JSP (Java Server Page)

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Elmer Reeves
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1 JSP (Java Server Page) Lab

2 JSP JSP simply puts Java inside HTML pages. <%-- hello1.jsp --%> <HTML> <BODY> Hello! The time is now <%= new java.util.date() %> 2

3 hello1_ex.jsp 3

4 hello1_ex.jsp <html> <body> <table border="2"> <thead> <tr> <th>name </th> <th>value</th> </tr> </thead> <tbody> <tr> <td>os.name</td><td><%= System.getProperty( os.name") %></td> </tr> <tr> <td>java.version</td><td><%= System.getProperty("java.version") %></td> </tr> <tr> <td>java.home</td><td><%= System.getProperty("java.home") %></td> </tr> <tr> <td>user.name</td><td><%= System.getProperty("user.name") %></td> </tr> <tr> <td>user.home</td><td><%= System.getProperty("user.home") %></td> </tr> <tr> <td>user.dir</td><td><%= System.getProperty("user.dir") %></td> </tr> </tbody> </table> </body> </html> 4

5 Scriptlets JSP also allows you to write blocks of Java code inside the JSP. You do this by placing your Java code between <% and %> characters (just like expressions, but without the = sign at the start of the sequence.) This block of code is known as a "scriptlet". By itself, a scriptlet doesn't contribute any HTML A scriptlet contains Java code that is executed every time the JSP is invoked 5

6 Scriptlets <HTML> <BODY> <% // This is a scriptlet. Notice that the "date" // variable we declare here is available in the // embedded expression later on. java.util.date date = new java.util.date(); %> Hello! The time is now <%= date %> 6

7 Scriptlets <HTML> <BODY> <% %> // This is a scriptlet. Notice that the "date" // variable we declare here is available in the // embedded expression later on. java.util.date date = new java.util.date(); Hello! The time is now <% %> // This scriptlet generates HTML output out.println( String.valueOf( date )); If a scriptlet wants to generate HTML, it can use a variable called "out". The "out" variable is of type javax.servlet.jsp.jspwriter 7

8 Scriptlets <HTML> <BODY> <% // This scriptlet declares and initializes "date" System.out.println( "Evaluating date now" ); java.util.date date = new java.util.date(); %> Hello! The time is now <% out.println( date ); out.println( "<BR>Your machine's address is " ); out.println( request.getremotehost()); %> 8

9 hello3.jsp 9

10 hello3.jsp <HTML> <BODY> <TABLE BORDER=2> <% int n = 10 ; for ( int i = 0; i < n; i++ ) { %> <TR> <TD>Number</TD> <TD><%= i+1 %></TD> </TR> <% } %> </TABLE> 10

11 JSP Directives page import="java.util.*" %> <HTML> <BODY> <% Date date = new Date(); %> Hello! The time is now <%= date %> <%@ page import="java.util.*" %> <HTML> <BODY> Going to include hello.jsp...<br> <%@ include file="hello.jsp" %> 11

12 JSP Declarations page import="java.util.*" %> <HTML> <BODY> <%! Date thedate = new Date(); Date getdate() { System.out.println( "In getdate() method" ); return thedate; } %> Hello! The time is now <%= getdate() %> 12

13 JSP Tags <html> <body> Going to include hello1.jsp...<br> <jsp:include page="hello1.jsp"/> <BR> Going to include hello1_ex.jsp... <jsp:include page="hello1_ex.jsp"/> </body> </html> 13

14 JSP Tags What if forward instead of include? 14

15 JSP Sessions 15

16 JSP Sessions Getname.html <HTML> <BODY> <FORM METHOD=POST ACTION="SaveName.jsp"> What's your name? <INPUT TYPE=TEXT NAME=username SIZE=20> <P> <INPUT TYPE=SUBMIT> </FORM> 16

17 JSP Sessions SaveName.jsp <% String name = request.getparameter( "username" ); session.setattribute( "thename", name ); %> <HTML> <BODY> <A HREF="NextPage.jsp">Continue</A> 17

18 JSP Sessions NextPage.jsp <HTML> <BODY> Hello, <%= session.getattribute( "thename" ) %> 18

19 Another Example 19

20 Another Example GetName2.html <HTML> <BODY> <FORM METHOD=POST ACTION="SaveName2.jsp"> What's your name? <INPUT TYPE=TEXT NAME=username SIZE=20> <BR>What's your address? <INPUT TYPE=TEXT NAME= SIZE=20> <BR> What's your age? <INPUT TYPE=TEXT NAME=age SIZE=4> <P> <INPUT TYPE=SUBMIT> </FORM> 20

21 Another Example SaveName2.jsp <jsp:usebean id="user" class="user.userdata" scope="session"/> <jsp:setproperty name="user" property="*"/> <HTML> <BODY> <A HREF="NextPage2.jsp">Continue</A> 21

22 Another Example user\userdata.java package user; public class UserData { private String username; private String ; private int age; } public void setusername( String value ) { username = value; } public void set ( String value ) { = value; } public void setage( int value ) { age = value; } public String getusername() { return username; } public String get () { return ; } public int getage() { return age; } 22

23 Another Example NextPage2.jsp <jsp:usebean id="user" class="user.userdata" scope="session"/> <HTML> <BODY> You entered<br> Name: <%= user.getusername() %> <BR> <%= user.get () %> <BR> Age: <%= user.getage() %> <BR> 23

Principles and Techniques of DBMS 6 JSP & Servlet

Principles and Techniques of DBMS 6 JSP & Servlet Haopeng Chen REliable, INtelligent and Scalable Systems Group (REINS) Shanghai Jiao Tong University Shanghai, China http://reins.se.sjtu.edu.cn/~chenhp