Truncated HTTP responses [SPR-8867]

[spring-projects-issues]

Harald Wellmann opened SPR-8867 and commented

After upgrading my Spring MVC application from Spring 3.0.6 to 3.1.0.RC1, I'm getting errors from some of my AJAX requests with JSON responses.

With Spring 3.0.6, the Content-Length header was not set. With Spring 3.1.0.RC1 the header is set, but the value does not match the actual length of the JSON string, which causes the truncation.

My controller method returns a HttpEntity where the Content-Type header is set to text/plain;charset=utf-8. The problem seems to be that StringHttpMessageConverter uses the charset from the output message for encoding the content in writeInternal(), but does not use the same character set for computing the length: getContentLength() derives the character set from the MediaType and defaults to iso-8559-1. This is why the Content-Length value is smaller than it should be.

---

Affects: 3.1 RC1

Issue Links:

• Regression: AbstractHttpMessageConverter does not set ContentType [SPR-11685] #16308 Regression: AbstractHttpMessageConverter does not set ContentType
• Allow configuration of whether HttpMessageConverters should set content-length header [SPR-8682] #13324 Allow configuration of whether HttpMessageConverters should set content-length header

Referenced from: commits spring-attic/spring-framework-issues@f9de7ce, spring-attic/spring-framework-issues@1f66876

[spring-projects-issues]

Rossen Stoyanchev commented

Harald, would you mind creating a quick test case over at the Spring Framework issues repo? You'll find a template project and instructions so it should be fairly quick.

[spring-projects-issues]

Harald Wellmann commented

Here's a simple test case:

spring-attic/spring-framework-issues#15

Change working directory to spring-framework-issues/SPR-8867
Run mvn jetty:run
Open browser at http://localhost:8080/SPR-8867/ to see a truncated text message

"Die Länge dieses Strings ist größer als im Header angege"

instead of

"Die Länge dieses Strings ist größer als im Header angegeben."

[spring-projects-issues]

Rossen Stoyanchev commented

There was indeed an issue with AbstractHttpMessageConverter using the requested Content-Type to determine the content length while the actual writing (in this case in StringHttpMessageConverter) uses the actual response Content-Type (set via ResponseEntity).

That issue is now resolved. However, keep in mind that in this case setting the Content-Type via ResponseEntity ignores the requested content type (the browser does send an Accept header).

A better alternative in 3.1 is to use the @RequestMapping produces condition, which first ensures the method is matched to the request by content type and second ensures that is the actual content type written. Here is an example of the modified controller from the sample issue project:

@Controller
public class StringMessageController {

    @RequestMapping(value = "/", produces="text/plain; charset=utf-8")
    public ResponseEntity<String> sendMessage(HttpServletRequest request,
            HttpServletResponse response) {

        String msg = "Die L\ufffdnge dieses Strings ist gr\ufffd\ufffder als im Header angegebe";
        return new ResponseEntity<String>(msg, HttpStatus.OK);
    }
}