Java Reference: JSP Quick Reference

Sunday, June 19, 2016

JSP Quick Reference

Java server pages

=>JSP Life Cycle

=>Implicit Objects

=>Directives

=>Actions

=>Database Interaction

=>Calling a JavaBean from a JSP page

=>Expression Langauage

=>JSP Standard Tag Library

=>Custom Tags

Day-1

===============

Nut and bolts of JSP
==============================
Directive
Scriptlet
Expression
Decleration

directive
-----------

decide behaviour of whole page

<%@ ............ %>

scriptlet

<% %>

pure java code

no html and jsp code

expression

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

declaration

<%! %>

JSP Comments

HTML Comment 

JSP Comment <%-- JSP Comment --%>

Understanding JSP with the help of a servlet:

class MySevlet extends HttpServlet
{
int i=0;

public void doGet(.........,...........)
{
sop("hi");

i++;
PrintWriter out=res.get...();
out.println(i);
}
}

abc.jsp

The counter code in Servlet

<%=i%>

out.println(i);

class MySevlet extends HttpServlet
{
int i=0;

public void foo(){}

public void doGet(.........,...........)
{
sop("hi");

i++;
PrintWriter out=res.get...();
out.println(i);
}
}

JSP directive

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.

<%@ page import="foo.*" session="false" %>

<%@ page language=“java” import=“java.util.Date(), java.util.Dateformate()” iserrorpage=“false”%>

A page directive can use up to thirteen different attributes *

Include directive

Defines text and code that gets added into the current page at translation time

<%@ include file="hi.html" %>

taglib directive

Defines tag libraries available to the JSP

<%@ taglib tagdir="/WEB-INF/tags/cool" prefix="cool" %>

import

Defines the Java import statements that'll be added to the generated servlet class isThreadSafe

Defines whether the generated servlet needs to implement the Single ThreadModel which as you know know is a bad thing

contentType
Defines the MIME type for the JSP response (default is "text/html")

isELIgnored*
Defines whether EL expressions are ignored when this page is translated

EL*

Expression language

isErrorPage

Defines whether the current page represents another JSPs error page

errorPage

Defines a URL to the resource to which uncaught Throwables should be sent

language

Defines the scripting language used in the scriptlets,
expressions and declarations,
only java is available at the moment

extends

Defines the superclass of the class this JSP will become

session

Defines whether the page will have an implicit session object

buffer

Defines how buffering is handled by the implicit out object (a reference to the jspWriter)

autoFlush

Defines whether the buffered output is flushed automatically

info

Defines a String that gets put into the translated page,
just so that you can get it using the generated servlets inherited getServletInfo() method

pageEncoding

Defines the character encoding for the JSP

----------------------------------------------------------------------------------

What is the syntax of the include directive?

a.jsp

b.jsp

<h1>file 2</h2>
<h1>india is shining?</h1>
<%=new Date()%>

we should not use include directive if the content of b.jsp is changing with time.

demo isError page and error page in JSP

a.jsp

<%@ page errorPage="b.jsp" isErrorPage="false"%>
<%

Dog d=null;

d.toString();

%>

b.jsp

<%@ page isErrorPage="true" %>

This is the Error page.The following error occurs:- <br>
<%= exception.toString() %>

Implicit Object

JspWriter out

HttpServletRequest request

request.setAttribute("key","foo");
String temp=request.getAttribute("key");

HttpServletResponse response

HttpSession session

session.setAttribute("key","foo");
String temp=session.getAttribute("key");

ServletContext application

application.setAttribute("key","foo");
String temp=application.getAttribute("key");

ServletConfig config

Throwable exception

PageContext pageContext (not in servlet)

is an handly way to access any type of scoped variable?

Object page (not in servlet)

Scope in JSP

application
session
page
request

Standard Actions

Tags that affect runtime behavior of JSP and
response send back to client

Std action types:

<jsp:useBean>
<jsp:setProperty>
<jsp:getProperty>
<jsp:forward/>
<<jsp:include/>
....
.....

RequestDispacher rd=request.getRequestDispacher("show.jsp");
rd.forward(req,res);

rd.include(req,res);

Equ code in JSP:

<jsp:include>
<jsp:forward>
(How to pass parameters in include and forward)

Simple login app with jsp only (bad code)
----------------------------------

<form action ="myLogin.jsp".
<input type="text" name="name"/>
<input type="password" name="pass"/>
<input type="submit"/>
</form>

<%
if((request.getParameter("name").equals("raj")) &&(request.getParameter("pass").equals("java")))
{
%>
<jsp:forward page="forward2.jsp"/>
<%
}
else
{
%>
<%@include file="index.jsp"%>
<%

