一般 说的 java 三级架构 是
Java项目基础三层的(dao、service、controller)
一句话 概括我们程序员做的事情
就是浏览器 请求服务器 去数据库 取数据 然后渲染在 浏览器上显示给用户，然后进行增删改查。
最初的架构 是 servlet + jsp + jdbc 打通浏览器， 服务器， 数据库，
六大原则 java项目 基础三大核心目的 ** 高扩展，低耦合，易维护** （程序员的要求） 更多的流量支持： （高可用 高并发 高性能）（架构师的要求）
出现了架构 ssh 框架 ssm 框架 sprintboot 等框架，而底层核心就是 servlet + jsp + jdbc
jsp & servlet 浅讲
jsp本质是servlet， 如果 servlet 要生成html 页面 返回给浏览器渲染 流动态生成， 就得是这样
* Generated by the Jasper component of Apache Tomcat
* Version: Apache Tomcat/9.0.83
* Generated at: 2023-11-19 15:47:30 UTC
* Note: The last modified time of this file was set to
* the last modified time of the source file after
* generation to assist with modification tracking.
*/
package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
public final class user_002dlist_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent,
org.apache.jasper.runtime.JspSourceImports {
private static final javax.servlet.jsp.JspFactory _jspxFactory =
javax.servlet.jsp.JspFactory.getDefaultFactory();
private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;
static {
_jspx_dependants = new java.util.HashMap<java.lang.String,java.lang.Long>(2);
_jspx_dependants.put("jar:file:/Users/huchangfeng/Downloads/baiduyun/config/tomcat/apache-tomcat-9.0.83/lib/standard.jar!/META-INF/c.tld", Long.valueOf(1098682290000L));
_jspx_dependants.put("file:/Users/huchangfeng/Downloads/baiduyun/config/tomcat/apache-tomcat-9.0.83/lib/standard.jar", Long.valueOf(1700376011780L));
}
private static final java.util.Set<java.lang.String> _jspx_imports_packages;
private static final java.util.Set<java.lang.String> _jspx_imports_classes;
static {
_jspx_imports_packages = new java.util.HashSet<>();
_jspx_imports_packages.add("javax.servlet");
_jspx_imports_packages.add("javax.servlet.http");
_jspx_imports_packages.add("javax.servlet.jsp");
_jspx_imports_classes = null;
}
private org.apache.jasper.runtime.TagHandlerPool _005fjspx_005ftagPool_005fc_005fforEach_0026_005fvar_005fitems;
private org.apache.jasper.runtime.TagHandlerPool _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody;
private volatile javax.el.ExpressionFactory _el_expressionfactory;
private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;
public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
return _jspx_dependants;
}
public java.util.Set<java.lang.String> getPackageImports() {
return _jspx_imports_packages;
}
public java.util.Set<java.lang.String> getClassImports() {
return _jspx_imports_classes;
}
public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
if (_el_expressionfactory == null) {
synchronized (this) {
if (_el_expressionfactory == null) {
_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
}
}
}
return _el_expressionfactory;
}
public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
if (_jsp_instancemanager == null) {
synchronized (this) {
if (_jsp_instancemanager == null) {
_jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
}
}
}
return _jsp_instancemanager;
}
public void _jspInit() {
_005fjspx_005ftagPool_005fc_005fforEach_0026_005fvar_005fitems = org.apache.jasper.runtime.TagHandlerPool.getTagHandlerPool(getServletConfig());
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody = org.apache.jasper.runtime.TagHandlerPool.getTagHandlerPool(getServletConfig());
}
public void _jspDestroy() {
_005fjspx_005ftagPool_005fc_005fforEach_0026_005fvar_005fitems.release();
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.release();
}
public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
throws java.io.IOException, javax.servlet.ServletException {
if (!javax.servlet.DispatcherType.ERROR.equals(request.getDispatcherType())) {
final java.lang.String _jspx_method = request.getMethod();
if ("OPTIONS".equals(_jspx_method)) {
