diff --git a/other/java/client/src/test/java/seaweedfs/client/SeaweedFilerTest.java b/other/java/client/src/test/java/seaweedfs/client/SeaweedFilerTest.java
index f9a2c3f76..ac3346c68 100644
--- a/other/java/client/src/test/java/seaweedfs/client/SeaweedFilerTest.java
+++ b/other/java/client/src/test/java/seaweedfs/client/SeaweedFilerTest.java
@@ -1,12 +1,24 @@
 package seaweedfs.client;
 
+import com.google.protobuf.ByteString;
+import java.awt.image.DataBuffer;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicLong;
+import org.junit.Assert;
+import org.junit.Test;
+import seaweedfs.client.FilerProto.Entry;
+import seaweedfs.client.FilerProto.FuseAttributes;
 
 public class SeaweedFilerTest {
+    private static FilerClient filerClient = new FilerClient("localhost", 18888);
     public static void main(String[] args){
 
-        FilerClient filerClient = new FilerClient("localhost", 18888);
-
         List<FilerProto.Entry> entries = filerClient.listEntries("/");
 
         for (FilerProto.Entry entry : entries) {
@@ -29,4 +41,49 @@ public class SeaweedFilerTest {
             System.out.println("/ should exists");
         }
     }
+
+    @Test
+    public void testExtendedKey() throws IOException {
+        String content = "hello";
+        String location = "/hello.txt";
+        HashMap<String, String> metadata = new HashMap<>();
+        // The storage format of key is Seaweed-mime, and the reading format is mime.
+        metadata.put("mime", "text/plain");
+        // The user-specified key "Seaweed-" prefix does not take effect
+        // The storage format of key is Seaweed-name1, and the reading format is name1
+        metadata.put("Seaweed-name1", "value1");
+
+        long ts = System.currentTimeMillis() / 1000;
+        String dir = SeaweedOutputStream.getParentDirectory(location);
+        String name = SeaweedOutputStream.getFileName(location);
+        FuseAttributes.Builder attributes = FuseAttributes.newBuilder()
+            .setMtime(ts)
+            .setCrtime(ts)
+            .setFileMode(755);
+        Entry.Builder entry = Entry.newBuilder()
+            .setName(name)
+            .setIsDirectory(false)
+            .setAttributes(attributes.build());
+        // put metadata
+        for (Map.Entry<String, String> metadataEntry : metadata.entrySet()) {
+            entry.putExtended(metadataEntry.getKey(),
+                ByteString.copyFromUtf8(metadataEntry.getValue()));
+        }
+        try (SeaweedOutputStream outputStream = new SeaweedOutputStream(filerClient, location, entry, 0,
+            1024, "")) {
+            outputStream.write(content.getBytes());
+        }
+
+
+        Entry getEntry = filerClient.lookupEntry(dir, name);
+        Assert.assertNotNull(getEntry);
+        Map<String, ByteString> extendedMap = getEntry.getExtendedMap();
+        HashSet<String> expectKeys = new HashSet<String>() {{
+            add("mime");
+            add("name1");
+        }};
+        Assert.assertEquals(expectKeys, extendedMap.keySet());
+
+        filerClient.deleteEntry(dir, name, true, false, true);
+    }
 }