[JSP] 서블릿 사용하기

클래스 생성

상속규칙2) javax.servlet.http.HttpServlet 클래스를 상속해서 사용

public class MyServlet extends HttpServlet{

}

상속규칙2) doGet(), doPost() 메서드를 선언 (오버라이딩)

// alt shift s v
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

상속규칙 4) java.io.IOException, java.servlet.ServletException을 통한 예외 처리(예외던지기)

// alt shift s v
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	System.out.println("MyServlet-doGet() 실행");
}

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	System.out.println("MyServlet-doPost() 실행");
}

없으면 당황하지 말고 만들기~

이름 우클릭 java ee tools ➡️ generate deployment descriptor sub

 

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
  <display-name>JSP7</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <!-- web.xml (배포서술자) : 서블릿을 매핑한다. 즉, 프로그램 시작할 때 빌리는 곳 -->
  <servlet>
  	<servlet-name>myServlet</servlet-name>
  	<servlet-class>com.itwillbs.servlet.MyServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
  	<servlet-name>myServlet</servlet-name>
	<url-pattern>/myServlet</url-pattern>
  </servlet-mapping>
  
</web-app>

 

package com.itwillbs.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyServlet extends HttpServlet{
	// <http://localhost:8088/JSP7/myServlet>
	
	// alt shift s v
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("MyServlet-doGet() 실행");
		doPost(request, response);
	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("MyServlet-doPost() 실행");
	}
	
}

 

• [x] init()

// alt shift s v -> init()
@Override
	public void init() throws ServletException { // init : initialized(초기화)
		System.out.println("init()실행 - 서블릿 클래스(객체) 초기화!");
	}

• [x] destory()

// alt shift s v -> destroy()
	@Override
	public void destroy() {
		System.out.println("destroy() 호출 - 서블릿 객체 소멸");
	}

package com.itwillbs.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyServlet extends HttpServlet{
	// 서버실행 : ctrl + 클릭
	// <http://localhost:8088/JSP7/myServlet>
	
	@Override
	public void init() throws ServletException { // init : initialized(초기화)
		System.out.println("init()실행 - 서블릿 클래스(객체) 초기화!");
	}
	
	// alt shift s v -> doget(), dopost()
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("MyServlet-doGet() 실행");
		doPost(request, response);
	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("MyServlet-doPost() 실행");
	}

	// alt shift s v -> destroy(), init()
	@Override
	public void destroy() {
		System.out.println("destroy() 호출 - 서블릿 객체 소멸");
	}

	
}

이때까지 다른점. 페이지만 뜨고 안에 내용이 보이지않음

💡어떻게?

@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("MyServlet-doPost() 실행");
		
		response.setContentType("text/html; charset=UTF-8");
		response.getWriter().append("안녕하세요!");
	}

html 코드를 넣고싶으면

@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("MyServlet-doPost() 실행");
		
		response.setContentType("text/html; charset=UTF-8");
		response.getWriter().append("안녕하세요!");
		response.getWriter().append("<h1> ITWILL 서블릿수업 </h1>");
	}

➡️ 직접적으로 태그를 작성해서 사용 (불편). 이를 해결하기 위해 JSP 페이지 사용

 

 

서블릿(서블릿주소 매핑) + JSP(화면) 같이 사용하는 방법은 다음 포스팅으로~