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发信人: agents (智能代理), 信区: Java
标  题: JSP语法（7）
发信站: BBS 水木清华站 (Tue Jan  2 14:50:19 2001)

【Page Directive】
Defines attributes that apply to an entire JSP page.

▲［JSP Syntax］
<%@ page
[ language="java" ]
[ extends="package.class" ]
[ import= "{ package.class | package.* }, ..." ]
[ session="true|false" ]
[ buffer="none|8kb|sizekb" ]
[ autoFlush="true|false" ]
[ isThreadSafe="true|false" ]
[ info="text" ]
[ errorPage="relativeURL" ]
[ contentType="mimeType [ ;charset=characterSet ]" |
  "text/html ; charset=ISO-8859-1" ]
[ isErrorPage="true|false" ]
%>

▲［Examples］

<%@ page import="java.util.*, java.lang.*" %>
<%@ page buffer="5kb" autoFlush="false" %>
<%@ page errorPage="error.jsp" %>

▲［Description］

   The page directive applies to an entire JSP file and any static files it
   includes with the Include Directive or <jsp:include>, which together are
   called  a translation unit. Note that the page directive does not apply
   to any dynamic included files; (see <jsp:include> for more information.)

   You can use the page directive more than once in a translation unit, but
   youcan only use each attribute, except import, once. (Because the import
   attribute is similar to the import statement in the Java programming
   language, you can use it more than once, just as you would use multiple
   import commands in the Java programming language) No matter where you
   position the page directive in the JSP file or included files, it applies
   to the entire translation unit. However, it is usually good programming
   style to place it at the top of the file.

▲［Attributes］

(1) language="java"

    The scripting language used in scriptlets, declarations, and expressions
    in the JSP file and any included files. In JSP 1.0, the only allowed value
    is java.

(2) extends="package.class"
    The fully qualified name of the superclass of the Java class file this JSP
    file will be compiled to. Use this attribute cautiously, as it can limit
    the JSP engine's ability to provide a specialized superclass that improves
    the quality of the compiled file.

(3) import= "{ package.class | package.* }, ..."
    A comma-separated list of one or more packages that the JSP file should
   import. The packages (and their classes) are available to scriptlets,
   expressions, declarations, and tags within the JSP file. You must place
   the import attribute before the tag that calls the imported class. If you
   want to import more than one package, you can specify a comma-separated
   list after import or you can use import more than once in a JSP file.

(4)session="true|false"
   Whether the client must join an HTTP session in order to use the JSP page.
   If the value is true, the session object refers to the current or new
   session. If the value is false, you cannot use the session object in the
   JSP file. The default value is true.

(5)buffer="none|8kb|sizekb"
   The buffer size in kilobytes used by the out object to handle output sent
   from the compiled JSP page to the client Web browser. The default value is
   8kb. If you specify a buffer size, the output is buffered with at least
   the size you specified.

(6)autoFlush="true|false"
   Whether the buffered output should be flushed automatically when the
   buffer is full. If true (the default value), means that the buffer will
   be flushed.If false, means that an exception will be raised when the
   buffer overflows.
   You cannot set autoFlush to false when the value of buffer is none.

(7)isThreadSafe="true|false"
   Whether thread safety is implemented in the JSP file. The default value is
   true, which means that the JSP engine can send multiple requests to the page
   concurrently. If you use true (the default value), multiple threads can
   access the JSP page, and you must synchronize them. If you use false, the
   JSP engine sends client requests one at a time to the JSP page.

(8)info="text"
   A text string that is incorporated verbatim in the compiled JSP page. You
   can later retrieve the string with the Servlet.getServletInfo() method.

(9)errorPage="relativeURL"
  A pathname to a JSP file that this JSP file sends exceptions to. If the path
  name begins with a /, the path is relative to the JSP application's document
  root directory and is resolved by the Web server. If not, the pathname is
  relative to the current JSP file.

(10)isErrorPage="true|false"
  Whether the JSP file displays an error page. If true, you can use the
  exception object, which contains a reference to the thrown exception,
  in the JSP file. If false (the default value), means that you cannot use
  the exception object in the JSP file.

(11)contentType="mimeType [ ;charset=characterSet ]" |
                            "text/html;charset=ISO-8859-1"

  The MIME type and character encoding the JSP file uses for the response it
  sends to the client. You can use any MIME type or character set that are
  valid for the JSP engine. The default MIME type is text/html, and the
  default character set is ISO-8859-1.

--

※ 修改:·agents 於 Jan  2 16:08:05 修改本文·[FROM:   166.111.54.22]
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