This example shows how to use unbuffered chunk-encoded POST request in HttpClient.

 /*
 * $Header: 
 * $Revision$
 * $Date$
 * ====================================================================
 *
 *  Copyright 2002-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */
import java.io.File;
import java.io.FileInputStream;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.InputStreamRequestEntity;
import org.apache.commons.httpclient.methods.PostMethod;

/**
 * Example how to use unbuffered chunk-encoded POST request.
 *
 * @author Oleg Kalnichevski
 */
public class ChunkEncodedPost {
    
    public static void main(String[] args) throws Exception {
        
        if (args.length != 1)  {
            System.out.println("Usage: ChunkEncodedPost <file>");
            System.out.println("<file> - full path to a file to be posted");
            System.exit(1);
        }
        
        HttpClient client = new HttpClient();
        
        PostMethod httppost = new PostMethod(
                "http://localhost:8080/httpclienttest/body");
        
        File file = new File(args[0]);
        
        httppost.setRequestEntity(
                new InputStreamRequestEntity(new FileInputStream(file)));
        
        httppost.setContentChunked(true);
        
        try {
            
            client.executeMethod(httppost);
            
            if (httppost.getStatusCode() == HttpStatus.SC_OK) {
                
                System.out.println(httppost.getResponseBodyAsString());
                
            } else {
                
                System.out.println("Unexpected failure: " + 
                        httppost.getStatusLine().toString());
                
            }
            
        } finally {
            httppost.releaseConnection();
        }
    }
}

Source: Apache HttpClient