Notes for J2EE
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Transcript of Notes for J2EE
select - dynamic projectWeb content - JSP, CSS, java script, images
startserver from window
select the JSP file --> run on server
URL has two parts -static and dynamic
http://localhost:8080/FirstProject/FirstPage.jsp-----static-----------------------|--dynamic---|
change the index.html to jsp page you want to display as first page --it shouldbe changed inweb.xml
after change in web.xml - restart the server
this will pick from web.xml to display the page
input tag for inputs
inside tag - we have attributes<input type="text">
end tage is not manadatory for input, bold, para,
<br> - break tag
<select> tag wll create empty drop down box<option> tag
type of button- submit, reset, button
to send the data from jsp
servlets - is java class, it will read value from user or web browser, and it validate the dataand it will pass the sl to database
finally it redirect to next page depend on sql output
URL mapping while creating servlets
add servlets jar - servlet- api.jar
eclipse create mapping in web.xml for all servlets
logic for normal button has to written using javascript
<form> tag --> will have configuration of which serlvet to be called when we click submit button
it has two attributes action - servlet name n method - which method in servlets
servlets has two methodsdoget , dopost
<form action="Registration" method="get">
reset - refresh ur pagesubmit - to call serlvetsnormal - no defualt action
logic for servlets1. read data from jsp2. validate data3. if validation is successful, connect to database , execute operation 3.1. forward to next page4. if validation fails - dont connect to database - forward to error page5. close db connection
input value are not passed in url in postmax url length - 255
doget is faster in dopost
3306127.0.0.1root
tomcat - 8080mysql - 3306oracle - 1521
primary keynot nullAI - auto increment
usernameemailphnogender
CREATE TABLE `j2eedb`.`new_table` ( `Id` INT NOT NULL AUTO_INCREMENT, `username` VARCHAR(45) NULL, `email` VARCHAR(45) NULL, `phnno` BIGINT NULL, `gender` CHAR(1) NULL, PRIMARY KEY (`Id`));
user_reg
Long phn= Long.parseLong(request.getParameter("phno"));
diff between parsing and casting
casting - changing the class type to another calssparsing means - value of class
type of statements- statement - to execute static query-prepared statement - to execute dynamic
-callable statement - to execute stored proceudres
stored procedure- to avoid compile time error in mysqlperformance issues
select - executequeryinsert update, delete alter - executeUpdate
UPDATE `j2eedb`.`user_reg` SET `gender`='f' WHERE `Id`='3';
it takes from url and pass to web.xmland servlet name
gives 404 error - page not found
ResultSet is a type of output from sql.
In jsp to read the values- use request.getattribute of keyname.
Scriplet - java in jsp
Three types -1. <% %> ---> normal scriplet tag--> to write any java logic
2. <%! %> ---> declarative tag --> to declare any variable in jsp
3. <%= %> ---> expression tag --> to display any output.
object class is super class of all classes
attributes to pass values (servlt to jsp)parameter to pass parameters from jsp to servlts
User user = (User) request.getAttribute("userObject");
keep all the class level as private.
we can access the private varialbes using gettr and setter
beforeName: <%= user.name %><br> aftrerName: <%= user.getName()%><br>
user.java is bean class - only atttribute and getter setters, constructors
bean class has access to jsp for get attributes
Use same name for the radio button to select one of the option else both will get selected
embed tag for the videoattribute autoplay to auto play the video as false to stop this autoplay option
commons.file.jarfileutils class
has lot of methods creating, deleting, copy, etc.
JSTL - java standard tag library - to avoid scriptlet
5types- core- format- sql- xml- functions
- add two jars1. jstl.jar2. standard.jar
- import particular tag
- to refer JSTL variables use ${varName}- to refer scriptlet variables use <%= varName %>
request - only in next jsp you can read - only for next immediate read - next page or next servlet
implicit objects in JSP - automatically avaialbe in your page, need not to create itrequestresponsesessionaplicationconfigoutpageContextpage
context information --> session is created for each usercontext for per aplication - application id, name, language,
CSS and Javascript --w3schools.cominside in head -css, javascript
import - top of jsp
link is tag to css in jsplink rel="stylesheet" href = " path"
p#btitle - will aplly to only this para
also we can define in jsp itself under head tag, stype tag
external css can be reused
control the behviour of screen. Click button..etc