More work on data file split/join, and added a test.

src/main/java/org/qortal/storage/DataFile.java

@@ -56,6 +56,7 @@ public class DataFile {
     public DataFile(String filePath) {
         this.createDataDirectory();
         this.filePath = filePath;
+        this.chunks = new ArrayList<>();
 
         if (!this.isInBaseDirectory(filePath)) {
             // Copy file to base directory
@@ -123,8 +124,7 @@ public class DataFile {
         Path source = Paths.get(this.filePath).toAbsolutePath();
         Path dest = Paths.get(outputFilePath).toAbsolutePath();
         try {
-            Files.copy(source, dest, StandardCopyOption.REPLACE_EXISTING);
-            return dest.toString();
+            return Files.copy(source, dest, StandardCopyOption.REPLACE_EXISTING).toString();
         } catch (IOException e) {
             throw new IllegalStateException("Unable to copy file to data directory");
         }
@@ -169,7 +169,10 @@ public class DataFile {
         return ValidationResult.OK;
     }
 
-    public int split() {
+    public void addChunk(DataFileChunk chunk) {
+        this.chunks.add(chunk);
+    }
+
     public int split(int chunkSize) {
         try {
 
@@ -205,6 +208,48 @@ public class DataFile {
         return this.chunks.size();
     }
 
+    public boolean join() {
+        // Ensure we have chunks
+        if (this.chunks != null && this.chunks.size() > 0) {
+
+            // Create temporary path for joined file
+            Path tempPath;
+            try {
+                tempPath = Files.createTempFile(this.chunks.get(0).base58Digest(), ".tmp");
+            } catch (IOException e) {
+                return false;
+            }
+            this.filePath = tempPath.toString();
+
+            // Join the chunks
+            File outputFile = new File(this.filePath);
+            try (BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outputFile))) {
+                for (DataFileChunk chunk : this.chunks) {
+                    File sourceFile = new File(chunk.filePath);
+                    BufferedInputStream in = new BufferedInputStream(new FileInputStream(sourceFile));
+                    byte[] buffer = new byte[2048];
+                    int inSize = -1;
+                    while ((inSize = in.read(buffer)) != -1) {
+                        out.write(buffer, 0, inSize);
+                    }
+                    in.close();
+                }
+                out.close();
+
+                // Copy temporary file to data directory
+                this.filePath = this.copyToDataDirectory();
+                Files.delete(tempPath);
+
+                return true;
+            } catch (FileNotFoundException e) {
+                return false;
+            } catch (IOException e) {
+                return false;
+            }
+        }
+        return false;
+    }
+
     public boolean delete() {
         // Delete the complete file
         Path path = Paths.get(this.filePath);
@@ -294,6 +339,10 @@ public class DataFile {
         }
     }
 
+    public int chunkCount() {
+        return this.chunks.size();
+    }
+
     private File getFile() {
         File file = new File(this.filePath);
         if (file.exists()) {
@@ -302,6 +351,10 @@ public class DataFile {
         return null;
     }
 
+    public String getFilePath() {
+        return this.filePath;
+    }
+
     public byte[] digest() {
         File file = this.getFile();
         if (file != null && file.exists()) {

src/test/java/org/qortal/test/DataTests.java

@@ -0,0 +1,45 @@
+package org.qortal.test;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.qortal.repository.DataException;
+import org.qortal.storage.DataFile;
+import org.qortal.test.common.Common;
+
+import static org.junit.Assert.*;
+
+public class DataTests extends Common {
+
+	@Before
+	public void beforeTest() throws DataException {
+		Common.useDefaultSettings();
+	}
+
+	@Test
+	public void testSplitAndJoin() {
+		String dummyDataString = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
+		DataFile dataFile = new DataFile(dummyDataString.getBytes());
+		assertTrue(dataFile.exists());
+		assertEquals(62, dataFile.size());
+		assertEquals("3eyjYjturyVe61grRX42bprGr3Cvw6ehTy4iknVnosDj", dataFile.base58Digest());
+
+		// Split into 7 chunks, each 10 bytes long
+		dataFile.split(10);
+		assertEquals(7, dataFile.chunkCount());
+
+		// Delete the original file
+		dataFile.delete();
+		assertFalse(dataFile.exists());
+		assertEquals(0, dataFile.size());
+
+		// Now rebuild the original file from the chunks
+		assertEquals(7, dataFile.chunkCount());
+		dataFile.join();
+
+		// Validate that the original file is intact
+		assertTrue(dataFile.exists());
+		assertEquals(62, dataFile.size());
+		assertEquals("3eyjYjturyVe61grRX42bprGr3Cvw6ehTy4iknVnosDj", dataFile.base58Digest());
+	}
+
+}