response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
return;
}
if (!"GET".equals(_jspx_method) && !"POST".equals(_jspx_method) && !"HEAD".equals(_jspx_method)) {
response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "JSP 只允许 GET、POST 或 HEAD。Jasper 还允许 OPTIONS");
return;
}
}
final javax.servlet.jsp.PageContext pageContext;
javax.servlet.http.HttpSession session = null;
final javax.servlet.ServletContext application;
final javax.servlet.ServletConfig config;
javax.servlet.jsp.JspWriter out = null;
final java.lang.Object page = this;
javax.servlet.jsp.JspWriter _jspx_out = null;
javax.servlet.jsp.PageContext _jspx_page_context = null;
try {
response.setContentType("text/html; charset=UTF-8");
pageContext = _jspxFactory.getPageContext(this, request, response,
null, true, 8192, true);
_jspx_page_context = pageContext;
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();
_jspx_out = out;
out.write("\n");
out.write("\n");
out.write("<html>\n");
out.write("<head>\n");
out.write("<title>User Management Application</title>\n");
out.write("<link rel=\"stylesheet\"\n");
out.write(" href=\"https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css\"\n");
out.write(" integrity=\"sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T\"\n");
out.write(" crossorigin=\"anonymous\">\n");
out.write("</head>\n");
out.write("<body>\n");
out.write("\n");
out.write(" <header>\n");
out.write(" <nav class=\"navbar navbar-expand-md navbar-dark\"\n");
out.write(" style=\"background-color: tomato\">\n");
out.write(" <div>\n");
out.write(" <a href=\"https://www.javaguides.net\" class=\"navbar-brand\"> User\n");
out.write(" Management App </a>\n");
out.write(" </div>\n");
out.write("\n");
out.write(" <ul class=\"navbar-nav\">\n");
out.write(" <li><a href=\"");
out.print(request.getContextPath());
out.write("/list\"\n");
out.write(" class=\"nav-link\">Users</a></li>\n");
out.write(" </ul>\n");
out.write(" </nav>\n");
out.write(" </header>\n");
out.write(" <br>\n");
out.write("\n");
out.write(" <div class=\"row\">\n");
out.write(" <!-- <div class=\"alert alert-success\" *ngIf='message'>{{message}}</div> -->\n");
out.write("\n");
out.write(" <div class=\"container\">\n");
out.write(" <h3 class=\"text-center\">List of Users</h3>\n");
out.write(" <hr>\n");
out.write(" <div class=\"container text-left\">\n");
out.write("\n");
out.write(" <a href=\"");
out.print(request.getContextPath());
out.write("/new\" class=\"btn btn-success\">Add\n");
out.write(" New User</a>\n");
out.write(" </div>\n");
out.write(" <br>\n");
out.write(" <table class=\"table table-bordered\">\n");
out.write(" <thead>\n");
out.write(" <tr>\n");
out.write(" <th>ID</th>\n");
out.write(" <th>Name</th>\n");
out.write(" <th>Email</th>\n");
out.write(" <th>Country</th>\n");
out.write(" <th>Actions</th>\n");
out.write(" </tr>\n");
out.write(" </thead>\n");
out.write(" <tbody>\n");
out.write(" <!-- for (Todo todo: todos) { -->\n");
out.write(" ");
if (_jspx_meth_c_005fforEach_005f0(_jspx_page_context))
return;
out.write("\n");
out.write(" <!-- } -->\n");
out.write(" </tbody>\n");
out.write("\n");
out.write(" </table>\n");
out.write(" </div>\n");
out.write(" </div>\n");
out.write("</body>\n");
out.write("</html>\n");
} catch (java.lang.Throwable t) {
if (!(t instanceof javax.servlet.jsp.SkipPageException)){
out = _jspx_out;
if (out != null && out.getBufferSize() != 0)
try {
if (response.isCommitted()) {
out.flush();
} else {
out.clearBuffer();
}
} catch (java.io.IOException e) {}
if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
else throw new ServletException(t);
}
} finally {
_jspxFactory.releasePageContext(_jspx_page_context);
}
}
