FEAT StreamUtils.digestStream + FileUtils.digestFileContent

src/main/java/de/nclazz/commons/io/FileUtils.java

@@ -1,14 +1,13 @@
 package de.nclazz.commons.io;
 
+import de.nclazz.commons.StringUtils;
 import lombok.NonNull;
 import lombok.SneakyThrows;
 
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.FileWriter;
-import java.io.Writer;
+import java.io.*;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.security.MessageDigest;
 import java.util.function.Consumer;
 
 public abstract class FileUtils {
@@ -95,7 +94,7 @@ public abstract class FileUtils {
 
         if(!file.exists()) file.createNewFile();
 
-        try(FileWriter writer = new FileWriter(file);) {
+        try(FileWriter writer = new FileWriter(file)) {
             writerConsumer.accept(writer);
         }catch(Exception e) {
             throw e;
@@ -104,4 +103,29 @@ public abstract class FileUtils {
         return file;
     }
 
+
+    /**
+     * Creates a hash from the file content of given file with given{@link MessageDigest}
+     * @param file to hash
+     * @param md hash algorithm
+     * @return  hex {@code String} hash
+     */
+    public static String digestFileContent(@NonNull  File file, @NonNull MessageDigest md) {
+        try(FileInputStream stream = new FileInputStream(file)) {
+            return StreamUtils.digestStream(stream, md);
+        }catch(Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @SneakyThrows
+    public static String generateSHA1FromFile(File file) {
+        return digestFileContent(file, MessageDigest.getInstance("SHA-1"));
+    }
+
+    @SneakyThrows
+    public static String generateMD5FromFile(File file) {
+        return digestFileContent(file, MessageDigest.getInstance("MD5"));
+    }
+
 }

src/main/java/de/nclazz/commons/io/StreamUtils.java

@@ -1,9 +1,10 @@
 package de.nclazz.commons.io;
 
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
+import de.nclazz.commons.StringUtils;
+import lombok.NonNull;
+
+import java.io.*;
+import java.security.MessageDigest;
 
 public abstract class StreamUtils {
 
@@ -15,7 +16,7 @@ public abstract class StreamUtils {
      *
      * @param streamIn InputStream
      * @param streamOut OutputStream
-     * @throws IOException
+     * @throws IOException on Error
      */
     public static void pipeStream(InputStream streamIn, OutputStream streamOut) throws IOException {
         byte[] bytes = new byte[4096]; //TODO make configurable? maybe as a sys property?
@@ -41,6 +42,26 @@ public abstract class StreamUtils {
         return bos.toByteArray();
     }
 
+    /**
+     * Digest an InputStream with given MessageDigest.
+     * The stream will not be closed after processing!
+     * @param stream to hash
+     * @param md hash algorithm
+     * @return new String hash
+     */
+    public static String digestStream(@NonNull InputStream stream, @NonNull MessageDigest md) {
+        try {
+            byte[] buffer = new byte[2048];
+            int len;
+            while((len = stream.read(buffer)) != -1) {
+                md.update(buffer, 0, len);
+            }
+            byte[] digest = md.digest();
+            return StringUtils.toHex(digest);
+        }catch(Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
 
 
 }

src/test/java/de/nclazz/commons/io/FileUtilsTests.java

@@ -4,6 +4,7 @@ import org.junit.jupiter.api.Test;
 
 import java.io.File;
 import java.io.IOException;
+import java.security.MessageDigest;
 
 import static org.junit.jupiter.api.Assertions.*;
 
@@ -22,15 +23,19 @@ public class FileUtilsTests {
         assertThrows(IllegalArgumentException.class, () -> FileUtils.deleteDirectoryRecursively(readmeFile));
         assertDoesNotThrow(() -> FileUtils.deleteDirectoryRecursively(dir));
 
-        assertTrue(!dir.exists());
+        assertFalse(dir.exists());
     }
 
     File createDirectory() throws IOException {
         File dir = new File("target/tmp/subdirs/secondlevel");
-        dir.mkdirs();
+        if(!dir.mkdirs())
+            throw new RuntimeException("Could not create directories!");
 
         for(int i = 0; i < 64; i++) {
-            new File(dir, "test_"+i+".txt").createNewFile();
+            String filename = "test_" + i + ".txt";
+            if(!new File(dir, filename).createNewFile()) {
+                throw new RuntimeException("Could not create File +'"  + filename + "'!");
+            }
         }
 
         return dir;
@@ -66,4 +71,13 @@ public class FileUtilsTests {
         assertFalse(tempFile.exists());
     }
 
+    @Test
+    void testDigestFileContent()  {
+        File file = new File("src/test/resources/test-files/alphabet-utf8.txt");
+        String sha1 = "db16441c4b330570a9ac83b0e0b006fcd74cc32b";
+        String md5 = "2ad372c377013baa4ee32ab6649d2449";
+
+        assertEquals(sha1, FileUtils.generateSHA1FromFile(file));
+        assertEquals(md5, FileUtils.generateMD5FromFile(file));
+    }
 }