{"id":2285,"date":"2022-12-08T20:38:51","date_gmt":"2022-12-08T12:38:51","guid":{"rendered":"https:\/\/qaqaq.top\/?p=2285"},"modified":"2022-12-19T20:42:22","modified_gmt":"2022-12-19T12:42:22","slug":"jstl%e6%a0%87%e7%ad%be%e5%ba%93-jstl%e6%a0%87%e7%ad%be%e5%ba%93%e7%9a%84%e4%bb%8b%e7%bb%8d%e3%80%81jstl%e6%a0%87%e7%ad%be%e5%ba%93-%e6%a0%87%e7%ad%be%e5%ba%93%e7%9a%84%e4%bd%bf%e7%94%a8%e6%ad%a5","status":"publish","type":"post","link":"https:\/\/qaqaq.top\/?p=2285","title":{"rendered":"JSTL\u6807\u7b7e\u5e93-JSTL\u6807\u7b7e\u5e93\u7684\u4ecb\u7ecd\u3001\u6807\u7b7e\u5e93\u7684\u4f7f\u7528\u6b65\u9aa4\u3001set\u6807\u7b7e\u3001if\u6807\u7b7e\u3001choose\u3001when\u3001otherwise\u6807\u7b7e\u3001\u4f7f\u7528forEach\u904d\u53861\u523010\u7684\u60c5\u51b5\u3001\u4f7f\u7528forEach\u904d\u5386Object\u6570\u7ec4\u3001\u4f7f\u7528forEach\u904d\u5386Map\u96c6\u5408\u3001\u4f7f\u7528forEach\u904d\u5386List\u96c6\u5408\u3001forEach\u6807\u7b7e\u6240\u6709\u5c5e\u6027\u7ec4\u5408\u4f7f\u7528\u4ecb\u7ecd"},"content":{"rendered":"\n

JSTL \u6807\u7b7e\u5e93(\u6b21\u91cd\u70b9****)<\/h1>\n\n\n\n

JSTL \u6807\u7b7e\u5e93 \u5168\u79f0\u662f\u6307 JSP Standard Tag Library JSP \u6807\u51c6\u6807\u7b7e\u5e93\u3002\u662f\u4e00\u4e2a\u4e0d\u65ad\u5b8c\u5584\u7684\u5f00\u653e\u6e90\u4ee3\u7801\u7684 JSP \u6807\u7b7e\u5e93\u3002
EL \u8868\u8fbe\u5f0f\u4e3b\u8981\u662f\u4e3a\u4e86\u66ff\u6362 jsp \u4e2d\u7684\u8868\u8fbe\u5f0f\u811a\u672c\uff0c\u800c\u6807\u7b7e\u5e93\u5219\u662f\u4e3a\u4e86\u66ff\u6362\u4ee3\u7801\u811a\u672c\u3002\u8fd9\u6837\u4f7f\u5f97\u6574\u4e2a jsp \u9875\u9762\u53d8\u5f97\u66f4\u4f73\u7b80\u6d01\u3002<\/p>\n\n\n\n

JSTL \u7531\u4e94\u4e2a\u4e0d\u540c\u529f\u80fd\u7684\u6807\u7b7e\u5e93\u7ec4\u6210\u3002<\/p>\n\n\n\n

\"\"<\/div><\/figure>\n\n\n\n
\u5728 jsp \u6807\u7b7e\u5e93\u4e2d\u4f7f\u7528 taglib \u6307\u4ee4\u5f15\u5165\u6807\u7b7e\u5e93\n\nCORE \u6807\u7b7e\u5e93\n<%@ taglib prefix=\"c\" uri=\"http:\/\/java.sun.com\/jsp\/jstl\/core\" %>\nXML \u6807\u7b7e\u5e93\n<%@ taglib prefix=\"x\" uri=\"http:\/\/java.sun.com\/jsp\/jstl\/xml\" %>\nFMT \u6807\u7b7e\u5e93\n<%@ taglib prefix=\"fmt\" uri=\"http:\/\/java.sun.com\/jsp\/jstl\/fmt\" %>\nSQL \u6807\u7b7e\u5e93\n<%@ taglib prefix=\"sql\" uri=\"http:\/\/java.sun.com\/jsp\/jstl\/sql\" %>\nFUNCTIONS \u6807\u7b7e\u5e93\n<%@ taglib prefix=\"fn\" uri=\"http:\/\/java.sun.com\/jsp\/jstl\/functions\" %><\/code><\/pre>\n\n\n\n
f) JSTL \u6807\u7b7e\u5e93\u7684\u4f7f\u7528\u6b65\u9aa4<\/h2>\n\n\n\n
1\u3001\u5148\u5bfc\u5165 jstl \u6807\u7b7e\u5e93\u7684 jar \u5305\u3002
taglibs-standard-impl-1.2.1.jar
