最开始接触java的时候，前端页面基本都是用jsp来写，最近公司项目要使用SpringBoot重构，查看SpringBoot文档，发现SpringBoot不建议使用JSP，因为jsp在使用内嵌servlet容器时会有一些限制
虽然以后项目中也会将jsp替换成Template Engines,而且这都是前端的事情，其实与后端并无比较大的联系，但比较好奇Springboot中对jsp的使用，故根据官方文档进行了简单测试验证
如果使用JSP，则需要将项目打包成war包，jar包不支持JSP。
打开JSP sample，这是一个github上的项目，点击Code标签页，clone or download下载源码，这里下载的代码中包含有很多个springboot项目，其中spring-boot-samples中包含有我们需要的spring-boot-sample-web-jsp
解压下载的文件，spring-boot-samples下项目很多，我们根据需要在eclipse中只导入spring-boot-sample-web-jsp项目，导入时可能出现以下异常
点击finish -- ok，pom.xml文件中出现异常
选择Mark goal validate as ignored in pom.xml忽略掉该信息
点击OK
此时若项目上还有红色的叉号，则在项目名称上右键 -- Maven -- Update Project -- OK。
项目结构
包sample.jsp下有两个类
控制器WelcomeController
1package sample.jsp; 2 3import java.util.Date; 4import java.util.Map; 5 6import org.springframework.beans.factory.annotation.Value; 7import org.springframework.stereotype.Controller; 8import org.springframework.web.bind.annotation.GetMapping; 9import org.springframework.web.bind.annotation.RequestMapping; 10 11@Controller 12public class WelcomeController { 13 14 @Value("${application.message:Hello World}") 15 private String message = "Hello World"; 16 17 @GetMapping("/") 18 public String welcome(Map<String, Object> model) { 19 model.put("time", new Date()); 20 model.put("message", this.message); 21 return "welcome"; 22 } 23 24 @RequestMapping("/foo") 25 public String foo(Map<String, Object> model) { 26 throw new RuntimeException("Foo"); 27 } 28}
启动类SampleWebJspApplication.java
1package sample.jsp; 2 3import org.springframework.boot.SpringApplication; 4import org.springframework.boot.autoconfigure.SpringBootApplication; 5import org.springframework.boot.builder.SpringApplicationBuilder; 6import org.springframework.boot.web.servlet.support.SpringBootServletInitializer; 7 8@SpringBootApplication 9public class SampleWebJspApplication extends SpringBootServletInitializer { 10 11 @Override 12 protected SpringApplicationBuilder configure(SpringApplicationBuilder application) { 13 return application.sources(SampleWebJspApplication.class); 14 } 15 16 public static void main(String[] args) { 17 SpringApplication.run(SampleWebJspApplication.class, args); 18 } 19}
两个jsp页面
welcome.jsp
1<!DOCTYPE html> 2 3<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%> 4<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> 5 6<html lang="en"> 7 8<body> 9 <c:url value="/resources/text.txt" var="url"/> 10 <spring:url value="/resources/text.txt" htmlEscape="true" var="springUrl" /> 11 Spring URL: ${springUrl} at ${time} 12 <br> 13 JSTL URL: ${url} 14 <br> 15 Message: ${message} 16</body> 17 18</html>
error.jsp
1<!DOCTYPE html> 2<html lang="en"> 3<body> 4Something went wrong: ${status} ${error} 5</body> 6</html>
pom.xml
1<?xml version="1.0" encoding="UTF-8"?> 2<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4 <modelVersion>4.0.0</modelVersion> 5 <parent> 6 <!-- Your own application should inherit from spring-boot-starter-parent --> 7 <groupId>org.springframework.boot</groupId> 8 <artifactId>spring-boot-samples</artifactId> 9 <version>${revision}</version> 10 </parent> 11 <artifactId>spring-boot-sample-web-jsp</artifactId> 12 <packaging>war</packaging> 13 <name>Spring Boot Web JSP Sample</name> 14 <description>Spring Boot Web JSP Sample</description> 15 <properties> 16 <main.basedir>${basedir}/../..