}
%>

Passing parameter with dispatching

<jsp:include page="/foo2.jsp" >
<jsp:param name="sessionID" value="<%= session.getId() %>" />
</jsp:include>

Sepration of concern

=====================================

no business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Separation of concern

No business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Example:

<form action ="LoginServlet" method="get">
ID:<input type="text" name="id"/></br>
Name:<input type="text" name="name"/></br>
Pass:<input type="password" name="pass"/></br>
<input type="submit"/>
</form>

automatic type conversion

processing of bean

API for the Generated Servlet

==============================

jspInit()

--------
This method is called from the
init() method and it can be overridden

jspDestroy()

----------
This method is called from the servlets
destroy()
method and it too can be overridden

_jspService()

This method is called from the servlets
service()
the method which means its runs
in a separate thread for each request,
the container passes the request and response
object to this method.

You cannot override this method.

Initializing your JSP

-------------------------

put this in web.xml
---------------------

<web-app ...>

<servlet>
<servlet-name>foo</servlet-name>
<jsp-file>/index.jsp</jsp-file>

<init-param>
<param-name>email</param-name>
<param-value>rgupta.mtech@gmail.com</param-value>
</init-param>

</servlet>

<servlet-mapping>
<servlet-name>foo</servlet-name>
<url-pattern>/index.jsp</url-pattern>
</servlet-mapping>

</web-app>

now getting them in init method
===============================

<%!
public void jspInit()
{

ServletConfig sConfig = getServletConfig();
String emailAddr = sConfig.getInitParameter("email");
ServletContext ctx = getServletContext();
ctx.setAttribute("mail", emailAddr);
}

%>

now get attributes in service method
===============================

<%= "Mail Attribute is: " + application.getAttribute("mail") %>

<%= "Mail Attribute is: " + pageContext.findAttribute("mail") %>

<%
ServletConfig sConfig = getServletConfig();
String emailAddr = sConfig.getInitParameter("email");
out.println("<br><br>Another way to get web.xml attributes: " + emailAddr );
%>

<%
out.println("<br><br>Yet another way to get web.xml attributes: " + getServletConfig().getInitParameter("email") );
%>

Setting scoped attributes in JSP
================================

Application
-----------

in servlet
----------
getServletContext().setAttribute("foo",barObj);

in jsp
--------
application.setAttribute("foo",barObj);

Request
--------

in servlet
----------
request.setAttribute("foo",barObj);

in jsp
--------
request.setAttribute("foo",barObj);

Session
--------

in servlet
----------
request.getSession().setAttribute("foo",barObj);

in jsp
--------
session.setAttribute("foo",barObj);

Page
-------

in servlet
----------
do not apply

in jsp
--------
pageContext.setAttribute("foo",barObj);

Note
============

Using the pageContext to get a session-scoped attribute
------------------------------------------------------------

<%= pageContext.getAttribute("foo", PageContext.SESSION_SCOPE ) %>

Using the pageContext to get an application-scoped attribute
------------------------------------------------------------
<%= pageContext.getAttribut("mail", PageContext.APPLICATION_SCOPE) %>

Using the pageContext to find an attribute
when you don't know the scope
-----------------------------
<%= pageContext.findAttribute("mail") %>

Basic of jsp model
-------------------

script file converted into eq servlet.

no diff between servlet and jsp

nut and bolts of jsp
-----------------

Directive
---------
include

taglib*

page

Scriptlet
-------
pure java code
must be avoided diff to avoide

expression
---------
aka of short cut for out.print()

decleation
----------
<%!

%>

whatever u want to put in insta/static

comments
-------
jsp comm
html comm:show in view source

include directive and include action
----------------------------------------
if content is changing dynamicall always go for action

scope
======
page
request
session
application

pageContext

Std action
---------
<jsp:useBean........./>

<jsp:setProperty ............/>
<jsp:getProperty ............../>

java bean internally use reflection and serl...?
------------------------------------------------
what is reflection *

JSP key topics
=======================
Java bean in jsp

EL: Expression language

JSTL

JSP std tag liberary

Custome tag

Should be used in place of scriptlet
---------

=============================
Day-2
==========================

Expression Language Introduction ( E L )
-----------------------------------

Putting java code in jsp is bad habbit

Scriplet in ur project u may be gone!

then what to do?
---------------

Use EL
JSP 2.0 spec. EL offers a simpler way to
invoke Java code but code itself belongs somewhere else

Although EL looks like Java it behaves differently,
so do not try and map the same Java with EL.

EL are always within curly braces
and prefixed with the dollar sign.

