前端發(fā)送Post請求，前端返回400 Bad Request，后端Controller層接口也沒進去，然后我就開始分析，是啥問題，我通過后端控制臺發(fā)現(xiàn)HttpMessageNotReadableException 提示信息，這個不是讀取請求的消息錯誤發(fā)生的異常嗎?

然后我通過IDEA 的DEBUG攔截這個異常發(fā)生的位置,然后將相關的代碼從新走了一遍發(fā)現(xiàn)在

AbstractMessageConverterMethodArgumentResolver->readWithMessageConverters

EmptyBodyCheckingHttpInputMessage 是內(nèi)部類

控制臺打印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

問題分析

這是因為有人在過濾器或者攔截器中對Request的請求體中的數(shù)據(jù)流讀取了一遍導致的，Springboot準備讀取Body數(shù)據(jù)映射到接口的實體類參數(shù)時候失敗，發(fā)現(xiàn)流已經(jīng)沒有內(nèi)容了，因為在接口數(shù)據(jù)流傳輸使用的都是InputStream 這個流只能被讀取一次

解決辦法

將InputStream 傳輸數(shù)據(jù)，緩存起來，保存到字符串中，之后用的時候?qū)⒆址D(zhuǎn)在轉(zhuǎn)換為流，那么這個字符串就能持續(xù)的被復用了

緩存數(shù)據(jù)

package com.schemautils;
/**
 * 解決獲取post請求的請求體body只能讀取一次問題
 */
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,我們手動初始化body ,內(nèi)部會將body內(nèi)容初始化到InputStream里
	        request.getParameterMap();
	        //然后在讀取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);
    }
}

添加過濾器并且配置緩存類

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;
//獲取請求中的流，將取出來的，再次轉(zhuǎn)換成流，然后把它放入到新request對象中
//必須保證在所有過濾器之前執(zhí)行,否則就會出現(xiàn)問題(按照首字母進行過濾器優(yōu)先級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);
        }
        //獲取請求中的流如何，將取出來的字符串，再次轉(zhuǎn)換成流，然后把它放入到新request對象中
        // 在chain.doFiler方法中傳遞新的request對象
        if(null == requestWrapper) {
            filterChain.doFilter(servletRequest, servletResponse);
        } else {
            filterChain.doFilter(requestWrapper, servletResponse);
        }
    }
    @Override
    public void destroy() {
    }
}

在啟動類上開啟掃描Filter注解

@SpringBootApplication(scanBasePackages = "com")
@ServletComponentScan //開啟掃描Filter
public class ApplicatioBoot {
    public static void main(String[] args) {
        SpringApplication.run(ApplicatioBoot.class,args);
    }
}

以上為個人經(jīng)驗，希望能給大家一個參考，也希望大家多多支持腳本之家。

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