using temp file for downloads to not end with corrupted files

Author: cansik

build.gradle

@@ -4,7 +4,7 @@ plugins {
 }
 
 group 'ch.bildspur'
-version '0.6.2'
+version '0.6.3'
 
 sourceCompatibility = 1.8
 

src/main/java/ch/bildspur/vision/dependency/Dependency.java

@@ -2,15 +2,20 @@
 
 import ch.bildspur.vision.web.NetworkUtility;
 
+import java.io.IOException;
+import java.nio.file.CopyOption;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.concurrent.atomic.AtomicReference;
 
+import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
+
 public class Dependency {
     private String name;
     private String url;
     private Path path;
+    private String tempSuffix = "_tmp";
 
     public Dependency(String name) {
         this(name, Repository.repositoryRootUrl + name);
@@ -30,11 +35,19 @@ public boolean resolve() {
             return true;
         }
 
+        // check temp file
+        Path tempPath = Paths.get(path.toString() + tempSuffix);
+        try {
+            Files.deleteIfExists(tempPath);
+        } catch (IOException e) {
+            System.err.println("Could not delete " + tempPath.toString());
+            return false;
+        }
+
         // try to download
-        // todo: download it as temp file to not brake it on hard processing exit!
         System.out.print("downloading " + name + ": ");
         AtomicReference<Integer> lastProgress = new AtomicReference<>(0);
-        NetworkUtility.downloadFile(url, path, (source, p) -> {
+        NetworkUtility.downloadFile(url, tempPath, (source, p) -> {
             int last = lastProgress.get();
             int progress = Math.round((float) p);
             int delta = progress - last;
@@ -44,13 +57,20 @@ public boolean resolve() {
                 System.out.print(".");
             }
         });
+
+        // switch name
+        try {
+            Files.move(tempPath, path, REPLACE_EXISTING);
+        } catch (IOException e) {
+            System.err.println("Could not move " + tempPath.toString() + " to " + path.toString());
+            e.printStackTrace();
+            return false;
+        }
+
         System.out.println(" done!");
 
         // second check after download
-        if (Files.exists(path)) {
-            return true;
-        }
-        return false;
+        return Files.exists(path);
     }
 
     public String getName() {

src/main/java/ch/bildspur/vision/web/NetworkUtility.java

@@ -1,6 +1,7 @@
 package ch.bildspur.vision.web;
 
 import java.io.FileOutputStream;
+import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.nio.channels.Channels;
@@ -9,7 +10,7 @@
 
 public class NetworkUtility {
     public static void downloadFile(String remoteURL, Path localPath, ProgressCallBack callback) {
-        FileOutputStream fos;
+        FileOutputStream fos = null;
         ReadableByteChannel rbc;
         URL url;
         try {
@@ -20,6 +21,14 @@ public static void downloadFile(String remoteURL, Path localPath, ProgressCallBa
             fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
         } catch (Exception e) {
             e.printStackTrace();
+        } finally {
+            if (fos != null) {
+                try {
+                    fos.close();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
         }
     }