filter过滤器的使用

Filter理解:

		对sevlet服务前后做些处理,主要针对request和response做一些过滤,鉴权,日志等操作:

Filter类

Filter过滤器实现的是javax.servlet.Filter接口的类，而在javax.servlet.Filter中定义了以下三个方法：

public interface Filter {
  
   //初始化过滤器后执行的操作
    default void init(FilterConfig filterConfig) throws ServletException {
    }
   // 对请求进行过滤
    void doFilter(ServletRequest var1, ServletResponse var2, FilterChain var3) throws IOException, ServletException;
   // 销毁过滤器后执行的操作，主要用户对某些资源的回收
    default void destroy() {
    }
}

自定Filter用config方式配置

/** 自定义过滤器使用config方式配置过滤器
 * @author ding
 * @version V1.0
 * @date 2019/11/6 16:24
 */
@Component
public class MyFilter implements Filter {

    private static final Logger logger = LoggerFactory.getLogger(MyFilter.class);
    // 初始化过滤器操作
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        logger.info("初始化过滤器: "+filterConfig.getFilterName());
    }

    // 具体过滤业务逻辑
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //对请求进行预处理
        logger.info("过滤器开始对请求进行预处理：");
        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        String requestURI = httpServletRequest.getRequestURI();
        logger.info("请求的接口为: "+requestURI);
        long startTime = System.currentTimeMillis();
        //通过 doFilter 方法实现过滤功能
        filterChain.doFilter(servletRequest, servletResponse);
        // 上面的 doFilter 方法执行结束后用户的请求已经返回
        long endTime = System.currentTimeMillis();
        System.out.println("该用户的请求已经处理完毕，请求花费的时间为：" + (endTime - startTime));
    }

    //  销毁过滤器后执行的操作，主要用户对某些资源的回收
    @Override
    public void destroy() {
        logger.info("销毁过滤器");
    }
}



/**
 * 在配置中注册自定义的过滤器
 *
 * 在配置中注册自定义的过滤器，通过FilterRegistrationBean 的setOrder 方法可以决定 Filter 的执行顺序。
 * @author ding
 * @version V1.0
 * @date 2019/11/6 16:32
 */
@Configuration
public class MyFilterConfig {

    @Autowired
    MyFilter myFilter;

    @Bean
    public FilterRegistrationBean<MyFilter> thirdFilter(){
        FilterRegistrationBean<MyFilter> filterRegistrationBean = new FilterRegistrationBean<>();
        filterRegistrationBean.setFilter(myFilter);//设置自定义的过滤类
        filterRegistrationBean.setUrlPatterns(new ArrayList<>(Arrays.asList("/api/*"))); // 设置过滤匹配url模式
        return filterRegistrationBean;
    }
}

自定Filter用注解方式配置

/**
 *  1.自定义过滤器使用注解方式配置过滤器
 *  2.该@WebFilter申明该类是一个 过滤器  filterName指定该过滤器的名称    urlPatterns指定过滤器的匹配模式
 *  3.另外，为了能让 Spring 找到它，你需要在启动类上加上 @ServletComponentScan 注解。
 * @author ding
 * @version V1.0
 * @date 2019/11/6 16:52
 */
@WebFilter(filterName = "MyFilterWithAnnotation", urlPatterns = "/api/annotation/*")
public class MyFilterWithAnnotation implements Filter {
    private static final Logger logger = LoggerFactory.getLogger(MyFilterWithAnnotation.class);

    @Override
    public void init(FilterConfig filterConfig) {
        logger.info("初始化过滤器");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //对请求进行预处理
        logger.info("过滤器开始对请求进行预处理：");
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String requestUri = request.getRequestURI();
        System.out.println("请求的接口为：" + requestUri);
        long startTime = System.currentTimeMillis();
        //通过 doFilter 方法实现过滤功能
        filterChain.doFilter(servletRequest, servletResponse);
        // 上面的 doFilter 方法执行结束后用户的请求已经返回
        long endTime = System.currentTimeMillis();
        System.out.println("该用户的请求已经处理完毕，请求花费的时间为：" + (endTime - startTime));
    }

    @Override
    public void destroy() {
        logger.info("销毁过滤器");
    }
}

多个过滤器执行顺序设置

再添加一个过滤器

@Component
public class MyFilter2 implements Filter {

    private static final Logger logger = LoggerFactory.getLogger(MyFilter2.class);
    // 初始化过滤器操作
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        logger.info("初始化过滤器2: "+filterConfig.getFilterName());
    }

    // 具体过滤业务逻辑
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //对请求进行预处理
        logger.info("过滤器开始对请求进行预处理2：");
        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        String requestURI = httpServletRequest.getRequestURI();
        logger.info("请求的接口为2: "+requestURI);
        long startTime = System.currentTimeMillis();
        //通过 doFilter 方法实现过滤功能
        filterChain.doFilter(servletRequest, servletResponse);
        // 上面的 doFilter 方法执行结束后用户的请求已经返回
        long endTime = System.currentTimeMillis();
        System.out.println("该用户的请求已经处理完毕，请求花费的时间为2：" + (endTime - startTime));
    }

    //  销毁过滤器后执行的操作，主要用户对某些资源的回收
    @Override
    public void destroy() {
        logger.info("销毁过滤器2");
    }
}

配置执行顺序

 @Bean
    public FilterRegistrationBean<MyFilter> thirdFilter(){
        FilterRegistrationBean<MyFilter> filterRegistrationBean = new FilterRegistrationBean<>();
        filterRegistrationBean.setFilter(myFilter);
        filterRegistrationBean.setOrder(2); //执行顺序
        filterRegistrationBean.setUrlPatterns(new ArrayList<>(Arrays.asList("/api/*")));
        return filterRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean<MyFilter2> thirdFilter2(){
        FilterRegistrationBean<MyFilter2> filterRegistrationBean = new FilterRegistrationBean<>();
        filterRegistrationBean.setOrder(1);
        filterRegistrationBean.setFilter(myFilter2);// 执行顺序
        filterRegistrationBean.setUrlPatterns(new ArrayList<>(Arrays.asList("/api/*")));
        return filterRegistrationBean;
    }

顺道验证

@RestController
@RequestMapping("/api")
public class MyController {

    @GetMapping("/ha")
    public String gethahah() throws InterruptedException {
        return "哈哈哈哈哈";
    }

}

参考文章