[JSp&Servlet] 서블릿 생성 및 실행

tony·2022년 3월 16일

JSP&Servlet

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1/1

path 설정하기

server.xml

Tomcat - Conf - server.xml을 편집해보자.

<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<!-- Note:  A "Server" is not itself a "Container", so you may not
     define subcomponents such as "Valves" at this level.
     Documentation at /docs/config/server.html
 -->
<Server port="-1" shutdown="SHUTDOWN">
  <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
  <!-- Security listener. Documentation at /docs/config/listeners.html
  <Listener className="org.apache.catalina.security.SecurityListener" />
  -->
  <!-- APR library loader. Documentation at /docs/apr.html -->
  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
  <!-- Prevent memory leaks due to use of particular java/javax APIs-->
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <!-- Global JNDI resources
       Documentation at /docs/jndi-resources-howto.html
  -->
  <GlobalNamingResources>
    <!-- Editable user database that can also be used by
         UserDatabaseRealm to authenticate users
    -->
    <Resource name="UserDatabase" auth="Container"
              type="org.apache.catalina.UserDatabase"
              description="User database that can be updated and saved"
              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
              pathname="conf/tomcat-users.xml" />
  </GlobalNamingResources>

  <!-- A "Service" is a collection of one or more "Connectors" that share
       a single "Container" Note:  A "Service" is not itself a "Container",
       so you may not define subcomponents such as "Valves" at this level.
       Documentation at /docs/config/service.html
   -->
  <Service name="Catalina">

    <!--The connectors can use a shared executor, you can define one or more named thread pools-->
    <!--
    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
        maxThreads="150" minSpareThreads="4"/>
    -->

    <!-- A "Connector" represents an endpoint by which requests are received
         and responses are returned. Documentation at :
         Java HTTP Connector: /docs/config/http.html
         Java AJP  Connector: /docs/config/ajp.html
         APR (HTTP/AJP) Connector: /docs/apr.html
         Define a non-SSL/TLS HTTP/1.1 Connector on port 8080
    -->
    <Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    <!-- A "Connector" using the shared thread pool-->
    <!--
    <Connector executor="tomcatThreadPool"
               port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    -->
    <!-- Define an SSL/TLS HTTP/1.1 Connector on port 8443
         This connector uses the NIO implementation. The default
         SSLImplementation will depend on the presence of the APR/native
         library and the useOpenSSL attribute of the AprLifecycleListener.
         Either JSSE or OpenSSL style configuration may be used regardless of
         the SSLImplementation selected. JSSE style configuration is used below.
    -->
    <!--
    <Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol"
               maxThreads="150" SSLEnabled="true">
        <SSLHostConfig>
            <Certificate certificateKeystoreFile="conf/localhost-rsa.jks"
                         type="RSA" />
        </SSLHostConfig>
    </Connector>
    -->
    <!-- Define an SSL/TLS HTTP/1.1 Connector on port 8443 with HTTP/2
         This connector uses the APR/native implementation which always uses
         OpenSSL for TLS.
         Either JSSE or OpenSSL style configuration may be used. OpenSSL style
         configuration is used below.
    -->
    <!--
    <Connector port="8443" protocol="org.apache.coyote.http11.Http11AprProtocol"
               maxThreads="150" SSLEnabled="true" >
        <UpgradeProtocol className="org.apache.coyote.http2.Http2Protocol" />
        <SSLHostConfig>
            <Certificate certificateKeyFile="conf/localhost-rsa-key.pem"
                         certificateFile="conf/localhost-rsa-cert.pem"
                         certificateChainFile="conf/localhost-rsa-chain.pem"
                         type="RSA" />
        </SSLHostConfig>
    </Connector>
    -->

    <!-- Define an AJP 1.3 Connector on port 8009 -->
    <!--
    <Connector protocol="AJP/1.3"
               address="::1"
               port="8009"
               redirectPort="8443" />
    -->

    <!-- An Engine represents the entry point (within Catalina) that processes
         every request.  The Engine implementation for Tomcat stand alone
         analyzes the HTTP headers included with the request, and passes them
         on to the appropriate Host (virtual host).
         Documentation at /docs/config/engine.html -->

    <!-- You should set jvmRoute to support load-balancing via AJP ie :
    <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
    -->
    <Engine name="Catalina" defaultHost="localhost">