The first named variable in the expression is either an implicit object or an attribute

how EL make my life easy....
-------------------------------

EL example
------------
old way don't do now
--------------------

Please contact: <%= application.getAttribute("mail") %>

EL way
------

please contact: ${applicationScope.mail}

stop JSP from using scripting elements
--------------------------------------

<web-app ...>
...
<jsp-config>

<jsp-property-group>

<url-pattern>*.jsp</url-pattern>

<scripting-invalid>true</scripting-invalid>

</jsp-property-group>

</jsp-config>
...
</web-app>

stop using EL
-------------
<%@ page isELIgnored="true" %>

Note: this takes priority over the DD tag above

Scriptless JSP
=============

why we should not use scriplet?

EL provide better way to accept DTO send from controller to view

Some Ex:
======

Consiser Servlet (controller) code
-----------------------------------

Person p = new Person();

p.setName("Paul");

request.setAttribute("person", p);

RequestDispatcher view = request.getRequestDispatcher("result.jsp");

view.forward(request, response);

JSP (view) code
-----------------
Person is: <%= request.getAttribute("person") %>

Does it work?

Correct way?
--------------
<% Person p = (Person) request.getAttribute("person");

Person is: <%= p.getName() %>

or

Person is: <%= ((Person) request.getAttribute ("person")).getName() %>

Correct Way
----------

<jsp:useBean id="person" class="foo.Person" scope="request" />

Person is: <jsp:getProperty name="person" property="name" />

class Person
{
private String name;
....
...
...
}

public class Dog
{
private String dogName;
.....
.....
}

public class Person
{
private String personName;
private Dog dog;

.....
.....
}

Person has A dog
----

Dog dog=new Dog();

dog.setDogName("myDog");

Person p=new Person();

p.setPersonName("foo");

p.setDog(dog);

request.setAttribute("person", p);

--------------------------------------------------------------------------------------

Expression Language
====================

More examples
--------------

consider controller code
----------------------

adding persons dog in request attributes in an servlet
-----------------------------------------------------------

foo.Person p = new foo.Person();

p.setName("Paul");

foo.Dog dog = new foo.Dog();

dog.setName("Spike");

p.setDog(dog);

request.setAttribute("person", p);

getting same in jsp
------------------------

using tags

<%= ((Person) request.getAttribute("person")).getDog().getName() %>

Dog name: ${person.dog.dogName}

using EL

Dog's name is: ${person.dog.name}

Some more examples
--------------------

in servlet
---------

String[] footballTeams = { "Liverpool", "Manchester Utd", "Arsenal", "Chelsea" }

request.setAttribute("footballList", footballTeams);

in jsp
---------

Favorite Team: ${footballList[0]}

Worst Team: ${footballList["1"]}

Note ["one"] would not work but ["10"] would

<%-- using the arraylist toString()
---------------------------------

All the teams: ${footballList}

Another Example
--------------

servlet code
----------------

java.util.Map foodMap = new java.util.HashMap();

foodMap.put("Fruit", "Banana");
foodMap.put("TakeAway", "Indian");
foodMap.put("Drink", "Larger");
foodMap.put("Dessert", "IceCream");
foodMap.put("HotDrink", "Coffee");

String[] foodTypes = {"Fruit", "TakeAway", "Drink", "Dessert", "HotDrink"}

request.setAttribute("foodMap", foodMap);
request.setAttribute("foodTypes",foodTypes);

JSP code
---------

Favorite Hot Drink is: ${foodMap.HotDrink}

Favorite Take-Away is: ${foodMap["TakeAway"]}

Favorite Dessert is: ${foodMap[foodTypes[3]]}

EL

Ex:
There may be cases when you want multiple values for one given
parameter name, which is when you use paramValues
============================================================

HTML Form
-----------

<html><body>

<form action="TestBean.jsp">
name: <input type="text" name="name">
ID: <input type="text" name="empID">

First food: <input type="text" name="food">
Second food: <input type="text" name="food">

<input type="submit">
</form>

</body></html>

JSP Code
-----------

Request param name is: ${param.name} <br>

Request param empID is: ${param.empID} <br>

<%-- you will only get the first value -->

Request param food is: ${param.food} <br>

First food is: ${paramValues.food[0]} <br>

Second food is: ${paramValues.food[1]} <br>

Here are some other parameters you can obtain,
-----------------------------------------------------

host header
--------

Host is: <%= request.getHeader("host”) %>

Host is: ${header["host"]}
Host is: $header.host}

whether Request is post or get ?
---------------------------------
Method is: ${pageContext.request.method}