taglibs-standard-spec-1.2.1.jar
2\u3001\u7b2c\u4e8c\u6b65\uff0c\u4f7f\u7528 taglib \u6307\u4ee4\u5f15\u5165\u6807\u7b7e\u5e93\u3002<\/p>\n\n\n\n
<%@ taglib prefix=\"c\" uri=\"http:\/\/java.sun.com\/jsp\/jstl\/core\" %><\/code><\/pre>\n\n\n\n
g)core \u6838\u5fc3\u5e93\u4f7f\u7528<\/h2>\n\n\n\n
i. <c:set \/>\uff08\u4f7f\u7528\u5f88\u5c11\uff09
\u4f5c\u7528\uff1aset \u6807\u7b7e\u53ef\u4ee5\u5f80\u57df\u4e2d\u4fdd\u5b58\u6570\u636e<\/p>\n\n\n\n
<%--\ni.<c:set \/>\n\u4f5c\u7528\uff1aset \u6807\u7b7e\u53ef\u4ee5\u5f80\u57df\u4e2d\u4fdd\u5b58\u6570\u636e\n\u57df\u5bf9\u8c61.setAttribute(key,value);\nscope \u5c5e\u6027\u8bbe\u7f6e\u4fdd\u5b58\u5230\u54ea\u4e2a\u57df\npage \u8868\u793a PageContext \u57df\uff08\u9ed8\u8ba4\u503c\uff09\nrequest \u8868\u793a Request \u57df\nsession \u8868\u793a Session \u57df\napplication \u8868\u793a ServletContext \u57dfvar \u5c5e\u6027\u8bbe\u7f6e key \u662f\u591a\u5c11value \u5c5e\u6027\u8bbe\u7f6e\u503c\n--%>\n\u4fdd\u5b58\u4e4b\u524d\uff1a${ sessionScope.abc } <br>\n<c:set scope=\"session\" var=\"abc\" value=\"abcValue\"\/>\n\u4fdd\u5b58\u4e4b\u540e\uff1a${ sessionScope.abc } <br><\/code><\/pre>\n\n\n\n
ii.<c:if \/>
if \u6807\u7b7e\u7528\u6765\u505a if \u5224\u65ad\u3002<\/p>\n\n\n\n
<%--\nii.<c:if \/>\nif \u6807\u7b7e\u7528\u6765\u505a if \u5224\u65ad\u3002\ntest \u5c5e\u6027\u8868\u793a\u5224\u65ad\u7684\u6761\u4ef6\uff08\u4f7f\u7528 EL \u8868\u8fbe\u5f0f\u8f93\u51fa\uff09--%><c:if test=\"${ 12 == 12 }\">\n<h1>12 \u7b49\u4e8e 12<\/h1><\/c:if><c:if test=\"${ 12 != 12 }\">\n<h1>12 \u4e0d\u7b49\u4e8e 12<\/h1><\/c:if><\/code><\/pre>\n\n\n\n
iii. <c:choose> <c:when> <c:otherwise>\u6807\u7b7e
\u4f5c\u7528\uff1a\u591a\u8def\u5224\u65ad\u3002\u8ddf switch \u2026 case \u2026. default \u975e\u5e38\u63a5\u8fd1<\/p>\n\n\n\n
<%--\niii.<c:choose> <c:when> <c:otherwise>\u6807\u7b7e\n\u4f5c\u7528\uff1a\u591a\u8def\u5224\u65ad\u3002\u8ddf switch ... case .... default \u975e\u5e38\u63a5\u8fd1\nchoose \u6807\u7b7e\u5f00\u59cb\u9009\u62e9\u5224\u65ad\nwhen \u6807\u7b7e\u8868\u793a\u6bcf\u4e00\u79cd\u5224\u65ad\u60c5\u51b5\ntest \u5c5e\u6027\u8868\u793a\u5f53\u524d\u8fd9\u79cd\u5224\u65ad\u60c5\u51b5\u7684\u503cotherwise \u6807\u7b7e\u8868\u793a\u5269\u4e0b\u7684\u60c5\u51b5\n<c:choose> <c:when> <c:otherwise>\u6807\u7b7e\u4f7f\u7528\u65f6\u9700\u8981\u6ce8\u610f\u7684\u70b9\uff1a\n1\u3001\u6807\u7b7e\u91cc\u4e0d\u80fd\u4f7f\u7528 html \u6ce8\u91ca\uff0c\u8981\u4f7f\u7528 jsp \u6ce8\u91ca\n2\u3001when \u6807\u7b7e\u7684\u7236\u6807\u7b7e\u4e00\u5b9a\u8981\u662f choose \u6807\u7b7e--%><%\nrequest.setAttribute(\"height\", 180);\n%>\n<c:choose>\n<%-- \u8fd9\u662f