重新学习Spring注解——servlet3.0

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53、servlet3.0-简介&测试

54、servlet3.0-ServletContainerInitializer

55、servlet3.0-ServletContext注册三大组件

1、Servlet容器启动会扫描,当前应用里面每一个jar包的
    ServletContainerInitializer的实现
2、提供ServletContainerInitializer的实现类;
    必须绑定在,META-INF/services/javax.servlet.ServletContainerInitializer
    文件的内容就是ServletContainerInitializer实现类的全类名;

总结:容器在启动应用的时候,会扫描当前应用每一个jar包里面
META-INF/services/javax.servlet.ServletContainerInitializer
指定的实现类,启动并运行这个实现类的方法;传入感兴趣的类型;


ServletContainerInitializer;
@HandlesTypes;
//容器启动的时候会将@HandlesTypes指定的这个类型下面的子类(实现类,子接口等)传递过来;
//传入感兴趣的类型;
@HandlesTypes(value={HelloService.class})
public class MyServletContainerInitializer implements ServletContainerInitializer {

    /**
     * 应用启动的时候,会运行onStartup方法;
     * 
     * Set<Class<?>> arg0:感兴趣的类型的所有子类型;
     * ServletContext arg1:代表当前Web应用的ServletContext;一个Web应用一个ServletContext;
     * 
     * 1)、使用ServletContext注册Web组件(Servlet、Filter、Listener)
     * 2)、使用编码的方式,在项目启动的时候给ServletContext里面添加组件;
     *         必须在项目启动的时候来添加;
     *         1)、ServletContainerInitializer得到的ServletContext;
     *         2)、ServletContextListener得到的ServletContext;
     */
    @Override
    public void onStartup(Set<Class<?>> arg0, ServletContext sc) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("感兴趣的类型:");
        for (Class<?> claz : arg0) {
            System.out.println(claz);
        }
        
        //注册组件  ServletRegistration  
        ServletRegistration.Dynamic servlet = sc.addServlet("userServlet", new UserServlet());
        //配置servlet的映射信息
        servlet.addMapping("/user");        
        
        //注册Listener
        sc.addListener(UserListener.class);
        
        //注册Filter  FilterRegistration
        FilterRegistration.Dynamic filter = sc.addFilter("userFilter", UserFilter.class);
        //配置Filter的映射信息
        filter.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST), true, "/*");        
    }
}

 

56、servlet3.0-与SpringMVC整合分析

57、springmvc-整合

58、springmvc-定制与接管SpringMVC

//Spring的容器不扫描controller;父容器
@ComponentScan(value="com.atguigu",excludeFilters={
        @Filter(type=FilterType.ANNOTATION,classes={Controller.class})
})
public class RootConfig {

}
//SpringMVC只扫描Controller;子容器
//useDefaultFilters=false 禁用默认的过滤规则;
@ComponentScan(value="com.atguigu",includeFilters={
        @Filter(type=FilterType.ANNOTATION,classes={Controller.class})
},useDefaultFilters=false)
@EnableWebMvc
public class AppConfig  extends WebMvcConfigurerAdapter  {

    //定制
    
    //视图解析器
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        // TODO Auto-generated method stub
        //默认所有的页面都从 /WEB-INF/ xxx .jsp
        //registry.jsp();
        registry.jsp("/WEB-INF/views/", ".jsp");
    }
    
    //静态资源访问
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        // TODO Auto-generated method stub
        configurer.enable();
    }
    
    //拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // TODO Auto-generated method stub
        //super.addInterceptors(registry);
        registry.addInterceptor(new MyFirstInterceptor()).addPathPatterns("/**");
    }

}
@Controller
public class AsyncController {
    
    
    @ResponseBody
    @RequestMapping("/createOrder")
    public DeferredResult<Object> createOrder(){
        DeferredResult<Object> deferredResult = new DeferredResult<>((long)3000, "create fail...");
            
        DeferredResultQueue.save(deferredResult);
        
        return deferredResult;
    }
    
    
    @ResponseBody
    @RequestMapping("/create")
    public String create(){
        //创建订单
        String order = UUID.randomUUID().toString();
        DeferredResult<Object> deferredResult = DeferredResultQueue.get();
        deferredResult.setResult(order);
        return "success===>"+order;
    }
    
