spring 零xml配置 & 内置tomcat 启动spring mvc

xml方式配置spring mvc

编写web.xml；注册listener、注册servlet、注册servlet-mapping
编写spring-mvc.xml
执行servlet规范：
在"根目录/resources/META-INF/services/"添加配置文件javax.servlet.ServletContainerInitializer
自定义一个类实现spring提供的WebApplicationInitializer接口，实例化&初始化spring容器
自定义controller类和业务逻辑
打包部署到web容器(通常使用tomcat)

零xml配置 & 内置tomcat 启动spring mvc

build.gradle添加依赖

    compile group: 'org.springframework', name: 'spring-webmvc', version: '5.1.12.RELEASE'
    // 内置tomcat需要
    compile group: 'org.apache.tomcat.embed', name: 'tomcat-embed-core', version: '8.5.31'
    // 消息转换器需要
    compile group: 'com.alibaba', name: 'fastjson', version: '1.2.47'

resources/META-INF/services/javax.servlet.ServletContainerInitializer

org.springframework.web.SpringServletContainerInitializer

UserEntity

public class UserEntity {
	private String name;
	private String age;
	...// get set constructor省略
}

AppConfig 代替spring-mvc.xml

@Configuration
@ComponentScan("com.tbryant.springmvctest")
// 注解方式驱动springmvc，等同于<annotation:driver>
// 不加不会解析WebMvcConfigurer接口
// 如果不加@EnableWebMvc，就要改成extends WebMvcConfigurationSupport
@EnableWebMvc
public class AppConfig implements WebMvcConfigurer {
	// 配置视图解析器
	@Override
	public void configureViewResolvers(ViewResolverRegistry registry) {
//		registry.jsp("/page/",".html");
	}
	// 配置消息转换器 这里用fastjson，可以自由选择
	@Override
	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
		FastJsonHttpMessageConverter fastJsonHttpMessageConverter=new FastJsonHttpMessageConverter();
		converters.add(fastJsonHttpMessageConverter);
	}
}

MyWebApplicationInitializer 注册servlet和注册servlet-mapping

// 该类从官方文档拷贝，主要目的初始化spring容器，注册servlet和注册servlet-mapping
public class MyWebApplicationInitializer implements WebApplicationInitializer {
	// ServletContext代替web.xml
	@Override
	public void onStartup(ServletContext servletCxt) {
		// 实例化spring容器
		AnnotationConfigWebApplicationContext ac = new AnnotationConfigWebApplicationContext();
		ac.register(AppConfig.class);
//		ac.refresh();
		// DispatcherServlet注册到web容器
		DispatcherServlet servlet = new DispatcherServlet(ac);// servlet
		ServletRegistration.Dynamic registration = servletCxt.addServlet("DispatcherServlet", servlet);
		registration.setLoadOnStartup(1);
		registration.addMapping("/");// servlet-mapping
	}
}

Application 内置tomcat & 注册listener

public class Application {
    public static void main(String[] args) throws Exception {
        // 内置tomcat
        Tomcat tomcat=new Tomcat();
        tomcat.setPort(8080);
        Context context=tomcat.addContext("/",System.getProperty("java.io.tmpdir"));
        // 注册listener
        context.addLifecycleListener((LifecycleListener)Class.forName(tomcat.getHost().getConfigClass()).newInstance());
        tomcat.start();
        tomcat.getServer().await();
    }
}

UserController

@Controller
public class UserController {
    @RequestMapping("/getuser")
    @ResponseBody
    public UserEntity getUser() {
        return new UserEntity("TBryant", "18");
    }
}