51 lines
1.3 KiB
Java
51 lines
1.3 KiB
Java
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Updating the client cache
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package com.ack.web.servlet;
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import java.io.IOException;
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import java.util.Date;
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import javax.servlet.ServletException;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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public class UpdatingTheClientCache extends HttpServlet {
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private Date lastUpdate;
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public void init() {
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lastUpdate = new Date( System.currentTimeMillis() );
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}
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/**
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* This will see the server stuffing the Last-Modified header
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* into the response that is used by the client during
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* page reloads to check whether content on the server has
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* changed.
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*
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* Refer to how the If-Modified-Since and Last-Modified
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* headers used within the HTTP protocol
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*
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*/
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public long getLastModified( HttpServletRequest req ) {
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// round time down to the last second
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return lastUpdate.getTime() / 1000 * 1000;
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}
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public void doGet( HttpServletRequest req, HttpServletResponse res )
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throws ServletException, IOException {
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boolean needToUpdate = false;
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// process some work
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if( needToUpdate ) {
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synchronized( this ) {
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lastUpdate = new Date( System.currentTimeMillis() );
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}
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}
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res.getWriter().println( "done some work" );
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}
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}
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