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
}
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