这个压缩包里的都是超级经典的java例子

				
				
				
				Saving Data Using JSTL in a JSP Page (Java Developers Almanac Example)
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				The Java Developers Almanac 1.4
				
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				    javax.servlet.jsp.jstl.core
				         [6 examples]
				    
				
				  e1067. Saving Data Using JSTL in a JSP Page
				
				When a JSP page needs to save data for its processing, it must
				specify a location, called the scope. See
				e1048 Saving Data in a JSP Page for an explanation of the four
				available scopes.
				
				 Data is saved using a mechanism called scoped variables.  A
				scoped variable has a name, which is of type String and a value,
				which is of type Object.  For non-page scoped variables, it is
				recommended that the name use the reverse domain name convention
				(e.g., prefixed with com_mycompany) to minimize unexpected collisions
				when integrating with third party modules.
				
				 When using the JSTL's expression language (see
				e1065 Enabling the JSTL Expression Language in a JSP Page), the variables in each
				scope are made available in the implicit objects pageScope,
				requestScope, sessionScope, and applicationScope.
				
				 This example saves and retrieves values in scoped variables in
				each of the four scopes:
				
				
				    <%-- Declare the core library --%>
				    <%@ taglib uri="/WEB-INF/tld/c.tld" prefix="c" %>
				    
				    <%-- Save data in scoped variables --%>
				    <c:set var="name1" value="value1" scope="page" />
				    <c:set var="com_mycompany_name2" value="value2" scope="request" />
				    <c:set var="com_mycompany_name3" value="value3" scope="session" />
				    <c:set var="com_mycompany_name4" value="value4" scope="application" />
				    
				    <%-- Show the saved values --%>
				    <c:out value='${pageScope.name1}' />
				    <c:out value='${requestScope.com_mycompany_name2}' />
				    <c:out value='${sessionScope.com_mycompany_name3}' />
				    <c:out value='${applicationScope.com_mycompany_name4}' />
				
				
				When retrieving a saved value, it is possible to omit the scope.  If
				the scope is omitted, the variable name is automatically searched for
				in each of the scopes, in the order pageScope,
				requestScope, sessionScope, and applicationScope.
				
				
				    <%-- Show the saved values without a specific scope --%>
				    <c:out value='${name1}' />
				    <c:out value='${com_mycompany_name2}' />
				    <c:out value='${com_mycompany_name3}' />
				    <c:out value='${com_mycompany_name4}' />
				
				
				It is also possible to specify the value to save using the contents
				of the body, rather than through the value attribute:
				
				
				    <%-- Save data using body content --%>
				    <c:set var="name1" scope="page">
				        value 1 in body
				    </c:set>
				    <c:set var="com_mycompany_name2" scope="request" >
				        value 2 in body
				    </c:set>
				    <c:set var="com_mycompany_name3" scope="session" >
				        value 3 in body
				    </c:set>
				    <c:set var="com_mycompany_name4" scope="application">
				        value 4 in body
				    </c:set>
				
				
				When specifying the value using body contents, the body contents
				is first trimmed of leading and trailing white space before it is
				saved. For example, 
				
				
				    <c:set var="name1" scope="page">
				        line 1
				        line 2
				    </c:set>
				
				would be saved as:
				
				    "line 1\n    line 2"
				
				
				
				
				             Related Examples
				
				
				
				
				e1064. 
				    Using the Java Standard Tag Library (JSTL) in a JSP Page
				
				
				
				e1065. 
				    Enabling the JSTL Expression Language in a JSP Page
				
				
				
				e1066. 
				    Getting a Request Parameter Using JSTL in a JSP Page
				
				
				
				e1068. 
				    Saving and Emitting HTML Fragments Using JSTL in a JSP Page
				
				
				
				e1069. 
				    Conditionally Generating Output Using JSTL in a JSP Page
				
				
				
				
				
				
				
				
				© 2002 Addison-Wesley.