How to read request.getInputStream() multiple times

Question

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) 

Answer 1

Working code based on the accepted answer.

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));                char[] charBuffer = new char[128];               int bytesRead = -1;                while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {                   stringBuilder.append(charBuffer, 0, bytesRead);               }           } 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 ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());      ServletInputStream inputStream = new ServletInputStream() {           public int read () throws IOException {               return byteArrayInputStream.read();           }       };      return inputStream;   }  } 

Answer 2

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 ...