SpringBoot * Filter的使用方法详解

前言：

最新Servlet 3.0 * 的使用

1.pom.xml添加需要使用的依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>top.ytheng</groupId>
<artifactId>springboot-demo</artifactId>
<version>0.0.1</version>
<packaging>jar</packaging>

<parent>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-parent</artifactId>
   <version>2.0.5.RELEASE</version>
   <relativePath/> <!-- lookup parent from repository -->
 </parent>

<properties>
   <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
   <java.version>1.8</java.version>
 </properties>

<dependencies>
   <dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-web</artifactId>
   </dependency>

<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-test</artifactId>
     <scope>test</scope>
   </dependency>

<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-thymeleaf</artifactId>
   </dependency>

<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-devtools</artifactId>
     <optional>true</optional>
      <scope>true</scope>
   </dependency>
 </dependencies>

<build>
   <!-- 打包的名称 -->
   <finalName>myspringboot</finalName>
   <plugins>
     <plugin>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-maven-plugin</artifactId>
     </plugin>
     <plugin>
       <artifactId>maven-compiler-plugin</artifactId>
       <configuration>
         <source>1.8</source>
         <target>1.8</target>
       </configuration>
     </plugin>
   </plugins>
 </build>
</project>

2.添加Filter *

package top.ytheng.demo.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

//Servlet3.0特性
//urlPatterns:拦截的url地址
//filterName: * 名称
@WebFilter(urlPatterns="/api/*", filterName="loginFilter")
public class LoginFilter implements Filter{

/*
  * 容器加载完成调用
  * */
 @Override
 public void init(FilterConfig filterConfig) throws ServletException {
   // TODO Auto-generated method stub
   System.out.println("filter init...");
 }

/*
  *  请求被拦截的时候调用
  * */
 @Override
 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
     throws IOException, ServletException {
   // TODO Auto-generated method stub
   System.out.println("doFilter...");

HttpServletRequest req = (HttpServletRequest)request;
   HttpServletResponse resp = (HttpServletResponse)response;

String username = req.getParameter("username");
   if(username.equals("theng")) {
     chain.doFilter(request, response);
   } else {
     //重定向
     resp.sendRedirect("/filter.html");
     return;
   }

}

/*
  * 容器被销毁的时候调用
  * */
 @Override
 public void destroy() {
   // TODO Auto-generated method stub
   System.out.println("filter destroy...");
 }

}

3.添加测试控制器

package top.ytheng.demo.controller;

import java.util.HashMap;
import java.util.Map;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api/v1/filter")
public class FilterController {

@RequestMapping("/test")
 public Object testFilter() {
   Map<String, Object> map = new HashMap<>();
   map.put("name", "theng");
   map.put("pwd", "123456");
   return map;
 }
}

4.添加启动类

package top.ytheng.demo;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication //等于下面3个
//@SpringBootConfiguration
//@EnableAutoConfiguration
//@ComponentScan
// * 用到
@ServletComponentScan
public class DemoApplication {

public static void main(String[] args) {
   SpringApplication.run(DemoApplication.class, args);
 }

}

5.添加拦截后调整的页面filter.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
 <h4>hello theng</h4>
 <h3>filter success</h3>
</body>
</html>

6.右键项目Run As启动项目，测试地址

http://localhost:8080/api/v1/filter/test?username=theng
http://localhost:8080/api/v1/filter/test?username=ytheng

另附：

来源：https://www.cnblogs.com/tianhengblogs/p/9781734.html