解决：getReader() has already been called for this request

问题现场：

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

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;public class BodyWrapperFilter implements Filter {@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {ServletRequest requestWrapper = null;if(servletRequest instanceof HttpServletRequest) {requestWrapper = new CustomHttpServletRequestWrapper((HttpServletRequest) servletRequest);}if(requestWrapper == null) {filterChain.doFilter(servletRequest, servletResponse);} else {filterChain.doFilter(requestWrapper, servletResponse);}}
}

CustomHttpServletRequestWrapper.java

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
import java.nio.charset.StandardCharsets;public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {private byte[] body;public CustomHttpServletRequestWrapper(HttpServletRequest request) throws IOException {super(request);BufferedReader reader = request.getReader();try (StringWriter writer = new StringWriter()) {int read;char[] buf = new char[1024 * 8];while ((read = reader.read(buf)) != -1) {writer.write(buf, 0, read);}this.body = writer.getBuffer().toString().getBytes();}}public String getBody(){return new String(body, StandardCharsets.UTF_8);}@Overridepublic ServletInputStream getInputStream() {final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body);return new ServletInputStream() {@Overridepublic boolean isFinished() {return false;}@Overridepublic boolean isReady() {return false;}@Overridepublic void setReadListener(ReadListener readListener) {}@Overridepublic int read() {return byteArrayInputStream.read();}};}@Overridepublic BufferedReader getReader() {return new BufferedReader(new InputStreamReader(this.getInputStream()));}
}

WebApplicationConfig.java

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class WebApplicationConfig {@BeanBodyWrapperFilter getBodyWrapperFilter(){return new BodyWrapperFilter();}@Bean("bodyWrapperFilter")public FilterRegistrationBean<BodyWrapperFilter> checkUserFilter(BodyWrapperFilter bodyWrapperFilter) {FilterRegistrationBean<BodyWrapperFilter> registrationBean = new FilterRegistrationBean();registrationBean.setFilter(bodyWrapperFilter);registrationBean.addUrlPatterns("/*");registrationBean.setOrder(1);registrationBean.setAsyncSupported(true);return registrationBean;}}

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：

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