java.lang.IllegalStateException:此请求已调用getReader() [英] java.lang.IllegalStateException: getReader() has already been called for this request

问题描述

我想将日志记录添加到我的Servlet中，所以我创建了Filter，它应该显示请求并转到Servlet.但不幸的是，我遇到了例外:

I want to add logging to my Servlet, so I've created Filter which should display request and go to the Servlet. But unfortunately I've encoutered exception:

java.lang.IllegalStateException: getReader() has already been called for this request
    at org.apache.catalina.connector.Request.getInputStream(Request.java:948)
    at org.apache.catalina.connector.RequestFacade.getInputStream(RequestFacade.java:338)
    at com.noelios.restlet.ext.servlet.ServletCall.getRequestEntityStream(ServletCall.java:190)

因此，为解决此问题，我找到了Wrapper解决方案，但它不起作用.我还能在代码中使用/更改什么?有什么想法吗?

So to fix this problem I've found solution with Wrapper, but it doesn't work. What else can I use/change in code? Any ideas?

[MyHttpServletRequestWrapper]

[MyHttpServletRequestWrapper]

public class MyHttpServletRequestWrapper extends HttpServletRequestWrapper
{
    public MyHttpServletRequestWrapper(HttpServletRequest request)
    {
        super(request);
    }

    private String getBodyAsString()
    {
        StringBuffer buff = new StringBuffer();
        buff.append(" BODY_DATA START [ ");
        char[] charArr = new char[getContentLength()];
        try
        {
            BufferedReader reader = new BufferedReader(getReader());
            reader.read(charArr, 0, charArr.length);
            reader.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        buff.append(charArr);
        buff.append(" ] BODY_DATA END ");
        return buff.toString();
    }

    public String toString()
    {
        return getBodyAsString();
    }
}

[MyFilter]

[MyFilter]

public class MyFilterimplements Filter
{
    @Override
    public void init(FilterConfig filterConfig) throws ServletException
    {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
    {
        final HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        final HttpServletResponse httpServletResponse = (HttpServletResponse) response;

        final HttpServletRequestWrapper requestWrapper = new MyHttpServletRequestWrapper(httpServletRequest);
        final String requestBody = requestWrapper.toString();

        chain.doFilter(request, response);
    }
}

推荐答案

好像restlet框架已在Request对象上调用了 getRequestEntityStream()，该对象又调用了 getInputStream()，因此在请求上调用 getReader()会引发 IllegalStateException .用于getReader()和getInputStream()的Servlet API文档说:

Looks like the restlet framework has called getRequestEntityStream() on the Request object which in turn calls getInputStream(), so calling getReader() on the request throws IllegalStateException. The Servlet API documentation for getReader() and getInputStream() says:

 public java.io.BufferedReader getReader()
    ...
    ...
Throws:
    java.lang.IllegalStateException - if getInputStream() method has been called on this request

 public ServletInputStream getInputStream()
    ...
    ...
    Throws:
    java.lang.IllegalStateException - if the getReader() method has already been called for this request

从文档看来，我们不能同时对Request对象调用getReader()和getInputStream().我建议您在包装器中使用 getInputStream()而不是 getReader().

From the documentation it seems that we cannot call both getReader() and getInputStream() on the Request object. I suggest you use getInputStream() rather than getReader() in your wrapper.

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