现在，我们编写的Jerrymouse Server运行一个简单的hello-webapp没问题，那么复杂的Web App呢？
我们来编写一个基于Spring MVC的Web App。
首先，我们要加载Spring内置的DispatcherServlet，如果用传统的web.xml配置，则可以编写如下配置文件：
<?xml version="1.0"?>
<web-app>
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextClass</param-name>
<param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
</init-param>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>com.itranswarp.sample.AppConfig</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
但是，我们已经干掉了通过web.xml配置的方式，只支持自动扫描@WebServlet，因此，需要编写一个继承自DispatcherServlet的AppDispatcherServlet：
@WebServlet(
urlPatterns = "/",
initParams = {
@WebInitParam(name = "contextClass", value = "org.springframework.web.context.support.AnnotationConfigWebApplicationContext"),
@WebInitParam(name = "contextConfigLocation", value = "com.itranswarp.sample.AppConfig") })
public class AppDispatcherServlet extends DispatcherServlet {
}
这样，Jerrymouse Server会自动扫描到AppDispatcherServlet，然后，根据@WebServlet的配置，启动Spring容器，类型为AnnotationConfigWebApplicationContext，配置类com.itranswarp.sample.AppConfig，所以还需要编写配置类AppConfig：
@Configuration
@ComponentScan
@EnableWebMvc
@EnableTransactionManagement
@PropertySource("classpath:/jdbc.properties")
public class AppConfig {
@Bean
WebMvcConfigurer createWebMvcConfigurer() {
return new WebMvcConfigurer() {
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/static/**").addResourceLocations("/static/");
registry.addResourceHandler("/favicon.ico").addResourceLocations("/");
}
};
}
@Bean
ViewResolver createViewResolver(@Autowired ServletContext servletContext) {
var engine = new PebbleEngine.Builder().autoEscaping(true)
// loader:
.loader(new Servlet5Loader(servletContext))
// build:
.build();
var viewResolver = new PebbleViewResolver(engine);
viewResolver.setPrefix("/WEB-INF/templates/");
viewResolver.setSuffix("");
return viewResolver;
}
@Bean
DataSource createDataSource(@Value("${jdbc.driver}") String jdbcDriver, @Value("${jdbc.url}") String jdbcUrl,
@Value("${jdbc.username}") String jdbcUsername, @Value("${jdbc.password}") String jdbcPassword) {
HikariConfig config = new HikariConfig();
config.setDriverClassName(jdbcDriver);
config.setJdbcUrl(jdbcUrl);
config.setUsername(jdbcUsername);
config.setPassword(jdbcPassword);
config.addDataSourceProperty("autoCommit", "false");
config.addDataSourceProperty("connectionTimeout", "5");
config.addDataSourceProperty("idleTimeout", "60");
return new HikariDataSource(config);
}
@Bean
JdbcTemplate createJdbcTemplate(@Autowired DataSource dataSource) {
return new JdbcTemplate(dataSource);
}
@Bean
PlatformTransactionManager createTxManager(@Autowired DataSource dataSource) {
return new DataSourceTransactionManager(dataSource);
}
}
AppConfig是标准的Spring配置类，我们正常配置MVC、ViewResolver、JDBC相关的DataSource、JdbcTemplate和PlatformTransactionManager，以及Spring容器需要的Service、Controller等，就可以实现一个完整的Spring MVC的WebApp。
用Maven编译spring-webapp，得到spring-webapp-1.0.war文件。用以下命令运行：
$ java -jar /path/to/jerrymouse-1.0.0.jar -w /path/to/spring-webapp-1.0.war
观察AppDispatcherServlet的输出：
10:48:08.200 [main] DEBUG o.s.w.c.s.AnnotationConfigWebApplicationContext -- Refreshing WebApplicationContext for namespace 'appDispatcherServlet-servlet'
...
10:48:08.223 [main] DEBUG c.i.j.engine.ServletContextImpl -- invoke ServletContextAttributeAdded: org.springframework.web.context.support.ServletContextScope = org.springframework.web.context.support.ServletContextScope@2616b618
10:48:08.225 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory -- Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
...
10:48:08.705 [main] DEBUG c.i.sample.AppDispatcherServlet -- Detected AcceptHeaderLocaleResolver
10:48:08.705 [main] DEBUG c.i.sample.AppDispatcherServlet -- Detected FixedThemeResolver
10:48:08.706 [main] DEBUG c.i.sample.AppDispatcherServlet -- Detected org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator@559fd5ec
10:48:08.706 [main] DEBUG c.i.sample.AppDispatcherServlet -- Detected org.springframework.web.servlet.support.SessionFlashMapManager@bb12f41
10:48:08.707 [main] DEBUG c.i.j.engine.ServletContextImpl -- invoke ServletContextAttributeAdded: org.springframework.web.servlet.FrameworkServlet.CONTEXT.appDispatcherServlet = WebApplicationContext for namespace 'appDispatcherServlet-servlet', started on Sat Jul 29 10:48:08 CST 2023
10:48:08.707 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool -- HikariPool-1 - Added connection org.hsqldb.jdbc.JDBCConnection@4b7d3c3b
10:48:08.707 [main] DEBUG c.i.sample.AppDispatcherServlet -- enableLoggingRequestDetails='false': request parameters and headers will be masked to prevent unsafe logging of potentially sensitive data
10:48:08.707 [main] INFO c.i.sample.AppDispatcherServlet -- Completed initialization in 511 ms
注意到AppDispatcherServlet是绑定到/的，因此，所有请求均全部由Spring提供的DispatcherServlet处理，包括静态文件。
访问http://localhost:8080，观察MVC的输出：
观察登录后的输出：
可见，Jerrymouse Server可以正常运行基于Spring MVC的Web App。不过，我们无法使用Spring提供的async相关功能，例如DeferredResult，也不能使用WebSocket相关功能。
参考源码
小结
通过正确配置Spring提供的DispatcherServlet，我们可以用Jerrymouse Server运行基于Spring MVC的Web App。