Cookie information
-----------------
Username is: ${cookie.userName.value}

Context init parameter (need to configure in dd)
-----------------------

email is: <%= application.getInitParameter("mainEmail") %>

email is: {$initParam.mainEmail}

What has been covered till now
--------------------------------

directive
--------
<%@ page import="java.util.*" %>

declaration
---------
<%! int y = 3; %>
EL Expression
-------------
email: ${applicationScope.mail}

scriptlet
---------
<% Float one = new Float(42.5); %>

expression
---------
<%= pageContext.getAttribute(foo") %>

action
---------
<jsp:include page="foo.html" />

JSTL

Custom tag

DONT COOK UR FOOD IF U GET GREATE COOKED FOOD

jstl

JSTL
====================================================
JSP std tag library
---------------------

core

formatting

sql

xml

String functions

Custom tags
-----------
user defind tags.

in case JSTL dont have tag to solve ur problem.

then go for custom tags

(Dont cook food urself if get cooked food)

JSTL
=======

The JSTL is hugh, version 1.2 has five libraries,
four with custom tags and one with a bunch of functions for String manipulation

•JSTL Core - core c

•JSTL fmt - formatting fmt

•JSTL XML - xml xmt

•JSTL sql - sql

•JSTL function - string manipulation

standard.jar
jstl.jar

Hello world jstl
======================

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html><body>
...
<c:forEach var="i" begin="1" end="10" >
<c:out value="${i}" />
</c:forEach>
...
</body></html>

JSp is all about how to display data in best way!!!

Example with map
=================

Map<Integer,String>map=new HashMap<Integer, String>();
map.put(22, "foo");
map.put(44, "bar");
map.put(55, "jar");
map.put(88, "war");
request.setAttribute("map", map);
RequestDispatcher rd=request.getRequestDispatcher("show2.jsp");
rd.forward(request,response);

Now in JSP
-------------------

<c:forEach var="i" items="${map}">
key: ${i.key }-value: ${i.value}<br>
</c:forEach>

Step 1:

create view:
---------------

create form:

<html><body>
<h1 align="center">Book Selection Page</h1>
<form action="SelectBook" method="post">
Select book <p>

Book:
<select name="topic" size="1">
<option value="Java">Java</option>
<option value="Servlet">Servlet</option>
<option value="Struts">Struts</option>

</select>
<br><br>
<center>
<input type="submit">
</center>
</form>
</body>
</html>

Create controller
---------------------

String topic=request.getParameter("topic");
List<String>choices=BookAdviser.bookAdviser(topic);
request.setAttribute("booklist", choices);
RequestDispatcher rd=request.getRequestDispatcher("show2.jsp");
rd.forward(request, response);

create model
-----------------

public class BookAdviser {

public static List<String> bookAdviser(String topic){
List<String>list=new ArrayList<String>();

if(topic.equalsIgnoreCase("Java")){
list.add("head first");
list.add("thinking in java");
}else if(topic.equalsIgnoreCase("Servlet")){
list.add("head first servlet jsp");
list.add("core servlet.com");
}else if(topic.equalsIgnoreCase("Struts")){
list.add("struts2 in action");
list.add("black book");
}else
list.add("no book");

return list;
}

view
------------

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<c:forEach var="book" items="${booklist}">
<b> ${book} </b><br/>
</c:forEach>

custom tag library
---------------------

custom tag that simply print "hi"

hello world
---------------
step 1:
create an simple tag handler SimpleHelloTag in com.tags package

public class SimpleHelloTag extends SimpleTagSupport {

@Override
public void doTag() throws JspException, IOException {
JspWriter out = getJspContext().getOut();

out.print("hi");
}
}

step 2:
create hello taglib tld file
--------------------------------

hello-taglib.tld

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<tlib-version>1.0</tlib-version>
<short-name>hello-taglib</short-name>

<tag>
<description>hello world exmple</description>
<name>hello</name>
<tag-class>coreservlets.tags.SimpleHelloTag</tag-class>
<body-content>empty</body-content>
</tag>

</taglib>

step 3:
----------

invoke from jsp;

<%@ taglib uri="/WEB-INF/tlds/hello-taglib.tld" prefix="hello" %>

<hello:hello/>

custom tag library
---------------------

hello world with attributes
----------------------------

step 1:
add following to tag definations

<attribute>
<name>length</name>
<required>false</required>
</attribute>

step 2:

provide getter setter in corrosponding tag handler class

public class SimpleHelloTag extends SimpleTagSupport {
private String length;

public String getLength() {
return length;
}

public void setLength(String length) {
this.length = length;
}

step 3:

then use it:

<hello:hello length="raj"/>

Ex 3:
including the tag body
----------------------

rather then
<hello:hello length="raj"/>

Now want to have:

<hello:hello length="raj">
this is an body example! (Scriptless jsp contents)
</hello:hello>

