SpringBoot支持JSP教程

项目背景

一些前端还是JSP的老项目，需要改造为springboot，所以需要springboot能支持JSP。

项目结构

afei-demo├──src/main                                           ├   ├──java ├   ├   ├──com.afei.test.demo├   ├   ├   ├──controller ├   ├   ├   ├──service  ├   ├   ├   ├──mapper├   ├   ├   ├──Application.java  springboot项目main方法所在的主类             ├   ├──resources            ├   ├   ├──css 存放css文件的地方├   ├   ├──images 存放.jpg，.png等图片资源的地方├   ├   ├──js 存放js文件的地方├   ├   ├──application.properties springboot配置文件├   ├──webapp    ├   ├   ├──WEB-INF/jsp 这个路径和视图配置中的spring.mvc.view.prefix要对应├   ├   ├   ├──index.jsp ├   ├   ├   ├──monitor 监控相关jsp页面├   ├   ├   ├──warning 告警相关jsp页面

依赖组件

springboot支持JSP的主要依赖组件如下：

spring-boot-starter-web版本为1.5.9.RELEASE；
jstl版本为1.2；
tomcat-embed-jasper版本为8.5.23；
spring-boot-maven-plugin版本为1.4.2.RELEASE；

核心POM

<dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--springboot tomcat jsp 支持开启 start--><dependency><groupId>org.apache.tomcat.embed</groupId><artifactId>tomcat-embed-jasper</artifactId><version>8.5.23</version></dependency><dependency><groupId>jstl</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency><!--springboot tomcat jsp 支持开启 end-->
</dependencies>

插件配置

<build><plugins><plugin><groupId>org.springframework.boot</groupId><!--springboot-maven不能使用1.5.9.RELEASE版本, 否则会导致WEB-INF下的jsp资源无法访问--><artifactId>spring-boot-maven-plugin</artifactId><version>1.4.2.RELEASE</version><configuration><!--指定springboot的main方法类，否则会由于某些测试类中也有main方法而导致构建失败--><mainClass>com.yyfax.fdfsfront.Application</mainClass></configuration><executions><execution> <goals> <goal>repackage</goal> </goals> </execution></executions></plugin><plugin><artifactId>maven-compiler-plugin</artifactId><version>3.1</version><configuration><source>1.8</source><target>1.8</target></configuration></plugin></plugins><resources><!-- 打包时将jsp文件拷贝到META-INF目录下--><resource><!-- 指定resources插件处理哪个目录下的资源文件 --><directory>src/main/webapp</directory><!--注意此次必须要放在此目录下才能被访问到--><targetPath>META-INF/resources</targetPath><includes><include>**/**</include></includes></resource><resource><directory>${project.basedir}/lib</directory><targetPath>BOOT-INF/lib/</targetPath><includes><include>**/*.jar</include></includes></resource><resource><directory>src/main/resources</directory><includes><include>**/**</include></includes><filtering>false</filtering></resource></resources></build>

再次强调，spring-boot-maven-plugin的版本是1.4.2.RELEASE，而spring-boot-starter-web的版本是1.5.9.RELEASE。否则会导致即使能成功构建JAR包，也无法访问JSP资源。这里坑浪费了我不少时间！

静态资源

resources标签下的配置非常重要，其作用是将webapp目录下所有的资源（主要是JSP资源，因为css，js，图片等资源放在resoures目录下）拷贝到最终springboot的JAR包中的META-INF/resources目录下。

为什么是/META-INF/resources目录？

这个与springboot的配置spring.resources.static-locations有关，其默认赋值在源码ResourceProperties.java中，由源码可知，classpath:/META-INF/resources/是其中一个默认的静态资源存放路径：