html \u6ce8\u91ca --%>\n<c:when test=\"${ requestScope.height > 190 }\">\n<h2>\u5c0f\u5de8\u4eba<\/h2><\/c:when><c:when test=\"${ requestScope.height > 180 }\">\n<h2>\u5f88\u9ad8<\/h2><\/c:when><c:when test=\"${ requestScope.height > 170 }\">\n<h2>\u8fd8\u53ef\u4ee5<\/h2><\/c:when>\n<c:otherwise>\n<c:choose>\n<c:when test=\"${requestScope.height > 160}\">\n<h3>\u5927\u4e8e 160<\/h3><\/c:when><c:when test=\"${requestScope.height > 150}\">\n<h3>\u5927\u4e8e 150<\/h3><\/c:when><c:when test=\"${requestScope.height > 140}\">\n<h3>\u5927\u4e8e 140<\/h3><\/c:when><c:otherwise>\n\u5176\u4ed6\u5c0f\u4e8e 140<\/c:otherwise>\n<\/c:choose>\n<\/c:otherwise>\n<\/c:choose><\/code><\/pre>\n\n\n\n
iv.
\u4f5c\u7528\uff1a\u904d\u5386\u8f93\u51fa\u4f7f\u7528\u3002<\/p>\n\n\n\n
1.\u904d\u5386 1 \u5230 10\uff0c\u8f93\u51fa<\/p>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801\uff1a\n\n<%--1.\u904d\u5386 1 \u5230 10\uff0c\u8f93\u51fa\nbegin \u5c5e\u6027\u8bbe\u7f6e\u5f00\u59cb\u7684\u7d22\u5f15\nend \u5c5e\u6027\u8bbe\u7f6e\u7ed3\u675f\u7684\u7d22\u5f15\nvar \u5c5e\u6027\u8868\u793a\u5faa\u73af\u7684\u53d8\u91cf(\u4e5f\u662f\u5f53\u524d\u6b63\u5728\u904d\u5386\u5230\u7684\u6570\u636e)\nfor (int i = 1; i < 10; i++)\n--%>\n<table border=\"1\">\n<c:forEach begin=\"1\" end=\"10\" var=\"i\">\n<tr>\n<td>\u7b2c${i}\u884c<\/td><\/tr>\n<\/c:forEach>\n<\/table><\/code><\/pre>\n\n\n\n
2.\u904d\u5386 Object \u6570\u7ec4<\/p>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801\uff1a\n\n<%-- 2.\u904d\u5386 Object \u6570\u7ec4\nfor (Object item: arr)\nitems \u8868\u793a\u904d\u5386\u7684\u6570\u636e\u6e90\uff08\u904d\u5386\u7684\u96c6\u5408\uff09\nvar \u8868\u793a\u5f53\u524d\u904d\u5386\u5230\u7684\u6570\u636e--%><%\nrequest.setAttribute(\"arr\", new String[]{\"18610541354\",\"18688886666\",\"18699998888\"});\n%>\n<c:forEach items=\"${ requestScope.arr }\" var=\"item\">\n${ item } <br>\n<\/c:forEach><\/code><\/pre>\n\n\n\n
3.\u904d\u5386 Map \u96c6\u5408<\/p>\n\n\n\n
\u793a\u4f8b\u4ee3\u7801\uff1a\n\n<%\nMap<String,Object> map = new HashMap<String, Object>();\nmap.put(\"key1\", \"value1\");\nmap.put(\"key2\", \"value2\");\nmap.put(\"key3\", \"value3\");\n\/\/\nfor ( Map.Entry<String,Object> entry : map.entrySet()) {\n\/\/\n}\nrequest.setAttribute(\"map\", map);\n%>\n<c:forEach items=\"${ requestScope.map }\" var=\"entry\">\n<h1>${entry.key} = ${entry.value}<\/h1>\n<\/c:forEach><\/code><\/pre>\n\n\n\n
  1. \u904d\u5386 List \u96c6\u5408—list \u4e2d\u5b58\u653e Student \u7c7b\uff0c\u6709\u5c5e\u6027\uff1a\u7f16\u53f7\uff0c\u7528\u6237\u540d\uff0c\u5bc6\u7801\uff0c\u5e74\u9f84\uff0c\u7535\u8bdd\u4fe1\u606f<\/li><\/ol>\n\n\n\n
