MultiReadHttpServletRequest.java

package org.pentaho.platform.web.http.request;

import org.apache.commons.io.IOUtils;

import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * @author Rowell Belen
 *
 * see http://stackoverflow.com/questions/10210645/http-servlet-request-lose-params-from-post-body-after-read-it-once
 */
public class MultiReadHttpServletRequest extends HttpServletRequestWrapper {
  private ByteArrayOutputStream cachedBytes;

  public MultiReadHttpServletRequest( HttpServletRequest request ) {
    super( request );
  }

  @Override
  public ServletInputStream getInputStream() throws IOException {
    if ( cachedBytes == null ) {
      cacheInputStream();
    }

    return new CachedServletInputStream();
  }

  @Override
  public BufferedReader getReader() throws IOException {
    return new BufferedReader( new InputStreamReader( getInputStream() ) );
  }

  private void cacheInputStream() throws IOException {
    cachedBytes = new ByteArrayOutputStream();
    IOUtils.copy( super.getInputStream(), cachedBytes );
  }

  /* An inputstream which reads the cached request body */
  public class CachedServletInputStream extends ServletInputStream {
    private ByteArrayInputStream input;

    public CachedServletInputStream() {
      /* create a new input stream from the cached request body */
      input = new ByteArrayInputStream( cachedBytes.toByteArray() );
    }

    @Override
    public int read() throws IOException {
      return input.read();
    }
  }
}