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties implements ResourceLoaderAware {private static final String[] SERVLET_RESOURCE_LOCATIONS = { "/" };private static final String[] CLASSPATH_RESOURCE_LOCATIONS = {"classpath:/META-INF/resources/", "classpath:/resources/","classpath:/static/", "classpath:/public/" };private static final String[] RESOURCE_LOCATIONS;static {RESOURCE_LOCATIONS = new String[CLASSPATH_RESOURCE_LOCATIONS.length+ SERVLET_RESOURCE_LOCATIONS.length];System.arraycopy(SERVLET_RESOURCE_LOCATIONS, 0, RESOURCE_LOCATIONS, 0,SERVLET_RESOURCE_LOCATIONS.length);System.arraycopy(CLASSPATH_RESOURCE_LOCATIONS, 0, RESOURCE_LOCATIONS,SERVLET_RESOURCE_LOCATIONS.length, CLASSPATH_RESOURCE_LOCATIONS.length);}/*** Locations of static resources. Defaults to classpath:[/META-INF/resources/,* /resources/, /static/, /public/] plus context:/ (the root of the servlet context).*/private String[] staticLocations = RESOURCE_LOCATIONS;... ...
}

至于其他的css，图片，js等静态资源文件，放到resources目录下即可，并结合如下核心代码：

@Configuration
@Slf4j
public class FdfsWebMvcConfigurerAdapter extends WebMvcConfigurerAdapter {@Beanpublic SecurityInterceptor getSecurityInterceptor() {return new SecurityInterceptor();}@Overridepublic void addInterceptors(InterceptorRegistry registry) {// 除了login登陆访问路径和error页面，其他都要经过SecurityInterceptor拦截器（SecurityInterceptor extends HandlerInterceptorAdapter）InterceptorRegistration addInterceptor = registry.addInterceptor(getSecurityInterceptor());// 排除配置addInterceptor.excludePathPatterns("/error");addInterceptor.excludePathPatterns("/login**");// 拦截配置addInterceptor.addPathPatterns("/**");}@Overridepublic void addViewControllers(ViewControllerRegistry registry) {// 配置welcome默认首页registry.addViewController("/").setViewName("forward:/main/index.shtml");registry.setOrder(Ordered.HIGHEST_PRECEDENCE);super.addViewControllers(registry);}@Beanpublic ServletRegistrationBean servletRegistrationBean(DispatcherServlet dispatcherServlet) {ServletRegistrationBean bean = new ServletRegistrationBean(dispatcherServlet);// RequestMapping路径都以.shtml结尾，例如：http://localhost/main/login.shtmlbean.addUrlMappings("*.shtml");// 其他文件该是什么后缀就是什么后缀bean.addUrlMappings("*.html");bean.addUrlMappings("*.css");bean.addUrlMappings("*.js");bean.addUrlMappings("*.png");bean.addUrlMappings("*.gif");bean.addUrlMappings("*.ico");bean.addUrlMappings("*.jpeg");bean.addUrlMappings("*.jpg");return bean;}@Overridepublic void addResourceHandlers(ResourceHandlerRegistry registry) {// 这里的配置很重要，由于我们把css，图片，js等静态资源文件放在resources目录下，所以必须增加这些ResourceHandler，才能访问到这些资源registry.addResourceHandler("/favicon.ico").addResourceLocations("classpath:/favicon.ico");registry.addResourceHandler("/css/**").addResourceLocations("classpath:/css/");registry.addResourceHandler("/images/**").addResourceLocations("classpath:/images/");registry.addResourceHandler("/js/**").addResourceLocations("classpath:/js/");registry.addResourceHandler("/500.html").addResourceLocations("classpath:/500.html");registry.addResourceHandler("/index.jsp").addResourceLocations("classpath:/index.jsp");super.addResourceHandlers(registry);}}

视图配置

spring.mvc.view.prefix=/WEB-INF/jsp/
spring.mvc.view.suffix=.jsp

这里的配置要非常注意，以笔者这两个配置为例，如果我在controller中return new ModelAndView("main/index");，那么它访问的资源路径是/WEB-INF/jsp/main/index.jsp（prefix+ModelAndView+suffix）。这里强烈建议spring.mvc.view.prefix的配置以/结尾，即配置/WEB-INF/jsp/而不要配置/WEB-INF/jsp。否则如果return new ModelAndView("main/index");就会抛出如下错误：

File [/WEB-INF/jspmain/index.jsp] not found

总结

配置为/WEB-INF/jsp/，那么return new ModelAndView("/main/index");和return new ModelAndView("main/index");都可以访问。
配置为/WEB-INF/jsp，那么只有return new ModelAndView("/main/index");才可以访问。