15. 过滤器 Filter 示例

原创已于 2022-01-24 16:28:08 修改 · 263 阅读

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于 2021-08-09 17:26:41 首次发布

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本文档展示了如何在Spring Boot应用程序中创建并注册自定义过滤器`TestFilter`，该过滤器用于拦截请求，获取请求头信息，并在响应中返回。过滤器的生命周期方法如`init()`和`destroy()`也被覆盖，用于初始化和销毁操作。同时，`OncePerRequestFilter`的子类`TestFilter`被定义，但未在实际过滤过程中使用。过滤器的注册通过`FilterRegistrationBean`完成，设置过滤器顺序、拦截路径和名称。

1.

过滤器

import com.alibaba.fastjson.JSON;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

/**
 * @author sheng_zs@126.com
 * @date 2021-07-08 10:47
 */
@Slf4j
@Component
public class TestFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.error("init()");
        log.error("getFilterName: {}", filterConfig.getFilterName());
        Enumeration<String> parameterNames = filterConfig.getInitParameterNames();
        while (parameterNames.hasMoreElements()) {
            log.error("parameterNames: {}", parameterNames.nextElement());
        }
        log.error("===================================");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.error("进入了拦截器");
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        request.getParameterMap().values().forEach(e -> {if (e != null) {
            for (String s : e) {
                log.error(s);
            }
        }});

        String queryString = request.getQueryString();
        log.error("queryString：{}", queryString);
        Map<String, Object> result = new HashMap<>();
        result.put("user", request.getHeader("user"));
        result.put("type", request.getHeader("type"));
        result.put("message", "信息参数有误");
        servletResponse.setCharacterEncoding("utf-8");
        servletResponse.setContentType("application/json; charset=utf-8");
        servletResponse.getWriter().println(JSON.toJSONString(result));
//        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {
        log.error("destroy()");
    }
}

@Slf4j
@Component
public class TestFilter extends OncePerRequestFilter {

    @Override
    protected boolean shouldNotFilter(HttpServletRequest request) throws ServletException {
        // 不过滤的方法设置
        return super.shouldNotFilter(request);
    }

    @Override
    protected void initFilterBean() throws ServletException {
		// init()
        super.initFilterBean();
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {

    }

}

过滤器注册

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Collections;

/**
 * @author sheng_zs@126.com
 * @date 2021-07-08 10:58
 */
@Configuration
public class TestFilterConfig {
    @Bean
    public FilterRegistrationBean filterRegistrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        // 设置过滤器顺序
        filterRegistrationBean.setOrder(1);
        // 注册 Filter
        filterRegistrationBean.setFilter(new TestFilter());
        // 设置要过滤的拦截路径
        filterRegistrationBean.setUrlPatterns(Collections.singletonList("/**"));
        // 过滤器的名字
        filterRegistrationBean.setName("testFilter");
        return filterRegistrationBean;
    }
}