JSP:
1. concept:
the Java Server Pages and the: java server pages
can be understood as: a special page, which can either specify the definition of html tags, they can be defined java code
to simplify the writing! ! !
2. Principle
JSP is essentially a Servlet
3. JSP script: JSP define how Java code
1. <Code%%>: java codes defined in the service process. What service method can be defined, what the script can be defined.
2. <! Code%%>: java code is defined, the position of the members jsp java class after conversion.
3. <% = Code%>: java code is defined, is output to the page. What output statement can be defined, what the script can be defined.
4. JSP built-in objects:
do not need to get in the jsp page and created objects can be used directly, jsp a total of nine built-in objects.
| variable name | Real type | effect |
| pageContext | PageContext | Current page to share data, you can also get other eight built-in objects |
| request | HttpServletRequest | A request for access to multiple resources (forward) |
| session | HttpSession | Requests a session among a plurality of |
| application | ServletContext | Among all users to share data |
| response | HttpServletResponse | Response Object |
| page | Object | Current page (Servlet) this object |
| out | JspWriter | Character output stream object. You can output the data on the page. And response.getWriter () similar response.getWriter () and out.write () the difference: before the real tomcat server responds to the client, will go first response data buffer, the buffer data to find out. That response.getWriter () output data always out.write () before |
| config | ServletConfig | Servlet configuration object |
| exception | Throwable | Exception object |
5. instruction
role: to configure JSP page, the resource file import
format:
<% @ directive name attribute name attribute value = 1 1 = Attribute Name Attribute Value 2 2 ...%>
Category:
1. Page: JSP page configuration
contentType: equivalent to response.setContentType ()
Import: guide package
errorPage: exception occurs after the current page will automatically jump to a specific error page
isErrorPage: identifies whether the current page is an error page.
true: yes, you can use the built-in object Exception
false: no. Defaults. Can not use the built-in object exception
2. include: the page contains. Import page resource file
<% @ the include File = "top.jsp"%>
3. taglib: Import Resources
<% @ taglib prefix = "c " uri = "http://java.sun.com/jsp/jstl/ Core "%>
prefix: prefix customized
6. Notes:
1. html Note:
! <- ->: html code fragment only comment, and the comment is sent to the browser, but not visible on the page
2. jsp Notes: recommended use
<% - -%>: You can annotate all