在 Spring Boot 中,您可以使用 ServletRegistrationBean、FilterRegistrationBean 和 ServletListenerRegistrationBean bean 定义来注册 Servlet、Filters、Listeners。
例如,考虑以下 Servlet 示例:
package com.example;
import org.springframework.stereotype.Component;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@Component
public class DemoServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.getWriter().write("called Servlet!");
}
}
我们可以使用 ServletRegistrationBean 注册 DemoServlet 并将其映射到 URL 模式 /myServlet,如下例所示:
package com.example;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
@Autowired private FilterServlet myServlet;
@Bean
public ServletRegistrationBean<DemoServlet> myServletBean() {
ServletRegistrationBean<DemoServlet> servlet = new ServletRegistrationBean<>();
servlet.setServlet(myServlet);
servlet.addUrlMappings("/myServlet");
return servlet;
}
}
如果您尝试请求 http://localhost:8080/myServlet,您可以检查是否调用了 DemoServlet
called Servlet!
通过使用这种方法,您可以利用 Spring 对 servlet、过滤器和侦听器的依赖注入。
为了为您的请求实现 Servlet 过滤器,您可以在 org.springframework.boot.web.servlet.FilterRegistrationBean 上注册过滤器。这允许选择将过滤器绑定到请求的 URL 模式。例如,当请求 URL 模式*/demo* 时,如何激活 doFilter 方法:
package com.example;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class RequestFilter implements Filter {
@Bean
public FilterRegistrationBean<RequestFilter> loggingFilter() {
FilterRegistrationBean<RequestFilter> registrationBean = new FilterRegistrationBean<>();
registrationBean.setFilter(new RequestFilter());
registrationBean.addUrlPatterns("/demo");
return registrationBean;
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
System.out.println("Called request " + req.getRequestURI());
chain.doFilter(request, response);
System.out.println("Response :" + res.getContentType());
}
}
请注意,您也可以使用 @Component 而不是 @Bean 来注释此类,但在这种情况下,将为每个请求执行过滤器:
@Component
public class RequestFilter implements Filter {
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
System.out.println("Called request " + req.getRequestURI());
chain.doFilter(request, response);
System.out.println("Response :" + res.getContentType());
}
}
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