spring boot 配置多个DispatcherServlet

传统的web项目，只需要在web.xml里配置多个即可，并且支持多个url-pattern

在spring boot中，我们默认无需配置，系统会自动装配一个，感兴趣的可以看下源码

org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration，里面有个 DispatcherServletRegistrationBean，关键是这里只能指定一个path，如下的源码截图

如果想要指定多个，我们只能自己写DispatcherServletRegistrationBean这个Bean了，那么系统就不会实例化内置的那个了，如下代码

@Autowired
private WebMvcProperties webMvcProperties;
@Autowired
private MultipartConfigElement multipartConfig;

@Bean
@Primary
public DispatcherServletRegistrationBean dispatcherServlet1(DispatcherServlet dispatcherServlet) {
    DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(
            dispatcherServlet, "/*");
    registration.setName("dispatcherServlet1");
    registration.setLoadOnStartup(
            this.webMvcProperties.getServlet().getLoadOnStartup());
    if (this.multipartConfig != null) {
        registration.setMultipartConfig(this.multipartConfig);
    }
    return registration;
}

@Bean
public DispatcherServletRegistrationBean dispatcherServlet2(DispatcherServlet dispatcherServlet) {
    DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(
            dispatcherServlet, "/aaa/*");
    registration.setName("dispatcherServlet2");
    registration.setLoadOnStartup(
            this.webMvcProperties.getServlet().getLoadOnStartup());
    if (this.multipartConfig != null) {
        registration.setMultipartConfig(this.multipartConfig);
    }
    return registration;
}

@Bean
public DispatcherServletRegistrationBean dispatcherServlet3(DispatcherServlet dispatcherServlet) {
    DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(
            dispatcherServlet, "/bbb/*");
    registration.setName("dispatcherServlet3");
    registration.setLoadOnStartup(
            this.webMvcProperties.getServlet().getLoadOnStartup());
    if (this.multipartConfig != null) {
        registration.setMultipartConfig(this.multipartConfig);
    }
    return registration;
}

这样我们参考底层源码，我们做了三个Bean，注意有一个一定要加上@Primary注解，否则启动会有报错。

如果我们系统有一个接口url是/api/test，那么通过/aaa/api/test或者/bbb/api/test也都可以访问了。

不建议的写法、、、

@Bean
    public ServletRegistrationBean apiDispatcherServlet(){
        AnnotationConfigWebApplicationContext applicationContext = new AnnotationConfigWebApplicationContext();
        applicationContext.scan("com.be.edge.asset.web.api");
        DispatcherServlet apiDispatcherServlet = new DispatcherServlet(applicationContext);
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(apiDispatcherServlet);
        registrationBean.addInitParameter("throwExceptionIfNoHandlerFound", "true");
        registrationBean.setLoadOnStartup(1);
        registrationBean.addUrlMappings("/api/*");
        registrationBean.setName("apiDispatcherServlet");
        return registrationBean;
    }

    @Bean
    public ServletRegistrationBean mgmtDispatcherServlet(){
        AnnotationConfigWebApplicationContext applicationContext = new AnnotationConfigWebApplicationContext();
        applicationContext.scan("com.be.edge.asset.web.controller");
        DispatcherServlet apiDispatcherServlet = new DispatcherServlet(applicationContext);
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(apiDispatcherServlet);
        registrationBean.setLoadOnStartup(2);
        registrationBean.addInitParameter("throwExceptionIfNoHandlerFound", "true");
        registrationBean.addUrlMappings("/mgmt/*");
        registrationBean.setName("mngDispatcherServlet");
        return registrationBean;
    }