SpringBoot------拦截器Filter的使用

前言：

最新Servlet 3.0拦截器的使用

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拦截器

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:拦截器名称
@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
//拦截器用到
@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：