Step 1;

call getJsbBody().invoke(null) method from doTag()

public void doTag() throws JspException, IOException {
JspWriter out = getJspContext().getOut();

out.print(length);

getJspBody().invoke(null);

out.print("hi");
}

Step 2;

change body contents form TLD from empty to scriptless

Example:
-----------------
custom tag with body:

step 1:

create an tag class

com.jsp.customtags packages

public class SubstrTagHandler extends TagSupport {
private String input;
private int start;
private int end;

@Override
public int doStartTag() throws JspException {

try {
//Get the writer object for output.
JspWriter out = pageContext.getOut();

//Perform substr operation on string.
out.println(input.substring(start, end));

} catch (IOException e) {
e.printStackTrace();
}
return SKIP_BODY;
}
public String getInput() {
return input;
}
public void setInput(String input) {
this.input = input;
}
public int getStart() {
return start;
}
public void setStart(int start) {
this.start = start;
}
public int getEnd() {
return end;
}
public void setEnd(int end) {
this.end = end;
}
}

step 2:
create an tld file:

<?xml version="1.0" encoding="UTF-8"?>
<taglib>
<tlibversion>1.0</tlibversion>
<jspversion>1.1</jspversion>
<shortname>substr</shortname>
<info>Sample taglib for Substr operation</info>
<uri>http://rajsupport.net/blogs/jsp/taglib/substr</uri>
<tag>
<name>substring</name>
<tagclass>com.jsp.customtags.SubstrTagHandler</tagclass>
<info>Substring function.</info>

<attribute>
<name>input</name>
<required>true</required>
</attribute>

<attribute>
<name>start</name>
<required>true</required>
</attribute>

<attribute>
<name>end</name>
<required>true</required>
</attribute>
</tag>
</taglib>

step 3:
use it in jsp

<%@taglib prefix="test" uri="/WEB-INF/SubstrDescriptor.tld"%>

<test:substring input="GOODMORNING" start="1" end="6"/>

Dynamic attribute and Looping tags
----------------------------------------

tag example that support dynamic Attribute values:

<rtexprvalue>true</rtexprvalue>

public class ForTag extends SimpleTagSupport {
private int count;

public void setCount(int count) {
this.count = count;
}

@Override
public void doTag() throws JspException, IOException {
for(int i=0; i<count; i++) {
getJspBody().invoke(null);
}
}
}

tld
----

<tag>
<description>
Loops specified number of times.
</description>
<name>for</name>
<tag-class>com.tags.ForTag</tag-class>
<body-content>scriptless</body-content>
<attribute>
<description>
Number of times to repeat body.
</description>
<name>count</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>

Coin bean
-----------
public class CoinBean {
public String getFlip() {
if (Math.random() < 0.5) {
return("Heads");
} else {
return("Tails");
}
}
}

Servlet
------------

....
CoinBean coin = new CoinBean();
request.setAttribute("coin", coin);

RequestDispatcher dispatcher =
request.getRequestDispatcher(test-loop.jsp);
dispatcher.forward(request, response);

testing
------------
<c:for count="<%=(int)(Math.random()*10)%>">
<LI>Blah
</c:for>
</UL>
<H2>Some Coin Flips</H2>
<UL>
<c:for count="<%=(int)(Math.random()*10)%>">
<LI>${coin.flip}
</c:for>

Complex Dynamic attribute and Looping tags
----------------------------------------

What if u want type other then String or primitive type for an tag
attribute value?

Attribute should accept an collection.

tag
--------

public class ForEachTag extends SimpleTagSupport {
private Object[] items;
private String attributeName;

public void setItems(Object[] items) {
this.items = items;
}

public void setVar(String attributeName) {
this.attributeName = attributeName;
}

@Override
public void doTag() throws JspException, IOException {
for(Object item: items) {
getJspContext().setAttribute(attributeName, item);
getJspBody().invoke(null);
}
}
}

<tag>
<description>
Loops down each element in an array
</description>
<name>forEach</name>
<tag-class>com.tags.ForEachTag</tag-class>
<body-content>scriptless</body-content>
<attribute>
<description>
The array of elements.
</description>
<name>items</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>
The name of the local variable that
each entry will be assigned to.
</description>
<name>var</name>
<required>true</required>
</attribute>
</tag>

Servlet
----------------

String[] servers =
{"Tomcat", "Resin", "Jetty", "WebLogic",
"WebSphere", "JBoss", "Glassfish" };
request.setAttribute("servers", servers);

