1. 静态导入示例
先总结：
1：静态include是把被引入的文件拼接到本页面中，再做为一个整体来编译，返回结果给客户端。
动态include是分别编译本页面和被引入的页面，再把结果合成一个html，返回结果给客户端。
2：动态include可以传参数，可以include静态页面，也可以Include动态页面
静态导入指令 :
<%@include file="error.jsp"%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>静态导入</title> </head> <body> <%@include file="error.jsp"%> </body> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>这是一个静态页面</title> </head> <body> 静态页面内容 </body> </html>
查看jsp编译之后的文件可以看到，index.jsp和error.jsp分别被编译成java文件和对应的class文件
error_jsp.class
error_jsp.java
index_jsp.class
index_jsp.java
index_jsp.java源码
package org.apache.jsp; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.jsp.*; public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase implements org.apache.jasper.runtime.JspSourceDependent { 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>(1); _jspx_dependants.put("/error.jsp", Long.valueOf(1429692772031L)); } private javax.el.ExpressionFactory _el_expressionfactory; private org.apache.tomcat.InstanceManager _jsp_instancemanager; public java.util.Map<java.lang.String,java.lang.Long> getDependants() { return _jspx_dependants; } public void _jspInit() { _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory(); _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig()); } public void _jspDestroy() { } public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response) throws java.io.IOException, javax.servlet.ServletException { 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(" "); out.write("<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> "); out.write("<html> "); out.write("<head> "); out.write("<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> "); out.write("<title>静态导入</title> "); out.write("</head> "); out.write("<body> "); out.write(" "); out.write(" "); out.write("<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> "); out.write("<html> "); out.write("<head> "); out.write("<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> "); out.write("<title>这是一个静态页面</title> "); out.write("</head> "); out.write("<body> "); out.write(" 静态页面内容 "); out.write("</body> "); out.write("</html>"); out.write(" "); out.write("</body> "); out.write("</html>"); } catch (java.lang.Throwable t) { if (!(t instanceof javax.servlet.jsp.SkipPageException)){ out = _jspx_out; if (out != null && out.getBufferSize() != 0) try { 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); } } }
从源代码里面可以看到,error.jsp的内容被整个融入到了index.jsp中
结论：静态include是将被导入页面的代码完全融入本页面中，两个页面融合成一个整体Servlet，返回给客户端
有一个问题，当被引入的页面中和本页面中有相同的变量定义时，会报错
2. 动态导入示例
动态导入指令
<jsp:include page="error.jsp" flush="true"></jsp:include>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>动态导入</title> </head> <body> <jsp:include page="error.jsp" flush="true"></jsp:include> </body> </html>
此时index_jsp.java的源码
out.write("
");
out.write("<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
");
out.write("<html>
");
out.write("<head>
");
out.write("<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
");
out.write("<title>动态导入</title>
");
out.write("</head>
");
out.write("<body>
");
out.write(" ");
org.apache.jasper.runtime.JspRuntimeLibrary.include(request, response, "error.jsp", out, true);
out.write("
");
out.write("</body>
");
out.write("</html>");
可以看到动态include只是用了include方法引入了被导入的文件
结论: 动态include先编译被引入的文件，在包含到本页面中
被引入的文件和本页面中有相同的变量定义时也不会报错
3. 动态include传参数
静态include是不能传参数的
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>动态导入</title> </head> <body> <jsp:include page="error.jsp" flush="true"> <jsp:param value="hello" name="param1"/> <jsp:param value="world" name="param2"/> </jsp:include> </body> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>这是一个静态页面</title> </head> <body> <% String param1 = request.getParameter("param1"); String param2 = request.getParameter("param2"); String param3 = "XXXXXOOOOOOO"; %> <%=param1 %> <%=param2 %> <%=param3 %> </body> </html>
结果: hello world XXXXXOOOOOOO