SpringBoot v2.2以上重復讀取Request Body內容
一、需求
項目有兩個場景會用到從Request的Body中讀取內容。
- 打印請求日志
- 提供Api接口，在api方法執行前，從Request Body中讀取參數進行驗簽，驗簽通過后在執行api方法
二、解決方案
2.1 自定義RequestWrapper
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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（網上抄的）
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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
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@WebFilterpublic 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
- 獲取RequestBody無問題
四、問題排查
經過排查，v2.2.x對比v2.1.x的不同在于一下代碼差異：
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BufferedReader bufferedReader = request.getReader();-----------------char[] buf = new char[bufferSize];while( ( read = reader.read(buf) ) != -1 ) { writer.write(buf, 0, read); total += read;} |
當表單提交時
- v2.1.x無法read到內容，讀取結果為-1
- v2.2.x、v2.3.x能夠讀取到內容
當表單提交時（x-www-form-urlencoded），inputStream讀取一次后后續不會觸發wrapper的getInputStream操作，所以Controller無法獲取到參數。
解決方案
MyRequestWrapper改造
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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參數的坑
后端拿參數相關
默認配置時，
getInputStream()和getReader()一起使用會報錯
使用兩遍getInputStream()，第二遍會為空
當存在@RequestBody等注解時，springMVC已讀取過一遍流，默認單獨使用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中配置路徑和優先級。
對于攔截器，必須在InterceptorRegistry中調用addInterceptor方法。（路徑可鏈式添加）
關于流
只能讀一遍，類似管子。
只承擔傳輸職責，而與處理和存儲無關。
對于byte流而言，進行重復讀取易于實現，但指針不重置，應是為了與InputStream接口定義保持一致。
以上為個人經驗，希望能給大家一個參考，也希望大家多多支持服務器之家。
原文鏈接：https://blog.csdn.net/jlcon/article/details/108520840
