是你慌了，其实那一页的开头就有了很好的说明了：(<input type="text" name="foo" value="${param["foo"]}"> ) This example illustrates some of the implicit objects available in the Expression Lanaguage. The following implicit objects are available (not all illustrated here): pageContext - the PageContext object pageScope - a Map that maps page-scoped attribute names to their values requestScope - a Map that maps request-scoped attribute names to their values sessionScope - a Map that maps session-scoped attribute names to their values applicationScope - a Map that maps application-scoped attribute names to their values param - a Map that maps parameter names to a single String parameter value paramValues - a Map that maps parameter names to a String[] of all values for that parameter header - a Map that maps header names to a single String header value headerValues - a Map that maps header names to a String[] of all values for that header initParam - a Map that maps context initialization parameter names to their String parameter value cookie - a Map that maps cookie names to a single Cookie object.
是传值吧，可以通过request取得所传的值
反正是外行，蒙它！说得越玄越好！！ 他们就是欠蒙！尤其是蒙不懂技术的部门经理，真TMD的爽！
是你慌了，其实那一页的开头就有了很好的说明了：(<input type="text" name="foo" value="${param["foo"]}"> ) This example illustrates some of the implicit objects available in the Expression Lanaguage. The following implicit objects are available (not all illustrated here): pageContext - the PageContext object pageScope - a Map that maps page-scoped attribute names to their values requestScope - a Map that maps request-scoped attribute names to their values sessionScope - a Map that maps session-scoped attribute names to their values applicationScope - a Map that maps application-scoped attribute names to their values param - a Map that maps parameter names to a single String parameter value paramValues - a Map that maps parameter names to a String[] of all values for that parameter header - a Map that maps header names to a single String header value headerValues - a Map that maps header names to a String[] of all values for that header initParam - a Map that maps context initialization parameter names to their String parameter value cookie - a Map that maps cookie names to a single Cookie object.
你慌了，其实那一页的开头就有了很好的说明了：(<input type="text" name="foo" value="${param["foo"]}"> ) This example illustrates some of the implicit objects available in the Expression Lanaguage. The following implicit objects are available (not all illustrated here): pageContext - the PageContext object pageScope - a Map that maps page-scoped attribute names to their values requestScope - a Map that maps request-scoped attribute names to their values sessionScope - a Map that maps session-scoped attribute names to their values applicationScope - a Map that maps application-scoped attribute names to their values param - a Map that maps parameter names to a single String parameter value paramValues - a Map that maps parameter names to a String[] of all values for that parameter header - a Map that maps header names to a single String header value headerValues - a Map that maps header names to a String[] of all values for that header initParam - a Map that maps context initialization parameter names to their String parameter value cookie - a Map that maps cookie names to a single Cookie object.
http://localhost:8080/jsp-examples/jsp2/el/implicit-objects.jsp?foo=bar
你就可以看到这玩意～～～
)
This example illustrates some of the implicit objects available in the Expression Lanaguage. The following implicit objects are available (not all illustrated here):
pageContext - the PageContext object
pageScope - a Map that maps page-scoped attribute names to their values
requestScope - a Map that maps request-scoped attribute names to their values
sessionScope - a Map that maps session-scoped attribute names to their values
applicationScope - a Map that maps application-scoped attribute names to their values
param - a Map that maps parameter names to a single String parameter value
paramValues - a Map that maps parameter names to a String[] of all values for that parameter
header - a Map that maps header names to a single String header value
headerValues - a Map that maps header names to a String[] of all values for that header
initParam - a Map that maps context initialization parameter names to their String parameter value
cookie - a Map that maps cookie names to a single Cookie object.
他们就是欠蒙！尤其是蒙不懂技术的部门经理，真TMD的爽！
)
This example illustrates some of the implicit objects available in the Expression Lanaguage. The following implicit objects are available (not all illustrated here):
pageContext - the PageContext object
pageScope - a Map that maps page-scoped attribute names to their values
requestScope - a Map that maps request-scoped attribute names to their values
sessionScope - a Map that maps session-scoped attribute names to their values
applicationScope - a Map that maps application-scoped attribute names to their values
param - a Map that maps parameter names to a single String parameter value
paramValues - a Map that maps parameter names to a String[] of all values for that parameter
header - a Map that maps header names to a single String header value
headerValues - a Map that maps header names to a String[] of all values for that header
initParam - a Map that maps context initialization parameter names to their String parameter value
cookie - a Map that maps cookie names to a single Cookie object.
)
This example illustrates some of the implicit objects available in the Expression Lanaguage. The following implicit objects are available (not all illustrated here):
pageContext - the PageContext object
pageScope - a Map that maps page-scoped attribute names to their values
requestScope - a Map that maps request-scoped attribute names to their values
sessionScope - a Map that maps session-scoped attribute names to their values
applicationScope - a Map that maps application-scoped attribute names to their values
param - a Map that maps parameter names to a single String parameter value
paramValues - a Map that maps parameter names to a String[] of all values for that parameter
header - a Map that maps header names to a single String header value
headerValues - a Map that maps header names to a String[] of all values for that header
initParam - a Map that maps context initialization parameter names to their String parameter value
cookie - a Map that maps cookie names to a single Cookie object.
就像我们用a、b或x、y一样，并没有什么特殊意义，只是习惯而已。靠，这也叫问题，真他妈晕！
你们好好去看看JSP2.0的规范吧!
param是JSP2.0中EL表达式中的内置对象,还有requestScope,sessionScope等内置对象,
param.foo相当于:request.getParameter("foo");
param.foo相当于:request.getParameter("foo");