如何从POST请求中获取XML并在Servlet过滤器中对其进行修改？

您不能两次使用InputStream，需要创建一个包装类，以保留InputStream的可重复副本。

public class ReadTwiceHttpServletRequestWrapper extends HttpServletRequestWrapper {private ByteArrayOutputStream outputStream = new ByteArrayOutputStream();public ReadTwiceHttpServletRequestWrapper(HttpServletRequest request) {    super(request);    try {        IOUtils.copy(request.getInputStream(), outputStream);    } catch (IOException e) {        e.printStackTrace();    }}@Overridepublic BufferedReader getReader() throws IOException {    return new BufferedReader(new InputStreamReader(new ByteArrayInputStream(outputStream.toByteArray())));}@Overridepublic ServletInputStream getInputStream() throws IOException {    final ByteArrayInputStream inputStream = new ByteArrayInputStream(outputStream.toByteArray());    return new ServletInputStream() {        @Override        public int readLine(byte[] b, int off, int len) throws IOException { return inputStream.read(b, off, len);        }        @Override        public boolean isFinished() { return inputStream.available() > 0;        }        @Override        public boolean isReady() { return true;        }        @Override        public void setReadListener(ReadListener arg0) { // TODO Auto-generated method stub        }        @Override        public int read() throws IOException { return inputStream.read();        }    };}public void setBody(String body) {    outputStream = new ByteArrayOutputStream();    try {        outputStream.write(body.getBytes());    } catch (IOException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }}public String getBody() {    return new String(outputStream.toByteArray());}

}

然后，您需要使用链中第一个过滤器进行初始化。

public class ReadTwiceFilter implements Filter {@Overridepublic void destroy() {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)        throws IOException, ServletException {    ReadTwiceHttpServletRequestWrapper readTwiceHttpServletRequestWrapper = new ReadTwiceHttpServletRequestWrapper( (HttpServletRequest) request);    String newBody = readTwiceHttpServletRequestWrapper.getBody().replace("<soap:studentId>1</soap:studentId>", "<soap:studentId>2</soap:studentId>");    readTwiceHttpServletRequestWrapper.setBody(newBody);    chain.doFilter(readTwiceHttpServletRequestWrapper, response);}@Overridepublic void init(FilterConfig arg0) throws ServletException {}

}