SpringBoot v2.2以上重复读取Request Body内容
一、需求
项目有两个场景会用到从Request的Body中读取内容。
打印请求日志 提供Api接口，在api方法执行前，从Request Body中读取参数进行验签，验签通过后在执行api方法
二、解决方案
2.1 自定义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（网上抄的）
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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 定义Filter
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@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、遇到问题
使用的SpringBoot v2.1.x版本
Form提交无问题 获取RequestBody无问题使用SpringBoot v2.2.0以上版本（包括v2.3.x）
Form提交无法获取参数 获取RequestBody无问题
四、问题排查
经过排查，v2.2.x对比v2.1.x的不同在于一下代码差异：
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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; } |
当表单提交时
v2.1.x无法read到内容，读取结果为-1 v2.2.x、v2.3.x能够读取到内容当表单提交时（x-www-form-urlencoded），inputStream读取一次后后续不会触发wrapper的getInputStream操作，所以Controller无法获取到参数。
解决方案
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 读取Request参数的坑
后端拿参数相关
默认配置时，
getInputStream()和getReader()一起使用会报错
使用两遍getInputStream()，第二遍会为空
当存在@RequestBody等注解时，springMVC已读取过一遍流，默认单独使用getInputStream()或getReader()都为空。
解决： 写filter继承HttpServletRequestWrapper，缓存InputStream，覆盖getInputStream()和getReader()方法，使用ByteArrayInputStream is = new ByteArrayInputStream(body.getBytes());读取InputStream。
注意： springboot中，过滤器只需@Component即可生效，另外可在FilterRegistrationBean中配置路径和优先级。
对于拦截器，必须在InterceptorRegistry中调用addInterceptor方法。（路径可链式添加）
关于流
只能读一遍，类似管子。
只承担传输职责，而与处理和存储无关。
对于byte流而言，进行重复读取易于实现，但指针不重置，应是为了与InputStream接口定义保持一致。
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。
原文链接：https://blog.csdn.net/jlcon/article/details/108520840
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