Question

I want to add logging to my Servlet, so I’ve created Filter which should display request and go to the Servlet. But unfortunately I’ve encoutered exception:

java.lang.IllegalStateException: getReader() has already been called for this request
    at org.apache.catalina.connector.Request.getInputStream(Request.java:948)
    at org.apache.catalina.connector.RequestFacade.getInputStream(RequestFacade.java:338)
    at com.noelios.restlet.ext.servlet.ServletCall.getRequestEntityStream(ServletCall.java:190)

So to fix this problem I’ve found solution with Wrapper, but it doesn’t work. What else can I use/change in code? Any ideas?

[MyHttpServletRequestWrapper]

public class MyHttpServletRequestWrapper extends HttpServletRequestWrapper
{
    public MyHttpServletRequestWrapper(HttpServletRequest request)
    {
        super(request);
    }

    private String getBodyAsString()
    {
        StringBuffer buff = new StringBuffer();
        buff.append(" BODY_DATA START [ ");
        char[] charArr = new char[getContentLength()];
        try
        {
            BufferedReader reader = new BufferedReader(getReader());
            reader.read(charArr, 0, charArr.length);
            reader.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        buff.append(charArr);
        buff.append(" ] BODY_DATA END ");
        return buff.toString();
    }

    public String toString()
    {
        return getBodyAsString();
    }
}

[MyFilter]

public class MyFilterimplements Filter
{
    @Override
    public void init(FilterConfig filterConfig) throws ServletException
    {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
    {
        final HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        final HttpServletResponse httpServletResponse = (HttpServletResponse) response;

        final HttpServletRequestWrapper requestWrapper = new MyHttpServletRequestWrapper(httpServletRequest);
        final String requestBody = requestWrapper.toString();

        chain.doFilter(request, response);
    }
}

Answer 1

Looks like the restlet framework has called getRequestEntityStream() on the Request object which in turn calls getInputStream(), so calling getReader() on the request throws IllegalStateException. The Servlet API documentation for getReader() and getInputStream() says:

 public java.io.BufferedReader getReader()
    ...
    ...
Throws:
    java.lang.IllegalStateException - if getInputStream() method has been called on this request

 public ServletInputStream getInputStream()
    ...
    ...
    Throws:
    java.lang.IllegalStateException - if the getReader() method has already been called for this request

From the documentation, it seems that we cannot call both getReader() and getInputStream() on the Request object. I suggest you use getInputStream() rather than getReader() in your wrapper.