SpringBoot——Filter过滤器的使用

蔚落 2022-11-05 11:47 237阅读 0赞

先写一个Post接口用来请求，给过滤器测试用

@RestController
    @RequestMapping(value = "api/tool")
    public class ToolModuleController { 
    
        /** * @param * @return * @创建日期:2020年3月5日 * @功能说明：生成UUID */
        @ApiOperation(value = "生成UUID(数字+字母)", notes = "生成UUID(数字+字母)")
        @PostMapping(value = "generateUuid")
        public String generateUuid() { 
            try { 
                String id = UUIDGeneratorUtil.buildMallOrderSn();
                return id;
            } catch (Exception e) { 
                log.error(e.getMessage(), e);
                return "失败";
            }
        }
      }

# 方式一：通过注解扫描的方式完成Filter组件的注册 #

过滤器的使用很简单，建一个类，实现`Filter`（引入的是`javax.servlet`），那么这个类就是过滤器了，加上`@WebFilter`配置过滤规则，`@Order`用于多个过滤器时定义执行顺序，值越小越先执行，最后要在启动类加上`@ServletComponentScan`，不加过滤器不生效。  
1、过滤器`init`方法是初始化的，程序（tomcat）启动的时候执行，`doFilter`方法里面就可以写过滤的逻辑了，`destroy`方法是程序（tomcat）关闭的时候执行的。  
1.1、web服务器在调用`doFilter`方法时，会传递一个`filterChain`对象进来，`filterChain`对象是filter接口中最重要的一个对 象，它也提供了一个`doFilter`方法，开发人员可以根据需求决定是否调用此方法，调用该方法，则`web`服务器就会调用`web`资源的`service`方 法，即`web`资源就会被访问，否则`web`资源不会被访问。有多个过滤器，会接着掉下一个过滤器  
2、@WebFilter讲解：  
2.1、`urlPatterns`注解过滤写法：  
①完全匹配：以“/”开头，以字母（非“*”）结束  
如：`/test/list`  
②目录匹配：以“/”开头且以“/*”结尾  
如： `/test/*`  
③扩展名匹配：以“\*.”开头，以扩展名结束  
如：`*.do`，`*.jsp`  
2.2、`filterName` 里面的值是当前类名

**新建第一个过滤器：`FilterDemo1`类**

package wwfww.warehouse.aaaTest.filter;
    
    
    
    import org.springframework.core.annotation.Order;
    
    import javax.servlet.*;
    import javax.servlet.annotation.WebFilter;
    import java.io.IOException;
    /** * @Order(int) 注解，配合 @WebFilter 注解使用，用于多个过滤器时定义执行顺序，值越小越先执行 */
    @Order(1)
    @WebFilter(filterName = "FilterDemo1",urlPatterns = { "/api/tool/*","*.jsp"})
    public class FilterDemo1 implements Filter { 
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException { 
            System.out.println("这边可以是初始化，可以干一些初始化的工作，比如初始化读取文件");
    
        }
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { 
            System.out.println("进入过滤器");
            if(request.getParameter("num").equals("1")){ 
                //假设这边是用来验证登录密码的
                request.setCharacterEncoding("密码错误");
            }else{ 
                /** * doFilter()的作用是将请求转发给过滤器链上下一个对象。这里的“下”指的是哪里 ？ *指的是下一个filter，如果没有filter那就是你请求的资源。 */
                chain.doFilter(request,response);
            }
            System.out.println("退出过滤器");
        }
    
        @Override
        public void destroy() { 
    
        }
    }

**新建第二个过滤器：FilterDemo2**

package wwfww.warehouse.aaaTest.filter;
    
    import org.springframework.core.annotation.Order;
    
    import javax.servlet.*;
    import javax.servlet.annotation.WebFilter;
    import java.io.IOException;
    /** * @Order(int) 注解，配合 @WebFilter 注解使用，用于多个过滤器时定义执行顺序，值越小越先执行 */
    @Order(2)
    @WebFilter(filterName = "FilterDemo2",urlPatterns = { "/api/tool/*"})
    public class FilterDemo2 implements Filter { 
        @Override
        public void init(FilterConfig filterConfig) throws ServletException { 
    
        }
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { 
            System.out.println("轮到我执行了");
             /** * doFilter()的作用是将请求转发给过滤器链上下一个对象。这里的“下”指的是哪里 ？ *指的是下一个filter，如果没有filter那就是你请求的资源。不加这句你的请求就到不了你的接口 */
            chain.doFilter(request,response);
        }
    
        @Override
        public void destroy() { 
    
        }
    }

启动类：

@SpringBootApplication
    @ServletComponentScan
    @MapperScan(basePackages = { "wwfww.warehouse.mapper"})//不加这句mapper依赖注入不进来
    public class WarehouseApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(WarehouseApplication.class, args);
        }
    