</main.basedir> 17 <m2eclipse.wtp.contextRoot>/</m2eclipse.wtp.contextRoot> 18 </properties> 19 <dependencies> 20 <!-- Compile --> 21 <dependency> 22 <groupId>org.springframework.boot</groupId> 23 <artifactId>spring-boot-starter-web</artifactId> 24 </dependency> 25 <dependency> 26 <groupId>javax.servlet</groupId> 27 <artifactId>jstl</artifactId> 28 </dependency> 29 <!-- Provided --> 30 <dependency> 31 <groupId>org.springframework.boot</groupId> 32 <artifactId>spring-boot-starter-tomcat</artifactId> 33 <scope>provided</scope> 34 </dependency> 35 <dependency> 36 <groupId>org.apache.tomcat.embed</groupId> 37 <artifactId>tomcat-embed-jasper</artifactId> 38 <scope>provided</scope> 39 </dependency> 40 <!-- Test --> 41 <dependency> 42 <groupId>org.springframework.boot</groupId> 43 <artifactId>spring-boot-starter-test</artifactId> 44 <scope>test</scope> 45 </dependency> 46 </dependencies> 47 <build> 48 <plugins> 49 <plugin> 50 <groupId>org.springframework.boot</groupId> 51 <artifactId>spring-boot-maven-plugin</artifactId> 52 </plugin> 53 <plugin> 54 <groupId>org.apache.maven.plugins</groupId> 55 <artifactId>maven-surefire-plugin</artifactId> 56 <configuration> 57 <useSystemClassLoader>false</useSystemClassLoader> 58 </configuration> 59 </plugin> 60 </plugins> 61 <pluginManagement> 62 <plugins> 63 <!--This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself.--> 64 <plugin> 65 <groupId>org.eclipse.m2e</groupId> 66 <artifactId>lifecycle-mapping</artifactId> 67 <version>1.0.0</version> 68 <configuration> 69 <lifecycleMappingMetadata> 70 <pluginExecutions> 71 <pluginExecution> 72 <pluginExecutionFilter> 73 <groupId> 74 io.spring.javaformat 75 </groupId> 76 <artifactId> 77 spring-javaformat-maven-plugin 78 </artifactId> 79 <versionRange> 80 [0.0.6,) 81 </versionRange> 82 <goals> 83 <goal>validate</goal> 84 </goals> 85 </pluginExecutionFilter> 86 <action> 87 <ignore></ignore> 88 </action> 89 </pluginExecution> 90 </pluginExecutions> 91 </lifecycleMappingMetadata> 92 </configuration> 93 </plugin> 94 </plugins> 95 </pluginManagement> 96 </build> 97</project>
View Code
以上为该Demo官网pom文件，但其中内容个人觉得有多余，spring-boot-starter-tomcat和tomcat-embed-jasper在spring-boot-starter-web中已经有引用，所以可以去掉
启动主函数
页面访问：http://localhost:8080/foo
一、本例中启动类继承了SpringBootServletInitializer，重写了configure方法，如果去掉该类的集成，能不能正常运行程序，其实是可以的（添加server.port=8081端口，与8080区分，测试）
二、SpringBootServletInitializer是做什么用处的？
springboot官方文档中 “91.1 Create a Deployable War File”有对该类的具体描述
三、按照当前pom.xml中配置，打包（eclipse中执行package），出现以下异常
[ERROR] Failed to execute goal io.spring.javaformat:spring-javaformat-maven-plugin:0.0.6:validate (default) on project spring-boot-sample-web-jsp: Formatting violations found in the following files:
日志中也给出了建议，使用：spring-javaformat:apply修复该问题
spring-javaformat:apply执行结束后，再次执行package，打包成功，打包过程中，会有很多的jar包下载。
进入到target目录，执行：java -jar .\spring-boot-sample-web-jsp-2.1.2.RELEASE.war，程序启动后，页面访问正常。
四、上面官方文档已经讲，打成可执行jar包，不支持JSP，下面尝试一下，是否如此，首先去掉主函数中集成SpringBootServletInitializer类，去掉重写的方法，pom.xml中war改为jar
1、运行主函数，jsp可正常访问
2、执行clean package打包，打包时出现异常，也许此异常与JSP无关，但此处就不在进行处理重新打包，毕竟官网也已经声明可执行jar不支持JSP
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:3.0.0:check (checkstyle-validation) on project spring-boot-sample-web-jsp: You have 2 Checkstyle violations. -> [Help 1]
五、以上demo跑通后，也需要自己新建一个使用jsp的web项目，来运行测试下。