private boolean _jspx_meth_c_005fforEach_005f0(javax.servlet.jsp.PageContext _jspx_page_context)
throws java.lang.Throwable {
javax.servlet.jsp.PageContext pageContext = _jspx_page_context;
javax.servlet.jsp.JspWriter out = _jspx_page_context.getOut();
// c:forEach
org.apache.taglibs.standard.tag.rt.core.ForEachTag _jspx_th_c_005fforEach_005f0 = (org.apache.taglibs.standard.tag.rt.core.ForEachTag) _005fjspx_005ftagPool_005fc_005fforEach_0026_005fvar_005fitems.get(org.apache.taglibs.standard.tag.rt.core.ForEachTag.class);
boolean _jspx_th_c_005fforEach_005f0_reused = false;
try {
_jspx_th_c_005fforEach_005f0.setPageContext(_jspx_page_context);
_jspx_th_c_005fforEach_005f0.setParent(null);
// /user-list.jsp(54,5) name = var type = java.lang.String reqTime = false required = false fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fforEach_005f0.setVar("user");
// /user-list.jsp(54,5) name = items type = java.lang.Object reqTime = true required = false fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fforEach_005f0.setItems((java.lang.Object) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${listUser}", java.lang.Object.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null));
int[] _jspx_push_body_count_c_005fforEach_005f0 = new int[] { 0 };
try {
int _jspx_eval_c_005fforEach_005f0 = _jspx_th_c_005fforEach_005f0.doStartTag();
if (_jspx_eval_c_005fforEach_005f0 != javax.servlet.jsp.tagext.Tag.SKIP_BODY) {
do {
out.write("\n");
out.write("\n");
out.write(" <tr>\n");
out.write(" <td>");
if (_jspx_meth_c_005fout_005f0(_jspx_th_c_005fforEach_005f0, _jspx_page_context, _jspx_push_body_count_c_005fforEach_005f0))
return true;
out.write("</td>\n");
out.write(" <td>");
if (_jspx_meth_c_005fout_005f1(_jspx_th_c_005fforEach_005f0, _jspx_page_context, _jspx_push_body_count_c_005fforEach_005f0))
return true;
out.write("</td>\n");
out.write(" <td>");
if (_jspx_meth_c_005fout_005f2(_jspx_th_c_005fforEach_005f0, _jspx_page_context, _jspx_push_body_count_c_005fforEach_005f0))
return true;
out.write("</td>\n");
out.write(" <td>");
if (_jspx_meth_c_005fout_005f3(_jspx_th_c_005fforEach_005f0, _jspx_page_context, _jspx_push_body_count_c_005fforEach_005f0))
return true;
out.write("</td>\n");
out.write(" <td><a href=\"edit?id=");
if (_jspx_meth_c_005fout_005f4(_jspx_th_c_005fforEach_005f0, _jspx_page_context, _jspx_push_body_count_c_005fforEach_005f0))
return true;
out.write("\">Edit</a>\n");
out.write(" <a\n");
out.write(" href=\"delete?id=");
if (_jspx_meth_c_005fout_005f5(_jspx_th_c_005fforEach_005f0, _jspx_page_context, _jspx_push_body_count_c_005fforEach_005f0))
return true;
out.write("\">Delete</a></td>\n");
out.write(" </tr>\n");
out.write(" ");
int evalDoAfterBody = _jspx_th_c_005fforEach_005f0.doAfterBody();
if (evalDoAfterBody != javax.servlet.jsp.tagext.BodyTag.EVAL_BODY_AGAIN)
break;
} while (true);
}
if (_jspx_th_c_005fforEach_005f0.doEndTag() == javax.servlet.jsp.tagext.Tag.SKIP_PAGE) {
return true;
}
} catch (java.lang.Throwable _jspx_exception) {
while (_jspx_push_body_count_c_005fforEach_005f0[0]-- > 0)
out = _jspx_page_context.popBody();
_jspx_th_c_005fforEach_005f0.doCatch(_jspx_exception);
} finally {
_jspx_th_c_005fforEach_005f0.doFinally();
}
_005fjspx_005ftagPool_005fc_005fforEach_0026_005fvar_005fitems.reuse(_jspx_th_c_005fforEach_005f0);
_jspx_th_c_005fforEach_005f0_reused = true;
} finally {
org.apache.jasper.runtime.JspRuntimeLibrary.releaseTag(_jspx_th_c_005fforEach_005f0, _jsp_getInstanceManager(), _jspx_th_c_005fforEach_005f0_reused);
}
return false;
}
private boolean _jspx_meth_c_005fout_005f0(javax.servlet.jsp.tagext.JspTag _jspx_th_c_005fforEach_005f0, javax.servlet.jsp.PageContext _jspx_page_context, int[] _jspx_push_body_count_c_005fforEach_005f0)
throws java.lang.Throwable {