    }

**控制台输出：**

2021-03-06 12:13:58.533  INFO 11976 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1601 ms
    这边可以是初始化，可以干一些初始化的工作，比如初始化读取文件
    Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
    2021-03-06 12:13:58.681  INFO 11976 --- [           main] com.zaxxer.hikari.HikariDataSource       : warehouse - Starting...
    2021-03-06 12:13:58.681  WARN 11976 --- [           main] com.zaxxer.hikari.util.DriverDataSource  : Registered driver with driverClassName=com.mysql.jdbc.Driver was not found, trying direct instantiation.
    2021-03-06 12:13:58.884  INFO 11976 --- [           main] com.zaxxer.hikari.HikariDataSource       : warehouse - Start completed.
    2021-03-06 12:13:58.937  INFO 11976 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [name: default]
    2021-03-06 12:13:59.001  INFO 11976 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate ORM core version 5.4.12.Final
    2021-03-06 12:13:59.140  INFO 11976 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations { 5.1.0.Final}
    2021-03-06 12:13:59.257  INFO 11976 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.MySQL8Dialect
    2021-03-06 12:13:59.460  INFO 11976 --- [           main] o.h.e.t.j.p.i.JtaPlatformInitiator       : HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
    2021-03-06 12:13:59.475  INFO 11976 --- [           main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
    2021-03-06 12:14:00.132  WARN 11976 --- [           main] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
    2021-03-06 12:14:00.249  INFO 11976 --- [           main] pertySourcedRequestMappingHandlerMapping : Mapped URL path [/v2/api-docs] onto method [springfox.documentation.swagger2.web.Swagger2Controller#getDocumentation(String, HttpServletRequest)]
    2021-03-06 12:14:00.356  INFO 11976 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
    2021-03-06 12:14:00.409  INFO 11976 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page template: index
    2021-03-06 12:14:00.559  INFO 11976 --- [           main] d.s.w.p.DocumentationPluginsBootstrapper : Context refreshed
    2021-03-06 12:14:00.580  INFO 11976 --- [           main] d.s.w.p.DocumentationPluginsBootstrapper : Found 1 custom documentation plugin(s)
    2021-03-06 12:14:00.612  INFO 11976 --- [           main] s.d.s.w.s.ApiListingReferenceScanner     : Scanning for api listing references
    2021-03-06 12:14:00.729  INFO 11976 --- [           main] .d.s.w.r.o.CachingOperationNameGenerator : Generating unique operation named: sendEmailUsingPOST_1
    2021-03-06 12:14:00.804  INFO 11976 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8888 (http) with context path ''
    2021-03-06 12:14:00.804  INFO 11976 --- [           main] wwfww.warehouse.WarehouseApplication     : Started WarehouseApplication in 4.425 seconds (JVM running for 6.183)
    2021-03-06 12:14:05.063  INFO 11976 --- [nio-8888-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
    2021-03-06 12:14:05.063  INFO 11976 --- [nio-8888-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2021-03-06 12:14:05.072  INFO 11976 --- [nio-8888-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 9 ms
    进入过滤器
    轮到我执行了
    退出过滤器

# 方式二、在启动类注册Filter #

方式二是新建一个类实现Filter,然后在启动类那边将这个类注册,可以通过`@Order()`来实现过滤器顺序

**新建FilterDemo3,并且实现Filter**

package wwfww.warehouse.aaaTest.filter;
    
    import javax.servlet.*;
    import java.io.IOException;
    
    public class FilterDemo3 implements Filter { 
        @Override
        public void init(FilterConfig filterConfig) throws ServletException { 
    
        }
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { 
            System.out.println("进入过滤器");
                /** * doFilter()的作用是将请求转发给过滤器链上下一个对象。这里的“下”指的是哪里 ？ *指的是下一个filter，如果没有filter那就是你请求的资源。 */
                chain.doFilter(request,response);
            System.out.println("退出过滤器");
    
        }
    
        @Override
        public void destroy() { 
    
        }
    }

**新建FilterDemo4类，并且实现Filter**

package wwfww.warehouse.aaaTest.filter;
    
    import javax.servlet.*;
    import java.io.IOException;
    
    public class FilterDemo4 implements Filter { 
        @Override
        public void init(FilterConfig filterConfig) throws ServletException { 
    
        }
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { 
            System.out.println("方式二轮到我了");
            chain.doFilter(request,response);
        }
    
        @Override
        public void destroy() { 
    
        }
    }

启动类注册Filter组件

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.boot.web.servlet.FilterRegistrationBean;
    import org.springframework.boot.web.servlet.ServletComponentScan;
    import org.springframework.context.annotation.Bean;
    import tk.mybatis.spring.annotation.MapperScan;
    import wwfww.warehouse.aaaTest.filter.FilterDemo3;
    
    @SpringBootApplication
    @MapperScan(basePackages = { "wwfww.warehouse.mapper"})//不加这句mapper依赖注入不进来
    public class WarehouseApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(WarehouseApplication.class, args);
        }
    
         /** * 注册Filter * @return */
        @Bean
        @Order(1)
        public FilterRegistrationBean getFilterRegistrationBean(){ 
            FilterRegistrationBean ben = new FilterRegistrationBean(new FilterDemo3());
            ben.addUrlPatterns(new String[]{ "/api/tool/*","*.jsp"});
            return ben;
    
        }
        /** * 注册Filter * @return */
        @Bean
        @Order(2)
        public FilterRegistrationBean getFilterRegistrationBean2(){ 
            FilterRegistrationBean ben = new FilterRegistrationBean(new FilterDemo4());
            ben.addUrlPatterns(new String[]{ "/api/tool/*","*.jsp"});
            return ben;
    
        }
    
    }

**控制台输出：**

进入过滤器
    方式二轮到我了
    退出过滤器

## 过滤器应用场景 ##

1）过滤敏感词汇（防止sql注入）

2）设置字符编码

@Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { 
            //转换
            HttpServletRequest request1 = (HttpServletRequest)request;
            HttpServletResponse response1 = (HttpServletResponse)response;
            //设置编码
            request1.setCharacterEncoding("UTF-8");
            response1.setCharacterEncoding("UTF-8");
            /* * 使用doFilter方法调用链中的下一个过滤器或目标资源（servlet或JSP页面）。 * chain.doFilter处理过滤器的其余部分（如果有的话），最终处理请求的servlet或JSP页面。 */
            chain.doFilter(request,response);
        }

3）URL级别的权限访问控制

4）压缩响应信息