Added catStream for getting contents of arbitrarily large files.

Author: ianopolous

src/main/java/org/ipfs/api/IPFS.java

@@ -71,6 +71,10 @@ public byte[] get(Multihash hash) throws IOException {
         return retrieve("get/" + hash);
     }
 
+    public InputStream catStream(Multihash hash) throws IOException {
+        return retrieveStream("cat/" + hash);
+    }
+
     public Map refs(Multihash hash, boolean recursive) throws IOException {
         return retrieveMap("refs?arg=" + hash +"&r="+recursive);
     }
@@ -433,6 +437,19 @@ private static byte[] get(URL target) throws IOException {
         }
     }
 
+    private InputStream retrieveStream(String path) throws IOException {
+        URL target = new URL("http", host, port, version + path);
+        return IPFS.getStream(target);
+    }
+
+    private static InputStream getStream(URL target) throws IOException {
+        HttpURLConnection conn = (HttpURLConnection) target.openConnection();
+        conn.setRequestMethod("GET");
+        conn.setRequestProperty("Content-Type", "application/json");
+
+        return conn.getInputStream();
+    }
+
     private Map postMap(String path, byte[] body, Map<String, String> headers) throws IOException {
         URL target = new URL("http", host, port, version + path);
         return (Map) JSONParser.parse(new String(post(target, body, headers)));

src/test/java/org/ipfs/api/Test.java

@@ -1,7 +1,6 @@
 package org.ipfs.api;
 
-import java.io.File;
-import java.io.IOException;
+import java.io.*;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
@@ -35,6 +34,34 @@ public void largeFileTest() {
         fileTest(largeFile);
     }
 
+//    @org.junit.Test
+    public void hugeFileStreamTest() {
+        byte[] hugeData = new byte[1000*1024*1024];
+        new Random(1).nextBytes(hugeData);
+        NamedStreamable.ByteArrayWrapper largeFile = new NamedStreamable.ByteArrayWrapper("massive.txt", hugeData);
+        try {
+            MerkleNode addResult = ipfs.add(largeFile);
+            InputStream in = ipfs.catStream(addResult.hash);
+
+            byte[] res = new byte[hugeData.length];
+            int offset = 0;
+            byte[] buf = new byte[4096];
+            int r;
+            while ((r = in.read(buf)) >= 0) {
+                try {
+                    System.arraycopy(buf, 0, res, offset, r);
+                    offset += r;
+                }catch (Exception e){
+                    e.printStackTrace();
+                }
+            }
+            if (!Arrays.equals(res, hugeData))
+                throw new IllegalStateException("Different contents!");
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     @org.junit.Test
     public void hostFileTest() {
         NamedStreamable hostFile = new NamedStreamable.FileWrapper(new File("Makefile"));