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这篇文章将为大家详细讲解有关Springboot中如何整合Servlet,文章内容质量较高,因此小编分享给大家做个参考,希望大家阅读完这篇文章后对相关知识有一定的了解。
• Spring Boot设计目的是用来简化新 Spring 应用的初始搭建以及开发过程。 • 嵌入的 Tomcat,无需部署 WAR 文件 • Spring Boot 并不是对 Spring 功能上的增强,而是提供了一种快速使用 Spring 的方式。
POM.xml
<!--springboot项目的父类,所有springboot项目都必须继承于它--> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.9.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <!--springboot启动器--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency>
springBoot启动器其实就是一些jar包的集合。SprigBoot一共提供44启动器。 1 spring-boot-starter-web 支持全栈式的web开发,包括了romcat和springMVC等jar 2 spring-boot-starter-jdbc 支持spring以jdbc方式操作数据库的jar包的集合 3 spring-boot-starter-redis 支持redis键值存储的数据库操作
Controller
package com.lee.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;
import java.util.Map;
@RestController
public class HelloWorld {
    @RequestMapping("/hello")
    public Map<String,Object> hello(){
        Map<String,Object> resultMap = new HashMap<>();
        resultMap.put("msg","hello world");
        return resultMap;
    }
}启动类
package com.lee;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringbootApplication {
    public static void main(String[] args) {
        SpringApplication.run(SpringbootApplication.class, args);
    }
}@SpringBootApplication包含: @SpringBootConfiguration、@EnableAutoConfiguration、@ComponentScan、@Configuration等注解,它是一个配置类,扫描了当前包和当前包下所有子包下的所有文件
结果:http://localhost:8080/hello
{"msg":"hello world"}两种方式完成组件的注册:
FirstServlet
package com.lee.servlet;
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;
/**
 * springboot整合servlet的第一种方式:
 *   原来
 *      <servlet>
 *          <servlet-name>firstServlet</servlet-name>
 *          <servlet-class>com.lee.FirstServlet</servlet-class>
 *      </servlet>
 *      <servlet-mapping>
 *          <servlet-name>firstServlet</servlet-name>
 *          <url-pattern>/firstServlet</url-pattern>
 *      </servlet-mapping>
 */
@WebServlet(name="firstServlet",urlPatterns = "/firstServlet")
public class FirstServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req,resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("firstServlet............");
    }
}启动类:
package com.lee;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
//该注解会扫描当前包和其子包下的 @WebServlet,
//并在启动类启动的时候将其实例化
@ServletComponentScan
@SpringBootApplication
public class SpringbootApplicationServlet1 {
    public static void main(String[] args) {
        SpringApplication.run(SpringbootApplicationServlet1.class,args);
    }
}结果:http://localhost:8080/firstServlet
firstServlet............
SecondServlet
package com.lee.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class SecondServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("secondServlet....");
    }
}启动类
package com.lee;
import com.lee.servlet.SecondServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class SpringbootApplicationServlet2 {
    public static void main(String[] args) {
        SpringApplication.run(SpringbootApplicationServlet2.class,args);
    }
    //将scondServlet注册到servletRegistrationBean中
    @Bean
    public ServletRegistrationBean secondServlet(){
        ServletRegistrationBean bean = new ServletRegistrationBean();
        bean.setServlet(new SecondServlet());
        bean.addUrlMappings("/secondServlet");
        return bean;
    }
}结果:http://localhost:8080/secondServlet
secondServlet....
两种方式完成组件的注册
FirstFilter
package com.lee.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
/**
 * <filter>
 *     <filter-name>FirstFilter</filter-name>
 *     <filter-class>com.lee.filter.FirstFilter</filter-class>
 * </filter>
 * <filter-mapping>
 *     <filter-name>FirstFilter</filter-name>
 *     <url-patter>/firstServlet</url-patter>
 * </filter-mapping>
 */
//@WebFilter(filterName = "firstFilter",urlPatterns = {"*.do","*.action"})
@WebFilter(filterName = "firstFilter",urlPatterns = "/firstServlet")
public class FirstFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println(" first filter init");
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("enter first filter");
        filterChain.doFilter(servletRequest, servletResponse);
        System.out.println("leave first filter");
    }
    @Override
    public void destroy() {
        System.out.println(" first filter destroy");
    }
}启动类
package com.lee;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
//该注解会扫描当前包和其子包下的 @WebServlet @WebFilter等,
//并在启动类启动的时候将其实例化
@ServletComponentScan
@SpringBootApplication
public class SpringbootApplicationFilter1 {
    public static void main(String[] args) {
        SpringApplication.run(SpringbootApplicationFilter1.class,args);
    }
}结果:http://localhost:8080/firstServlet
first filter init enter first filter firstServlet............ leave first filter
SecondFilter
package com.lee.filter;
import javax.servlet.*;
import java.io.IOException;
public class SecondFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println(" second filter init");
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("enter second filter");
        filterChain.doFilter(servletRequest, servletResponse);
        System.out.println("leave second filter");
    }
    @Override
    public void destroy() {
        System.out.println(" second filter destroy");
    }
}启动类
package com.lee;
import com.lee.filter.SecondFilter;
import com.lee.servlet.SecondServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class SpringbootApplicationFilter2 {
    public static void main(String[] args) {
        SpringApplication.run(SpringbootApplicationFilter2.class,args);
    }
    //将scondServlet注册到servletRegistrationBean中
    @Bean
    public ServletRegistrationBean secondServlet(){
        ServletRegistrationBean bean = new ServletRegistrationBean();
        bean.setServlet(new SecondServlet());
        bean.addUrlMappings("/secondServlet");
        return bean;
    }
    @Bean
    public FilterRegistrationBean secondFilter(){
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.setFilter(new SecondFilter());
        bean.addUrlPatterns("/secondServlet");
        return bean;
    }
}结果:
second filter init enter second filter secondServlet.... leave second filter
之前在 《springboot使用redis和ThreadLocal做单点登录 》中,已经使用过拦截器,有兴趣的可以看一下。
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency>
public class MyInterceptor implements HandlerInterceptor {
 
    private final Logger logger = LoggerFactory.getLogger(this.getClass().getCanonicalName());
 
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws Exception {
        logger.info("{}:在请求处理之前进行调用(Controller方法调用之前)", this.getClass().getSimpleName());
        return true;//只有返回true才会继续向下执行,返回false取消当前请求
    }
 
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object o, ModelAndView modelAndView) throws Exception {
        logger.info("{}:请求处理之后进行调用,但是在视图被渲染之前(Controller方法调用之后)", this.getClass().getSimpleName());
    }
 
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object o, Exception e) throws Exception {
        logger.info("{}:在整个请求结束之后被调用,也就是在DispatcherServlet 渲染了对应的视图之后执行(主要是用于进行资源清理工作)", this.getClass().getSimpleName());
    }
}@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter{
 
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**");//用于添加拦截规则
        // 多个拦截器组成一个拦截器链
        // excludePathPatterns 用户排除拦截
    }
}关于Springboot中如何整合Servlet就分享到这里了,希望以上内容可以对大家有一定的帮助,可以学到更多知识。如果觉得文章不错,可以把它分享出去让更多的人看到。
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