7. Servlet 컨텍스트 영역에 값넣기
서블릿 컨텍스트 영역에 값 넣기 예제
<< 서블릿의 영역(scope) ** >>
1. ServletContext영역
- 모든 서블릿이 공유하는 영역
- 하나의 웹어플리케이션당 하나가 만들어짐.
2. ServletConfig영역
- 서블릿 하나당 할당되는 영역
1. web.xml
2. main.html
3. MyServlet.java
4. ServletScope.java
5. ServletScope1.java
6. TestServlet.java
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>day02_servlet01</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>
<servlet>
<servlet-name>myservlet</servlet-name>
<servlet-class>test.servlet.MyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myservlet</servlet-name>
<url-pattern>/my.do</url-pattern>
</servlet-mapping>
<!-- 서블릿 컨텍스트 영역에 값 넣기 -->
<context-param>
<param-name>user</param-name>
<param-value>scott</param-value>
</context-param>
<servlet>
<servlet-name>scope1</servlet-name>
<servlet-class>test.servlet.ServletScope1</servlet-class>
<!-- 초기화 파라미터 설정하기(서블릿컨피그를 통해 사용가능함.!!) -->
<init-param>
<param-name>id</param-name>
<param-value>song</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>scope1</servlet-name>
<url-pattern>/scope1.do</url-pattern>
</servlet-mapping>
</web-app>
2. main.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=EUC-KR">
<title>Insert title here</title>
</head>
<body>
<a href="my.do">myservlet</a><br/>
<a href="scope.do">scope</a><br/>
<a href="test.do">test</a><br/>
</body>
</html>
3. MyServlet.java
; myservlet 클릭하면
package test.servlet;
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 MyServlet extends HttpServlet{
//서블릿이 최초로 요청될때 딱한번만 호출됨.(초기화작업)
@Override
public void init() throws ServletException {
System.out.println("init메소드가 호출됨!!");
}
//서블릿이 종료될때 ( 메모리에서 제거될때 ) 호출됨.(자원해제등, .. )
//일정시간 동안 서블릿이 호출되지 않거나 웹서버가 종료되면 서블릿은 제거됨.
@Override
public void destroy() {
System.out.println("destroy");
}
// 서블릿을 요청할때마다 호출됨.
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType("text/html;charset=euc-kr");
PrintWriter pw = resp.getWriter();
pw.println("<h2>service메소드 호출!</h2>");
pw.close();
}
}
4. ServletScope.java
package test.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/scope.do")
public class ServletScope extends HttpServlet{
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//서블릿컨텍스트 객체 얻어오기
ServletContext sc = getServletContext();
//서블릿컨텍스트 영역에 값넣기
sc.setAttribute("url", "localhost");
//서블릿컨텍스트 영역에서 값 꺼내오기
String url=(String)sc.getAttribute("url");
//web.xml에 설정된 초기화파라미터 읽어오기.
String user = sc.getInitParameter("user");
resp.setContentType("text/html;charset=euc-kr");
PrintWriter pw = resp.getWriter();
pw.println("url:" + url);
pw.println("user:" + user);
pw.println("<a href='test.do'>testservlet</a><br/>");
pw.close();
}
}
; user에 scott를 보여준다.(xml에서 읽기)
5. ServletScope1.java
package test.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ServletScope1 extends HttpServlet{
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//서블릿컨피그 객체 얻어오기.
ServletConfig sc = getServletConfig();
String id = sc.getInitParameter("id");
resp.setContentType("text/html;charset=euc-kr");
PrintWriter pw = resp.getWriter();
pw.println("id:" + id);
pw.close();
}
}
6. TestServlet.java
package test.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/test.do")
public class TestServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
ServletContext sc=getServletContext();
String url=(String)sc.getAttribute("url");
resp.setContentType("text/html;charset=euc-kr");
PrintWriter pw = resp.getWriter();
pw.println("서블릿컨텍스트에 담긴 url:" + url);
pw.close();
}
}
