/*
 * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/methods/multipart/MultipartRequestEntity.java,v 1.1 2004/10/06 03:39:59 mbecke Exp $
 * $Revision: 502647 $
 * $Date: 2007-02-02 17:22:54 +0100 (Fri, 02 Feb 2007) $
 *
 * ====================================================================
 *
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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/>.
 *
 */
package org.apache.commons.httpclient.methods.multipart;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import org.apache.commons.httpclient.methods.RequestEntity;
import org.apache.commons.httpclient.params.HttpMethodParams;
import org.apache.commons.httpclient.util.EncodingUtil;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

Implements a request entity suitable for an HTTP multipart POST method.

The HTTP multipart POST method is defined in section 3.3 of
RFC1867:

The media-type multipart/form-data follows the rules of all multipart
MIME data streams as outlined in RFC 1521. The multipart/form-data contains 
a series of parts. Each part is expected to contain a content-disposition 
header where the value is "form-data" and a name attribute specifies 
the field name within the form, e.g., 'content-disposition: form-data; 
name="xxxxx"', where xxxxx is the field name corresponding to that field.
Field names originally in non-ASCII character sets may be encoded using 
the method outlined in RFC 1522.


This entity is designed to be used in conjunction with the post method to provide multipart posts. Example usage:
 File f = new File("/path/fileToUpload.txt");
 PostMethod filePost = new PostMethod("http://host/some_path");
 Part[] parts = {
     new StringPart("param_name", "value"),
     new FilePart(f.getName(), f)
 };
 filePost.setRequestEntity(
     new MultipartRequestEntity(parts, filePost.getParams())
     );
 HttpClient client = new HttpClient();
 int status = client.executeMethod(filePost);

Since:
3.0/**
 * Implements a request entity suitable for an HTTP multipart POST method.
 * <p>
 * The HTTP multipart POST method is defined in section 3.3 of
 * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC1867</a>:
 * <blockquote>
 * The media-type multipart/form-data follows the rules of all multipart
 * MIME data streams as outlined in RFC 1521. The multipart/form-data contains 
 * a series of parts. Each part is expected to contain a content-disposition 
 * header where the value is "form-data" and a name attribute specifies 
 * the field name within the form, e.g., 'content-disposition: form-data; 
 * name="xxxxx"', where xxxxx is the field name corresponding to that field.
 * Field names originally in non-ASCII character sets may be encoded using 
 * the method outlined in RFC 1522.
 * </blockquote>
 * </p>
 * <p>This entity is designed to be used in conjunction with the 
 * {@link org.apache.commons.httpclient.methods.PostMethod post method} to provide
 * multipart posts.  Example usage:</p>
 * <pre>
 *  File f = new File("/path/fileToUpload.txt");
 *  PostMethod filePost = new PostMethod("http://host/some_path");
 *  Part[] parts = {
 *      new StringPart("param_name", "value"),
 *      new FilePart(f.getName(), f)
 *  };
 *  filePost.setRequestEntity(
 *      new MultipartRequestEntity(parts, filePost.getParams())
 *      );
 *  HttpClient client = new HttpClient();
 *  int status = client.executeMethod(filePost);
 * </pre>
 * 
 * @since 3.0
 */
public class MultipartRequestEntity implements RequestEntity {

    private static final Log log = LogFactory.getLog(MultipartRequestEntity.class);
    
    
The Content-Type for multipart/form-data. /** The Content-Type for multipart/form-data. */
    private static final String MULTIPART_FORM_CONTENT_TYPE = "multipart/form-data";
    
    
The pool of ASCII chars to be used for generating a multipart boundary.
/**
     * The pool of ASCII chars to be used for generating a multipart boundary.
     */
    private static byte[] MULTIPART_CHARS = EncodingUtil.getAsciiBytes(
        "-_1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
    
    
Generates a random multipart boundary string.
Returns:
/**
     * Generates a random multipart boundary string.
     * @return
     */
    private static byte[] generateMultipartBoundary() {
        Random rand = new Random();
        byte[] bytes = new byte[rand.nextInt(11) + 30]; // a random size from 30 to 40
        for (int i = 0; i < bytes.length; i++) {
            bytes[i] = MULTIPART_CHARS[rand.nextInt(MULTIPART_CHARS.length)];
        }
        return bytes;
    }
    
    
The MIME parts as set by the constructor /** The MIME parts as set by the constructor */
    protected Part[] parts;
    
    private byte[] multipartBoundary;
    
    private HttpMethodParams params;
    
    
Creates a new multipart entity containing the given parts.
Params:
parts – The parts to include.
params – The params of the HttpMethod using this entity./**
     * Creates a new multipart entity containing the given parts.
     * @param parts The parts to include.
     * @param params The params of the HttpMethod using this entity.
     */
    public MultipartRequestEntity(Part[] parts, HttpMethodParams params) {
        if (parts == null) {
            throw new IllegalArgumentException("parts cannot be null");
        }
        if (params == null) {
            throw new IllegalArgumentException("params cannot be null");
        }
        this.parts = parts;
        this.params = params;
    }

    
Returns the MIME boundary string that is used to demarcate boundaries of
this part. The first call to this method will implicitly create a new
boundary string. To create a boundary string first the 
HttpMethodParams.MULTIPART_BOUNDARY parameter is considered. Otherwise 
a random one is generated.
Returns:
The boundary string of this entity in ASCII encoding./**
     * Returns the MIME boundary string that is used to demarcate boundaries of
     * this part. The first call to this method will implicitly create a new
     * boundary string. To create a boundary string first the 
     * HttpMethodParams.MULTIPART_BOUNDARY parameter is considered. Otherwise 
     * a random one is generated.
     * 
     * @return The boundary string of this entity in ASCII encoding.
     */
    protected byte[] getMultipartBoundary() {
        if (multipartBoundary == null) {
            String temp = (String) params.getParameter(HttpMethodParams.MULTIPART_BOUNDARY);
            if (temp != null) {
                multipartBoundary = EncodingUtil.getAsciiBytes(temp);
            } else {
                multipartBoundary = generateMultipartBoundary();
            }
        }
        return multipartBoundary;
    }

    
Returns true if all parts are repeatable, false otherwise.
See Also:
isRepeatable.isRepeatable()/**
     * Returns <code>true</code> if all parts are repeatable, <code>false</code> otherwise.
     * @see org.apache.commons.httpclient.methods.RequestEntity#isRepeatable()
     */
    public boolean isRepeatable() {
        for (int i = 0; i < parts.length; i++) {
            if (!parts[i].isRepeatable()) {
                return false;
            }
        }
        return true;
    }

    /* (non-Javadoc)
     * @see org.apache.commons.httpclient.methods.RequestEntity#writeRequest(java.io.OutputStream)
     */
    public void writeRequest(OutputStream out) throws IOException {
        Part.sendParts(out, parts, getMultipartBoundary());
    }

    /* (non-Javadoc)
     * @see org.apache.commons.httpclient.methods.RequestEntity#getContentLength()
     */
    public long getContentLength() {
        try {
            return Part.getLengthOfParts(parts, getMultipartBoundary());            
        } catch (Exception e) {
            log.error("An exception occurred while getting the length of the parts", e);
            return 0;
        }
    }

    /* (non-Javadoc)
     * @see org.apache.commons.httpclient.methods.RequestEntity#getContentType()
     */
    public String getContentType() {
        StringBuffer buffer = new StringBuffer(MULTIPART_FORM_CONTENT_TYPE);
        buffer.append("; boundary=");
        buffer.append(EncodingUtil.getAsciiString(getMultipartBoundary()));
        return buffer.toString();
    }

}