javax.servlet.jsp.PageContext pageContext = _jspx_page_context;
javax.servlet.jsp.JspWriter out = _jspx_page_context.getOut();
// c:out
org.apache.taglibs.standard.tag.rt.core.OutTag _jspx_th_c_005fout_005f0 = (org.apache.taglibs.standard.tag.rt.core.OutTag) _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.get(org.apache.taglibs.standard.tag.rt.core.OutTag.class);
boolean _jspx_th_c_005fout_005f0_reused = false;
try {
_jspx_th_c_005fout_005f0.setPageContext(_jspx_page_context);
_jspx_th_c_005fout_005f0.setParent((javax.servlet.jsp.tagext.Tag) _jspx_th_c_005fforEach_005f0);
// /user-list.jsp(57,11) name = value type = null reqTime = true required = true fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fout_005f0.setValue((java.lang.Object) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${user.id}", java.lang.Object.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null));
int _jspx_eval_c_005fout_005f0 = _jspx_th_c_005fout_005f0.doStartTag();
if (_jspx_th_c_005fout_005f0.doEndTag() == javax.servlet.jsp.tagext.Tag.SKIP_PAGE) {
return true;
}
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.reuse(_jspx_th_c_005fout_005f0);
_jspx_th_c_005fout_005f0_reused = true;
} finally {
org.apache.jasper.runtime.JspRuntimeLibrary.releaseTag(_jspx_th_c_005fout_005f0, _jsp_getInstanceManager(), _jspx_th_c_005fout_005f0_reused);
}
return false;
}
private boolean _jspx_meth_c_005fout_005f1(javax.servlet.jsp.tagext.JspTag _jspx_th_c_005fforEach_005f0, javax.servlet.jsp.PageContext _jspx_page_context, int[] _jspx_push_body_count_c_005fforEach_005f0)
throws java.lang.Throwable {
javax.servlet.jsp.PageContext pageContext = _jspx_page_context;
javax.servlet.jsp.JspWriter out = _jspx_page_context.getOut();
// c:out
org.apache.taglibs.standard.tag.rt.core.OutTag _jspx_th_c_005fout_005f1 = (org.apache.taglibs.standard.tag.rt.core.OutTag) _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.get(org.apache.taglibs.standard.tag.rt.core.OutTag.class);
boolean _jspx_th_c_005fout_005f1_reused = false;
try {
_jspx_th_c_005fout_005f1.setPageContext(_jspx_page_context);
_jspx_th_c_005fout_005f1.setParent((javax.servlet.jsp.tagext.Tag) _jspx_th_c_005fforEach_005f0);
// /user-list.jsp(58,11) name = value type = null reqTime = true required = true fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fout_005f1.setValue((java.lang.Object) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${user.name}", java.lang.Object.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null));
int _jspx_eval_c_005fout_005f1 = _jspx_th_c_005fout_005f1.doStartTag();
if (_jspx_th_c_005fout_005f1.doEndTag() == javax.servlet.jsp.tagext.Tag.SKIP_PAGE) {
return true;
}
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.reuse(_jspx_th_c_005fout_005f1);
_jspx_th_c_005fout_005f1_reused = true;
} finally {
org.apache.jasper.runtime.JspRuntimeLibrary.releaseTag(_jspx_th_c_005fout_005f1, _jsp_getInstanceManager(), _jspx_th_c_005fout_005f1_reused);
}
return false;
}
private boolean _jspx_meth_c_005fout_005f2(javax.servlet.jsp.tagext.JspTag _jspx_th_c_005fforEach_005f0, javax.servlet.jsp.PageContext _jspx_page_context, int[] _jspx_push_body_count_c_005fforEach_005f0)
throws java.lang.Throwable {
javax.servlet.jsp.PageContext pageContext = _jspx_page_context;
javax.servlet.jsp.JspWriter out = _jspx_page_context.getOut();
// c:out
org.apache.taglibs.standard.tag.rt.core.OutTag _jspx_th_c_005fout_005f2 = (org.apache.taglibs.standard.tag.rt.core.OutTag) _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.get(org.apache.taglibs.standard.tag.rt.core.OutTag.class);
boolean _jspx_th_c_005fout_005f2_reused = false;
try {
_jspx_th_c_005fout_005f2.setPageContext(_jspx_page_context);
