2.1 Petunjuk JSP

Amarga kita nemokake manawa file JSP diowahi dadi servlet biasa, mula sampeyan bisa nulis kode Java normal ing kono. Lan ing kode Jawa iki, sampeyan bisa nggunakake macem-macem kelas (Math saka conto). Iki malah luwih apik! Nanging kita bisa ndeleng manawa kabeh kode wis dipindhah menyang doGet()cara servlet. Lan iki langsung nuwuhake sawetara pitakonan:

  • Kepiye carane supaya kode kasebut dipindhah menyang metode kasebut doPost()?
  • Kepiye cara nambah kode dhewe menyang metode kasebut init()?
  • Carane ing pungkasan kanggo ndhaftar impor kelas?
Java university

Pitakonan sing apik, lan, mesthi, duwe jawaban - arahan JSP. Kabeh kode non-HTML ing JSP kudu dilampirake ing kurung khusus <%lan %>. Kabeh arahan JSP diwenehake dening cithakan:

<%@ directive %>

Iki minangka dhaptar atribut arahan kaca sing paling populer:

Tuladha Katrangan
1 ngimpor <%@ page import="java.util.Date" %> Ngimpor kelas
2 jinis konten <%@ page contentType=text/html %> Nyetel contentType
3 ngluwihi <%@ page extends="Object" %> Sampeyan bisa nyetel kelas dhasar
4 info <%@ page info="Author: Peter Ivanovich; version:1.0" %> Nyetel data kanggo getServletInfo()
5 panyangga <%@ page buffer="16kb" %> Nyetel ukuran buffer respon
6 basa <%@ page language="java" %> Nemtokake basa, standar yaiku Jawa
7 digatekake <%@ page isELIgnored="true" %> Ngidini sampeyan mateni skrip EL
8 ikuThreadSafe <%@ page isThreadSafe="false" %> Titik kanggo threadsafe
9 autoFlush <%@ page autoFlush="false" %> Ngatur buffer nyerat
10 sesi <%@ page session="false" %> Sampeyan bisa mateni sesi kanggo kaca
sewelas pageEncoding <%@ page pageEncoding="UTF-8"%> Sampeyan bisa nyetel enkoding kaca
12 kesalahanPage <%@ page errorPage="errorpage.jsp" %> Sampeyan bisa nyetel kaca kesalahan

2.2 Impor

Ayo nambah sawetara impor menyang file JSP kanggo seneng-seneng lan nemtokake kelas dhasar.

Tuladha file JSP:


    <%@ page import="java.util.Date" %> 
    <%@ page import="java.lang.Math" %> 
    <%@ page extends="com.codegym.MyHttpServlet" %> 
 
    <html> 
    <body> 
    <%
        double num = Math.random();
        if (num > 0.95) {
     %>
         <h2>You are lucky, user!</h2><p>(<%= num %>)</p>
    <%
    }
    %> 
  </body> 
   </html>

Lan iki sing bakal teka:

import java.util.Date;
import java.lang.Math;

public class HelloServlet extends com.codegym.MyHttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)  throws Exception {
    PrintWriter out = response.getWriter();
    out.print("<html>  ");
    out.print("<body> ");
        double num = Math.random();
        if (num >  0.95) {
             out.print("<h2> You're lucky, user! </h2> <p> (" + num + ")</p> ");
        }
    out.print("</body> ");
    out.print("</html> ");
    }
}

Nyambut gawe. apik tenan!