'Back-End'에 해당되는 글 135건

Action Tags_1

- The action tags are used to control the flow between pages and to use Java Bean.

- The jsp:useBean, jsp:setProperty, jsp:getProperty tags are used for bean development

1. jsp:forward action tag

- The jsp:forward action tag is used to forward the request to another resource it may be jsp, html or another resource

1_1 without parameter

1_2. with parameter

2. jsp:include action tag

- The jsp:include action tag is used to include the content of another resource it may be jsp, html or servlet

- It is better for dynamic pages because there might be changes in future

Example   

1) index.jsp

2) process.jsp

3) result

Exception 

- In JSP, there are two ways to perform exception handling

1) By errorPage and isErrorPage attributes of page directive

2) By <error-page> element in web.xml file

1. By the elements of page directive

1_1. index.jsp

1_2. process.jsp

1_3. error.jsp

1_4. result

2. By specifying the error-page element in web.xml

- This approach is better because you don't need to specify the errorPage attribute in each jsp page

- In this case, either specify exception-type or error code with the location element

2_1. web.xml

- If you want to handle any exception

- If you want to handle the exception for a specific error code

2_2 . error.jsp

Include & taglib directive

1. Include

- The include directive is used to include the contents of any resource it may be jsp file, html file or text file.

Example

2. Taglib

- The JSP taglib directive is used to define a tag library that defines many tags

- We can use the TLD(Tag Library Descriptor) file to define the tags

Page directives

- The jsp directives are messages that tells the web container how to translate a JSP page into the corresponding servlet

1. Syntax

<%@ directive attribute="value" %>

2. page directive

- The page directive defines attributes that apply to an entire JSP page

2_1. Syntax

<%@ page attribute="value" %>

2_2. Attributes

• import
• contentType
• extends
• info
• buffer
• language
• isELIgnored
• isThreadSafe
• autoFlush
• session
• pageEncoding
• errorPage
• isErrorPage

2_3. How to use

1) import

- It is used to import class, interface or all the members of a package

- It is similar to import keyword in java class 

Example

2) contentType

- The contentType attribute defines the MIME(Multipurpose Internet Mail Extension) type of the HTTP response

- Default value is "text/html; charset-ISO-8859-1"

Example

- When I reload the welcome.jsp page, welcome.jsp page is downloaded

3) buffer

- The buffer attribute sets the buffer size in kilobytes to handle output generated by the JSP page

- The default size of the buffer is 8Kb

Example

4) isELIgnored

 - We can ignore the Expression Language(EL) in jsp by the isELIgnored attribute

- By default its value is false i.e. Expression Language is enabled by default

Example

5) errorPage

- The errorPage attribute is used to define the error page, if exception occurs in the current page, it will be redirected to the error page

Example

6) isErrorPage

- This attribute is used to declare that the current page is the error page

Example