_jspx_th_c_005fout_005f2.setParent((javax.servlet.jsp.tagext.Tag) _jspx_th_c_005fforEach_005f0);
// /user-list.jsp(59,11) name = value type = null reqTime = true required = true fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fout_005f2.setValue((java.lang.Object) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${user.email}", java.lang.Object.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null));
int _jspx_eval_c_005fout_005f2 = _jspx_th_c_005fout_005f2.doStartTag();
if (_jspx_th_c_005fout_005f2.doEndTag() == javax.servlet.jsp.tagext.Tag.SKIP_PAGE) {
return true;
}
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.reuse(_jspx_th_c_005fout_005f2);
_jspx_th_c_005fout_005f2_reused = true;
} finally {
org.apache.jasper.runtime.JspRuntimeLibrary.releaseTag(_jspx_th_c_005fout_005f2, _jsp_getInstanceManager(), _jspx_th_c_005fout_005f2_reused);
}
return false;
}
private boolean _jspx_meth_c_005fout_005f3(javax.servlet.jsp.tagext.JspTag _jspx_th_c_005fforEach_005f0, javax.servlet.jsp.PageContext _jspx_page_context, int[] _jspx_push_body_count_c_005fforEach_005f0)
throws java.lang.Throwable {
javax.servlet.jsp.PageContext pageContext = _jspx_page_context;
javax.servlet.jsp.JspWriter out = _jspx_page_context.getOut();
// c:out
org.apache.taglibs.standard.tag.rt.core.OutTag _jspx_th_c_005fout_005f3 = (org.apache.taglibs.standard.tag.rt.core.OutTag) _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.get(org.apache.taglibs.standard.tag.rt.core.OutTag.class);
boolean _jspx_th_c_005fout_005f3_reused = false;
try {
_jspx_th_c_005fout_005f3.setPageContext(_jspx_page_context);
_jspx_th_c_005fout_005f3.setParent((javax.servlet.jsp.tagext.Tag) _jspx_th_c_005fforEach_005f0);
// /user-list.jsp(60,11) name = value type = null reqTime = true required = true fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fout_005f3.setValue((java.lang.Object) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${user.country}", java.lang.Object.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null));
int _jspx_eval_c_005fout_005f3 = _jspx_th_c_005fout_005f3.doStartTag();
if (_jspx_th_c_005fout_005f3.doEndTag() == javax.servlet.jsp.tagext.Tag.SKIP_PAGE) {
return true;
}
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.reuse(_jspx_th_c_005fout_005f3);
_jspx_th_c_005fout_005f3_reused = true;
} finally {
org.apache.jasper.runtime.JspRuntimeLibrary.releaseTag(_jspx_th_c_005fout_005f3, _jsp_getInstanceManager(), _jspx_th_c_005fout_005f3_reused);
}
return false;
}
private boolean _jspx_meth_c_005fout_005f4(javax.servlet.jsp.tagext.JspTag _jspx_th_c_005fforEach_005f0, javax.servlet.jsp.PageContext _jspx_page_context, int[] _jspx_push_body_count_c_005fforEach_005f0)
throws java.lang.Throwable {
javax.servlet.jsp.PageContext pageContext = _jspx_page_context;
javax.servlet.jsp.JspWriter out = _jspx_page_context.getOut();
// c:out
org.apache.taglibs.standard.tag.rt.core.OutTag _jspx_th_c_005fout_005f4 = (org.apache.taglibs.standard.tag.rt.core.OutTag) _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.get(org.apache.taglibs.standard.tag.rt.core.OutTag.class);
boolean _jspx_th_c_005fout_005f4_reused = false;
try {
_jspx_th_c_005fout_005f4.setPageContext(_jspx_page_context);
_jspx_th_c_005fout_005f4.setParent((javax.servlet.jsp.tagext.Tag) _jspx_th_c_005fforEach_005f0);
// /user-list.jsp(61,28) name = value type = null reqTime = true required = true fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fout_005f4.setValue((java.lang.Object) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${user.id}", java.lang.Object.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null));
int _jspx_eval_c_005fout_005f4 = _jspx_th_c_005fout_005f4.doStartTag();
