這個Servlet 擴充了HttpServlet 類別，並改寫繼承的doGet()方法，當伺服器收到送往這Servlet的Get Request 時，伺服器便會呼叫 doGet()，並傳入一個HttpServletRequest 物件和HttpServletResponse物件。
HttpServletRequest 物件代表client提出的申請，讓servlet 得到client的資訊
request的參數。HttpServletResponse 物件代表Servlet 要回傳給client的回覆
，內容可以是各種型態，但必須在response中註明是何種type。在此程式中先用setContenType 方法將內容型態定義為"text/html"
在NetBeans中的使用方式如下
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import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorld extends HttpServlet {
/**
* Processes requests for both HTTP
* <code>GET</code> and
* <code>POST</code> methods.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
/* TODO output your page here. You may use following sample code. */
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet HelloWorld</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Servlet HelloWorld at " + request.getContextPath() + "</h1>");
out.println("</body>");
out.println("</html>");
} finally {
out.close();
}
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
* Handles the HTTP
* <code>GET</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doGet(HttpServletRequest request
, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out=response.getWriter();
out.println("<HTML>");
out.println("<HEAD><TITLE>hello World</TITLE></HEAD>");
out.println("<BODY>");
out.println("<Big>Hello World11</Big>");
out.println("</BODY></html>");
// processRequest(request, response);
}
/**
* Handles the HTTP
* <code>POST</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Returns a short description of the servlet.
*
* @return a String containing servlet description
*/
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}
