The response is garbled characters

[a09090443]

I create a example, and response was a Chinese content, but I find the response in log file is correct, below image

when I use Claude desktop, I got wrong respose

this is my code

I don't know what's the problem.

note: I try to use spring ai mcp, the reponse was correct content like below

[mkouba]

We'll need a simple reproducer app + your environment info (OS, Java, locale, etc.). It's very likely some encoding issue...

[a09090443]

My environment information:
OS: windows 11
JAVA: OpenJdk 21
Project examples: url
Claude configuration:
{ "mcpServers": { "example": { "command": "java", "args": [ "-jar", "D:\\MCP\\spring-0.0.1-SNAPSHOT.jar" ] } } }

thanks.

[mkouba]

I've tried to copy your tool method in a demo app and call the tool from the Dev UI and it seems to work fine.

@a09090443 have you tried to use the -Dfile.encoding=UTF-8 system property?

@maxandersen does it ring a bell? It looks like an encoding issue...

[a09090443]

@mkouba Thanks for your reply.
I tried before and got same error.

and I wrote unit test and used MCP Inspector

the unit test was right, but MCP Inspector had same issue.

the spring use MCP Inspector test was right.

Not only Claude desktop, same problem happend in other software like Cherrys studio.

[mkouba]

I tested your tool with the MCP Inspector and OpenJDK Runtime Environment Temurin-21.0.3+9 (build 21.0.3+9-LTS) on my Linux box and I see no problem.

So I guess that it could be related to the OS - Windows. Unfortunately, I don't have a Windows box to make more tests 🤷.

[a09090443]

Ok, I'll use Linux test again.

[maxandersen]

Very weird - never seen it.

If you can share as much as possible I'll try reproduce on my windows box.

As Martin says it's most likely an encoding issue so something different in the OS / Claude desktop or java call used when running it.

Just need to spot what.

[a09090443]

Guys, I found the issue because of Windows settings,
I change Windows encoding to utf8, the mcp server response right content.
Windows has to enable (BETA: Use Unicode UTF-8 for worldwide language support checkbox)

But I don't understand why Spring works fine.