Created builder for DiskBasedAsyncCache (google#360)

Co-authored-by: Scott Phillips <[email protected]>
Co-authored-by: Jeff Davidson <[email protected]>

src/main/java/com/android/volley/toolbox/DiskBasedAsyncCache.java

@@ -59,16 +59,10 @@ public class DiskBasedAsyncCache extends AsyncCache {
     /**
      * Constructs an instance of the DiskBasedAsyncCache at the specified directory.
      *
-     * @param rootDirectory The root directory of the cache.
+     * @param rootDirectorySupplier The root directory supplier of the cache.
      */
-    public DiskBasedAsyncCache(final File rootDirectory, int maxCacheSizeInBytes) {
-        mRootDirectorySupplier =
-                new FileSupplier() {
-                    @Override
-                    public File get() {
-                        return rootDirectory;
-                    }
-                };
+    private DiskBasedAsyncCache(FileSupplier rootDirectorySupplier, int maxCacheSizeInBytes) {
+        mRootDirectorySupplier = rootDirectorySupplier;
         mMaxCacheSizeInBytes = maxCacheSizeInBytes;
     }
 
@@ -411,4 +405,58 @@ private void deleteFileAndInvokeCallback(
         mTotalSize = DiskBasedCacheUtility.removeEntry(key, mTotalSize, mEntries);
         callback.onGetComplete(null);
     }
+
+    /**
+     * Builder is used to build an instance of {@link DiskBasedAsyncCache} from values configured by
+     * the setters.
+     */
+    public static class Builder {
+        @Nullable private FileSupplier rootDirectorySupplier = null;
+        @Nullable private File rootDirectory = null;
+        private int maxCacheSizeInBytes = DiskBasedCacheUtility.DEFAULT_DISK_USAGE_BYTES;
+
+        /**
+         * Sets the root directory of the cache. Must be called if {@link
+         * Builder#setRootDirectorySupplier(FileSupplier)} is not.
+         */
+        public Builder setRootDirectory(File rootDirectory) {
+            this.rootDirectory = rootDirectory;
+            return this;
+        }
+
+        /**
+         * Sets the root directory supplier of the cache. Must be called if {@link
+         * Builder#setRootDirectory(File)} is not.
+         */
+        public Builder setRootDirectorySupplier(FileSupplier rootDirectorySupplier) {
+            this.rootDirectorySupplier = rootDirectorySupplier;
+            return this;
+        }
+
+        /**
+         * Sets the max size of the cache in bytes. Will default to {@link
+         * DiskBasedCacheUtility#DEFAULT_DISK_USAGE_BYTES} if not called.
+         */
+        public Builder setMaxCacheSizeInBytes(int maxCacheSizeInBytes) {
+            this.maxCacheSizeInBytes = maxCacheSizeInBytes;
+            return this;
+        }
+
+        /** Builds a DiskBasedAsyncCache from the provided parameters. */
+        public DiskBasedAsyncCache build() {
+            if (rootDirectory == null && rootDirectorySupplier == null) {
+                throw new IllegalArgumentException("Must set either file or supplier");
+            }
+            if (rootDirectorySupplier == null) {
+                rootDirectorySupplier =
+                        new FileSupplier() {
+                            @Override
+                            public File get() {
+                                return rootDirectory;
+                            }
+                        };
+            }
+            return new DiskBasedAsyncCache(rootDirectorySupplier, maxCacheSizeInBytes);
+        }
+    }
 }

src/test/java/com/android/volley/toolbox/DiskBasedAsyncCacheTest.java

@@ -68,7 +68,11 @@ public void onWriteComplete() {
                     }
                 };
         // Initialize empty cache
-        cache = new DiskBasedAsyncCache(temporaryFolder.getRoot(), MAX_SIZE);
+        cache =
+                new DiskBasedAsyncCache.Builder()
+                        .setRootDirectory(temporaryFolder.getRoot())
+                        .setMaxCacheSizeInBytes(MAX_SIZE)
+                        .build();
         cache.initialize(futureCallback);
         future.get();
     }
@@ -310,7 +314,11 @@ public void testReinitialize() throws ExecutionException, InterruptedException {
         Cache.Entry entry = CacheTestUtils.randomData(1023);
         putEntry("key", entry).get();
 
-        final AsyncCache copy = new DiskBasedAsyncCache(temporaryFolder.getRoot(), MAX_SIZE);
+        final AsyncCache copy =
+                new DiskBasedAsyncCache.Builder()
+                        .setRootDirectory(temporaryFolder.getRoot())
+                        .setMaxCacheSizeInBytes(MAX_SIZE)
+                        .build();
         final CompletableFuture<Cache.Entry> getEntry = new CompletableFuture<>();
         copy.initialize(
                 new AsyncCache.OnWriteCompleteCallback() {