    Student \u7c7b\uff1a\n\npublic class Student {\n\/\/4.\u7f16\u53f7\uff0c\u7528\u6237\u540d\uff0c\u5bc6\u7801\uff0c\u5e74\u9f84\uff0c\u7535\u8bdd\u4fe1\u606f\nprivate Integer id;\nprivate String username;\nprivate String password;\nprivate Integer age;\nprivate String phone;<\/code><\/pre>\n\n\n\n
    \u793a\u4f8b\u4ee3\u7801\uff1a\n\n<%--4.\u904d\u5386 List \u96c6\u5408---list \u4e2d\u5b58\u653e Student \u7c7b\uff0c\u6709\u5c5e\u6027\uff1a\u7f16\u53f7\uff0c\u7528\u6237\u540d\uff0c\u5bc6\u7801\uff0c\u5e74\u9f84\uff0c\u7535\u8bdd\u4fe1\u606f--%>\n<%\nList<Student> studentList = new ArrayList<Student>();\nfor (int i = 1; i <= 10; i++) {\nstudentList.add(new Student(i,\"username\"+i ,\"pass\"+i,18+i,\"phone\"+i));\n}\nrequest.setAttribute(\"stus\", studentList);\n%>\n<table>\n<tr>\n<th>\u7f16\u53f7<\/th>\n<th>\u7528\u6237\u540d<\/th>\n<th>\u5bc6\u7801<\/th>\n<th>\u5e74\u9f84<\/th>\n<th>\u7535\u8bdd<\/th>\n<th>\u64cd\u4f5c<\/th><\/tr><%--\nitems \u8868\u793a\u904d\u5386\u7684\u96c6\u5408\nvar \u8868\u793a\u904d\u5386\u5230\u7684\u6570\u636e\nbegin \u8868\u793a\u904d\u5386\u7684\u5f00\u59cb\u7d22\u5f15\u503c\nend \u8868\u793a\u7ed3\u675f\u7684\u7d22\u5f15\u503c\nstep \u5c5e\u6027\u8868\u793a\u904d\u5386\u7684\u6b65\u957f\u503c\nvarStatus \u5c5e\u6027\u8868\u793a\u5f53\u524d\u904d\u5386\u5230\u7684\u6570\u636e\u7684\u72b6\u6001\nfor\uff08int i = 1; i < 10; i+=2\uff09\n--%>\n<c:forEach begin=\"2\" end=\"7\" step=\"2\" varStatus=\"status\" items=\"${requestScope.stus}\" var=\"stu\">\n<tr>\n<td>${stu.id}<\/td>\n<td>${stu.username}<\/td>\n<td>${stu.password}<\/td>\n<td>${stu.age}<\/td>\n<td>${stu.phone}<\/td>\n<td>${status.step}<\/td>\n<\/tr>\n<\/c:forEach>\n<\/table><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
    JSTL \u6807\u7b7e\u5e93(\u6b21\u91cd\u70b9****) JSTL \u6807\u7b7e\u5e93 \u5168\u79f0\u662f\u6307 JSP Standard Tag Librar […]<\/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-2285","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\/2285"}],"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=2285"}],"version-history":[{"count":2,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/2285\/revisions"}],"predecessor-version":[{"id":2711,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/2285\/revisions\/2711"}],"wp:attachment":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2285"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2285"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2285"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}