\u4e00\u4e2a\u7b80\u5355\u7684\u8bed\u6cd5<\/strong><\/div>\n
\u5178\u578b\u7684\uff0c\u5f53\u60a8\u9700\u8981\u5728JSP\u6807\u7b7e\u4e2d\u6307\u5b9a\u4e00\u4e2a\u5c5e\u6027\u503c\u65f6\uff0c\u53ea\u9700\u8981\u7b80\u5355\u5730\u4f7f\u7528\u5b57\u7b26\u4e32\u5373\u53ef\uff1a<\/p>\n
<jsp:setProperty<\/span> <\/span>name<\/span>=<\/span>\"box\"<\/span> <\/span>property<\/span>=<\/span>\"perimeter\"<\/span> <\/span>value<\/span>=<\/span>\"100\"<\/span>\/><\/span><\/pre>\n
JSP EL\u5141\u8bb8\u60a8\u6307\u5b9a\u4e00\u4e2a\u8868\u8fbe\u5f0f\u6765\u8868\u793a\u5c5e\u6027\u503c\u3002\u4e00\u4e2a\u7b80\u5355\u7684\u8868\u8fbe\u5f0f\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n
$<\/span>{<\/span>expr<\/span>}<\/span><\/pre>\n
\u5176\u4e2d\uff0cexpr\u6307\u7684\u662f\u8868\u8fbe\u5f0f\u3002\u5728JSP EL\u4e2d\u901a\u7528\u7684\u64cd\u4f5c\u7b26\u662f . \u548c {} \u3002\u8fd9\u4e24\u4e2a\u64cd\u4f5c\u7b26\u5141\u8bb8\u60a8\u901a\u8fc7\u5185\u5d4c\u7684JSP\u5bf9\u8c61\u8bbf\u95ee\u5404\u79cd\u5404\u6837\u7684JavaBean\u5c5e\u6027\u3002<\/p>\n
\u4e3e\u4f8b\u6765\u8bf4\uff0c\u4e0a\u9762\u7684\u6807\u7b7e\u53ef\u4ee5\u4f7f\u7528\u8868\u8fbe\u5f0f\u8bed\u8a00\u6539\u5199\u6210\u5982\u4e0b\u5f62\u5f0f\uff1a<\/p>\n
<jsp:setProperty<\/span> <\/span>name<\/span>=<\/span>\"box\"<\/span> <\/span>property<\/span>=<\/span>\"perimeter\"<\/span> \r\n <\/span>value<\/span>=<\/span>\"${2*box.width+2*box.height}\"<\/span>\/><\/span><\/pre>\n
\u5f53JSP\u7f16\u8bd1\u5668\u5728\u5c5e\u6027\u4e2d\u89c1\u5230\"${}\"\u683c\u5f0f\u540e\uff0c\u5b83\u4f1a\u4ea7\u751f\u4ee3\u7801\u6765\u8ba1\u7b97\u8fd9\u4e2a\u8868\u8fbe\u5f0f\uff0c\u5e76\u4e14\u4ea7\u751f\u4e00\u4e2a\u66ff\u4ee3\u54c1\u6765\u4ee3\u66ff\u8868\u8fbe\u5f0f\u7684\u503c\u3002<\/p>\n
\u60a8\u4e5f\u53ef\u4ee5\u5728\u6807\u7b7e\u7684\u6a21\u677f\u6587\u672c\u4e2d\u4f7f\u7528\u8868\u8fbe\u5f0f\u8bed\u8a00\u3002\u6bd4\u5982\u6807\u7b7e\u7b80\u5355\u5730\u5c06\u5176\u4e3b\u4f53\u4e2d\u7684\u6587\u672c\u63d2\u5165\u5230JSP\u8f93\u51fa\u4e2d\uff1a<\/p>\n
<jsp:text><\/span>\r\n<\/span><h1><\/span>Hello JSP!<\/span><\/h1><\/span>\r\n<\/span><\/jsp:text><\/span><\/pre>\n
\u73b0\u5728\uff0c\u5728<\/jsp:text>\u6807\u7b7e\u4e3b\u4f53\u4e2d\u4f7f\u7528\u8868\u8fbe\u5f0f\uff0c\u5c31\u50cf\u8fd9\u6837\uff1a<\/p>\n
<jsp:text><\/span>\r\nBox Perimeter is: ${2*box.width + 2*box.height}\r\n<\/span><\/jsp:text><\/span><\/pre>\n
