getReader() has already been called for this request

Bertha 。 2023-09-28 11:52 216阅读 0赞

问题现场：

2bdfb985918e49259c9746e86f5753ac.png

原因:

HttpServletRequest 的 getInputStream() 和 getReader() 都只能读取一次。

因为 我们使用@RequestBody 注解，读取body参数；而 又 写了拦截器，也需要将post请求，body数据拿出来。
由于@RequestBody 也是流的形式读取，流读了一次就没有了。

解决方案：

过滤器是优先于拦截器的， 我们写一个过滤器，在过滤器里面 把流数据 copy一份出来用，也就是复写一哈。
在拦截器上使用我们复写的流数据就行。

BodyWrapperFilter.java

  1. import javax.servlet.*;
  2. import javax.servlet.http.HttpServletRequest;
  3. import java.io.IOException;
  6. /**
  7.  * @Author: JCccc
  8.  * @Date: 2022-6-12 10:35
  9.  * @Description:
  10.  */
  11. public class BodyWrapperFilter implements Filter {
  12.     @Override
  13.     public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
  14.         ServletRequest requestWrapper = null;
  15.         if(servletRequest instanceof HttpServletRequest) {
  16.             requestWrapper = new CustomHttpServletRequestWrapper((HttpServletRequest) servletRequest);
  17.         }
  18.         if(requestWrapper == null) {
  19.             filterChain.doFilter(servletRequest, servletResponse);
  20.         } else {
  21.             filterChain.doFilter(requestWrapper, servletResponse);
  22.         }
  23.     }
  24. }

CustomHttpServletRequestWrapper.java

  1. import javax.servlet.ReadListener;
  2. import javax.servlet.ServletInputStream;
  3. import javax.servlet.http.HttpServletRequest;
  4. import javax.servlet.http.HttpServletRequestWrapper;
  5. import java.io.*;
  6. import java.nio.charset.StandardCharsets;
  8. /**
  9.  * @Author: JCccc
  10.  * @Date: 2022-6-12 10:36
  11.  * @Description:  重写一个自己的 RequestWrapper 拿出body给自己用
  12.  */
  14. public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {
  15.     private byte[] body;
  16.     public CustomHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
  17.         super(request);
  18.         BufferedReader reader = request.getReader();
  19.         try (StringWriter writer = new StringWriter()) {
  20.             int read;
  21.             char[] buf = new char[1024 * 8];
  22.             while ((read = reader.read(buf)) != -1) {
  23.                 writer.write(buf, 0, read);
  24.             }
  25.             this.body = writer.getBuffer().toString().getBytes();
  26.         }
  27.     }
  28.     public String getBody(){
  29.         return new String(body, StandardCharsets.UTF_8);
  30.     }
  31.     @Override
  32.     public ServletInputStream getInputStream() {
  33.         final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body);
  34.         return new ServletInputStream() {
  35.             @Override
  36.             public boolean isFinished() {
  37.                 return false;
  38.             }
  39.             @Override
  40.             public boolean isReady() {
  41.                 return false;
  42.             }
  44.             @Override
  45.             public void setReadListener(ReadListener readListener) {
  46.             }
  48.             @Override
  49.             public int read() {
  50.                 return byteArrayInputStream.read();
  51.             }
  52.         };
  53.     }
  54.     @Override
  55.     public BufferedReader getReader() {
  56.         return new BufferedReader(new InputStreamReader(this.getInputStream()));
  57.     }
  58. }

WebApplicationConfig.java

  1. import org.springframework.boot.web.servlet.FilterRegistrationBean;
  2. import org.springframework.context.annotation.Bean;
  3. import org.springframework.context.annotation.Configuration;
  5. /**
  6.  * @Author: JCccc
  7.  * @Date: 2022-6-23 10:52
  8.  * @Description:
  9.  */
  10. @Configuration
  11. public class WebApplicationConfig {
  13.     @Bean
  14.     BodyWrapperFilter getBodyWrapperFilter(){
  15.         return new BodyWrapperFilter();
  16.     }
  17.     @Bean("bodyWrapperFilter")
  18.     public FilterRegistrationBean<BodyWrapperFilter> checkUserFilter(BodyWrapperFilter bodyWrapperFilter) {
  19.         FilterRegistrationBean<BodyWrapperFilter> registrationBean = new FilterRegistrationBean();
  20.         registrationBean.setFilter(bodyWrapperFilter);
  21.         registrationBean.addUrlPatterns("/*");
  22.         registrationBean.setOrder(1);
  23.         registrationBean.setAsyncSupported(true);
  24.         return registrationBean;
  25.     }
  27. }

然后就是在拦截器里面，如果我们想取出body，我们改成这样用： 

  1. CustomHttpServletRequestWrapper wrapper = (CustomHttpServletRequestWrapper) request;
  2. String  nowParams = wrapper.getBody();

效果：
af38c8b1a24b4304a0a1080ea7656d61.png

好的，这篇就到这。

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