如何使用 Spring Boot 注册 servlet? [英] How can I register a servlet with Spring Boot?

问题描述

此代码无效

我有一个 web.xml 需要翻译成 Spring Boot

I have a web.xml that needs to be translated into a spring boot

    <servlet>       
            <servlet-name>page-resolver</servlet-name>       
            <servlet-class>com.bk.ForwardServlet</servlet-class>         
            <init-param>
                <param-name>page</param-name>
                <param-value>/index.jsp</param-value>         
            </init-param>         
    </servlet>
    <servlet-mapping>                            
        <servlet-name>page-resolver</servlet-name>         
        <url-pattern>/index.html</url-pattern>
        <url-pattern>/login</url-pattern>
        <url-pattern>/qmgr/*</url-pattern>  
    </servlet-mapping>

还有这个班

@WebServlet
public class ForwardServlet extends HttpServlet {

private String page;

@Override
public void init(ServletConfig config) throws ServletException {
    super.init(config);
    page = config.getInitParameter("page");
}

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    req.getRequestDispatcher(page).forward(req, resp);
}
}

我编写了注册此 bean 的代码，但它不起作用，我不明白为什么

I wrote code that registers this bean but it doesn't work and I don't understand why

@Configuration
public class ConfigureWeb implements ServletContextInitializer {

private void registerServlet(ServletContext servletContext) {
    ServletRegistrationBean serviceServlet =
            new ServletRegistrationBean(new ForwardServlet(), "/index.html","/login","/qmgr/*");

    serviceServlet.addUrlMappings("/index.jsp");
}

@Override
public void onStartup(ServletContext servletContext) throws ServletException {
    registerServlet(servletContext);
}
}

推荐答案

首先检查并确认所有资源都保存在正确的目录中.对于 spring-boot，jsp 页面将保存在目录 <代码>src->main->webapp->WEB-INF->view->*.jsp.

First of all check and verify that all your resources are being kept in the correct directory.For spring-boot the jsp pages are to be kept in the directory src->main->webapp->WEB-INF->view->*.jsp .

在使用嵌入式tomcat时，您应该在pom中添加以下依赖项以正确编译jsp:

You should have the following dependencies added in pom to compile the jsp properly when using embedded tomcat :

<!-- JSTL -->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
</dependency>
<!-- To compile JSP files -->
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-jasper</artifactId>
    <scope>provided</scope>
</dependency>

现在我们需要告诉spring jsp文件所在的位置，我们可以有两种方法:

Now we need to tell spring where the jsp files reside, we can have two approaches for this :

在 application.properties 中添加条目

spring.mvc.view.prefix=/WEB-INF/view/
spring.mvc.view.suffix=.jsp

这里我们可以指定jsp文件所在的文件夹，以及定义视图.或

Here we can specify the folder where the jsp files are to be expected, as well as define the view. or

配置 InternalResourceViewResolver 以提供 JSP 页面

@Configuration
@EnableWebMvc
@ComponentScan
public class MvcConfiguration extends WebMvcConfigurerAdapter
{
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/view/");
        resolver.setSuffix(".jsp");
        resolver.setViewClass(JstlView.class);
        registry.viewResolver(resolver);
    }
}

现在注册 servlet :

ServletRegistrationBean 用于在 Servlet 3.0 + 容器中注册 Servlet.我们需要在我们的 JavaConfig 中创建一个 ServletRegistrationBean bean.查找 ServletRegistrationBean 的一些方法，用于配置 Servlet.setServlet(): 设置要注册的 servlet.addUrlMappings(): 为 Servlet 添加 URL 映射.setLoadOnStartup:设置启动时加载 Servlet 的优先级.

ServletRegistrationBean is used to register Servlets in Servlet 3.0 + container. We need to create a bean of ServletRegistrationBean in our JavaConfig. Find some methods of ServletRegistrationBean used to configure a Servlet. setServlet(): Sets the servlet to be registered. addUrlMappings(): Add URL mappings for the Servlet. setLoadOnStartup: Sets priority to load Servlet on startup.

假设我们有两个 Servlet，分别是 HelloCountryServlet 和 HelloStateServlet 然后我们将使用 ServletRegistrationBean 向 Spring Boot 注册它们，如下所示:

Suppose we have two Servlets as HelloCountryServlet and HelloStateServlet then we will register them with Spring Boot using ServletRegistrationBean as following :

@Configuration
public class WebConfig {
   @Bean    
   public ServletRegistrationBean<HttpServlet> countryServlet() {
       ServletRegistrationBean<HttpServlet> servRegBean = new ServletRegistrationBean<>();
       servRegBean.setServlet(new HelloCountryServlet());
       servRegBean.addUrlMappings("/country/*");
       servRegBean.setLoadOnStartup(1);
       return servRegBean;
   }
   @Bean    
   public ServletRegistrationBean<HttpServlet> stateServlet() {
       ServletRegistrationBean<HttpServlet> servRegBean = new ServletRegistrationBean<>();
       servRegBean.setServlet(new HelloStateServlet());
       servRegBean.addUrlMappings("/state/*");
       servRegBean.setLoadOnStartup(1);
       return servRegBean;
   }   
}  

我们为每个 Servlet 创建一个 ServletRegistrationBean bean.servlet 类将如下所示:

For every Servlet we create a ServletRegistrationBean bean. And the servlet class will look like :

public class HelloCountryServlet extends HttpServlet   {
    private static final long serialVersionUID = 1L;
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException{
        doGet(request,response);
    }
        public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
            response.setContentType("text/html");
            PrintWriter out = response.getWriter();
        out.println("<h3>Hello India!</h3>");   
    }
}

这是一种方法.

另一种在 spring-boot 中注册 servlet 的方法是使用注解:@ServletComponentScan 和 @WebServlet.Spring Boot 中的 @ServletComponentScan 将扫描用 @WebServlet 注释的 Servlets、用 @WebFilter 注释的过滤器和用 @WebListener.注解@ServletComponentScan在类级别的JavaConfig上使用.@ServletComponentScan 仅使用嵌入式 Web 服务器 来扫描 Servlet、过滤器和侦听器.找到用@WebServlet 注释的 Servlet.

Another method to register servlets in spring-boot is using annotations : @ServletComponentScan and @WebServlet. @ServletComponentScan in Spring Boot will scan Servlets annotated with @WebServlet, Filters annotated with @WebFilter and Listeners annotated with @WebListener.The annotation @ServletComponentScan is used on JavaConfig at class level. @ServletComponentScan scans Servlets, Filters and Listeners only using an embedded web server. Find the Servlets annotated with @WebServlet.

所以早期的 HelloCountryServlet servlet 可以提供为:

So the earlier HelloCountryServlet servlet can be provided as :

@WebServlet(urlPatterns = "/country/*", loadOnStartup = 1)
public class HelloCountryServlet extends HttpServlet   {
    private static final long serialVersionUID = 1L;
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException{
         doGet(request,response);
    }
        public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
             response.setContentType("text/html");
             PrintWriter out = response.getWriter();
         out.println("<h3>Hello India!</h3>");  
    }
}

并提供 ServletComponentScan 注释，如:

and provide the ServletComponentScan annotation like :

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

这篇关于如何使用 Spring Boot 注册 servlet?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！