java - 如何多次读取 request.getInputStream()

Question

我有这个代码:

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException, ServletException {
    logger.info("Filter start...");

    HttpServletRequest httpRequest = (HttpServletRequest) request;
    HttpServletResponse httpResponse = (HttpServletResponse) response;

    String ba = getBaId(getBody(httpRequest));

    if (ba == null) {
        logger.error("Wrong XML");
        httpResponse.setStatus(HttpServletResponse.SC_BAD_REQUEST);
    } else {      

        if (!clients.containsKey(ba)) {
            clients.put(ba, 1);
            logger.info("Client map : init...");
        } else {
            clients.put(ba, clients.get(ba).intValue() + 1);
            logger.info("Threads for " + ba + " = " + clients.get(ba).toString());
        }

        chain.doFilter(request, response);
    }
}

还有这个 web.xml(包被缩短了，名字也变了，但是看起来一样)

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app>
  <filter>
    <filter-name>TestFilter</filter-name>
    <filter-class>pkg.TestFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>TestFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>WEB-INF/applicationContext.xml</param-value>
  </context-param>

  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <servlet>
    <servlet-name>Name</servlet-name>
    <display-name>Name</display-name>
    <servlet-class>pkg.Name</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Name</servlet-name>
    <url-pattern>/services/*</url-pattern>
  </servlet-mapping>
</web-app>

我想在过滤器之后调用 Servlet。我希望 chain.doFilter(...) 可以做到这一点，但我总是在 chain.doFilter(...):

java.lang.IllegalStateException: getInputStream() can't be called after getReader()
at com.caucho.server.connection.AbstractHttpRequest.getInputStream(AbstractHttpRequest.java:1933)
at org.apache.cxf.transport.http.AbstractHTTPDestination.setupMessage(AbstractHTTPDestination.java:249)
at org.apache.cxf.transport.servlet.ServletDestination.invoke(ServletDestination.java:82)
at org.apache.cxf.transport.servlet.ServletController.invokeDestination(ServletController.java:283)
at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:166)
at org.apache.cxf.transport.servlet.AbstractCXFServlet.invoke(AbstractCXFServlet.java:174)
at org.apache.cxf.transport.servlet.AbstractCXFServlet.doPost(AbstractCXFServlet.java:152)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:153)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:91)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:103)
at pkg.TestFilter.doFilter(TestFilter.java:102)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:187)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:265)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:273)
at com.caucho.server.port.TcpConnection.run(TcpConnection.java:682)
at com.caucho.util.ThreadPool$Item.runTasks(ThreadPool.java:743)
at com.caucho.util.ThreadPool$Item.run(ThreadPool.java:662)
at java.lang.Thread.run(Thread.java:619)

Answer 1

基于接受的答案的工作代码。

public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {

private static final Logger logger = Logger.getLogger(CustomHttpServletRequestWrapper.class);
private final String body;

public CustomHttpServletRequestWrapper(HttpServletRequest request) {
    super(request);

    StringBuilder stringBuilder = new StringBuilder();  
    BufferedReader bufferedReader = null;  

    try {  
        InputStream inputStream = request.getInputStream(); 

        if (inputStream != null) {  
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream));  

            char[] charBuffer = new char[128];  
            int bytesRead = -1;  

            while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {  
                stringBuilder.append(charBuffer, 0, bytesRead);  
            }  
        } else {  
            stringBuilder.append("");  
        }  
    } catch (IOException ex) {  
        logger.error("Error reading the request body...");  
    } finally {  
        if (bufferedReader != null) {  
            try {  
                bufferedReader.close();  
            } catch (IOException ex) {  
                logger.error("Error closing bufferedReader...");  
            }  
        }  
    }  

    body = stringBuilder.toString();  
}

@Override  
public ServletInputStream getInputStream () throws IOException {          
    final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());

    ServletInputStream inputStream = new ServletInputStream() {  
        public int read () throws IOException {  
            return byteArrayInputStream.read();  
        }  
    };

    return inputStream;  
} 
}