filter失去request的body/content

filter得到request的body/content
public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest req = (HttpServletRequest) request;

        int length = req.getContentLength();
        if (length > 0) {
            BufferedRequestWrapper bufferedRequest = new BufferedRequestWrapper(req,length);

            InputStream is = bufferedRequest.getInputStream();
            byte[] content = new byte[length];
           
            int pad = 0;
            while(pad < length){
                pad += is.read(content, pad, length);
            }

            request = bufferedRequest;
        }
        chain.doFilter(request, response);     
    }


BufferedRequestWrapper .java

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class BufferedRequestWrapper extends HttpServletRequestWrapper {

    ByteArrayInputStream bais;

    BufferedServletInputStream bsis;

    byte[] buffer;

    public BufferedRequestWrapper(HttpServletRequest req,int length) throws IOException {
        super(req);
        // Read InputStream and store its content in a buffer.
        InputStream is = req.getInputStream();
        buffer = new byte[length];

        int pad = 0;
        while(pad < length){
            pad += is.read(buffer, pad, length);
        }
    }

    public ServletInputStream getInputStream() {
        try {
            // Generate a new InputStream by stored buffer
            bais = new ByteArrayInputStream(buffer);
            // Istantiate a subclass of ServletInputStream
            // (Only ServletInputStream or subclasses of it are accepted by the
            // servlet engine!)
            bsis = new BufferedServletInputStream(bais);
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
        }
        return bsis;
    }

}