      <!--For clustering, please take a look at documentation at:
          /docs/cluster-howto.html  (simple how to)
          /docs/config/cluster.html (reference documentation) -->
      <!--
      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
      -->

      <!-- Use the LockOutRealm to prevent attempts to guess user passwords
           via a brute-force attack -->
      <Realm className="org.apache.catalina.realm.LockOutRealm">
        <!-- This Realm uses the UserDatabase configured in the global JNDI
             resources under the key "UserDatabase".  Any edits
             that are performed against this UserDatabase are immediately
             available for use by the Realm.  -->
        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
               resourceName="UserDatabase"/>
      </Realm>

      <Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true">

        <!-- SingleSignOn valve, share authentication between web applications
             Documentation at: /docs/config/valve.html -->
        <!--
        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
        -->

        <!-- Access log processes all example.
             Documentation at: /docs/config/valve.html
             Note: The pattern used is equivalent to using pattern="common" -->
        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               prefix="localhost_access_log" suffix=".txt"
               pattern="%h %l %u %t &quot;%r&quot; %s %b" />

      </Host>
    </Engine>
  </Service>
</Server>

위 코드에서 localhost의 설정을 선언한 부분을 살펴보자

<Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true">

여기서 특정 파일의 path를 path명을 지정하여 선언해줄 수 있다.

localhost의 설정값에 아래 내용을 추가해주자.

<Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true">
		<Context path = "path명" 
				docBase="추가하고 싶은 실제 path"
				privileged="true"/>

실제 예시 코드를 봐보도록 하자.

<Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true">
		<Context path = "it" 
				docBase="C:\Users\user\Desktop\JSP\Tomcat-8.5\webapps\ROOT\ITWEB"
				privileged="true"/>

이렇게 하면 ROOT아래의 ITWEB 디렉토리를 url에서 it라는 이름을 통해 접속할 수 있게 된다.

Servlet 생성 및 실행해보기

Client가 직접 리소스에 접근

위에서 지정한 Context Path를 통해 원하는 경로의 리소스들을 요청하고 응답받을 수 있다. 그런데 본디 이런 과정은 비정상적이다. 이렇게 하면 서버의 모든 자원에 접근가능하고, 서버 측에서의 제어가 존재하지 않게된다.

우리는 client가 요하는 요청사항을 받아 해당 요청사항을 실제 파일과 Mapping을 통해 응답을 해줄 것이다.

동작과정

Client측에서 서버에 접속한 뒤, url을 날려준다.
localhost:8080/hello
Server측에서는 Client측에ㅓ 요청한 path의 문자열과 mapping되는 경로를 찾는다. 이는 WEB-INF 디렉토리 내에 web.xml에 선언되어있다.

<servlet>
      <servlet-name>na</servlet-name>
      <servlet-class>Nana1</servlet-class>
  </servlet>

  <servlet-mapping>
      <servlet-name>na</servlet-name>
      <url-pattern>/hello</url-pattern>
  </servlet-mapping>

  <display-name>Welcome to Tomcat</display-name>
  <description>
     Welcome to Tomcat
  </description>

</web-app>

위 코드를 보면 na와 hello가 매핑되어있고, na는 Nana1.class와 매핑되어있음을 볼 수 있다.

Nana1.class를 실행시킨다.

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class Nana1 extends HttpServlet{
	public void service(HttpServletRequest request,HttpServletResponse response)
							throws IOException,ServletException{
		// 출력스트림 오픈
		OutputStream os = response.getOutputStream();
		// PrintStream을 통해 출력스트림에 data를 print할 수 있는 기능 더함
		PrintStream out = new PrintStream(os,true); //auto-fflush
		// data 출력
		out.println("hello servlet");
	}						
}

여기서 주의해야할 점이 있는데, System.out.println()을 통해 콘솔창에 출력하려 하면 Server 측 콘솔창에 출력하게 된다는 것이다!

따라서 반드시 service 메소드의 매개인자 response를 통해 입출력 스트림을 열어주어야만 Client측에게 데이터를 전달할 수 있게 된다.

Reference

Apache Tomcat Context 경로설정
https://sambalim.tistory.com/76
Tomcat 구조
https://hamdi.tistory.com/23
server.xml 설정
https://2dubbing.tistory.com/11
[Web] web.xml 설정 내용, 역할 및 간단한 예시 이해하기
https://gmlwjd9405.github.io/2018/10/29/web-application-structure.html

tony

내 코드로 세상이 더 나은 방향으로 나아갈 수 있기를