RequestDispatcher dispatcher =
request.getRequestDispatcher(loop-test.jsp);
dispatcher.forward(request, response);

using it
------------

<c:forEach items="${servers}" var="server">
<LI>${server}
</c:forEach>

.metadata\.plugins\org.eclipse.wst.server.core\tmp0

http://www.sitepoint.com/jsp-2-simple-tags/

http://www.coderanch.com/t/174748/java-Web-Component-SCWCD/certification/Difference-EVAL-BODY-INCLUDE-EVAL

https://www.mail-archive.com/jsp-interest@java.sun.com/msg15923.html

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Sunday, June 19, 2016

JSP Quick Reference

Java server pages

scriptlet

<% %>

pure java code

no html and jsp code

expression

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

declaration

<%! %>

JSP Comments

HTML Comment 

JSP Comment <%-- JSP Comment --%>

Understanding JSP with the help of a servlet:

class MySevlet extends HttpServlet
{
int i=0;

public void doGet(.........,...........)
{
sop("hi");

i++;
PrintWriter out=res.get...();
out.println(i);
}
}

abc.jsp

The counter code in Servlet

JSP directive

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.

<%@ page import="foo.*" session="false" %>

<%@ page language=“java” import=“java.util.Date(), java.util.Dateformate()” iserrorpage=“false”%>

A page directive can use up to thirteen different attributes *

Include directive

Defines text and code that gets added into the current page at translation time

<%@ include file="hi.html" %>

taglib directive

Defines tag libraries available to the JSP

<%@ taglib tagdir="/WEB-INF/tags/cool" prefix="cool" %>

import

EL*

Expression language

isErrorPage

Defines whether the current page represents another JSPs error page

errorPage

Defines a URL to the resource to which uncaught Throwables should be sent

language

Defines the scripting language used in the scriptlets,
expressions and declarations,
only java is available at the moment

extends

Defines the superclass of the class this JSP will become

session

Defines whether the page will have an implicit session object

buffer

Defines how buffering is handled by the implicit out object (a reference to the jspWriter)

autoFlush

Defines whether the buffered output is flushed automatically

info

Defines a String that gets put into the translated page,
just so that you can get it using the generated servlets inherited getServletInfo() method

pageEncoding

Defines the character encoding for the JSP

----------------------------------------------------------------------------------

What is the syntax of the include directive?

a.jsp

b.jsp

<h1>file 2</h2>
<h1>india is shining?</h1>
<%=new Date()%>

we should not use include directive if the content of b.jsp is changing with time.

demo isError page and error page in JSP

a.jsp

<%@ page errorPage="b.jsp" isErrorPage="false"%>
<%

Dog d=null;

d.toString();

%>

b.jsp

<%@ page isErrorPage="true" %>

This is the Error page.The following error occurs:- <br>
<%= exception.toString() %>

Implicit Object

ServletContext application

Scope in JSP

application
session
page
request

Standard Actions

Passing parameter with dispatching

<jsp:include page="/foo2.jsp" >
<jsp:param name="sessionID" value="<%= session.getId() %>" />
</jsp:include>

Sepration of concern

=====================================

no business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Separation of concern

No business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Example:

API for the Generated Servlet

==============================

jspInit()

--------
This method is called from the
init() method and it can be overridden

jspDestroy()

----------
This method is called from the servlets
destroy()
method and it too can be overridden

_jspService()

Initializing your JSP

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

Sunday, June 19, 2016

JSP Quick Reference

Java server pages

scriptlet

<% %>

pure java code

no html and jsp code

expression

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

declaration

<%! %>

JSP Comments

HTML Comment 

JSP Comment <%-- JSP Comment --%>

Understanding JSP with the help of a servlet:

class MySevlet extends HttpServlet
{
int i=0;

public void doGet(.........,...........)
{
sop("hi");

i++;
PrintWriter out=res.get...();
out.println(i);
}
}

abc.jsp

The counter code in Servlet

JSP directive

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.

<%@ page import="foo.*" session="false" %>

<%@ page language=“java” import=“java.util.Date(), java.util.Dateformate()” iserrorpage=“false”%>

A page directive can use up to thirteen different attributes *

Include directive

Defines text and code that gets added into the current page at translation time

<%@ include file="hi.html" %>

taglib directive

Defines tag libraries available to the JSP

<%@ taglib tagdir="/WEB-INF/tags/cool" prefix="cool" %>

import

EL*

Expression language

isErrorPage

Defines whether the current page represents another JSPs error page

errorPage

Defines a URL to the resource to which uncaught Throwables should be sent

language

Defines the scripting language used in the scriptlets,
expressions and declarations,
only java is available at the moment

extends

Defines the superclass of the class this JSP will become

session

Defines whether the page will have an implicit session object

buffer

Defines how buffering is handled by the implicit out object (a reference to the jspWriter)

autoFlush

Defines whether the buffered output is flushed automatically

info

Defines a String that gets put into the translated page,
just so that you can get it using the generated servlets inherited getServletInfo() method

pageEncoding

Defines the character encoding for the JSP

----------------------------------------------------------------------------------

