JSP入门的简单学习

我的第一个JSP文件是非常简单的JSP,如下:

pageEncoding="UTF-8"%>

我使用的是Tomcat7.0服务器,加载到Eclipse后,会编译我上面的JSP文件,把该JSP文件通过编译器编译成一个

Servlet的java文件,如下图:

package org.apache.jsp;

import javax.servlet.*;

import javax.servlet.http.*;

import javax.servlet.jsp.*;

import java.util.Date;

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 _jspx_dependants;

private javax.el.ExpressionFactory _el_expressionfactory;

private org.apache.tomcat.InstanceManager _jsp_instancemanager;

public java.util.Map 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("\r\n");

out.write("\r\n");

out.write("\r\n");

out.write("\r\n");

out.write("

\r\n");

out.write("\r\n");

out.write("

\r\n");

out.write("\r\n");

out.write("

\r\n");

out.print("hello" );

out.write("\r\n");

out.write("\r\n");

out.write("");

} 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);

}

}

}

,java.lang.long>,java.lang.long>

可以看出,JSP文件确实在后台服务器中被编译成一个java文件,我们只关注我们在JSP页面中写入的内容,而对html标签的解析我们不去关注

//JSP文件会被jsp文件名会被编译成以index_jsp命名的类(我的jsp文件名为index.jsp)

public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase

implements org.apache.jasper.runtime.JspSourceDependent {

//通过工厂模式来产生一个JSP文件的的解析器

private static final javax.servlet.jsp.JspFactory _jspxFactory =

javax.servlet.jsp.JspFactory.getDefaultFactory();

//调用初始化方法通过全局上下文来获取JSP参数

public void _jspInit() {

_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();

_jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());

}

//编译完成后会销毁该线程

public void _jspDestroy() {

}

//这里是核心,是对JSP文件的完整解析

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;

//这里是解析后的内容

out.write("\r\n");

out.write("\r\n");

out.write("\r\n");

out.write("\r\n");

out.write("

\r\n");

out.write("\r\n");

out.write("

\r\n");

out.write("\r\n");

out.write("

\r\n");

out.print("hello" );

out.write("\r\n");

out.write("\r\n");

out.write("");