jsp的本质
- jsp的本质就是
servlet，使用过tomcat部署过javaweb项目，都知道在work目录生成jsp页面对应的sevlet。 - servlet的本质就是封装了socket
jsp页面
<%--
Created by IntelliJ IDEA.
User: wy
Date: 2019/11/26
Time: 下午11:21 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h2>Hello</h2> <a href="login">登录</a> </body> </html> 对应的Servlrt
ublic final class index_jsp extends org.apache.jasper.runtime.HttpJspBase implements org.apache.jasper.runtime.JspSourceDependent, org.apache.jasper.runtime.JspSourceImports { ....... public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response) throws java.io.IOException, javax.servlet.ServletException { ......... 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>Title</title>\n"); out.write(" 111111111111\n"); out.write("</head>\n"); out.write("<body>\n"); out.write("<h2>Hello</h2>\n"); out.write("<a href=\"login\">登录</a>\n"); out.write("</body>\n"); out.write("</html>\n"); } catch (java.lang.Throwable t) { ..... } finally { _jspxFactory.releasePageContext(_jspx_page_context); } } } SpringBoot中使用jsp
- springboot默认不支持jsp的，要让springboot支持jsp需要引入以下依赖
<dependency>
<groupId>org.apache.tomcat.embed</groupId> <artifactId>tomcat-embed-jasper</artifactId> </dependency> - 完整的依赖如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.2.4.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.apache.tomcat.embed</groupId> <artifactId>tomcat-embed-jasper</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> - 编写测试程序
package com.example.demo.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.view.InternalResourceView; @Controller public class HelloController { @RequestMapping("/hello") public ModelAndView hello(){ ModelAndView mv = new ModelAndView(); InternalResourceView internalResourceView = new InternalResourceView("index.jsp"); mv.setView(internalResourceView); return mv; } } 在maven项目中创建webapp文件夹，创建index.jsp文件，访问http://localhost:8080/hello
现在我们在springboot中使用了jsp的视图解析器，那么生成的jsp文件在哪里？
- 这里可以确定的是，只要使用jsp作为视图必定是要生成相应的
servlet文件。 - 在linux系统中，jsp生成的servlet页面在
/tmp文件中
├── tomcat.6136740723794350932.8080
│ └── work
│ └── Tomcat
│ └── localhost
│ └── ROOT
│ └── org
│ └── apache
│ └── jsp
│ ├── index_jsp.class
│ └── index_jsp.
注意：当第一次访问对应的jsp页面才会生成对应的
servlet页面