What is the syntax of the include directive?

a.jsp

b.jsp

<h1>file 2</h2>
<h1>india is shining?</h1>
<%=new Date()%>

we should not use include directive if the content of b.jsp is changing with time.

demo isError page and error page in JSP

a.jsp

<%@ page errorPage="b.jsp" isErrorPage="false"%>
<%

Dog d=null;

d.toString();

%>

b.jsp

<%@ page isErrorPage="true" %>

This is the Error page.The following error occurs:- <br>
<%= exception.toString() %>

Implicit Object

ServletContext application

Scope in JSP

application
session
page
request

Standard Actions

Passing parameter with dispatching

<jsp:include page="/foo2.jsp" >
<jsp:param name="sessionID" value="<%= session.getId() %>" />
</jsp:include>

Sepration of concern

=====================================

no business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Separation of concern

No business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Example:

API for the Generated Servlet

==============================

jspInit()

--------
This method is called from the
init() method and it can be overridden

jspDestroy()

----------
This method is called from the servlets
destroy()
method and it too can be overridden

_jspService()

Initializing your JSP

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

Sunday, June 19, 2016

JSP Quick Reference

Java server pages

scriptlet

<% %>

pure java code

no html and jsp code

expression

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

declaration

<%! %>

JSP Comments

HTML Comment 

JSP Comment <%-- JSP Comment --%>

Understanding JSP with the help of a servlet:

class MySevlet extends HttpServlet
{
int i=0;

public void doGet(.........,...........)
{
sop("hi");

i++;
PrintWriter out=res.get...();
out.println(i);
}
}

abc.jsp

The counter code in Servlet

JSP directive

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.

<%@ page import="foo.*" session="false" %>

<%@ page language=“java” import=“java.util.Date(), java.util.Dateformate()” iserrorpage=“false”%>

A page directive can use up to thirteen different attributes *

Include directive

Defines text and code that gets added into the current page at translation time

<%@ include file="hi.html" %>

taglib directive

Defines tag libraries available to the JSP

<%@ taglib tagdir="/WEB-INF/tags/cool" prefix="cool" %>

import

EL*

Expression language

isErrorPage

Defines whether the current page represents another JSPs error page

errorPage

Defines a URL to the resource to which uncaught Throwables should be sent

language

Defines the scripting language used in the scriptlets,
expressions and declarations,
only java is available at the moment

extends

Defines the superclass of the class this JSP will become

session

Defines whether the page will have an implicit session object

buffer

Defines how buffering is handled by the implicit out object (a reference to the jspWriter)

autoFlush

Defines whether the buffered output is flushed automatically

info

Defines a String that gets put into the translated page,
just so that you can get it using the generated servlets inherited getServletInfo() method

pageEncoding

Defines the character encoding for the JSP

----------------------------------------------------------------------------------

What is the syntax of the include directive?

a.jsp

b.jsp

<h1>file 2</h2>
<h1>india is shining?</h1>
<%=new Date()%>

we should not use include directive if the content of b.jsp is changing with time.

demo isError page and error page in JSP

a.jsp

<%@ page errorPage="b.jsp" isErrorPage="false"%>
<%

Dog d=null;

d.toString();

%>

b.jsp

<%@ page isErrorPage="true" %>

This is the Error page.The following error occurs:- <br>
<%= exception.toString() %>

Implicit Object

ServletContext application

Scope in JSP

application
session
page
request

Standard Actions

Passing parameter with dispatching

<jsp:include page="/foo2.jsp" >
<jsp:param name="sessionID" value="<%= session.getId() %>" />
</jsp:include>

Sepration of concern

=====================================

no business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Separation of concern

No business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Example:

API for the Generated Servlet

==============================

jspInit()

--------
This method is called from the
init() method and it can be overridden

jspDestroy()

----------
This method is called from the servlets
destroy()
method and it too can be overridden

_jspService()

Initializing your JSP

No comments:

Post a Comment

Sunday, June 19, 2016

JSP Quick Reference

Java server pages

scriptlet

<% %>

pure java code

no html and jsp code

expression

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

declaration

<%! %>

JSP Comments

HTML Comment 

JSP Comment <%-- JSP Comment --%>

Understanding JSP with the help of a servlet:

class MySevlet extends HttpServlet
{
int i=0;

public void doGet(.........,...........)
{
sop("hi");

i++;
PrintWriter out=res.get...();
out.println(i);
}
}

abc.jsp

The counter code in Servlet

JSP directive

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.

