我目前正在处理一个需求,我需要在请求到达Spring控制器之前在servlet过滤器中获取XML(来自POST请求),然后我需要处理XML(切断一些空节点/元素)过滤,然后呼叫应继续进行.
我尝试了下面的代码(只附加了代码片段),我能够获取请求体(XML)并能够设置修改后的响应.
HttpServletRequest httpRequest &＃61; (HttpServletRequest) request;
HttpServletResponse httpResponse &＃61; (HttpServletResponse) response;
if (httpRequest.getMethod().equalsIgnoreCase("POST")) {
extractDataFromRequest(httpRequest);
httpResponse.getWriter().write("");
}
chain.doFilter(request, wrappedResponse);
public static String extractDataFromRequest(HttpServletRequest request) throws IOException {
String line;
StringBuilder builder &＃61; new StringBuilder();
BufferedReader reader &＃61; request.getReader();
while ((line &＃61; reader.readLine()) !&＃61; null) {
builder.append(line);
}
return builder.toString();
}
但是,spring因以下异常而失败.
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施.
解决方法:
您不能两次使用InputStream,您需要创建一个包装类,它保留InputStream的可重复副本.
public class ReadTwiceHttpServletRequestWrapper extends HttpServletRequestWrapper {
private ByteArrayOutputStream outputStream &＃61; new ByteArrayOutputStream();
public ReadTwiceHttpServletRequestWrapper(HttpServletRequest request) {
super(request);
try {
IOUtils.copy(request.getInputStream(), outputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
&＃64;Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(new ByteArrayInputStream(outputStream.toByteArray())));
}
&＃64;Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream inputStream &＃61; new ByteArrayInputStream(outputStream.toByteArray());
return new ServletInputStream() {
&＃64;Override
public int readLine(byte[] b, int off, int len) throws IOException {
return inputStream.read(b, off, len);
}
&＃64;Override
public boolean isFinished() {
return inputStream.available() > 0;
}
&＃64;Override
public boolean isReady() {
return true;
}
&＃64;Override
public void setReadListener(ReadListener arg0) {
// TODO Auto-generated method stub
}
&＃64;Override
public int read() throws IOException {
return inputStream.read();
}
};
}
public void setBody(String body) {
outputStream &＃61; 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());
}
}
然后你需要使用链中第一个过滤器来初始化它.
public class ReadTwiceFilter implements Filter {
&＃64;Override
public void destroy() {
}
&＃64;Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
ReadTwiceHttpServletRequestWrapper readTwiceHttpServletRequestWrapper &＃61; new ReadTwiceHttpServletRequestWrapper(
(HttpServletRequest) request);
String newBody &＃61; readTwiceHttpServletRequestWrapper.getBody().replace("1", "2");
readTwiceHttpServletRequestWrapper.setBody(newBody);
chain.doFilter(readTwiceHttpServletRequestWrapper, response);
}
&＃64;Override
public void init(FilterConfig arg0) throws ServletException {
}
}
标签&＃xff1a;java,spring,spring-mvc,servlets,servlet-filters
来源&＃xff1a; https://codeday.me/bug/20191003/1846690.html
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