if (_jspx_th_c_005fout_005f4.doEndTag() == javax.servlet.jsp.tagext.Tag.SKIP_PAGE) {
return true;
}
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.reuse(_jspx_th_c_005fout_005f4);
_jspx_th_c_005fout_005f4_reused = true;
} finally {
org.apache.jasper.runtime.JspRuntimeLibrary.releaseTag(_jspx_th_c_005fout_005f4, _jsp_getInstanceManager(), _jspx_th_c_005fout_005f4_reused);
}
return false;
}
private boolean _jspx_meth_c_005fout_005f5(javax.servlet.jsp.tagext.JspTag _jspx_th_c_005fforEach_005f0, javax.servlet.jsp.PageContext _jspx_page_context, int[] _jspx_push_body_count_c_005fforEach_005f0)
throws java.lang.Throwable {
javax.servlet.jsp.PageContext pageContext = _jspx_page_context;
javax.servlet.jsp.JspWriter out = _jspx_page_context.getOut();
// c:out
org.apache.taglibs.standard.tag.rt.core.OutTag _jspx_th_c_005fout_005f5 = (org.apache.taglibs.standard.tag.rt.core.OutTag) _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.get(org.apache.taglibs.standard.tag.rt.core.OutTag.class);
boolean _jspx_th_c_005fout_005f5_reused = false;
try {
_jspx_th_c_005fout_005f5.setPageContext(_jspx_page_context);
_jspx_th_c_005fout_005f5.setParent((javax.servlet.jsp.tagext.Tag) _jspx_th_c_005fforEach_005f0);
// /user-list.jsp(63,24) name = value type = null reqTime = true required = true fragment = false deferredValue = false expectedTypeName = null deferredMethod = false methodSignature = null
_jspx_th_c_005fout_005f5.setValue((java.lang.Object) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${user.id}", java.lang.Object.class, (javax.servlet.jsp.PageContext)_jspx_page_context, null));
int _jspx_eval_c_005fout_005f5 = _jspx_th_c_005fout_005f5.doStartTag();
if (_jspx_th_c_005fout_005f5.doEndTag() == javax.servlet.jsp.tagext.Tag.SKIP_PAGE) {
return true;
}
_005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody.reuse(_jspx_th_c_005fout_005f5);
_jspx_th_c_005fout_005f5_reused = true;
} finally {
org.apache.jasper.runtime.JspRuntimeLibrary.releaseTag(_jspx_th_c_005fout_005f5, _jsp_getInstanceManager(), _jspx_th_c_005fout_005f5_reused);
}
return false;
}
}
但是如果使用jsp
就会是 这样
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
<title>User Management Application</title>
<link rel="stylesheet"
href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T"
crossorigin="anonymous">
</head>
<body>
<header>
<nav class="navbar navbar-expand-md navbar-dark"
style="background-color: tomato">
<div>
<a href="https://www.javaguides.net" class="navbar-brand"> User
Management App </a>
</div>
<ul class="navbar-nav">
<li><a href="<%=request.getContextPath()%>/list"
class="nav-link">Users</a></li>
</ul>
</nav>
</header>
<br>
<div class="row">
<!-- <div class="alert alert-success" *ngIf='message'>{{message}}</div> -->
<div class="container">
<h3 class="text-center">List of Users</h3>
<hr>
<div class="container text-left">
<a href="<%=request.getContextPath()%>/new" class="btn btn-success">Add
New User</a>
</div>
<br>
<table class="table table-bordered">
<thead>
<tr>
<th>ID</th>
<th>Name</th>
<th>Email</th>
<th>Country</th>
<th>Actions</th>
</tr>
</thead>
<tbody>
<!-- for (Todo todo: todos) { -->
<c:forEach var="user" items="${listUser}">
<tr>
<td><c:out value="${user.id}" /></td>
<td><c:out value="${user.name}" /></td>
<td><c:out value="${user.email}" /></td>
<td><c:out value="${user.country}" /></td>
<td><a href="edit?id=<c:out value='${user.id}' />">Edit</a>
<a
href="delete?id=<c:out value='${user.id}' />">Delete</a></td>
</tr>
</c:forEach>
<!-- } -->
</tbody>
</table>
</div>
</div>
</body>
</html>
jsp 解决了 servlet 开发效率低下的问题，每个 jsp页面 就是一个servlet 实例 jsp 由系统编译生成 servlet ，Servlet 再负责相应用户请求 也就是 jsp是servlet 的一个简化
jsp 缺点： 每个 jsp页面 的第一个访问者 速度会很慢 需要等jsp 变异成Servlet jsp 优点 大大提高了java 动态网站的开发效率
