springboot-filter过滤器

本节介绍spring filter过滤器使用，一般做乱码处理、权限控制等操作，可以预先在过滤中加载，以下是过滤器的基本操作

创建项目

在pom.xml中引入依赖包

<?xml version="1.0" encoding="UTF-8"?>
<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>com.example.springboot</groupId>
   <artifactId>springboot-filter</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <packaging>jar</packaging>

   <name>springboot-filter</name>
   <description>Demo project for Spring Boot</description>

   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>1.5.12.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>1.7</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>
   </dependencies>

   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
      </plugins>
   </build>
</project>

创建自定义过滤器

编写一个类，实现Filter过滤器，实现其方法即可，如下：

package com.example.springboot.filter.filter;

import javax.servlet.*;
import java.io.IOException;

/**
 * @desc 自定义过滤器，可以在这里处理中文乱码等问题
 * @Author wangsh
 * @date 2018/5/6 15:44
 * @return
 */
public class CharacterFilter implements Filter {

   /**
    * 服务启动,调用初始化方法
    *
    * @param filterConfig
    * @throws ServletException
    */
   @Override
   public void init(FilterConfig filterConfig) throws ServletException {

      System.out.println("服务启动,调用过滤器Filter初始化方法init()..........");
   }


   /**
    * 请求时调用
    *
    * @param servletRequest
    * @param servletResponse
    * @param filterChain
    * @throws IOException
    * @throws ServletException
    */
   @Override
   public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

      System.out.println("发送请求时,调用过滤器Filter的doFilter()方法..........");
      //放行通过
      filterChain.doFilter(servletRequest, servletResponse);
   }

   /**
    * 销毁调用
    */
   @Override
   public void destroy() {

      System.out.println("服务关闭，调用过滤器Filter的销毁方法destroy()..........");
   }
}

将过滤器添加到过滤器链中

package com.example.springboot.filter.config;

import com.example.springboot.filter.filter.CharacterFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.util.ArrayList;
import java.util.List;

/**
 * @desc 注册bean, 将自定义过滤器添加到过滤器链中
 * @Author wangsh
 * @date 2018/5/6 15:48
 * @return
 */
@Configuration
public class WebConfig {

   /**
    * 注册过滤器,有两种方式：
    * 1) 使用 @Component 注解<br>
    * 2) 添加到过滤器链中，此方式适用于使用第三方的过滤器。将过滤器写到 WebConfig 类中，如下：
    */
   @Bean
   public FilterRegistrationBean filterRegistrationBean() {

      FilterRegistrationBean registrationBean = new FilterRegistrationBean();

      CharacterFilter filter = new CharacterFilter();
      registrationBean.setFilter(filter);

      //设置过滤器拦截请求
      List<String> urls = new ArrayList<>();
      urls.add("/*");
      registrationBean.setUrlPatterns(urls);

      return registrationBean;
   }

}

创建controller类

package com.example.springboot.filter.controller;

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

/**
 * @desc
 * @Author wangsh
 * @date 2018/5/6 15:49
 * @return
 */
@RestController
public class FilterController {
   /**
    * 请求映射：http://localhost:8080/hello
    *
    * @return
    */
   @RequestMapping("/hello")
   public String hello() {
      System.out.println("测试filter过滤器...........");
      return "hello";
   }
}

创服务启动类

package com.example.springboot.filter;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringbootFilterApplication {

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

//针对自定义 Servlet、Filter 和 Listener 的配置另一种方式：
//@SpringBootApplication
//public class SpringbootWebApplication implements ServletContextInitializer {
//
// @Override
// public void onStartup(ServletContext servletContext) throws ServletException {
//    // 配置 Servlet
//    servletContext.addServlet("servletTest",new xxxxServlet())
//          .addMapping("/servletTest");
//    // 配置过滤器
//    servletContext.addFilter("timeFilter",new xxxxFilter())
//          .addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST),true,"/*");
//    // 配置监听器
//    servletContext.addListener(new xxxxListener());
// }
//
// public static void main(String[] args) {
//    SpringApplication.run(SpringbootWebApplication.class, args);
// }
//}

启动服务测试

在浏览器访问：http://localhost:8080//hello， 从日志可以看出，当服务启动时，首先调用filter初始化方法init(), 当浏览器发送请求时调用dofilter()方法，如下：