'Back-End/Jsp'에 해당되는 글 14건

(2)Action Tags_useBean

1) jsp:useBean action tag

- The jsp:useBean action tag is used to locate or instantiate a bean class

- If bean object of the Bean class is already created, it doesn't create the bean depending on the scope

- If object of bean is not created, it instantiates the bean

Example

1_1. index.jsp

1_2. java

2) jsp: setProperty and jsp: getProperty

- The setProperty and getProperty action tags are used for developing web application with Java Bean

- It is a reusable software component that represents data

2_1. setProperty

- It you have to set all the values of incoming request in the bean

<jsp: setProperty name="bean" property="*"/>

- If you have to set value of the incoming specific property

<jsp: setProperty name="bean" property="username"/>

- If you have to set a specific value in the property

<jsp: setProperty name="bean" property="username" value="Kunar"/>

2_2. getProperty

- The jsp: getProperty action tag returns the value of the property

<jsp: getProperty name="obj" property="name"/>

2_3. Example

- index.html

- process.jsp

- The part of the red is set for property

- The part of a green can get values

- Java

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