JSP的动态Include的静态Include

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 %>&nbsp;&nbsp;<%=param2 %>&nbsp;&nbsp;<%=param3 %>
</body>
</html>

结果: hello  world  XXXXXOOOOOOO

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原文地址：https://www.cnblogs.com/liuchao102/p/4448118.html