 50, 69, 57, 66, 66,53, 67, 48, 70, 50, 67, 56, 56, 66, 13, 10, 77, 68, 53, 58, 32,56, 67, 49, 69, 48, 67, 70, 67, 56, 69, 52, 70, 68, 66, 54, 51,56, 52, 50, 69, 57, 66, 66, 53, 67, 48, 70, 50, 67, 56, 56, 66,61, 61, 61, 13, 10, 77, 68, 53, 58, 32, 56, 67, 49, 69, 48, 67,70, 67, 56, 69, 52, 70, 68, 66, 54, 51, 56, 52, 50, 69, 57, 66,66, 53, 67, 48, 70, 50, 67, 56, 56, 66, 45, 45, 45, 45, 45, 45,13, 10, 13, 10, 83, 72, 65, 49, 58, 32, 51, 55, 57, 56, 68, 70,55, 67, 70, 65, 68, 70, 57, 48, 57, 69, 67, 54, 68, 67, 69, 51,69, 49, 69, 67, 52, 52, 69, 54, 48, 48, 66, 57, 53, 53, 56, 65,50, 57, 13, 10, 83, 72, 65, 49, 58, 32, 51, 55, 57, 56, 68, 70,55, 67, 70, 65, 68, 70, 57, 48, 57, 69, 67, 54, 68, 67, 69, 51,69, 49, 69, 67, 52, 52, 69, 54, 48, 48, 66, 57, 53, 53, 56, 65,50, 57, 61, 61, 61, 13, 10, 83, 72, 65, 49, 58, 32, 51, 55, 57,56, 68, 70, 55, 67, 70, 65, 68, 70, 57, 48, 57, 69, 67, 54, 68,67, 69, 51, 69, 49, 69, 67, 52, 52, 69, 54, 48, 48, 66, 57, 53,53, 56, 65, 50, 57, 45, 45, 45, 45, 45, 45, 13, 10 };byte[] expected = { -14, 68, 120, 16, -108, 71, 91, 84, 8, -61, 35,-78, -60, -35, 41, -49 };byte[] target = null;try {target = DigestUtil.digestBytes(byteMessage, "MD5");} catch (NoSuchAlgorithmException e) {e.printStackTrace();}assertArrayEquals(expected, target);}@Testpublic void testToHexString() {String expected = "8c:1e:0c:fc:8e:4f:db:63:84:2e:9b:b5:c0:f2:c8:8b";byte[] byteMge = { -116, 30, 12, -4, -114, 79, -37, 99, -124, 46, -101,-75, -64, -14, -56, -117 };assertEquals(expected, DigestUtil.toHexString(byteMge));}}