Java example source code file (URLEncodedUtils.java)

This example source code file (URLEncodedUtils.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java tags/keywords

arraylist, basicnamevaluepair, headerelement, httpentity, illegalargumentexception, io, ioexception, list, namevaluepair, net, network, parameter_separator, scanner, string, stringbuilder, unsupportedencodingexception, uri, util

The URLEncodedUtils.java example source code

/*
 * ====================================================================
 * 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.http.client.utils;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

import org.apache.http.annotation.Immutable;

import org.apache.http.Header;
import org.apache.http.HeaderElement;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;

/**
 * A collection of utilities for encoding URLs.
 *
 * @since 4.0
 */
@Immutable
public class URLEncodedUtils {

    public static final String CONTENT_TYPE = "application/x-www-form-urlencoded";
    private static final String PARAMETER_SEPARATOR = "&";
    private static final String NAME_VALUE_SEPARATOR = "=";

    /**
     * Returns a list of {@link NameValuePair NameValuePairs} as built from the
     * URI's query portion. For example, a URI of
     * http://example.org/path/to/file?a=1&b=2&c=3 would return a list of three
     * NameValuePairs, one for a=1, one for b=2, and one for c=3.
     * <p>
     * This is typically useful while parsing an HTTP PUT.
     * 
     * @param uri
     *            uri to parse
     * @param encoding
     *            encoding to use while parsing the query
     */
    public static List <NameValuePair> parse (final URI uri, final String encoding) {
        List <NameValuePair> result = Collections.emptyList();
        final String query = uri.getRawQuery();
        if (query != null && query.length() > 0) {
            result = new ArrayList <NameValuePair>();
            parse(result, new Scanner(query), encoding);
        }
        return result;
    }

    /**
     * Returns a list of {@link NameValuePair NameValuePairs} as parsed from an
     * {@link HttpEntity}. The encoding is taken from the entity's
     * Content-Encoding header.
     * <p>
     * This is typically used while parsing an HTTP POST.
     * 
     * @param entity
     *            The entity to parse
     * @throws IOException
     *             If there was an exception getting the entity's data.
     */
    public static List <NameValuePair> parse (
            final HttpEntity entity) throws IOException {
        List <NameValuePair> result = Collections.emptyList();
        
        String contentType = null;
        String charset = null;
        
        Header h = entity.getContentType();
        if (h != null) {
            HeaderElement[] elems = h.getElements();
            if (elems.length > 0) {
                HeaderElement elem = elems[0];
                contentType = elem.getName();
                NameValuePair param = elem.getParameterByName("charset");
                if (param != null) {
                    charset = param.getValue();
                }
            }
        }
        
        if (contentType != null && contentType.equalsIgnoreCase(CONTENT_TYPE)) {
            final String content = EntityUtils.toString(entity, HTTP.ASCII);
            if (content != null && content.length() > 0) {
                result = new ArrayList <NameValuePair>();
                parse(result, new Scanner(content), charset);
            }
        }
        return result;
    }

    /**
     * Returns true if the entity's Content-Type header is
     * <code>application/x-www-form-urlencoded.
     */
    public static boolean isEncoded (final HttpEntity entity) {
        Header h = entity.getContentType();
        if (h != null) {
            HeaderElement[] elems = h.getElements();
            if (elems.length > 0) {
                String contentType = elems[0].getName();
                return contentType.equalsIgnoreCase(CONTENT_TYPE);
            } else {
                return false;
            }
        } else {
            return false;
        }
    }

    /**
     * Adds all parameters within the Scanner to the list of
     * <code>parameters, as encoded by encoding. For
     * example, a scanner containing the string <code>a=1&b=2&c=3 would
     * add the {@link NameValuePair NameValuePairs} a=1, b=2, and c=3 to the
     * list of parameters.
     * 
     * @param parameters
     *            List to add parameters to.
     * @param scanner
     *            Input that contains the parameters to parse.
     * @param encoding
     *            Encoding to use when decoding the parameters.
     */
    public static void parse (
            final List <NameValuePair> parameters, 
            final Scanner scanner, 
            final String encoding) {
        scanner.useDelimiter(PARAMETER_SEPARATOR);
        while (scanner.hasNext()) {
            final String[] nameValue = scanner.next().split(NAME_VALUE_SEPARATOR);
            if (nameValue.length == 0 || nameValue.length > 2)
                throw new IllegalArgumentException("bad parameter");

            final String name = decode(nameValue[0], encoding);
            String value = null;
            if (nameValue.length == 2)
                value = decode(nameValue[1], encoding);
            parameters.add(new BasicNameValuePair(name, value));
        }
    }

    /**
     * Returns a String that is suitable for use as an <code>application/x-www-form-urlencoded
     * list of parameters in an HTTP PUT or HTTP POST.
     * 
     * @param parameters  The parameters to include.
     * @param encoding The encoding to use.
     */
    public static String format (
            final List <? extends NameValuePair> parameters, 
            final String encoding) {
        final StringBuilder result = new StringBuilder();
        for (final NameValuePair parameter : parameters) {
            final String encodedName = encode(parameter.getName(), encoding);
            final String value = parameter.getValue();
            final String encodedValue = value != null ? encode(value, encoding) : "";
            if (result.length() > 0)
                result.append(PARAMETER_SEPARATOR);
            result.append(encodedName);
            result.append(NAME_VALUE_SEPARATOR);
            result.append(encodedValue);
        }
        return result.toString();
    }

    private static String decode (final String content, final String encoding) {
        try {
            return URLDecoder.decode(content, 
                    encoding != null ? encoding : HTTP.DEFAULT_CONTENT_CHARSET);
        } catch (UnsupportedEncodingException problem) {
            throw new IllegalArgumentException(problem);
        }
    }

    private static String encode (final String content, final String encoding) {
        try {
            return URLEncoder.encode(content, 
                    encoding != null ? encoding : HTTP.DEFAULT_CONTENT_CHARSET);
        } catch (UnsupportedEncodingException problem) {
            throw new IllegalArgumentException(problem);
        }
    }
    
}