如何从POST请求中获取XML并在Servlet过滤器中对其进行修改？

  • Z时代
  • 2024-01-10
  • 分类：问答

我目前正在处理一个要求，即在请求到达Spring控制器之前，我需要在servlet过滤器中获取XML（从POST请求中获取），然后需要在XML处理程序中处理XML（切断一些空节点/元素）。过滤，然后调用应继续进行。

我尝试了下面的代码（仅附加了代码段），并且能够获取请求正文（XML）并能够设置修改后的响应。

    HttpServletRequest httpRequest = (HttpServletRequest) request;
    HttpServletResponse httpResponse = (HttpServletResponse) response;
    if (httpRequest.getMethod().equalsIgnoreCase("POST")) {
      extractDataFromRequest(httpRequest);
      httpResponse.getWriter().write("<root><root>");
    }
    chain.doFilter(request, wrappedResponse);
   public static String extractDataFromRequest(HttpServletRequest request) throws IOException {
    String line;
    StringBuilder builder = new StringBuilder();
    BufferedReader reader = request.getReader();
    while ((line = reader.readLine()) != null) {
      builder.append(line);
    }
    return builder.toString();
  }

但是，spring失败，但以下例外。

Severe: java.lang.IllegalStateException: PWC3997: getReader() has already been called for this request
    at org.apache.catalina.connector.Request.getInputStream(Request.java:1178)
    at org.apache.catalina.connector.RequestFacade.getInputStream(RequestFacade.java:407)
    at org.springframework.http.server.ServletServerHttpRequest.getBody(ServletServerHttpRequest.java:165)
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:120)
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:100)

我正在寻找专家对此要求的具体实现。

回答：

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();
    }
}
@Override
public BufferedReader getReader() throws IOException {
    return new BufferedReader(new InputStreamReader(new ByteArrayInputStream(outputStream.toByteArray())));
}
@Override
public 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 {
@Override
public void destroy() {
}
@Override
public 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);
}
@Override
public void init(FilterConfig arg0) throws ServletException {
}

}

以上是 如何从POST请求中获取XML并在Servlet过滤器中对其进行修改？ 的全部内容， 来源链接： utcz.com/qa/410939.html

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