springBoot中新建拦截器

最近项目中需要将请求中的header中增加几个字段，第一反应就是可不可以用拦截器拦截请求后将字段放进请求头中，经过网上一番学习后发现该方案可行，故将此方法记录下来供大家参考，也算是对自己学习成果的一个沉淀。

• 首先建一个拦截器类

• package com.chwtest.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;
  
  @WebFilter(filterName = "testFilter", urlPatterns = { "/testFilter" })
  public class RequestFilter implements Filter {
  
      @Override
      public void init(FilterConfig filterConfig) throws ServletException {
          Filter.super.init(filterConfig);
      }
  
      @Override
      public void destroy() {
          Filter.super.destroy();
      }
  
      @Override
      public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
              throws IOException, ServletException {
  
          System.out.println("拦截器生效");
          chain.doFilter(request, response);
      }
  
  }

  该类需要一个注解：@WebFilter ，并且需要实现 Filter 并重写doFilter方法

• 在启动类中增加注解：@ServletComponentScan

• package com.chwtest;
  
  import org.springframework.boot.SpringApplication;
  import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
  import org.springframework.boot.autoconfigure.SpringBootApplication;
  import org.springframework.boot.web.servlet.ServletComponentScan;
  
  @SpringBootApplication
  @ServletComponentScan
  @EnableAutoConfiguration
  public class App {
      public static void main(String[] args) {
          SpringApplication.run(App.class, args);
      }
  }

   

• 新建一个controller

• package com.chwtest.controller;
  
  import javax.servlet.http.HttpServletRequest;
  
  import org.springframework.web.bind.annotation.RequestMapping;
  import org.springframework.web.bind.annotation.RestController;
  
  @RestController
  public class Controller {
      @RequestMapping("testFilter")
      public String testFilter(HttpServletRequest request) {        
          return "hello word!";
      }
  
  }

   

• 启动程序
• 

   

   

   

   至此拦截器已建好！

• 接下来是如何新增请求头字段
• 建一个RequestWrapper 继承HttpServletRequestWrapper，并重写父类方法

• package com.chwtest.filter;
  
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletRequestWrapper;
  
  public class RequestWrapper extends HttpServletRequestWrapper {
      public RequestWrapper(HttpServletRequest request) {
          super(request);
      }
  
      private Map<String, String> headerMap = new HashMap<>();
  
      public void addHeader(String name, String value) {
          headerMap.put(name, value);
      }
  
      @Override
      public String getHeader(String name) {
          String headerValue = super.getHeader(name);
          if (headerMap.containsKey(name)) {
              headerValue = headerMap.get(name);
          }
          return headerValue;
      }
  
      @Override
      public Enumeration<String> getHeaders(String name) {
          List<String> values = Collections.list(super.getHeaders(name));
          if (headerMap.containsKey(name)) {
              values = Arrays.asList(headerMap.get(name));
          }
          return Collections.enumeration(values);
      }
  
      @Override
      public Enumeration<String> getHeaderNames() {
          List<String> names = Collections.list(super.getHeaderNames());
          for (String name : headerMap.keySet()) {
              names.add(name);
          }
          return Collections.enumeration(names);
      }
  
      @Override
      public int getIntHeader(String name) {
          return super.getIntHeader(name);
      }
  }

   

• filter中将heaer赋值

• package com.chwtest.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;
  
  @WebFilter(filterName = "testFilter", urlPatterns = { "/testFilter" })
  public class RequestFilter implements Filter {
  
  	@Override
  	public void init(FilterConfig filterConfig) throws ServletException {
  		Filter.super.init(filterConfig);
  	}
  
  	@Override
  	public void destroy() {
  		Filter.super.destroy();
  	}
  
  	@Override
  	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
  			throws IOException, ServletException {
  		HttpServletRequest req = (HttpServletRequest) request;
  		RequestWrapper requestMapper = new RequestWrapper(req);
  		requestMapper.addHeader("name", "陈浩文");
  		System.out.println("拦截器生效");
  		chain.doFilter(requestMapper, response);
  	}
  
  }
  

  　　

   

• controller中将我们新增的header打印出来
• 

   

   

• 打印成功
•