Database Systems Lab. 11. JSP I 충남대학교컴퓨터공학과 데이타베이스시스템연구실

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1 데이타베이스시스템연구실 Database Systems Lab. 11. JSP I 충남대학교컴퓨터공학과 데이타베이스시스템연구실

2 Overview What is JavaServer Pages? JavaServer Pages (JSP) is a server-side programming technology that enables the creation of dynamic, platform-independent method for building Webbased applications. A technology for developing web pages that support dynamic content which helps developers insert java code in HTML pages by making use of special JSP tags, most of which start with <% and end with %>. 2

3 Overview (cont d) Advantages of JSP Offer several advantages in comparison with the CGI Performance is significantly better because JSP allows embedding Dynamic Elements in HTML Pages itself instead of having a separate CGI files JSP are always compiled before it s processed by the server unlike CGI/Perl which requires the server to load an interpreter and the target script each time the page is requested. JavaServer Pages are built on top of the Java Servelts API, so like Servelts, JSP also has access to all the powerful Enterprise Java APIs, including JDBC, JNDI, EJB, JAXP etc JSP pages can be used in combination with servlets that handle the business logic, the model supported by Java servlet template engines 3

4 CGI(Common Gateway Interface) 최초의웹애플리케이션기술 웹애플리케이션을독립적인프로그램형태로작성 문제점 각프로그램이하나의프로세스로수행됨 독립적인프로그램실행을하기위해시스템자원이많이필요 그결과웹서버로많은요청이한꺼번에들어오면너무많은 CGI 프로그램의프로세스가동시에실행되어컴퓨터전체가다운되는일이빈번히발생 4

5 서블릿 (Servlet) 자바를기반으로하는웹애플리케이션프로그래밍기술 처음에 Sun Microsystems 의해개발되었지만, 그후에자바표준개발을전담하는기관인 JCP(Java community Process) 로이관되어서발전 자바클래스형태로웹애플리케이션작성 이클래스를서블릿클래스라함 5

6 서블릿클래스의예 HttpServletResponse 파라미터를이용해서 HTML 코드를출력함 import javax.servlet.*; import javax.servlet.http.*; import java.io.*; Public class HundredServlet extends HttpServlet { } public void doget(httpservletrequest request, HttpServletResponse response) throws ServletException, IOException { printwriter out = response.getwriter(); out.printin( <HTML> ); out.printin( <HEAD><TITLE>Sum of 1 to 100</TITLE></HEAD> ); } out.printin( <BODY> ); int total = 0; for(int cnt =1;cnt <=100; cnt++) total += cnt ; out.printin( = +total); out.printin( </BODY> ); out.printin( </HTML> ); HttpServlet 클래스를상속 doget 또는 dopost 매서드안에서블릿클래스가해야할일을써넣음 6

7 서블릿장점과단점 장점 단점 자바의플랫폼독립성 : 서블릿실행코드를다양한운영체제에서수행가능 네트워크환경에서보안이용이 시스템부하가적은멀티스레드기능이지원됨 프로그래밍작업의효율성이떨어짐 HTML 코드가자바코드안으로들어가는구조로인함 이러한구조는서블릿클래스가출력하는동적 HTML 문서의구조를이해하기어렵게함 또한, 웹페이지의디자인작업을위해서도소스코드에손을대게만드는비효율성을낳음 자바의유용한장점을살리면서서블릿기술의단점을보완하는새로운기술 JSP 가개발됨 7

8 JSP (JavaServer Pages) 자바를기반으로한웹애플리케이션 JSP 는웹애플리케이션서버의서블릿컨테이너에서서블릿원시코드로변환된후에서블릿원시코드는바로컴파일된후실행 JSP 페이지는 HTML 문서에자바코드가삽입되는구조 page contenttype= text/html; charset=utf-8 %> <HTML> <HEAD><TITLE>1 부터 100 까지의합 </TITLE></HEAD> <BODY> <% int total = 0; for (int cnt=1; cnt <= 100; cnt++) total += cnt; %> 1 부터 100 까지의합은? <%=total %> </BODY> </HTML> 자바코드 8

