Spring Boot 内嵌servlet容器的Servlets +Filters + listeners

Posted 2020-10-15 否定之否定

一：servlet

（1）启动类

@SpringBootApplication
@ServletComponentScan
public class Application {
    public static void main(String[] args){
        SpringApplication.run(Application.class, args);
    }
}

启动类用@ServletComponentScan注解标注

（2）继承HttpServlet

@WebServlet(name = "webServlet", urlPatterns = "/webServlet", loadOnStartup = 2)
public class WebServletTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("########doGet###########");
        System.out.println("WebServletTest.doGet");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("########doPost###########");
        System.out.println("WebServletTest.doPost");
    }
}

（3）访问http://localhost:8080/webServlet    运行结果：

 

 二：Filters

测试示例1

@WebFilter(urlPatterns = "/*",filterName="CharacterEncodeFilter",
        initParams={
                @WebInitParam(name="encoding",value="UTF-8"),
                @WebInitParam(name = "forceEncoding", value = "true")
        })
@Singleton
public class CharacterEncodingFilter implements Filter {
    private String encoding = "UTF-8";
    private boolean forceEncoding = true;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.encoding = filterConfig.getInitParameter("encoding");
        String force = filterConfig.getInitParameter("forceEncoding");
        this.forceEncoding = (force == null) || Boolean.valueOf(force);
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        if (this.forceEncoding || servletRequest.getCharacterEncoding() == null) {
            servletRequest.setCharacterEncoding(this.encoding);
            servletResponse.setCharacterEncoding(this.encoding);
        }
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {

    }
}

测试示例2

@WebFilter(urlPatterns = "/*", filterName = "indexFilter")
public class IndexFilter implements Filter {
    private final static Logger logger = LoggerFactory.getLogger(IndexFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        logger.info("init IndexFilter");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        logger.info("IndexFilter.doFilter exec");
        filterChain.doFilter(servletRequest,servletResponse);

    }

    @Override
    public void destroy() {

    }
}

 

三： listeners

示例

@WebListener
public class MyServletContextListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        System.out.println("ServletContex初始化");
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        System.out.println("ServletContex销毁");
    }
}

运行结果：