    /**
     * 1、控制器返回Callable
     * 2、Spring异步处理,将Callable 提交到 TaskExecutor 使用一个隔离的线程进行执行
     * 3、DispatcherServlet和所有的Filter退出web容器的线程,但是response 保持打开状态;
     * 4、Callable返回结果,SpringMVC将请求重新派发给容器,恢复之前的处理;
     * 5、根据Callable返回的结果。SpringMVC继续进行视图渲染流程等(从收请求-视图渲染)。
     * 
     * preHandle.../springmvc-annotation/async01
        主线程开始...Thread[http-bio-8081-exec-3,5,main]==>1513932494700
        主线程结束...Thread[http-bio-8081-exec-3,5,main]==>1513932494700
        =========DispatcherServlet及所有的Filter退出线程============================
        
        ================等待Callable执行==========
        副线程开始...Thread[MvcAsync1,5,main]==>1513932494707
        副线程开始...Thread[MvcAsync1,5,main]==>1513932496708
        ================Callable执行完成==========
        
        ================再次收到之前重发过来的请求========
        preHandle.../springmvc-annotation/async01
        postHandle...(Callable的之前的返回值就是目标方法的返回值)
        afterCompletion...
        
        异步的拦截器:
            1)、原生API的AsyncListener
            2)、SpringMVC:实现AsyncHandlerInterceptor;
     * @return
     */
    @ResponseBody
    @RequestMapping("/async01")
    public Callable<String> async01(){
        System.out.println("主线程开始..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
        
        Callable<String> callable = new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("副线程开始..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
                Thread.sleep(2000);
                System.out.println("副线程开始..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
                return "Callable<String> async01()";
            }
        };
        
        System.out.println("主线程结束..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
        return callable;
    }

}

 

1、web容器在启动的时候,会扫描每个jar包下的META-INF/services/javax.servlet.ServletContainerInitializer
2、加载这个文件指定的类SpringServletContainerInitializer
3、spring的应用一启动会加载感兴趣的WebApplicationInitializer接口的下的所有组件;
4、并且为WebApplicationInitializer组件创建对象(组件不是接口,不是抽象类)
    1)、AbstractContextLoaderInitializer:创建根容器;createRootApplicationContext();
    2)、AbstractDispatcherServletInitializer:
            创建一个web的ioc容器;createServletApplicationContext();
            创建了DispatcherServlet;createDispatcherServlet();
            将创建的DispatcherServlet添加到ServletContext中;
                getServletMappings();
    3)、AbstractAnnotationConfigDispatcherServletInitializer:注解方式配置的DispatcherServlet初始化器
            创建根容器:createRootApplicationContext()
                    getRootConfigClasses();传入一个配置类
            创建web的ioc容器: createServletApplicationContext();
                    获取配置类;getServletConfigClasses();
    
总结:
    以注解方式来启动SpringMVC;继承AbstractAnnotationConfigDispatcherServletInitializer;
实现抽象方法指定DispatcherServlet的配置信息;

===========================
定制SpringMVC;
1)、@EnableWebMvc:开启SpringMVC定制配置功能;
    <mvc:annotation-driven/>;

2)、配置组件(视图解析器、视图映射、静态资源映射、拦截器。。。)
    extends WebMvcConfigurerAdapter

 

59、servlet3.0-异步请求

@WebServlet(value="/async",asyncSupported=true)
public class HelloAsyncServlet extends HttpServlet {
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1、支持异步处理asyncSupported=true
        //2、开启异步模式
        System.out.println("主线程开始。。。"+Thread.currentThread()+"==>"+System.currentTimeMillis());
        AsyncContext startAsync = req.startAsync();
        
        //3、业务逻辑进行异步处理;开始异步处理
        startAsync.start(new Runnable() {
            @Override
            public void run() {
                try {
                    System.out.println("副线程开始。。。"+Thread.currentThread()+"==>"+System.currentTimeMillis());
                    sayHello();
                    startAsync.complete();
                    //获取到异步上下文
                    AsyncContext asyncContext = req.getAsyncContext();
                    //4、获取响应
                    ServletResponse response = asyncContext.getResponse();
                    response.getWriter().write("hello async...");
                    System.out.println("副线程结束。。。"+Thread.currentThread()+"==>"+System.currentTimeMillis());
                } catch (Exception e) {
                }
            }
        });        
        System.out.println("主线程结束。。。"+Thread.currentThread()+"==>"+System.currentTimeMillis());
    }

    public void sayHello() throws Exception{
        System.out.println(Thread.currentThread()+" processing...");
        Thread.sleep(3000);
    }
}

60、springmvc-异步请求-返回Callable

61、springmvc-异步请求-返回DeferredResult

 

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