一、Spring Boot 提供了 ServletRegistrationBean, FilterRegistrationBean, ServletListenerRegistrationBean 三个类分别用来注册 Servlet, Filter, Listener
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class RegisterServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
String name = getServletConfig().getInitParameter("name");
String sex = getServletConfig().getInitParameter("sex");
resp.getOutputStream().println("name is " + name);
resp.getOutputStream().println("sex is " + sex);
}
}
@Bean
public ServletRegistrationBean registerServlet() {
ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new RegisterServlet(), "/registerServlet");
servletRegistrationBean.addInitParameter("name", "javastack");
servletRegistrationBean.addInitParameter("sex", "man");
return servletRegistrationBean;
}二、Servlet 3.0 之前，Servlet、Filter、Listener 这些组件都需要在 web.xml 中进行配置，3.0 之后开始不再需要 web.xml 这个配置文件了，所有的组件都可以通过代码配置或者注解@WebServlet/@WebFilter/@WebListener来达到目的。
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet(name = "javaServlet", urlPatterns = "/javastack.cn", asyncSupported = true,
initParams = {
@WebInitParam(name = "name", value = "javastack"),
@WebInitParam(name = "sex", value = "man") })
public class JavaServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
String name = getServletConfig().getInitParameter("name");
String sex = getServletConfig().getInitParameter("sex");
resp.getOutputStream().println("name is " + name);
resp.getOutputStream().println("sex is " + sex);
}
}**注意：**需要在启动类上配置上注解@ServletComponentScan来扫描这三个注解@ServletComponentScan扫描@WebServlet和@WebFilter及@WebListener的配置
三、实现org.springframework.boot.web.servlet.ServletContextInitializer向容器中注入bean的方式动态注册
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet(name = "javaServlet", urlPatterns = "/javastack.cn", asyncSupported = true,
initParams = {
@WebInitParam(name = "name", value = "javastack"),
@WebInitParam(name = "sex", value = "man") })
public class JavaServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
String name = getServletConfig().getInitParameter("name");
String sex = getServletConfig().getInitParameter("sex");
resp.getOutputStream().println("name is " + name);
resp.getOutputStream().println("sex is " + sex);
}
}
import cn.javastack.springbootbestpractice.servlet.InitServlet;
import org.springframework.boot.web.servlet.ServletContextInitializer;
import org.springframework.stereotype.Component;
import javax.servlet.ServletContext;
import javax.servlet.ServletRegistration;
@Component
public class ServletConfig implements ServletContextInitializer {
@Override
public void onStartup(ServletContext servletContext) {
ServletRegistration initServlet = servletContext.addServlet("initServlet", InitServlet.class);
initServlet.addMapping("/initServlet");
initServlet.setInitParameter("name", "javastack");
initServlet.setInitParameter("sex", "man");
}
}四、 使用org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.registerMapping()方法运行时动态注册
private void registerServerEndpoint(String path, Object bean) throws NoSuchMethodException {
RequestMappingHandlerMapping mapping = applicationContext.getBean(RequestMappingHandlerMapping.class);
RequestMappingInfo.BuilderConfiguration config = new RequestMappingInfo.BuilderConfiguration();
if (webMvcProperties.getPathmatch().getMatchingStrategy() == WebMvcProperties.MatchingStrategy.PATH_PATTERN_PARSER) {
config.setPatternParser(new PathPatternParser());
} else {
config.setPathMatcher(new AntPathMatcher());
}
RequestMappingInfo handleGet = RequestMappingInfo.paths(path).methods(RequestMethod.GET).options(config).build();
mapping.registerMapping(handleGet, bean, ServletHttpHandler.class.getMethod("handleGet"));
RequestMappingInfo handlePost = RequestMappingInfo.paths(path).methods(RequestMethod.POST).options(config).build();
mapping.registerMapping(handlePost, bean, ServletHttpHandler.class.getMethod("handlePost", String.class));
}五、使用org.springframework.web.servlet.function.RouterFunction注册
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.MediaType;
import org.springframework.web.servlet.function.RouterFunction;
import org.springframework.web.servlet.function.RouterFunctions;
import org.springframework.web.servlet.function.ServerRequest;
import org.springframework.web.servlet.function.ServerResponse;
import javax.servlet.ServletException;
import java.io.IOException;
import java.time.Duration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
public class StreamServer {
private final ObjectMapper objectMapper = new ObjectMapper();
private final String endpoint;
private final RouterFunction<ServerResponse> router;
public StreamServer(String endpoint) {
this.endpoint = endpoint;
this.router = RouterFunctions.route()
.POST(this.endpoint, this::handlePost)
.build();
}
public RouterFunction<ServerResponse> getRouter() {
return this.router;
}
private ServerResponse handlePost(ServerRequest request) throws ServletException, IOException {
List<MediaType> acceptHeaders = request.headers().asHttpHeaders().getAccept();
if (!acceptHeaders.contains(MediaType.TEXT_EVENT_STREAM)
|| !acceptHeaders.contains(MediaType.APPLICATION_JSON)) {
return ServerResponse.badRequest()
.body("Invalid Accept headers. Expected TEXT_EVENT_STREAM and APPLICATION_JSON");
}
String body = request.body(String.class);
log.info("body:{}", body);
String sessionId = UUID.randomUUID().toString();
return ServerResponse.sse(sseBuilder -> {
sseBuilder.onComplete(() -> {
log.debug("Request response stream completed for session: {}", sessionId);
});
sseBuilder.onTimeout(() -> {
log.debug("Request response stream timed out for session: {}", sessionId);
});
try {
for (int i = 0; i < 100; ++i) {
Map<String, Object> row = new HashMap<>();
row.put("rowId", i + 1);
row.put("rowName", i + 1);
String json = objectMapper.writeValueAsString(row);
sseBuilder.id(sessionId)
.event("message")
.data(json);
}
sseBuilder.complete();
} catch (Exception e) {
log.error("Failed to handle request stream: {}", e.getMessage());
sseBuilder.error(e);
}
}, Duration.ZERO);
}
}
import com.github.kylewka.smartai.demo.stream.StreamServer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.function.RouterFunction;
import org.springframework.web.servlet.function.ServerResponse;
@Configuration
public class StreamServerConfig {
@Bean
public StreamServer streamServer() {
return new StreamServer("/test/stream");
}
@Bean
public RouterFunction<ServerResponse> sseRoute(StreamServer streamServer) {
return streamServer.getRouter();
}
}总结：
1 参考文章： https://huanghaoheng.blog.csdn.net/article/details/128703156