springboot项目还是ssm等java常用框架都会有这样的问题，解决办法通用
问题场景
前端发送Post请求，前端返回400 Bad Request，后端Controller层接口也没进去，然后我就开始分析，是啥问题，我通过后端控制台发现HttpMessageNotReadableException 提示信息，这个不是读取请求的消息错误发生的异常吗?
然后我通过IDEA 的DEBUG拦截这个异常发生的位置,然后将相关的代码从新走了一遍发现在
AbstractMessageConverterMethodArgumentResolver->readWithMessageConverters
EmptyBodyCheckingHttpInputMessage 是内部类
控制台打印warn 信息如下：
org.springframework.http.converter.HttpMessageNotReadableException: I/O error while reading input message; nested exception is java.io.IOException: Stream closed
问题分析
这是因为有人在过滤器或者拦截器中对Request的请求体中的数据流读取了一遍导致的，Springboot准备读取Body数据映射到接口的实体类参数时候失败，发现流已经没有内容了，因为在接口数据流传输使用的都是InputStream 这个流只能被读取一次
解决办法
将InputStream 传输数据，缓存起来，保存到字符串中，之后用的时候将字符串转在转换为流，那么这个字符串就能持续的被复用了
缓存数据
package com.schemautils;
import com.alibaba.fastjson.JSONObject;
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
public class RequestWrapper extends HttpServletRequestWrapper {
private final String body;
public RequestWrapper(HttpServletRequest request) {
super(request);
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
InputStream inputStream = null;
try {
//防止未初始化body,我们手动初始化body ,内部会将body内容初始化到InputStream里
request.getParameterMap();
//然后在读取InputStream
inputStream = request.getInputStream();
if (inputStream != null) {
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
char[] charBuffer = new char[128];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
} else {
stringBuilder.append("");
}
} catch (IOException ex) {
} finally {
if (inputStream != null) {
try {
inputStream.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
if (bufferedReader != null) {
try {
bufferedReader.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
body = stringBuilder.toString();
}
@Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
ServletInputStream servletInputStream = new ServletInputStream() {
@Override
public boolean isFinished() {
return false;
}
@Override
public boolean isReady() {
return false;
}
@Override
public void setReadListener(ReadListener readListener) {
}
@Override
public int read() throws IOException {
return byteArrayInputStream.read();
}
};
return servletInputStream;
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
public JSONObject getBody() {
return JSONObject.parseObject(this.body);
}
}
添加过滤器并且配置缓存类
package com.schemautils;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
//获取请求中的流，将取出来的，再次转换成流，然后把它放入到新request对象中
//必须保证在所有过滤器之前执行,否则就会出现问题(按照首字母进行过滤器优先级A>B>C)
@WebFilter(filterName = "ACacheHttpServletRequestFilter", urlPatterns = "/")
public class CacheHttpServletRequestFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
ServletRequest requestWrapper = null;
if(servletRequest instanceof HttpServletRequest) {
requestWrapper = new RequestWrapper((HttpServletRequest) servletRequest);
}
//获取请求中的流如何，将取出来的字符串，再次转换成流，然后把它放入到新request对象中
// 在chain.doFiler方法中传递新的request对象
if(null == requestWrapper) {
filterChain.doFilter(servletRequest, servletResponse);
} else {
filterChain.doFilter(requestWrapper, servletResponse);
}
}
@Override
public void destroy() {
}
}在启动类上开启扫描Filter注解
@SpringBootApplication(scanBasePackages = "com")
@ServletComponentScan //开启扫描Filter
public class ApplicatioBoot {
public static void main(String[] args) {
SpringApplication.run(ApplicatioBoot.class,args);
}
}以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程网。