9 JSP (JavaServer Pages) (cont d) <%. %>, <%= %> JSP 문법이태그안에자바프로그래밍언어로작성된코드가있음이코드는웹서버에서실행됨 <%..%> : 1부터 100까지의수를더해서 total 변수에대입 <%= %> : total 변수의값을웹브라우저로전송 웹디자이너가그대로가져다가디자인작업을할수있고, 디자인작업이끝나면프로그래머가다시가져다가자바부분을수정할수있음 9

10 Architecture The web server needs a JSP engine ie. container to process JSP pages. JSP container is responsible for intercepting requests for JSP pages. Apache has built-in JSP container(tomcat) to support JSP pages development 10

11 Architecture (cont d) JSP Processing 11

12 Architecture (cont d) As with a normal page, your browser sends an HTTP request to the web server The web server recognizes that the HTTP request is for a JSP page and forwards it to a JSP engine. This is done by using the URL or JSP page which ends with.jsp instead of.html The JSP engine loads the JSP page from disk and converts it into a servlet content. All template text is converted to println( ) statements All JSP elements are converted to Java code that implements the corresponding dynamic behavior of the page. The JSP engine compiles the servlet into an executable class and forwards the original request to a servlet engine. A part of the web server called the servlet engine loads the Servlet class and executes it. During execution, the servlet produces an output in HTML format, which the servlet engine passes to the web server inside an HTTP response. 12

13 Architecture (cont d) The web server forwards the HTTP response to your browser in terms of static HTML content. Finally web browser handles the dynamically generated HTML page inside the HTTP response exactly as if it were a static page. 13

14 JSP 기초문법 JSP 문법의형태 1. <%... %> 2. ${...} 3. XML 태그형태 : <jsp:forward> 나 <c:if> <%...%> 로끝나는문법지시자 (directive) 스크립팅요소 (scripting elements) : scriptlet 과 expression ${ } 로끝나는문법익스프레션언어 (expression language) XML 태그형태로기술액션 (Action) 14

15 JSP 의문법 - 지시자와스크립트요소예 지시자 (directive) <%@ page contenttype= text/html; charset=utf-8 %> <HTML> <HEAD><TITLE>1부터 100까지의합 </TITLE></HEAD> <BODY> <% int total = 0; for (int cnt=1; cnt <= 100; cnt++) total += cnt; %> 1부터 100까지의합은? <%=total %> </BODY> </HTML> 스크립틀릿 (scriptlet) 익스프레션 (expression) 15

16 Syntax :Scriptlet The Scriptlet Contain any number of JAVA language statements, variable or method declarations, or expressions that are valid in the page scripting language. The syntax of Scriptlet <% code fragment %> Example Try it! <html> <head><title>hello World</title><head> <body> Hello World!<br> <% out.println("your IP address is " + request.getremoteaddr()); %> </body> </head> 16

17 Syntax : JSP Declaration JSP Declarations Declares one or more variables or methods that you can use in Java code later in the JSP files. The syntax of JSP Declarations <%! declaration; [declaration; ] +. %> Example <%! int i=0; %> <%! int a, b, c; %> <%! Circle a= new Circle(2.0) ; %> 17

18 Syntax : JSP Expression JSP Expression JSP expression element contains a scripting language expression that is evaluated, converted to a String, and inserted where the expression appears in the JSP file. The syntax of JSP Expression <%= expression %> Example Try it <html> <head><title>a Comment Test</title><head> <body> <p> Today's date: <%= (new java.util.date()).tolocalestring()%> </p> </body> </head> 18

19 Syntax : JSP Comments JSP Comments The syntax of JSP Comments <%-- This is JSP comment -- %> Example Try it! <html> <head><title>a Comment Test</title><head> <body> <h2> A Test of Comments </h2> <%-- This comment will not be visible in the page source --%> </h2> </body> </head> 19

