Java如何解决发送Post请求报Stream closed问题

目录

• 问题场景
• 问题分析
• 解决办法

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;
/**
 * 解决获取post请求的请求体body只能读取一次问题
 */
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我们。