JSP Implicit Objects CS 422 Dick Steflik

Implicit Objects Objects created by the servlet container application session request response exception out Config pageContext page

Application Object Used to share data between all of the pages that make up an application All users share the Application Object Can be accessed from any JSP in the application via the ServletContext javax.servlet.http.ServletContext

Application Object Methods getAttribute(String name) getAttributeNames setAttribute(String objName, Object object) removeAttribute(String objName) getMajorVersion() getMinorVersion() getServerInfo() getInitParameter(String name) getInitParameterNames getResourceAsStream(Path) log(Message)

Sessions A session is a concept that represents a series of HTTP requests and responses between a specific browser and a specific server. Sessions are managed by the server Created by the server when the first request is received from a browser on a new host the server starts the session and assigns it an ID. The ID is sent to the browser as a cookie and remembered by the server

Sessions (more) The server creates a Session object that contains the attributes: Creation Time ID Last Time Accessed Maximum Inactive Time allowed

HTTPSession Interface getAttribute() – returns the object associated with the specified key string getAttributeNames() – returns an enumeration of the key strings in the session getCreationTime() – returns the time the session was created; millsecs past midnight since Jan 1, 1970 GMT getID() – returns the session ID as a string getLastAccessedTime() – returns thelast time the client sent a request for this session getMaxInactiveInterval() – returns the maximun amount of time that the servlet container between client requests before timing out the session setAttribute() – associates an object with a key string in the session removeAttribute() – remove an attribute from the session setMaxInactiveInterval() – set the time in seconds allowed between client requests isNew() – true if a new session, false otherwise

request Object Javax.servlet. http.httpservletrequest. The object request is of type Javax.servlet.http.httpservletrequest. This denotes the data included with the HTTP Request. The client makes a request that is then passed to the server. The requested object is used to take the value from client’s web browser and pass it to the server. This is performed using HTTP request like headers, cookies and arguments.

response Object Javax.servlet.http.HttpServletResponse The HTTP Response data. The result or the information that fulfills an Http request The object response is of type javax.servlet.http. >httpservletresponse. Generally, the object response is used with cookies. The response object is used to build the HTTP response header

pageContext Object Javax.servlet.jsp.pagecontext Used to access page attributes and also to access all the namespaces associated with a JSP page.

Out Object The Output stream in the context of page. The class or the interface name of the Out object is jsp.JspWriter. The Out object is written: Javax.servlet.jsp.JspWriter

config Object This is used to get information regarding the Servlet configuration The class or the interface name of the Config object is ServletConfig. The object Config is written Javax.servlet.http.ServletConfig

page Object The Page object denotes the JSP page Used for calling any instance of a Page's servlet. The class or the interface name of the Page object is jsp.HttpJspPage. The Page object is written: Java.lang.Object

Passing Values from Page to Page Put values in the session object Put the values in the application object Put values at the end of the URL