[FIXED] How to read request.getInputStream() multiple times

Issue

I have this code:

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException, ServletException {
    logger.info("Filter start...");

    HttpServletRequest httpRequest = (HttpServletRequest) request;
    HttpServletResponse httpResponse = (HttpServletResponse) response;

    String ba = getBaId(getBody(httpRequest));

    if (ba == null) {
        logger.error("Wrong XML");
        httpResponse.setStatus(HttpServletResponse.SC_BAD_REQUEST);
    } else {      

        if (!clients.containsKey(ba)) {
            clients.put(ba, 1);
            logger.info("Client map : init...");
        } else {
            clients.put(ba, clients.get(ba).intValue() + 1);
            logger.info("Threads for " + ba + " = " + clients.get(ba).toString());
        }

        chain.doFilter(request, response);
    }
}

and this web.xml (packages are shortened and names changed, but it looks the same)

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app>
  <filter>
    <filter-name>TestFilter</filter-name>
    <filter-class>pkg.TestFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>TestFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>WEB-INF/applicationContext.xml</param-value>
  </context-param>

  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <servlet>
    <servlet-name>Name</servlet-name>
    <display-name>Name</display-name>
    <servlet-class>pkg.Name</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Name</servlet-name>
    <url-pattern>/services/*</url-pattern>
  </servlet-mapping>
</web-app>

I want to invoke the Servlet after the Filter. I was hoping chain.doFilter(...) could do the trick, but i always get this error on the line with chain.doFilter(...):

java.lang.IllegalStateException: getInputStream() can't be called after getReader()
at com.caucho.server.connection.AbstractHttpRequest.getInputStream(AbstractHttpRequest.java:1933)
at org.apache.cxf.transport.http.AbstractHTTPDestination.setupMessage(AbstractHTTPDestination.java:249)
at org.apache.cxf.transport.servlet.ServletDestination.invoke(ServletDestination.java:82)
at org.apache.cxf.transport.servlet.ServletController.invokeDestination(ServletController.java:283)
at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:166)
at org.apache.cxf.transport.servlet.AbstractCXFServlet.invoke(AbstractCXFServlet.java:174)
at org.apache.cxf.transport.servlet.AbstractCXFServlet.doPost(AbstractCXFServlet.java:152)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:153)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:91)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:103)
at pkg.TestFilter.doFilter(TestFilter.java:102)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:187)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:265)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:273)
at com.caucho.server.port.TcpConnection.run(TcpConnection.java:682)
at com.caucho.util.ThreadPool$Item.runTasks(ThreadPool.java:743)
at com.caucho.util.ThreadPool$Item.run(ThreadPool.java:662)
at java.lang.Thread.run(Thread.java:619)

Solution

You probably start consuming the HttpServletRequest using getReader() in :

String ba = getBaId(getBody(httpRequest)); 

Your servlet tries to call getInputStream() on the same request, which is not allowed. What you need to do is use a ServletRequestWrapper to make a copy of the body of the request, so you can read it with multiple methods. I dont have the time to find a complete example right know ... sorry ...

Answered By - Guillaume