Reading httprequest content from spring exception handler

Question

I Am using Spring\'s @ExceptionHandler annotation to catch exceptions in my controllers.

Some requests hold POST data as plain XML string written to the req

Answer 1

I've tried your code and I've found some mistakes in the exception handler, when you read from the InputStream:

Writer writer = new StringWriter();
byte[] buffer = new byte[1024];

//Reader reader2 = new BufferedReader(new InputStreamReader(request.getInputStream()));
InputStream reader = request.getInputStream();
int n;
while ((n = reader.read(buffer)) != -1) {
    writer.toString();

}
String retval = writer.toString();
retval = "";

I've replaced your code with this one:

BufferedReader reader = new BufferedReader(new   InputStreamReader(request.getInputStream()));
String line = "";
StringBuilder stringBuilder = new StringBuilder();
while ( (line=reader.readLine()) != null ) {
    stringBuilder.append(line).append("\n");
}

String retval = stringBuilder.toString();

Then I'm able to read from InputStream in the exception handler, it works! If you can't still read from InputStream, I suggest you to check how you POST xml data to the request body. You should consider that you can consume the Inputstream only one time per request, so I suggest you to check that there isn't any other call to getInputStream(). If you have to call it two or more times you should write a custom HttpServletRequestWrapper like this to make a copy of the request body, so you can read it more times.

UPDATE
Your comments has helped me to reproduce the issue. You use the annotation @RequestBody, so it's true that you don't call getInputStream(), but Spring invokes it to retrieve the request's body. Have a look at the class org.springframework.web.bind.annotation.support.HandlerMethodInvoker: if you use @RequestBody this class invokes resolveRequestBody method, and so on... finally you can't read anymore the InputStream from your ServletRequest. If you still want to use both @RequestBody and getInputStream() in your own method, you have to wrap the request to a custom HttpServletRequestWrapper to make a copy of the request body, so you can manually read it more times. This is my wrapper:

public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {

    private static final Logger logger = Logger.getLogger(CustomHttpServletRequestWrapper.class);
    private final String body;

    public CustomHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);

        StringBuilder stringBuilder = new StringBuilder();
        BufferedReader bufferedReader = null;

        try {
            InputStream inputStream = request.getInputStream();
            if (inputStream != null) {
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                String line = "";
                while ((line = bufferedReader.readLine()) != null) {
                    stringBuilder.append(line).append("\n");
                }
            } else {
                stringBuilder.append("");
            }
        } catch (IOException ex) {
            logger.error("Error reading the request body...");
        } finally {
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                } catch (IOException ex) {
                    logger.error("Error closing bufferedReader...");
                }
            }
        }

        body = stringBuilder.toString();
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        final StringReader reader = new StringReader(body);
        ServletInputStream inputStream = new ServletInputStream() {
            public int read() throws IOException {
                return reader.read();
            }
        };
        return inputStream;
    }
}

Then you should write a simple Filter to wrap the request:

public class MyFilter implements Filter {

    public void init(FilterConfig fc) throws ServletException {

    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        chain.doFilter(new CustomHttpServletRequestWrapper((HttpServletRequest)request), response);

    }

    public void destroy() {

    }

}

Finally, you have to configure your filter in your web.xml:

     
    MyFilter   
    test.MyFilter  
 
   
    MyFilter   
    /*   

You can fire your filter only for controllers that really needs it, so you should change the url-pattern according to your needs.

If you need this feature in only one controller, you can also make a copy of the request body in that controller when you receive it through the @RequestBody annotation.