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AndriiPiatakhaAndriiPiatakha
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Servlet API demo
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‎online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/DisplayHeadersServlet.java

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package com.itbulls.learnit.onlinestore.web.servlets;
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import jakarta.servlet.http.HttpServlet;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.util.Enumeration;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.annotation.WebServlet;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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@WebServlet("/headers")
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public class DisplayHeadersServlet extends HttpServlet {
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// Method to handle GET method request.
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public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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// Set response content type
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response.setContentType("text/html");
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PrintWriter out = response.getWriter();
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String title = "HTTP Header Request Example";
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String docType = "<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
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out.println(docType + "<html>\n" + "<head><title>" + title + "</title></head>\n"
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+ "<body bgcolor = \"#f0f0f0\">\n" + "<h1 align = \"center\">" + title + "</h1>\n"
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+ "<table width = \"100%\" border = \"1\" align = \"center\">\n" + "<tr bgcolor = \"#949494\">\n"
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+ "<th>Header Name</th><th>Header Value(s)</th>\n" + "</tr>\n");
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Enumeration headerNames = request.getHeaderNames();
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while (headerNames.hasMoreElements()) {
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String paramName = (String) headerNames.nextElement();
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out.print("<tr><td>" + paramName + "</td>\n");
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String paramValue = request.getHeader(paramName);
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out.println("<td> " + paramValue + "</td></tr>\n");
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}
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out.println("</table>\n</body></html>");
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}
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}

‎online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/RedirectDemo.java

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package com.itbulls.learnit.onlinestore.web.servlets;
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import jakarta.servlet.http.HttpServlet;
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import java.io.IOException;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.annotation.WebServlet;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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@WebServlet("/redirect")
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public class RedirectDemo extends HttpServlet {
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protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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response.sendRedirect("http://google.com");
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}
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}

‎online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/RestrictedAccessServlet.java

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package com.itbulls.learnit.onlinestore.web.servlets;
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import jakarta.servlet.http.HttpServlet;
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import java.io.IOException;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.annotation.WebServlet;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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@WebServlet("/restricted")
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public class RestrictedAccessServlet extends HttpServlet {
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protected void doGet(HttpServletRequest request, jakarta.servlet.http.HttpServletResponse response) throws ServletException, IOException {
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response.sendError(403, "You are not allowed to access this resource");
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}
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}

‎online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/ServletDemo.java

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package com.itbulls.learnit.onlinestore.web.servlets;
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import jakarta.servlet.http.HttpServlet;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.util.Locale;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.annotation.WebInitParam;
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import jakarta.servlet.annotation.WebServlet;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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@WebServlet(urlPatterns = { "/demo", "/demo1" }, initParams = {
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@WebInitParam(name = "firstName", value = "Andrii"),
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@WebInitParam(name = "lastName", value = "Piatakha")
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})
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public class ServletDemo extends HttpServlet {
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protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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String firstName = getInitParameter("firstName");
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String lastName = getInitParameter("lastName");
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PrintWriter writer = response.getWriter();
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writer.println("firstName = " + firstName + "; ");
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writer.println("lastName = " + lastName);
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writer.println("</br>");
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writer.println("Servlet name: " + getServletConfig().getServletName());
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writer.println("</br>");
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writer.println("Servlet name: " + getServletName());
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writer.println("</br>");
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writer.println("Context path: " + getServletContext().getContextPath());
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writer.println("</br>");
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getServletContext().setAttribute("locale", Locale.US);
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String param = request.getParameter("param");
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writer.println("Request param value: " + param);
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writer.println("</br>");
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writer.println("Request attribute: " + request.getAttribute("attr"));
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}
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}

‎online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/ServletDemo2.java

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package com.itbulls.learnit.onlinestore.web.servlets;
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import jakarta.servlet.http.HttpServlet;
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import java.io.IOException;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.annotation.WebServlet;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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@WebServlet("/demo2")
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public class ServletDemo2 extends HttpServlet {
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protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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response.getWriter()
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.println("Locale attribute: " + getServletContext().getAttribute("locale"));
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}
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}

‎online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/ServletDemo3.java

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package com.itbulls.learnit.onlinestore.web.servlets;
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import jakarta.servlet.http.HttpServlet;
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import java.io.IOException;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.annotation.WebServlet;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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@WebServlet("/demo3")
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public class ServletDemo3 extends HttpServlet {
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protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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request.setAttribute("attr", "Test Attribute Value");
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request.getRequestDispatcher("/demo").forward(request, response);
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}
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}

‎online-store.web/src/main/java/com/itbulls/learnit/onlinestore/web/servlets/SetHeaderServlet.java

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package com.itbulls.learnit.onlinestore.web.servlets;
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import jakarta.servlet.http.HttpServlet;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.util.Calendar;
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import java.util.GregorianCalendar;
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import jakarta.servlet.ServletException;
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import jakarta.servlet.annotation.WebServlet;
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import jakarta.servlet.http.HttpServletRequest;
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import jakarta.servlet.http.HttpServletResponse;
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@WebServlet("/refresh-header")
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public class SetHeaderServlet extends HttpServlet {
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public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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// Set refresh, autoload time as 2 seconds
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response.setIntHeader("Refresh", 2);
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// Set response content type
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response.setContentType("text/html");
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// Get current time
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Calendar calendar = new GregorianCalendar();
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String am_pm;
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int hour = calendar.get(Calendar.HOUR);
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int minute = calendar.get(Calendar.MINUTE);
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int second = calendar.get(Calendar.SECOND);
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if (calendar.get(Calendar.AM_PM) == 0)
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am_pm = "AM";
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else
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am_pm = "PM";
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String CT = hour + ":" + minute + ":" + second + " " + am_pm;
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PrintWriter out = response.getWriter();
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String title = "Auto Refresh Header Setting";
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String docType = "<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
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out.println(
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docType + "<html>\n" + "<head><title>" + title + "</title></head>\n" + "<body bgcolor = \"#f0f0f0\">\n"
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+ "<h1 align = \"center\">" + title + "</h1>\n" + "<p>Current Time is: " + CT + "</p>\n");
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}
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}

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