Basic syntax of JSP--Request forwarding and redirect __js

Basic syntax for JSP:
1. JSP expression: Provides a way to directly calculate the Java variable or expression to the client's simplified way, it will output the variable
Or an expression is encapsulated directly in the <%=%>.


2. Methods:
Object setattribute (String name): Gets the specified property
Enumertion getattributenames (): Gets the names of all the properties of the enumeration object
RemoveAttribute (String name): Removing the specified property
void setattribute (String name,object o): Setting properties

The following--domain objects--all have these methods:
PageContext: The scope is limited to the current JSP page.
Request: The scope of the property is limited to the same request.
Session: Scope Limited to one conversation (browser open until shutdown is called a session)
Application: Scoped to the current Web application, is the scope of the largest range of properties.
Called a domain object

***
Redirection and forwarding of requests:

Forwarded for Request: Request.getrequestdispatcher ("/c.jsp"). Forward (request, response);
Redirect: Response.sendredirect ("c.jsp");

1. Essential difference:

1 The requested forwarding only makes one request, and the redirect makes two requests.


2 Forwarding of requests: can only be forwarded to the root directory of the current Web application.
Redirect: Can be directed to any resource.

3 The requested forwarding:/represents the current Web application's root directory.
Redirect:/represents the root directory of the current Web site.

4 Request Forwarding: In the final servlet, the request object and the relay request are the same object.
Redirect: In the final servlet, the request object and the transfer request are not the same object