<%@ page import="foo.*" session="false" %>

<%@ page language=“java” import=“java.util.Date(), java.util.Dateformate()” iserrorpage=“false”%>

A page directive can use up to thirteen different attributes *

Include directive

Defines text and code that gets added into the current page at translation time

<%@ include file="hi.html" %>

taglib directive

Defines tag libraries available to the JSP

<%@ taglib tagdir="/WEB-INF/tags/cool" prefix="cool" %>

import

EL*

Expression language

isErrorPage

Defines whether the current page represents another JSPs error page

errorPage

Defines a URL to the resource to which uncaught Throwables should be sent

language

Defines the scripting language used in the scriptlets,
expressions and declarations,
only java is available at the moment

extends

Defines the superclass of the class this JSP will become

session

Defines whether the page will have an implicit session object

buffer

Defines how buffering is handled by the implicit out object (a reference to the jspWriter)

autoFlush

Defines whether the buffered output is flushed automatically

info

Defines a String that gets put into the translated page,
just so that you can get it using the generated servlets inherited getServletInfo() method

pageEncoding

Defines the character encoding for the JSP

----------------------------------------------------------------------------------

What is the syntax of the include directive?

a.jsp

b.jsp

<h1>file 2</h2>
<h1>india is shining?</h1>
<%=new Date()%>

we should not use include directive if the content of b.jsp is changing with time.

demo isError page and error page in JSP

a.jsp

<%@ page errorPage="b.jsp" isErrorPage="false"%>
<%

Dog d=null;

d.toString();

%>

b.jsp

<%@ page isErrorPage="true" %>

This is the Error page.The following error occurs:- <br>
<%= exception.toString() %>

Implicit Object

ServletContext application

Scope in JSP

application
session
page
request

Standard Actions

Passing parameter with dispatching

<jsp:include page="/foo2.jsp" >
<jsp:param name="sessionID" value="<%= session.getId() %>" />
</jsp:include>

Sepration of concern

=====================================

no business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Separation of concern

No business logic should be done in jsp at any cost

<jsp:useBean>

<jsp:setProperty>

<jsp:getProperty>

Example:

API for the Generated Servlet

==============================

jspInit()

--------
This method is called from the
init() method and it can be overridden

jspDestroy()

----------
This method is called from the servlets
destroy()
method and it too can be overridden

Sunday, June 19, 2016

JSP Quick Reference

Java server pages

scriptlet

expression

<%= i %> out.prinln(i); the expression is a replacement (Shortcut of out.println() )

declaration

<%! %>

JSP Comments

HTML Comment  JSP Comment <%-- JSP Comment --%>

Understanding JSP with the help of a servlet:

The counter code in Servlet

JSP directive

<%@ .... %> •page directive

Defines page-specific properties such as character encoding, the content type for this pages response and whether this the page should have the implicit session object.

<%@ page import="foo.*" session="false" %>

<%@ page language=“java” import=“java.util.Date(), java.util.Dateformate()” iserrorpage=“false”%>

A page directive can use up to thirteen different attributes *

Include directive

taglib directive

import

EL*

Expression language

isErrorPage

errorPage

language

extends

session

buffer

autoFlush

info

pageEncoding

What is the syntax of the include directive?

a.jsp

b.jsp

we should not use include directive if the content of b.jsp is changing with time.

demo isError page and error page in JSP

a.jsp

b.jsp

Implicit Object

ServletContext application

Scope in JSP

Standard Actions

Passing parameter with dispatching

Sepration of concern

no business logic should be done in jsp at any cost

Separation of concern

No business logic should be done in jsp at any cost

Example:

API for the Generated Servlet

jspInit()

jspDestroy()

_jspService()

Initializing your JSP

No comments:

Post a Comment

Java server pages

scriptlet

expression

<%= i %> out.prinln(i); the expression is a replacement (Shortcut of out.println() )

declaration

<%! %>

JSP Comments

HTML Comment  JSP Comment <%-- JSP Comment --%>

Understanding JSP with the help of a servlet:

The counter code in Servlet

JSP directive

<%@ .... %> •page directive

Defines page-specific properties such as character encoding, the content type for this pages response and whether this the page should have the implicit session object.

<%@ page import="foo.*" session="false" %>

<%@ page language=“java” import=“java.util.Date(), java.util.Dateformate()” iserrorpage=“false”%>

A page directive can use up to thirteen different attributes *

Include directive

taglib directive

import

EL*

Expression language

isErrorPage

errorPage

language

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

HTML Comment 

JSP Comment <%-- JSP Comment --%>

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

HTML Comment 

JSP Comment <%-- JSP Comment --%>

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.

<%= i %>

out.prinln(i);

the expression is a replacement (Shortcut of out.println() )

HTML Comment 

JSP Comment <%-- JSP Comment --%>

<%@ .... %>
•page directive

Defines page-specific properties such as character encoding,
the content type for this pages response and whether this the page should have the implicit session object.