SpringBoot 无XML的相关配置

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SpringBoot 无XML的相关配置

Setting context-params

在Servlet 2.0是在web.xml来设置context-params

<context-param>    <param-name>facelets.DEVELOPMENT</param-name>    <param-value>true</param-value></context-param>

在基于Servlet 3.0的SpringBoot上可使用

@Configuration@ComponentScan@EnableAutoConfigurationpublic class Application implements ServletContextInitializer {    public static void main(String[] args) {        SpringApplication.run(Application.class, args);    }    @Override    public void onStartup(ServletContext servletContext)            throws ServletException {            servletContext.setInitParameter("facelets.DEVELOPMENT", "true");    }}

添加Interceptor

import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;@Configurationpublic class MyWebAppConfigurer extends WebMvcConfigurerAdapter {    @Override    public void addInterceptors(InterceptorRegistry registry) {        // 多个拦截器组成一个拦截器链        // addPathPatterns 用于添加拦截规则        // excludePathPatterns 用户排除拦截        registry.addInterceptor(new MyInterceptor1()).addPathPatterns("/**");        registry.addInterceptor(new MyInterceptor2()).addPathPatterns("/**");        super.addInterceptors(registry);    }}

Tips:Filter与Interceptor的区别

使用范围不同：Filter是Servlet规范规定的，只能用于Web程序中。而拦截器既可以用于Web程序，也可以用于Application、Swing程序中。
规范不同：Filter是在Servlet规范中定义的，是Servlet容器支持的。而拦截器是在Spring容器内的，是Spring框架支持的。
使用的资源不同：同其他的代码块一样，拦截器也是一个Spring的组件，归Spring管理，配置在Spring文件中，因此能使用Spring里的任何资源、对象，例如Service对象、数据源、事务管理等，通过IoC注入到拦截器即可；而Filter则不能。
深度不同：Filter在只在Servlet前后起作用。而拦截器能够深入到方法前后、异常抛出前后等，因此拦截器的使用具有更大的弹性。所以在Spring构架的程序中，要优先使用拦截器。

浏览器发起请求执行顺序

Client -> Listener -> ServletContainer -> Filter -> Servlet -> Interceptor

添加Servlet、Filer、Listener

在SpringBootApplication上使用@ServletComponentScan注解后，Servlet、Filter、Listener可以直接通过@WebServlet、@WebFilter、@WebListener注解自动注册，无需其他代码。

启动扫描

import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.web.servlet.ServletComponentScan;@SpringBootApplication//这个就是扫描相应的Servlet包;@ServletComponentScanpublic class SiteConfig {    public static void main(String[] args) {        SpringApplication.run(SiteConfig.class, args);    }}

import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.io.PrintWriter;@WebServlet(urlPatterns="/myServlet/*", description="Servlet的说明")public class MyServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        System.out.println(">>>>>>>>>>doGet()<<<<<<<<<<<");        doPost(req, resp);    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        System.out.println(">>>>>>>>>>doPost()<<<<<<<<<<<");        resp.setContentType("text/html;charset=UTF-8");        PrintWriter out = resp.getWriter();        out.println("<html>");        out.println("<head>");        out.println("<title>Hello World</title>");        out.println("</head>");        out.println("<body>");        out.println("<h1>这是：MyServlet</h1>");        out.println("</body>");        out.println("</html>");    }}

import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.annotation.WebFilter;import java.io.IOException;/*** 使用注解标注过滤器* @WebFilter将一个实现了javax.servlet.Filter接口的类定义为过滤器* 属性filterName声明过滤器的名称,可选* 属性urlPatterns指定要过滤的URL模式,也可使用属性value来声明.(指定要过滤的URL模式是必选属性)*/@WebFilter(filterName = "myFilter", urlPatterns = "/*")public class MyFilter implements Filter {    @Override    public void init(FilterConfig config) throws ServletException {        System.out.println("过滤器初始化");    }    @Override    public void doFilter(ServletRequest request, ServletResponse response,                        FilterChain chain) throws IOException, ServletException {        System.out.println("执行过滤操作");        chain.doFilter(request, response);    }    @Override    public void destroy() {        System.out.println("过滤器销毁");    }}

import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import javax.servlet.annotation.WebListener;/*** 使用@WebListener注解，实现ServletContextListener接口*/@WebListenerpublic class MyServletContextListener implements ServletContextListener {    @Override    public void contextDestroyed(ServletContextEvent arg0) {        System.out.println("ServletContex销毁");    }    @Override    public void contextInitialized(ServletContextEvent arg0) {        System.out.println("ServletContex初始化");    }}

代码注册通过ServletRegistrationBean、FilterRegistrationBean和ServletListenerRegistrationBean获得控制。

@Bean    public FilterRegistrationBean sessionFilter() {        FilterRegistrationBean bean = new FilterRegistrationBean();        bean.setFilter(new HttpSessionFilter());        return bean;    }

可以通过实现ServletContextInitializer接口直接注册。

    @Override    public void onStartup(ServletContext servletContext) throws ServletException {        // Servlet        ServletRegistration.Dynamic dispatcher = servletContext.addServlet("dispatcher", new DispatcherServlet(dispatcherContext));        dispatcher.addMapping("/");        dispatcher.setLoadOnStartup(1);        dispatcher.setInitParameter("defaultHtmlEscape", "true");        // Filter        FilterRegistration.Dynamic filter = container.addFilter("encodingFilter", CharacterEncodingFilter.class);        filter.addMappingForUrlPatterns(null, false, "/*");        filter.setInitParameter("encoding", "UTF-8");        filter.setInitParameter("forceEncoding", "true");        // Listener        servletContext.addListener(TestServletContextListener.class);        super.onStartup(servletContext);    }

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