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SpringBoot v2.2以上重復(fù)讀取Request Body內(nèi)容的解決方案

 更新時(shí)間：2021年10月26日 14:39:00   作者：jlcon  
這篇文章主要介紹了SpringBoot v2.2以上重復(fù)讀取Request Body內(nèi)容的解決方案，具有很好的參考價(jià)值，希望對(duì)大家有所幫助。如有錯(cuò)誤或未考慮完全的地方，望不吝賜教

SpringBoot v2.2以上重復(fù)讀取Request Body內(nèi)容

一、需求

項(xiàng)目有兩個(gè)場景會(huì)用到從Request的Body中讀取內(nèi)容。

  • 打印請(qǐng)求日志
  • 提供Api接口，在api方法執(zhí)行前，從Request Body中讀取參數(shù)進(jìn)行驗(yàn)簽，驗(yàn)簽通過后在執(zhí)行api方法

二、解決方案

2.1 自定義RequestWrapper

public class MyRequestWrapper extends HttpServletRequestWrapper {
 private final String body;
 public MyRequestWrapper(HttpServletRequest request) throws IOException {
  super(request);
  this.body = RequestReadUtils.read(request);
 }
 public String getBody() {
  return body;
 }
 @Override
 public ServletInputStream getInputStream() throws IOException {
  final ByteArrayInputStream bais = new ByteArrayInputStream(body.getBytes());  
  return new ServletInputStream() {
   ...略
  };
 }
 @Override
 public BufferedReader getReader() throws IOException {
  return new BufferedReader(new InputStreamReader(this.getInputStream()));
 }
}

RequestReadUtils（網(wǎng)上抄的）

private static final int BUFFER_SIZE = 1024 * 8;
  
    public static String read(HttpServletRequest request) throws IOException {
        BufferedReader bufferedReader = request.getReader();
        for (Enumeration<String> iterator = request.getHeaderNames(); iterator.hasMoreElements();) {
         String type = iterator.nextElement();
   System.out.println(type+" = "+request.getHeader(type));
  }
        System.out.println();
        StringWriter writer = new StringWriter();
        write(bufferedReader,writer);
        return writer.getBuffer().toString();
    }
 
    public static long write(Reader reader,Writer writer) throws IOException {
        return write(reader, writer, BUFFER_SIZE);
    }
 
    public static long write(Reader reader, Writer writer, int bufferSize) throws IOException
    {
        int read;
        long total = 0;
        char[] buf = new char[bufferSize];
        while( ( read = reader.read(buf) ) != -1 ) {
            writer.write(buf, 0, read);
            total += read;
        }
        return total;
    }

2.2 定義Filter

@WebFilter
public class TestFilter implements Filter{
 @Override
 public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain){
  HttpServletRequest request = (HttpServletRequest) servletRequest;
  HttpServletResponse response = (HttpServletResponse) servletResponse;
  
  MyRequestWrapper wrapper = WebUtils.getNativeRequest(request, MyRequestWrapper.class);
  chain.doFilter(wrapper == null ? new MyRequestWrapper(request) :wrapper,servletRequest);
 }
}

三、遇到問題

使用的SpringBoot v2.1.x版本

  • Form提交無問題
  • 獲取RequestBody無問題

使用SpringBoot v2.2.0以上版本（包括v2.3.x）

  • Form提交無法獲取參數(shù)
  • 獲取RequestBody無問題

四、問題排查

經(jīng)過排查，v2.2.x對(duì)比v2.1.x的不同在于一下代碼差異：

BufferedReader bufferedReader = request.getReader();
-----------------
char[] buf = new char[bufferSize];
while( ( read = reader.read(buf) ) != -1 ) {
    writer.write(buf, 0, read);
    total += read;
}

當(dāng)表單提交時(shí)

  • v2.1.x無法read到內(nèi)容，讀取結(jié)果為-1
  • v2.2.x、v2.3.x能夠讀取到內(nèi)容

當(dāng)表單提交時(shí)（x-www-form-urlencoded），inputStream讀取一次后后續(xù)不會(huì)觸發(fā)wrapper的getInputStream操作，所以Controller無法獲取到參數(shù)。

解決方案

MyRequestWrapper改造

public class MyRequestWrapper extends HttpServletRequestWrapper {
 private final String body;
 public MyRequestWrapper(HttpServletRequest request) throws IOException {
  super(request);
  this.body = getBodyString(request);
 }
 public String getBody() {
  return body;
 }
 
 public String getBodyString(final HttpServletRequest request) throws IOException {
     String contentType = request.getContentType();
     String bodyString = "";
     StringBuilder sb = new StringBuilder();
     if (StringUtils.isNotBlank(contentType) && (contentType.contains("multipart/form-data") || contentType.contains("x-www-form-urlencoded"))) {
         Map<String, String[]> parameterMap = request.getParameterMap();
         for (Map.Entry<String, String[]> next : parameterMap.entrySet()) {
             String[] values = next.getValue();
             String value = null;
             if (values != null) {
                 if (values.length == 1) {
                     value = values[0];
                 } else {
                     value = Arrays.toString(values);
                 }
             }
             sb.append(next.getKey()).append("=").append(value).append("&");
         }
         if (sb.length() > 0) {
             bodyString = sb.toString().substring(0, sb.toString().length() - 1);
         }
         return bodyString;
     } else {
         return IOUtils.toString(request.getInputStream());
     }
 }
 @Override
 public ServletInputStream getInputStream() throws IOException {
  final ByteArrayInputStream bais = new ByteArrayInputStream(body.getBytes());
  
  return new ServletInputStream() {
   @Override
   public boolean isFinished() {
    return false;
   }
   @Override
   public boolean isReady() {
    return false;
   }
   @Override
   public int read() {
    return bais.read();
   }
   @Override
   public void setReadListener(ReadListener readListener) {
   }
  };
 }
 @Override
 public BufferedReader getReader() throws IOException {
  return new BufferedReader(new InputStreamReader(this.getInputStream()));
 }
}

SpringBoot 讀取Request參數(shù)的坑

后端拿參數(shù)相關(guān)

默認(rèn)配置時(shí)，

getInputStream()和getReader()一起使用會(huì)報(bào)錯(cuò)

使用兩遍getInputStream()，第二遍會(huì)為空

當(dāng)存在@RequestBody等注解時(shí)，springMVC已讀取過一遍流，默認(rèn)單獨(dú)使用getInputStream()或getReader()都為空。

解決：寫filter繼承HttpServletRequestWrapper，緩存InputStream，覆蓋getInputStream()和getReader()方法，使用ByteArrayInputStream is = new ByteArrayInputStream(body.getBytes());讀取InputStream。

注意：springboot中，過濾器只需@Component即可生效，另外可在FilterRegistrationBean中配置路徑和優(yōu)先級(jí)。

對(duì)于攔截器，必須在InterceptorRegistry中調(diào)用addInterceptor方法。（路徑可鏈?zhǔn)教砑樱?/p>

關(guān)于流

只能讀一遍，類似管子。

只承擔(dān)傳輸職責(zé)，而與處理和存儲(chǔ)無關(guān)。

對(duì)于byte流而言，進(jìn)行重復(fù)讀取易于實(shí)現(xiàn)，但指針不重置，應(yīng)是為了與InputStream接口定義保持一致。

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

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