Usman Ismail Usman Ismail - 4 months ago 73
Java Question

Why is HttpServletRequest inputstream empty?

I have this code where I read the input from a request input stream and use a JacksonMapper to convert into a POJO. Its running in a jetty 7 container with guice support.

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

try {
RequestType requestType = mapper.readValue(req.getInputStream(), RequestType.class);
} Catch(Exception ex) {
....
}
}


However, sometimes under load the following exception is thrown. I have checked my client and I am sure its sending a valid json string. What is going wrong? Is it expected behavior for Jetty 7 under load?

java.io.EOFException: No content to map to Object due to end of input
at org.codehaus.jackson.map.ObjectMapper._initForReading(ObjectMapper.java:2433)
at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2385)
at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1637)
at com.ea.wsop.user.LoginServlet.processRequest(LoginServlet.java:69)
at com.ea.wsop.user.LoginServlet.doPost(LoginServlet.java:63)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd.CGLIB$doPost$0(<generated>)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd$$FastClassByGuice$$c6f479ee.invoke(<generated>)
at com.google.inject.internal.cglib.proxy.$MethodProxy.invokeSuper(MethodProxy.java:228)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:72)
at com.ea.monitor.MethodExecutionTimer.invoke(MethodExecutionTimer.java:130)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:72)
at com.google.inject.internal.InterceptorStackCallback.intercept(InterceptorStackCallback.java:52)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd.doPost(<generated>)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd.CGLIB$service$8(<generated>)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd$$FastClassByGuice$$c6f479ee.invoke(<generated>)
at com.google.inject.internal.cglib.proxy.$MethodProxy.invokeSuper(MethodProxy.java:228)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:72)
at com.ea.monitor.MethodExecutionTimer.invoke(MethodExecutionTimer.java:130)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:72)
at com.google.inject.internal.InterceptorStackCallback.intercept(InterceptorStackCallback.java:52)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd.service(<generated>)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd.CGLIB$service$9(<generated>)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd$$FastClassByGuice$$c6f479ee.invoke(<generated>)
at com.google.inject.internal.cglib.proxy.$MethodProxy.invokeSuper(MethodProxy.java:228)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:72)
at com.ea.monitor.MethodExecutionTimer.invoke(MethodExecutionTimer.java:130)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:72)
at com.google.inject.internal.InterceptorStackCallback.intercept(InterceptorStackCallback.java:52)
at com.ea.wsop.user.LoginServlet$$EnhancerByGuice$$a91c2ebd.service(<generated>)
at com.google.inject.servlet.ServletDefinition.doService(ServletDefinition.java:263)

Answer

It will be empty if it's already consumed beforehand. This will be implicitly done whenever you call getParameter(), getParameterValues(), getParameterMap(), getReader(), etc on the HttpServletRequest. Make sure that you don't call any of those kind of methods which by themselves need to gather information from the request body before calling getInputStream(). If your servlet isn't doing that, then start checking the servlet filters which are mapped on the same URL pattern.


Update: this seems to be GAE 1.5 specific. See also

I'm afraid that there's no solution/workaround until they get it fixed. You could try to check if it's available inside a Filter and if so, then copy and store it as request attribute. But this might affect further processing by some GAE servlet.

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