\u5728EL\u8868\u8fbe\u5f0f\u4e2d\u53ef\u4ee5\u4f7f\u7528\u5706\u62ec\u53f7\u6765\u7ec4\u7ec7\u5b50\u8868\u8fbe\u5f0f\u3002\u6bd4\u5982${(1 + 2) * 3}\u7b49\u4e8e9\uff0c\u4f46\u662f${1 + (2 * 3)} \u7b49\u4e8e7\u3002<\/p>\n
\u60f3\u8981\u505c\u7528\u5bf9EL\u8868\u8fbe\u5f0f\u7684\u8bc4\u4f30\u7684\u8bdd\uff0c\u9700\u8981\u4f7f\u7528page\u6307\u4ee4\u5c06isELIgnored\u5c5e\u6027\u503c\u8bbe\u4e3atrue\uff1a<\/p>\n
<%@<\/span> page isELIgnored <\/span>=<\/span>\"true|false\"<\/span> %><\/span><\/pre>\n
EL\u4e2d\u7684\u57fa\u7840\u64cd\u4f5c\u7b26<\/strong><\/div>\n
EL\u8868\u8fbe\u5f0f\u652f\u6301\u5927\u90e8\u5206Java\u6240\u63d0\u4f9b\u7684\u7b97\u672f\u548c\u903b\u8f91\u64cd\u4f5c\u7b26\uff1a<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\n\t\t\t\t\u64cd\u4f5c\u7b26<\/strong><\/th>\n \n\t\t\t\t\u63cf\u8ff0<\/strong><\/th>\n<\/tr>\n
\n\t\t\t\t.<\/td>\n \n\t\t\t\t\u8bbf\u95ee\u4e00\u4e2aBean\u5c5e\u6027\u6216\u8005\u4e00\u4e2a\u6620\u5c04\u6761\u76ee<\/td>\n<\/tr>\n
\n\t\t\t\t[]<\/td>\n \n\t\t\t\t\u8bbf\u95ee\u4e00\u4e2a\u6570\u7ec4\u6216\u8005\u94fe\u8868\u7684\u5143\u7d20<\/td>\n<\/tr>\n
\n\t\t\t\t( )<\/td>\n \n\t\t\t\t\u7ec4\u7ec7\u4e00\u4e2a\u5b50\u8868\u8fbe\u5f0f\u4ee5\u6539\u53d8\u4f18\u5148\u7ea7<\/td>\n<\/tr>\n
\n\t\t\t\t+<\/td>\n \n\t\t\t\t\u52a0<\/td>\n<\/tr>\n
\n\t\t\t\t-<\/td>\n \n\t\t\t\t\u51cf\u6216\u8d1f<\/td>\n<\/tr>\n
\n\t\t\t\t*<\/td>\n \n\t\t\t\t\u4e58<\/td>\n<\/tr>\n
\n\t\t\t\t\/ or div<\/td>\n \n\t\t\t\t\u9664<\/td>\n<\/tr>\n
\n\t\t\t\t% or mod<\/td>\n \n\t\t\t\t\u53d6\u6a21<\/td>\n<\/tr>\n
\n\t\t\t\t== or eq<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u662f\u5426\u76f8\u7b49<\/td>\n<\/tr>\n
\n\t\t\t\t!= or ne<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u662f\u5426\u4e0d\u7b49<\/td>\n<\/tr>\n
\n\t\t\t\t< or lt<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u662f\u5426\u5c0f\u4e8e<\/td>\n<\/tr>\n
\n\t\t\t\t> or gt<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u662f\u5426\u5927\u4e8e<\/td>\n<\/tr>\n
\n\t\t\t\t<= or le<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u662f\u5426\u5c0f\u4e8e\u7b49\u4e8e<\/td>\n<\/tr>\n
\n\t\t\t\t>= or ge<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u662f\u5426\u5927\u4e8e\u7b49\u4e8e<\/td>\n<\/tr>\n
\n\t\t\t\t&& or and<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u903b\u8f91\u4e0e<\/td>\n<\/tr>\n
\n\t\t\t\t|| or or<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u903b\u8f91\u6216<\/td>\n<\/tr>\n
\n\t\t\t\t! or not<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u53d6\u53cd<\/td>\n<\/tr>\n
\n\t\t\t\tempty<\/td>\n \n\t\t\t\t\u6d4b\u8bd5\u662f\u5426\u7a7a\u503c<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
JSP EL\u4e2d\u7684\u51fd\u6570<\/strong><\/div>\n
JSP EL\u5141\u8bb8\u60a8\u5728\u8868\u8fbe\u5f0f\u4e2d\u4f7f\u7528\u51fd\u6570\u3002\u8fd9\u4e9b\u51fd\u6570\u5fc5\u987b\u88ab\u5b9a\u4e49\u5728\u81ea\u5b9a\u4e49\u6807\u7b7e\u5e93\u4e2d\u3002\u51fd\u6570\u7684\u4f7f\u7528\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n
${ns:func(param1, param2, ...)}<\/pre>\n
ns\u6307\u7684\u662f\u547d\u540d\u7a7a\u95f4\uff08namespace\uff09\uff0cfunc\u6307\u7684\u662f\u51fd\u6570\u7684\u540d\u79f0\uff0cparam1\u6307\u7684\u662f\u7b2c\u4e00\u4e2a\u53c2\u6570\uff0cparam2\u6307\u7684\u662f\u7b2c\u4e8c\u4e2a\u53c2\u6570\uff0c\u4ee5\u6b64\u7c7b\u63a8\u3002\u6bd4\u5982\uff0c\u6709\u51fd\u6570fn:length\uff0c\u5728JSTL\u5e93\u4e2d\u5b9a\u4e49\uff0c\u53ef\u4ee5\u50cf\u4e0b\u9762\u8fd9\u6837\u6765\u83b7\u53d6\u4e00\u4e2a\u5b57\u7b26\u4e32\u7684\u957f\u5ea6\uff1a<\/p>\n
${fn:length(\"Get my length\")}<\/pre>\n
\u8981\u4f7f\u7528\u4efb\u4f55\u6807\u7b7e\u5e93\u4e2d\u7684\u51fd\u6570\uff0c\u60a8\u9700\u8981\u5c06\u8fd9\u4e9b\u5e93\u5b89\u88c5\u5728\u670d\u52a1\u5668\u4e2d\uff0c\u7136\u540e\u4f7f\u7528\u6807\u7b7e\u5728JSP\u6587\u4ef6\u4e2d\u5305\u542b\u8fd9\u4e9b\u5e93\u3002<\/p>\n
JSP EL\u9690\u542b\u5bf9\u8c61<\/strong><\/div>\n
JSP EL\u652f\u6301\u4e0b\u8868\u5217\u51fa\u7684\u9690\u542b\u5bf9\u8c61\uff1a<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\n\t\t\t\t\u9690\u542b\u5bf9\u8c61<\/strong><\/th>\n \n\t\t\t\t\u63cf\u8ff0<\/strong><\/th>\n<\/tr>\n
\n\t\t\t\tpageScope<\/td>\n \n\t\t\t\tpage \u4f5c\u7528\u57df<\/td>\n<\/tr>\n
\n\t\t\t\trequestScope<\/td>\n \n\t\t\t\trequest \u4f5c\u7528\u57df<\/td>\n<\/tr>\n
\n\t\t\t\tsessionScope<\/td>\n \n\t\t\t\tsession \u4f5c\u7528\u57df<\/td>\n<\/tr>\n
\n\t\t\t\tapplicationScope<\/td>\n \n\t\t\t\tapplication \u4f5c\u7528\u57df<\/td>\n<\/tr>\n
\n\t\t\t\tparam<\/td>\n \n\t\t\t\tRequest \u5bf9\u8c61\u7684\u53c2\u6570\uff0c\u5b57\u7b26\u4e32<\/td>\n<\/tr>\n
\n\t\t\t\tparamValues<\/td>\n \n\t\t\t\tRequest\u5bf9\u8c61\u7684\u53c2\u6570\uff0c\u5b57\u7b26\u4e32\u96c6\u5408<\/td>\n<\/tr>\n
\n\t\t\t\theader<\/td>\n \n\t\t\t\tHTTP \u4fe1\u606f\u5934\uff0c\u5b57\u7b26\u4e32<\/td>\n<\/tr>\n
\n\t\t\t\theaderValues<\/td>\n \n\t\t\t\tHTTP \u4fe1\u606f\u5934\uff0c\u5b57\u7b26\u4e32\u96c6\u5408<\/td>\n<\/tr>\n
\n\t\t\t\tinitParam<\/td>\n \n\t\t\t\t\u4e0a\u4e0b\u6587\u521d\u59cb\u5316\u53c2\u6570<\/td>\n<\/tr>\n
\n\t\t\t\tcookie<\/td>\n \n\t\t\t\tCookie\u503c<\/td>\n<\/tr>\n
\n\t\t\t\tpageContext<\/td>\n \n\t\t\t\t\u5f53\u524d\u9875\u9762\u7684pageContext<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u60a8\u53ef\u4ee5\u5728\u8868\u8fbe\u5f0f\u4e2d\u4f7f\u7528\u8fd9\u4e9b\u5bf9\u8c61\uff0c\u5c31\u50cf\u4f7f\u7528\u53d8\u91cf\u4e00\u6837\u3002\u63a5\u4e0b\u6765\u4f1a\u7ed9\u51fa\u51e0\u4e2a\u4f8b\u5b50\u6765\u66f4\u597d\u7684\u7406\u89e3\u8fd9\u4e2a\u6982\u5ff5\u3002<\/p>\n
pageContext\u5bf9\u8c61<\/strong><\/div>\n
pageContext\u5bf9\u8c61\u662fJSP\u4e2dpageContext\u5bf9\u8c61\u7684\u5f15\u7528\u3002\u901a\u8fc7pageContext\u5bf9\u8c61\uff0c\u60a8\u53ef\u4ee5\u8bbf\u95eerequest\u5bf9\u8c61\u3002\u6bd4\u5982\uff0c\u8bbf\u95eerequest\u5bf9\u8c61\u4f20\u5165\u7684\u67e5\u8be2\u5b57\u7b26\u4e32\uff0c\u5c31\u50cf\u8fd9\u6837\uff1a<\/p>\n
$<\/span>{<\/span>pageContext<\/span>.<\/span>request<\/span>.<\/span>queryString<\/span>}<\/span><\/pre>\n
Scope\u5bf9\u8c61<\/strong><\/div>\n
pageScope\uff0crequestScope\uff0csessionScope\uff0capplicationScope\u53d8\u91cf\u7528\u6765\u8bbf\u95ee\u5b58\u50a8\u5728\u5404\u4e2a\u4f5c\u7528\u57df\u5c42\u6b21\u7684\u53d8\u91cf\u3002<\/p>\n
\u4e3e\u4f8b\u6765\u8bf4\uff0c\u5982\u679c\u60a8\u9700\u8981\u663e\u5f0f\u8bbf\u95ee\u5728applicationScope\u5c42\u7684box\u53d8\u91cf\uff0c\u53ef\u4ee5\u8fd9\u6837\u6765\u8bbf\u95ee\uff1aapplicationScope.box\u3002<\/p>\n
param\u548cparamValues\u5bf9\u8c61<\/strong><\/div>\n
param\u548cparamValues\u5bf9\u8c61\u7528\u6765\u8bbf\u95ee\u53c2\u6570\u503c\uff0c\u901a\u8fc7\u4f7f\u7528request.getParameter\u65b9\u6cd5\u548crequest.getParameterValues\u65b9\u6cd5\u3002<\/p>\n
\u4e3e\u4f8b\u6765\u8bf4\uff0c\u8bbf\u95ee\u4e00\u4e2a\u540d\u4e3aorder\u7684\u53c2\u6570\uff0c\u53ef\u4ee5\u8fd9\u6837\u4f7f\u7528\u8868\u8fbe\u5f0f\uff1a${param.order}\uff0c\u6216\u8005${param[\"order\"]}\u3002<\/p>\n
\u63a5\u4e0b\u6765\u7684\u4f8b\u5b50\u8868\u660e\u4e86\u5982\u4f55\u8bbf\u95eerequest\u4e2d\u7684username\u53c2\u6570\uff1a<\/p>\n
<%@<\/span> page <\/span>import<\/span>=<\/span>\"java.io.*,java.util.*\"<\/span> %>\r\n<\/span><%<\/span>\r\n <\/span>String<\/span> title <\/span>=<\/span> <\/span>\"Accessing Request Param\"<\/span>;<\/span>\r\n%>\r\n<\/span><html><\/span>\r\n<\/span><head><\/span>\r\n<\/span><title><\/span><%<\/span> <\/span>out<\/span>.<\/span>print<\/span>(<\/span>title<\/span>);<\/span> %><\/span><\/title><\/span>\r\n<\/span><\/head><\/span>\r\n<\/span><body><\/span>\r\n<\/span><center><\/span>\r\n<\/span><h1><\/span><%<\/span> <\/span>out<\/span>.<\/span>print<\/span>(<\/span>title<\/span>);<\/span> %><\/span><\/h1><\/span>\r\n<\/span><\/center><\/span>\r\n<\/span><div<\/span> <\/span>align<\/span>=<\/span>\"center\"<\/span>><\/span>\r\n<\/span><p><\/span>${param[\"username\"]}<\/span><\/p><\/span>\r\n<\/span><\/div><\/span>\r\n<\/span><\/body><\/span>\r\n<\/span><\/html><\/span><\/pre>\n
param\u5bf9\u8c61\u8fd4\u56de\u5355\u4e00\u7684\u5b57\u7b26\u4e32\uff0c\u800cparamValues\u5bf9\u8c61\u5219\u8fd4\u56de\u4e00\u4e2a\u5b57\u7b26\u4e32\u6570\u7ec4\u3002<\/p>\n
header\u548cheaderValues\u5bf9\u8c61<\/strong><\/div>\n
header\u548cheaderValues\u5bf9\u8c61\u7528\u6765\u8bbf\u95ee\u4fe1\u606f\u5934\uff0c\u901a\u8fc7\u4f7f\u7528 request.getHeader\u65b9\u6cd5\u548crequest.getHeaders\u65b9\u6cd5\u3002<\/p>\n
\u4e3e\u4f8b\u6765\u8bf4\uff0c\u8981\u8bbf\u95ee\u4e00\u4e2a\u540d\u4e3auser-agent\u7684\u4fe1\u606f\u5934\uff0c\u53ef\u4ee5\u8fd9\u6837\u4f7f\u7528\u8868\u8fbe\u5f0f\uff1a${header.user-agent}\uff0c\u6216\u8005${header[\"user-agent\"]}\u3002<\/p>\n
\u63a5\u4e0b\u6765\u7684\u4f8b\u5b50\u8868\u660e\u4e86\u5982\u4f55\u8bbf\u95eeuser-agent\u4fe1\u606f\u5934\uff1a<\/p>\n
<%@<\/span> page <\/span>import<\/span>=<\/span>\"java.io.*,java.util.*\"<\/span> %>\r\n<\/span><%<\/span>\r\n <\/span>String<\/span> title <\/span>=<\/span> <\/span>\"User Agent Example\"<\/span>;<\/span>\r\n%>\r\n<\/span><html><\/span>\r\n<\/span><head><\/span>\r\n<\/span><title><\/span><%<\/span> <\/span>out<\/span>.<\/span>print<\/span>(<\/span>title<\/span>);<\/span> %><\/span><\/title><\/span>\r\n<\/span><\/head><\/span>\r\n<\/span><body><\/span>\r\n<\/span><center><\/span>\r\n<\/span><h1><\/span><%<\/span> <\/span>out<\/span>.<\/span>print<\/span>(<\/span>title<\/span>);<\/span> %><\/span><\/h1><\/span>\r\n<\/span><\/center><\/span>\r\n<\/span><div<\/span> <\/span>align<\/span>=<\/span>\"center\"<\/span>><\/span>\r\n<\/span><p><\/span>${header[\"user-agent\"]}<\/span><\/p><\/span>\r\n<\/span><\/div><\/span>\r\n<\/span><\/body><\/span>\r\n<\/span><\/html><\/span><\/pre>\n
\u8fd0\u884c\u7ed3\u679c\u5982\u4e0b\uff1a
\n $\"\"$
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