servlets

问题 By default the JSESSIONID cookie is expired when you close the browser, but how long is the associated HttpSession really valid on the server side? 回答1: It defaults to 30 minutes on most containers which you can configure by <session-config> in your webapp's web.xml . <session-config> <session-timeout>10</session-timeout> </session-config> The above example will change the server side session timeout to 10 minutes. So in other words, when the client do not interact with the server for more

问题 I often hear people saying that session scoped objects should implement Serializable ? Why it is so ? What will be the result if one doesn't do this ? Why not make this a part of the servlet specification then ? I know Tomcat doesn't complain if we do not do this . What about other app servers like JBoss, WebSphere or Weblogic ? 回答1: This allows the servlet container to either store the contents of a session on disk, or to transfer session contents over the network to another server. Why does

问题 import java.net.*; import java.io.*; public class sample { public static void main (String args[]) { String line; try { URL url = new URL( "http://localhost:8080/WeighPro/CommPortSample" ); BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream())); line = in.readLine(); System.out.println( line ); in.close(); } catch (Exception e) { System.out.println("Hello Project::"+e.getMessage()); } } } My Servlet is invoking another Jsp page like the below, RequestDispatcher rd

问题 I am using Jetty Websockets in my Web Application . When i am trying to redirect to a logoff jsp , i am getting this error oejs.ServletHandler:/test java.lang.IllegalStateException: Committed at org.eclipse.jetty.server.Response.resetBuffer(Response.java:1069) at javax.servlet.ServletResponseWrapper.resetBuffer(ServletResponseWrapper.java:232) at org.eclipse.jetty.http.gzip.GzipResponseWrapper.resetBuffer(GzipResponseWrapper.java:273) at org.eclipse.jetty.server.Dispatcher.forward(Dispatcher

问题 I have a java Rest WebService URL http://localhost:8080/WebServiceEx/rest/hello/dgdg When i execute the URL ,the WebService Method Returns a String My Requirement is to call the above WebService URL inside a Servlet ,Could any one Help? ServletCode: public Class StoreServlet extends HttpServlet{ protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException { //Invoke WebService and Get Response String Here } WebService Code: public class

问题 We have a system where a client makes an HTTP GET request, the system does some processing on the backend, zips the results, and sends it to the client. Since the processing can take some time, we send this as a ZipOutputStream wrapping the response.getOutputStream() . However, when we have an exceptionally small amount of data in the first ZipEntry , and the second entry takes a long time, the browser the client is using times out. We've tried flushing the stream buffer, but no response

问题 We have a system where a client makes an HTTP GET request, the system does some processing on the backend, zips the results, and sends it to the client. Since the processing can take some time, we send this as a ZipOutputStream wrapping the response.getOutputStream() . However, when we have an exceptionally small amount of data in the first ZipEntry , and the second entry takes a long time, the browser the client is using times out. We've tried flushing the stream buffer, but no response

问题 In my web application i neet to check session already exist or not. i want to check this in my servlet and in jsp also. is there any way to check this. Thanks 回答1: You can test it with HttpServletRequest#getSession(boolean create) with create=false . It will return null if not created yet. HttpSession session = request.getSession(false); if (session == null) { // Session is not created. } else { // Session is already created. } If you actually want to create the session anyway if it doesn't

问题 Is it possible to use two filters that have the same url-mapping? <filter> <filter-name>TeeFilter</filter-name> <filter-class>filter1r</filter-class> </filter> <filter-mapping> <filter-name>TeeFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <display-name>CredentialsFilter</display-name> <filter-name>CredentialsFilter</filter-name> <filter-class>filter2</filter-class> </filter> <filter-mapping> <filter-name>CredentialsFilter</filter-name> <url-pattern>/*</url

问题 I want to intercept a request using the RequestDispatcher, and then I want to forward the request along to another servlet -- something like this: RequestDispatcher dispatcher = request.getRequestDispatcher("/servlet/some.ThirdPartyServlet" + "?" + "param_name=" + "somevalue"); dispatcher.forward(request, response); If the incoming request were a POST, will the request dispatcher take my new parameters, and include them in the message body, or does this forward now become a GET? 回答1: It