add some method

src/main/java/com/qiniu/http/Client.java

@@ -394,6 +394,10 @@ private Response patch(String url, RequestBody body, StringMap headers) throws Q
         return send(requestBuilder, headers);
     }
 
+    public Response head(String url, StringMap headers) throws QiniuException {
+        Request.Builder requestBuilder = new Request.Builder().url(url).head();
+        return send(requestBuilder, headers);
+    }
 
     public Response send(final Request.Builder requestBuilder, StringMap headers) throws QiniuException {
         if (headers != null) {

src/main/java/com/qiniu/storage/BucketManager.java

@@ -1332,6 +1332,10 @@ private void setExecBucket(String bucket) {
         public String execBucket() {
             return execBucket;
         }
+
+        public int size() {
+            return ops.size();
+        }
     }
 
     /**

src/test/java/test/com/qiniu/storage/BucketManagerTest.java

@@ -0,0 +1,27 @@
+package test.com.qiniu.storage;
+
+import com.qiniu.storage.BucketManager;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+
+public class BucketManagerTest {
+    @Test
+    @Tag("UnitTest")
+    public void testBatchOperationsSize() {
+        BucketManager.BatchOperations batchOperations = new BucketManager.BatchOperations();
+        Assertions.assertEquals(0, batchOperations.size());
+
+        batchOperations.addDeleteOp("bucket1", "1", "2");
+        Assertions.assertEquals(2, batchOperations.size());
+
+        batchOperations.addCopyOp(
+                "fromBucket", "fromFileKey",
+                "toBucket", "toFileKey"
+        );
+        Assertions.assertEquals(3, batchOperations.size());
+
+        batchOperations.addRenameOp("fromBucket", "fromFileKey", "toFileKey");
+        Assertions.assertEquals(4, batchOperations.size());
+    }
+}