Add exists() to java client

other/java/client/src/main/java/seaweedfs/client/FilerClient.java

@@ -126,6 +126,11 @@ public class FilerClient extends FilerGrpcClient {
 
     }
 
+    public boolean exists(String path){
+        File pathFile = new File(path);
+        return lookupEntry(pathFile.getParent(), pathFile.getName()) != null;
+    }
+
     public boolean rm(String path, boolean isRecursive, boolean ignoreRecusiveError) {
 
         File pathFile = new File(path);

other/java/client/src/test/java/seaweedfs/client/SeaweedFilerTest.java

@@ -16,8 +16,14 @@ public class SeaweedFilerTest {
         filerClient.mkdirs("/new_folder", 0755);
         filerClient.touch("/new_folder/new_empty_file", 0755);
         filerClient.touch("/new_folder/new_empty_file2", 0755);
+        if(!filerClient.exists("/new_folder/new_empty_file")){
+            System.out.println("/new_folder/new_empty_file should exists");
+        }
+
         filerClient.rm("/new_folder/new_empty_file", false, true);
         filerClient.rm("/new_folder", true, true);
-
+        if(filerClient.exists("/new_folder/new_empty_file")){
+            System.out.println("/new_folder/new_empty_file should not exists");
+        }
     }
 }