20 Syntax : JSP Comments (cont d) A small numbers of special constructs you can use in various cases to insert comments or characters that would otherwise be treated specially 20

21 Syntax : Control-Flow Statement Control-Flow Statements You can use all the APIs and building blocks of Java in your JSP programming including decision making statements, loops etc Decision-Making Statements If else block. Try it! <%! int day = 3; %> <html> <head><title>if...else Example</title></head> <body> <% if (day == 1 day ==7) { %> <p> Today is weekend</p> <% } else {%> <p> Today is not weekend</p> <% } %> </body> </html> 21

22 Syntax : Control-Flow Statement (cont d) switch case block Try it! <%! int day = 3; %> <html> <head><title>switch...case Example</title></head> <body> <% switch(day) { case 0: out.println("it\'s Sunday."); break; case 1: out.println("it\'s Monday."); break; case 2: out.println("it\'s Tuesday."); break; case 3: case 4: case 5: default: } %> </body> </html> out.println("it\'s Wednesday."); break; out.println("it\'s Thursday."); break; out.println("it\'s Friday."); break; out.println("it\'s Saturday."); 22

23 Syntax : Control-Flow Statement (cont d) Loop Statements You can also use three basic types of looping blocks in Java : for, while, and do while blocks in your JSP programming. for loop Try it! <%! int fontsize; %> <html> <head><title>for LOOP Example</title></head> <body> <%for (fontsize =1;fontSize <=3;fontSize++) { %> <font color="green" size="<%=fontsize %>"> JSP Tutorial </font><br> <% } %> </body> </html> 23

24 Syntax : Control-Flow Statement (cont d) while loop <%! int fontsize; %> <html> <head><title>for LOOP Example</title></head> <body> <%while (fontsize <=3) { %> <font color="green" size="<%=fontsize %>"> JSP Tutorial </font><br> <%fontsize++; %> <%}%> </body> </html> 24

25 Syntax : Operators JSP Operators Following table give a list of all the operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom 25

26 Syntax : Literals JSP Literals Boolean : true and false Integer : as in Java Floating point : as in Java String : with single and double quotes; is escaped as \, is escaped as \, and \ is escaped as \\ Null : null 26

27 지시자의문법 목적 구성 웹컨테이너가 JSP 페이지를서블릿클래스로변환할때필요한여러가지정보들을기술하기위해사용하는문법 page 지시자 JSP 페이지전체에적용되는정보를기술 include 지시자 JSP 페이지에포함시킬파일 taglib 지시자 page 애트리뷰트 _ 목록 %> 해당페이지가 taglib library를사용할것인지의여부 Tag library의 URI <%@ include 애트리뷰트 _ 목록 %> 지시자이름 <%@ taglib 애트리뷰트 _ 목록 %> 27

28 Syntax : JSP Directives JSP Directives JSP directive affects the overall structure of the servlet class Usually has the following form <%@ directive attribute = value %> Three types of directive tag 28

29 Syntax : JSP Actions JSP Actions Use constructs in XML syntax to control the behavior of the servlet engine. You can dynamically insert a file, reuse JavaBeans components, forward the user to another page, or generate HTML for the Java plugin Syntax <jsp:action_name attribute= value > 29

30 Syntax : JSP Actions (cont d) Basically predefined functions 30

31 Syntax : Implicit Object JSP Implicit Objects 31

JSP - SYNTAX. Any text, HTML tags, or JSP elements you write must be outside the scriptlet. Following is the simple and first example for JSP:

JSP - SYNTAX. Any text, HTML tags, or JSP elements you write must be outside the scriptlet. Following is the simple and first example for JSP: http://www.tutorialspoint.com/jsp/jsp_syntax.htm JSP - SYNTAX Copyright tutorialspoint.com This tutorial will give basic idea on simple syntax ie. elements involved with JSP development: The Scriptlet: