{"id":2259,"date":"2022-12-08T17:04:21","date_gmt":"2022-12-08T09:04:21","guid":{"rendered":"https:\/\/qaqaq.top\/?p=2259"},"modified":"2022-12-19T20:41:30","modified_gmt":"2022-12-19T12:41:30","slug":"el%e8%a1%a8%e8%be%be%e5%bc%8f-%e4%bb%80%e4%b9%88%e6%98%afel%e8%a1%a8%e8%be%be%e5%bc%8f%ef%bc%8c%e4%bb%a5%e5%8f%8a%e5%ae%83%e7%9a%84%e4%bd%9c%e7%94%a8%e3%80%81el%e8%a1%a8%e8%be%be%e5%bc%8f-%e4%bb%80","status":"publish","type":"post","link":"https:\/\/qaqaq.top\/?p=2259","title":{"rendered":"EL\u8868\u8fbe\u5f0f-\u4ec0\u4e48\u662fEL\u8868\u8fbe\u5f0f\uff0c\u4ee5\u53ca\u5b83\u7684\u4f5c\u7528\u3001EL\u8868\u8fbe\u5f0f\u8f93\u51fa\u590d\u6742\u7684Bean\u5bf9\u8c61\u3001\u5173\u7cfb\u8fd0\u7b97\u3001\u903b\u8f91\u8fd0\u7b97\u3001\u7b97\u672f\u8fd0\u7b97\u3001empty\u8fd0\u7b97\u3001\u70b9\u8fd0\u7b97\u548c\u4e2d\u62ec\u53f7\u8fd0\u7b97\u300111\u4e2aEL\u9690\u542b\u5bf9\u8c61\u7684\u4ecb\u7ecd\u3001pageScope\u3001requestScope\u3001sessionScope\u3001applicationScope\u7684\u793a\u4f8b\u3001pageContext\u6f14\u793a\u3001\u5176\u4ed6EL\u9690\u542b\u5bf9\u8c61\u7684\u793a\u4f8b"},"content":{"rendered":"\n

EL \u8868\u8fbe\u5f0f<\/h1>\n\n\n\n

a)\u4ec0\u4e48\u662f EL \u8868\u8fbe\u5f0f\uff0cEL \u8868\u8fbe\u5f0f\u7684\u4f5c\u7528?<\/h2>\n\n\n\n

EL \u8868\u8fbe\u5f0f\u7684\u5168\u79f0\u662f\uff1aExpression Language\u3002\u662f\u8868\u8fbe\u5f0f\u8bed\u8a00\u3002
EL \u8868\u8fbe\u5f0f\u7684\u4ec0\u4e48\u4f5c\u7528\uff1aEL \u8868\u8fbe\u5f0f\u4e3b\u8981\u662f\u4ee3\u66ff jsp \u9875\u9762\u4e2d\u7684\u8868\u8fbe\u5f0f\u811a\u672c\u5728 jsp \u9875\u9762\u4e2d\u8fdb\u884c\u6570\u636e\u7684\u8f93\u51fa\u3002
\u56e0\u4e3a EL \u8868\u8fbe\u5f0f\u5728\u8f93\u51fa\u6570\u636e\u7684\u65f6\u5019\uff0c\u8981\u6bd4 jsp \u7684\u8868\u8fbe\u5f0f\u811a\u672c\u8981\u7b80\u6d01\u5f88\u591a\u3002<\/p>\n\n\n\n

<body>\n<%\nrequest.setAttribute(\"key\",\"\u503c\");%>\u8868\u8fbe\u5f0f\u811a\u672c\u8f93\u51fa key \u7684\u503c\u662f\uff1a\n<%=request.getAttribute(\"key1\")==null?\"\":request.getAttribute(\"key1\")%><br\/>\nEL \u8868\u8fbe\u5f0f\u8f93\u51fa key \u7684\u503c\u662f\uff1a${key1}<\/body><\/code><\/pre>\n\n\n\n
EL \u8868\u8fbe\u5f0f\u7684\u683c\u5f0f\u662f\uff1a${\u8868\u8fbe\u5f0f}
EL \u8868\u8fbe\u5f0f\u5728\u8f93\u51fa null \u503c\u7684\u65f6\u5019\uff0c\u8f93\u51fa\u7684\u662f\u7a7a\u4e32\u3002jsp \u8868\u8fbe\u5f0f\u811a\u672c\u8f93\u51fa null \u503c\u7684\u65f6\u5019\uff0c\u8f93\u51fa\u7684\u662f null \u5b57\u7b26\u4e32\u3002<\/p>\n\n\n\n
b)EL \u8868\u8fbe\u5f0f\u641c\u7d22\u57df\u6570\u636e\u7684\u987a\u5e8f<\/h2>\n\n\n\n
EL \u8868\u8fbe\u5f0f\u4e3b\u8981\u662f\u5728 jsp \u9875\u9762\u4e2d\u8f93\u51fa\u6570\u636e\u3002
\u4e3b\u8981\u662f\u8f93\u51fa\u57df\u5bf9\u8c61\u4e2d\u7684\u6570\u636e\u3002
\u5f53\u56db\u4e2a\u57df\u4e2d\u90fd\u6709\u76f8\u540c\u7684 key \u7684\u6570\u636e\u7684\u65f6\u5019\uff0cEL \u8868\u8fbe\u5f0f\u4f1a\u6309\u7167\u56db\u4e2a\u57df\u7684\u4ece\u5c0f\u5230\u5927\u7684\u987a\u5e8f\u53bb\u8fdb\u884c\u641c\u7d22\uff0c\u627e\u5230\u5c31\u8f93\u51fa\u3002<\/p>\n\n\n\n
<body>\n<%\n\/\/\u5f80\u56db\u4e2a\u57df\u4e2d\u90fd\u4fdd\u5b58\u4e86\u76f8\u540c\u7684 key \u7684\u6570\u636e\u3002\nrequest.setAttribute(\"key\", \"request\");\nsession.setAttribute(\"key\", \"session\");\napplication.setAttribute(\"key\", \"application\");\npageContext.setAttribute(\"key\", \"pageContext\");\n%>\n${ key }\n<\/body><\/code><\/pre>\n\n\n\n
c)EL \u8868\u8fbe\u5f0f\u8f93\u51fa Bean \u7684\u666e\u901a\u5c5e\u6027\uff0c\u6570\u7ec4\u5c5e\u6027\u3002List \u96c6\u5408\u5c5e\u6027\uff0cmap \u96c6\u5408\u5c5e\u6027<\/h2>\n\n\n\n
i. \u9700\u6c42\u2014\u2014\u8f93\u51fa Person \u7c7b\u4e2d\u666e\u901a\u5c5e\u6027\uff0c\u6570\u7ec4\u5c5e\u6027\u3002list \u96c6\u5408\u5c5e\u6027\u548c map \u96c6\u5408\u5c5e\u6027\u3002<\/p>\n\n\n\n
Person \u7c7b\n\npublic class Person {\n\/\/ i.\u9700\u6c42\u2014\u2014\u8f93\u51fa Person \u7c7b\u4e2d\u666e\u901a\u5c5e\u6027\uff0c\u6570\u7ec4\u5c5e\u6027\u3002list \u96c6\u5408\u5c5e\u6027\u548c map \u96c6\u5408\u5c5e\u6027\u3002\nprivate String name;\nprivate String[] phones;\nprivate List<String> cities;\nprivate Map<String,Object> map;\npublic int getAge() {\nreturn 18;\n}<\/code><\/pre>\n\n\n\n
\u8f93\u51fa\u7684\u4ee3\u7801\uff1a\n\n<body>\n<%\nPerson person = new Person();\nperson.setName(\"\u56fd\u54e5\u597d\u5e05\uff01\");\nperson.setPhones(new String[]{\"18610541354\",\"18688886666\",\"18699998888\"});\nList<String> cities = new ArrayList<String>();\ncities.add(\"\u5317\u4eac\");\ncities.add(\"\u4e0a\u6d77\");\ncities.add(\"\u6df1\u5733\");\nperson.setCities(cities);\nMap<String,Object>map = new HashMap<>();\nmap.put(\"key1\",\"value1\");\nmap.put(\"key2\",\"value2\");\nmap.put(\"key3\",\"value3\");\nperson.setMap(map);\npageContext.setAttribute(\"p\", person);\n%>\n\u8f93\u51fa Person\uff1a${ p }<br\/>\n\u8f93\u51fa Person \u7684 name \u5c5e\u6027\uff1a${p.name} <br>\n\u8f93\u51fa Person \u7684 pnones \u6570\u7ec4\u5c5e\u6027\u503c\uff1a${p.phones[2]} <br>\n\u8f93\u51fa Person \u7684 cities \u96c6\u5408\u4e2d\u7684\u5143\u7d20\u503c\uff1a${p.cities} <br>\n\u8f93\u51fa Person \u7684 List \u96c6\u5408\u4e2d\u4e2a\u522b\u5143\u7d20\u503c\uff1a${p.cities[2]} <br>\n\u8f93\u51fa Person \u7684 Map \u96c6\u5408: ${p.map} <br>\n\u8f93\u51fa Person \u7684 Map \u96c6\u5408\u4e2d\u67d0\u4e2a key \u7684\u503c: ${p.map.key3} <br>\n\u8f93\u51fa Person \u7684 age \u5c5e\u6027\uff1a${p.age} <br>\n<\/body><\/code><\/pre>\n\n\n\n
d)EL \u8868\u8fbe\u5f0f\u2014\u2014\u8fd0\u7b97<\/h2>\n\n\n\n
\u8bed\u6cd5\uff1a${ \u8fd0\u7b97\u8868\u8fbe\u5f0f } \uff0c EL \u8868\u8fbe\u5f0f\u652f\u6301\u5982\u4e0b\u8fd0\u7b97\u7b26\uff1a<\/p>\n\n\n\n
1\uff09\u5173\u7cfb\u8fd0\u7b97<\/h3>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
2\uff09\u903b\u8f91\u8fd0\u7b97<\/h3>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
3\uff09\u7b97\u6570\u8fd0\u7b97<\/h3>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
i. empty \u8fd0\u7b97<\/h3>\n\n\n\n
empty \u8fd0\u7b97\u53ef\u4ee5\u5224\u65ad\u4e00\u4e2a\u6570\u636e\u662f\u5426\u4e3a\u7a7a\uff0c\u5982\u679c\u4e3a\u7a7a\uff0c\u5219\u8f93\u51fa true,\u4e0d\u4e3a\u7a7a\u8f93\u51fa false\u3002
\u4ee5\u4e0b\u51e0\u79cd\u60c5\u51b5\u4e3a\u7a7a\uff1a
1\u3001\u503c\u4e3a null \u503c\u7684\u65f6\u5019\uff0c\u4e3a\u7a7a
2\u3001\u503c\u4e3a\u7a7a\u4e32\u7684\u65f6\u5019\uff0c\u4e3a\u7a7a
3\u3001\u503c\u662f Object \u7c7b\u578b\u6570\u7ec4\uff0c\u957f\u5ea6\u4e3a\u96f6\u7684\u65f6\u5019
4\u3001list \u96c6\u5408\uff0c\u5143\u7d20\u4e2a\u6570\u4e3a\u96f6
5\u3001map \u96c6\u5408\uff0c\u5143\u7d20\u4e2a\u6570\u4e3a\u96f6<\/p>\n\n\n\n
<body>\n<%\n\/\/\n1\u3001\u503c\u4e3a null \u503c\u7684\u65f6\u5019\uff0c\u4e3a\u7a7a\nrequest.setAttribute(\"emptyNull\", null);\n\/\/\n2\u3001\u503c\u4e3a\u7a7a\u4e32\u7684\u65f6\u5019\uff0c\u4e3a\u7a7a\nrequest.setAttribute(\"emptyStr\", \"\");\n\/\/\n3\u3001\u503c\u662f Object \u7c7b\u578b\u6570\u7ec4\uff0c\u957f\u5ea6\u4e3a\u96f6\u7684\u65f6\u5019\nrequest.setAttribute(\"emptyArr\", new Object[]{});\n\/\/\n4\u3001list \u96c6\u5408\uff0c\u5143\u7d20\u4e2a\u6570\u4e3a\u96f6\nList<String> list = new ArrayList<>();\n\/\/\nlist.add(\"abc\");\nrequest.setAttribute(\"emptyList\", list);\n\/\/\n5\u3001map \u96c6\u5408\uff0c\u5143\u7d20\u4e2a\u6570\u4e3a\u96f6\nMap<String,Object> map = new HashMap<String, Object>();\n\/\/\nmap.put(\"key1\", \"value1\");\nrequest.setAttribute(\"emptyMap\", map);\n%>\n${ empty emptyNull } <br\/>\n${ empty emptyStr } <br\/>\n${ empty emptyArr } <br\/>\n${ empty emptyList } <br\/>\n${ empty emptyMap } <br\/>\n<\/body><\/code><\/pre>\n\n\n\n
ii. \u4e09\u5143\u8fd0\u7b97<\/h3>\n\n\n\n
\u8868\u8fbe\u5f0f 1\uff1f\u8868\u8fbe\u5f0f 2\uff1a\u8868\u8fbe\u5f0f 3
\u5982\u679c\u8868\u8fbe\u5f0f 1 \u7684\u503c\u4e3a\u771f\uff0c\u8fd4\u56de\u8868\u8fbe\u5f0f 2 \u7684\u503c\uff0c\u5982\u679c\u8868\u8fbe\u5f0f 1 \u7684\u503c\u4e3a\u5047\uff0c\u8fd4\u56de\u8868\u8fbe\u5f0f 3 \u7684\u503c\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a\n${ 12 != 12 ? \"\u56fd\u54e5\u5e05\u5446\":\"\u56fd\u54e5\u53c8\u9a97\u4eba\u5566\" }<\/code><\/pre>\n\n\n\n
iii. \u201c.\u201d\u70b9\u8fd0\u7b97 \u548c [] \u4e2d\u62ec\u53f7\u8fd0\u7b97\u7b26<\/h3>\n\n\n\n
.\u70b9\u8fd0\u7b97\uff0c\u53ef\u4ee5\u8f93\u51fa Bean \u5bf9\u8c61\u4e2d\u67d0\u4e2a\u5c5e\u6027\u7684\u503c\u3002
[]\u4e2d\u62ec\u53f7\u8fd0\u7b97\uff0c\u53ef\u4ee5\u8f93\u51fa\u6709\u5e8f\u96c6\u5408\u4e2d\u67d0\u4e2a\u5143\u7d20\u7684\u503c\u3002
\u5e76\u4e14[]\u4e2d\u62ec\u53f7\u8fd0\u7b97\uff0c\u8fd8\u53ef\u4ee5\u8f93\u51fa map \u96c6\u5408\u4e2d key \u91cc\u542b\u6709\u7279\u6b8a\u5b57\u7b26\u7684 key \u7684\u503c\u3002<\/p>\n\n\n\n
<body>\n<%\nMap<String,Object> map = new HashMap<String, Object>();\nmap.put(\"a.a.a\", \"aaaValue\");\nmap.put(\"b+b+b\", \"bbbValue\");\nmap.put(\"c-c-c\", \"cccValue\");\nrequest.setAttribute(\"map\", map);\n%>\n${ map['a.a.a'] } <br>\n${ map[\"b+b+b\"] } <br>\n${ map['c-c-c'] } <br>\n<\/body><\/code><\/pre>\n\n\n\n
e)EL \u8868\u8fbe\u5f0f\u7684 11 \u4e2a\u9690\u542b\u5bf9\u8c61<\/h2>\n\n\n\n
EL \u4e2a\u8fbe\u5f0f\u4e2d 11 \u4e2a\u9690\u542b\u5bf9\u8c61\uff0c\u662f EL \u8868\u8fbe\u5f0f\u4e2d\u81ea\u5df1\u5b9a\u4e49\u7684\uff0c\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528\u3002\n\n\u53d8\u91cf                \u7c7b\u578b                     \u4f5c\u7528\npageContext         PageContextImpl         \u5b83\u53ef\u4ee5\u83b7\u53d6 jsp \u4e2d\u7684\u4e5d\u5927\u5185\u7f6e\u5bf9\u8c61\n\npageScope           Map<String,Object>      \u5b83\u53ef\u4ee5\u83b7\u53d6 pageContext \u57df\u4e2d\u7684\u6570\u636e\nrequestScope        Map<String,Object>      \u5b83\u53ef\u4ee5\u83b7\u53d6 Request \u57df\u4e2d\u7684\u6570\u636e\nsessionScope        Map<String,Object>      \u5b83\u53ef\u4ee5\u83b7\u53d6 Session \u57df\u4e2d\u7684\u6570\u636e\napplicationScope    Map<String,Object>      \u5b83\u53ef\u4ee5\u83b7\u53d6 ServletContext \u57df\u4e2d\u7684\u6570\u636e\n\nparam               Map<String,String>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u53c2\u6570\u7684\u503c\nparamValues         Map<String,String[]>    \u5b83\u4e5f\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u53c2\u6570\u7684\u503c\uff0c\u83b7\u53d6\u591a\u4e2a\u503c\u7684\u65f6\u5019\u4f7f\u7528\u3002\n\nheader              Map<String,String>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u5934\u7684\u4fe1\u606f\nheaderValues        Map<String,String[]>    \u5b83\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u5934\u7684\u4fe1\u606f\uff0c\u5b83\u53ef\u4ee5\u83b7\u53d6\u591a\u4e2a\u503c\u7684\u60c5\u51b5\n\ncookie              Map<String,Cookie>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u5f53\u524d\u8bf7\u6c42\u7684 Cookie \u4fe1\u606f\n\ninitParam           Map<String,String>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u5728 web.xml \u4e2d\u914d\u7f6e\u7684<context-param>\u4e0a\u4e0b\u6587\u53c2\u6570<\/code><\/pre>\n\n\n\n
i. EL \u83b7\u53d6\u56db\u4e2a\u7279\u5b9a\u57df\u4e2d\u7684\u5c5e\u6027<\/h3>\n\n\n\n
    pageScope           ======      pageContext \u57df\n    requestScope        ======      Request \u57df\n    sessionScope        ======      Session \u57df\n    applicationScope    ======      ServletContext \u57df<\/code><\/pre>\n\n\n\n
<body>\n<%\npageContext.setAttribute(\"key1\", \"pageContext1\");\npageContext.setAttribute(\"key2\", \"pageContext2\");\nrequest.setAttribute(\"key2\", \"request\");\nsession.setAttribute(\"key2\", \"session\");\napplication.setAttribute(\"key2\", \"application\");\n%>\n${ applicationScope.key2 }\n<\/body><\/code><\/pre>\n\n\n\n
ii. pageContext \u5bf9\u8c61\u7684\u4f7f\u7528<\/h3>\n\n\n\n
  1. \u534f\u8bae\uff1a<\/li>
  2. \u670d\u52a1\u5668 ip\uff1a<\/li>
  3. \u670d\u52a1\u5668\u7aef\u53e3\uff1a<\/li>
  4. \u83b7\u53d6\u5de5\u7a0b\u8def\u5f84\uff1a<\/li>
  5. \u83b7\u53d6\u8bf7\u6c42\u65b9\u6cd5\uff1a<\/li>
  6. \u83b7\u53d6\u5ba2\u6237\u7aef ip \u5730\u5740\uff1a<\/li>
  7. \u83b7\u53d6\u4f1a\u8bdd\u7684 id \u7f16\u53f7\uff1a<\/li><\/ol>\n\n\n\n
    <body>\n<%--\nrequest.getScheme() \u5b83\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u7684\u534f\u8bae\nrequest.getServerName() \u83b7\u53d6\u8bf7\u6c42\u7684\u670d\u52a1\u5668 ip \u6216\u57df\u540d\nrequest.getServerPort() \u83b7\u53d6\u8bf7\u6c42\u7684\u670d\u52a1\u5668\u7aef\u53e3\u53f7\ngetContextPath() \u83b7\u53d6\u5f53\u524d\u5de5\u7a0b\u8def\u5f84\nrequest.getMethod() \u83b7\u53d6\u8bf7\u6c42\u7684\u65b9\u5f0f\uff08GET \u6216 POST\uff09\nrequest.getRemoteHost() \u83b7\u53d6\u5ba2\u6237\u7aef\u7684 ip \u5730\u5740\nsession.getId() \u83b7\u53d6\u4f1a\u8bdd\u7684\u552f\u4e00\u6807\u8bc6\n--%>\n<%\npageContext.setAttribute(\"req\", request);\n%>\n<%=request.getScheme() %> <br>\n1.\u534f\u8bae\uff1a ${ req.scheme }<br>\n2.\u670d\u52a1\u5668 ip\uff1a${ pageContext.request.serverName }<br>\n3.\u670d\u52a1\u5668\u7aef\u53e3\uff1a${ pageContext.request.serverPort }<br>\n4.\u83b7\u53d6\u5de5\u7a0b\u8def\u5f84\uff1a${ pageContext.request.contextPath }<br>\n5.\u83b7\u53d6\u8bf7\u6c42\u65b9\u6cd5\uff1a${ pageContext.request.method }<br>\n6.\u83b7\u53d6\u5ba2\u6237\u7aef ip \u5730\u5740\uff1a${ pageContext.request.remoteHost }<br>\n7.\u83b7\u53d6\u4f1a\u8bdd\u7684 id \u7f16\u53f7\uff1a${ pageContext.session.id }<br>\n<\/body><\/code><\/pre>\n\n\n\n
    iii. EL \u8868\u8fbe\u5f0f\u5176\u4ed6\u9690\u542b\u5bf9\u8c61\u7684\u4f7f\u7528<\/h3>\n\n\n\n
     param           Map<String,String>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u53c2\u6570\u7684\u503c\n paramValues     Map<String,String[]>    \u5b83\u4e5f\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u53c2\u6570\u7684\u503c\uff0c\u83b7\u53d6\u591a\u4e2a\u503c\u7684\u65f6\u5019\u4f7f\u7528<\/code><\/pre>\n\n\n\n
    \u793a\u4f8b\u4ee3\u7801\uff1a<\/p>\n\n\n\n
    \u8f93\u51fa\u8bf7\u6c42\u53c2\u6570 username \u7684\u503c\uff1a${ param.username } <br>\n\u8f93\u51fa\u8bf7\u6c42\u53c2\u6570 password \u7684\u503c\uff1a${ param.password } <br>\n\u8f93\u51fa\u8bf7\u6c42\u53c2\u6570 username \u7684\u503c\uff1a${ paramValues.username[0] } <br>\n\u8f93\u51fa\u8bf7\u6c42\u53c2\u6570 hobby \u7684\u503c\uff1a${ paramValues.hobby[0] } <br>\n\u8f93\u51fa\u8bf7\u6c42\u53c2\u6570 hobby \u7684\u503c\uff1a${ paramValues.hobby[1] } <br><\/code><\/pre>\n\n\n\n
    \u8bf7\u6c42\u5730\u5740\uff1a
    http:\/\/localhost:8080\/09_EL_JSTL\/other_el_obj.jsp?username=wzg168&password=666666&hobby=java&hobby=cpp<\/p>\n\n\n\n
        header          Map<String,String>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u5934\u7684\u4fe1\u606f\n    headerValues    Map<String,String[]>    \u5b83\u53ef\u4ee5\u83b7\u53d6\u8bf7\u6c42\u5934\u7684\u4fe1\u606f\uff0c\u5b83\u53ef\u4ee5\u83b7\u53d6\u591a\u4e2a\u503c\u7684\u60c5\u51b5<\/code><\/pre>\n\n\n\n
    \u793a\u4f8b\u4ee3\u7801\uff1a<\/p>\n\n\n\n
    \u8f93\u51fa\u8bf7\u6c42\u5934\u3010User-Agent\u3011\u7684\u503c\uff1a${ header['User-Agent'] } <br>\n\u8f93\u51fa\u8bf7\u6c42\u5934\u3010Connection\u3011\u7684\u503c\uff1a${ header.Connection } <br>\n\u8f93\u51fa\u8bf7\u6c42\u5934\u3010User-Agent\u3011\u7684\u503c\uff1a${ headerValues['User-Agent'][0] } <br><\/code><\/pre>\n\n\n\n
    cookie          Map<String,Cookie>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u5f53\u524d\u8bf7\u6c42\u7684 Cookie \u4fe1\u606f<\/code><\/pre>\n\n\n\n
    \u793a\u4f8b\u4ee3\u7801\uff1a<\/p>\n\n\n\n
    \u83b7\u53d6 Cookie \u7684\u540d\u79f0\uff1a${ cookie.JSESSIONID.name } <br>\n\u83b7\u53d6 Cookie \u7684\u503c\uff1a${ cookie.JSESSIONID.value } <br><\/code><\/pre>\n\n\n\n
    initParam       Map<String,String>      \u5b83\u53ef\u4ee5\u83b7\u53d6\u5728 web.xml \u4e2d\u914d\u7f6e\u7684<context-param>\u4e0a\u4e0b\u6587\u53c2\u6570<\/code><\/pre>\n\n\n\n
    web.xml \u4e2d\u7684\u914d\u7f6e\uff1a<\/p>\n\n\n\n
    <context-param>\n<param-name>username<\/param-name>\n<param-value>root<\/param-value>\n<\/context-param>\n<context-param>\n<param-name>url<\/param-name>\n<param-value>jdbc:mysql:\/\/\/test<\/param-value>\n<\/context-param><\/code><\/pre>\n\n\n\n
    \u793a\u4f8b\u4ee3\u7801\uff1a<\/p>\n\n\n\n
    \u8f93\u51fa&lt;Context-param&gt;username \u7684\u503c\uff1a${ initParam.username } <br>\n\u8f93\u51fa&lt;Context-param&gt;url \u7684\u503c\uff1a${ initParam.url } <br><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
    EL \u8868\u8fbe\u5f0f a)\u4ec0\u4e48\u662f EL \u8868\u8fbe\u5f0f\uff0cEL \u8868\u8fbe\u5f0f\u7684\u4f5c\u7528? EL \u8868\u8fbe\u5f0f\u7684\u5168\u79f0\u662f\uff1aExpression La […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[59],"tags":[61],"class_list":["post-2259","post","type-post","status-publish","format-standard","hentry","category-javaweb-code","tag-javaweb"],"_links":{"self":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/2259"}],"collection":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2259"}],"version-history":[{"count":4,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/2259\/revisions"}],"predecessor-version":[{"id":2709,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/2259\/revisions\/2709"}],"wp:attachment":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2259"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2259"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2259"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}