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The coolest XML library for Java around. Define typesafe views (projections) to xml. Use XPath to read and write XML. Bind XML to Java collections. Requires at least Java6, supports Java8 features and has no further runtime dependencies.
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/**
 *  Copyright 2013 Sven Ewald
 *
 *  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.
 */
package org.xmlbeam.util;

import java.net.HttpURLConnection;
import java.net.URL;

import java.util.Arrays;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.TreeMap;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;

import javax.xml.bind.DatatypeConverter;

/**
 * A set of tiny helper methods used in the projection framework and free to use for framework
 * clients. This methods are part of the public framework API and will not change in minor version
 * updates.
 * 
 * @author Sven Ewald
 */
public final class IOHelper {

    /**
     * Copies request properties to a connection.
     * 
     * @param requestProperties
     *            (if null, connection will not be changed)
     * @param connection
     */
    private static void addRequestProperties(Map requestProperties, HttpURLConnection connection) {
        if (requestProperties != null) {
            for (Entry entry : requestProperties.entrySet()) {
                connection.addRequestProperty(entry.getKey(), entry.getValue());
            }
        }
    }

    /**
     * Create HTTP Basic credentials to be used in HTTP get or post methods.
     * 
     * @param username
     * @param password
     * @return Map containing
     */
    public static Map createBasicAuthenticationProperty(String username, String password) {
        Map map = new TreeMap();
        try {
            String base64Binary = DatatypeConverter.printBase64Binary((username + ":" + password).getBytes("US-ASCII"));
            map.put("Authorization", "Basic " + base64Binary);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
        return map;
    }

    /**
     * Simple http get imlementation. Supports HTTP Basic authentication via request properties. You
     * may want to use {@link #createBasicAuthenticationProperty} to add authentication.
     * 
     * @param httpurl
     *            get url
     * @param requestProperties
     *            optional http header fields (key->value)
     * @return input stream of response
     * @throws IOException
     */
    public static InputStream httpGet(String httpurl, Map... requestProperties) throws IOException {
        HttpURLConnection connection = (HttpURLConnection) new URL(httpurl).openConnection();        
        for (Map props : requestProperties) {
            addRequestProperties(props, connection);
        }        
        return connection.getInputStream();
    }

    /**
     * Simple http post implementation. Supports HTTP Basic authentication via request properties.
     * You may want to use {@link #createBasicAuthenticationProperty} to add authentication.
     * 
     * @param httpurl
     *            target url
     * @param data
     *            String with content to post
     * @param requestProperties
     *            optional http header fields (key->value)
     * @return input stream of response
     * @throws IOException
     */
    public static InputStream httpPost(String httpurl, String data, Map... requestProperties) throws IOException {
        byte[] bytes = data.getBytes("utf-8");
        java.net.URL url = new java.net.URL(httpurl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("charset", "utf-8");
        connection.setRequestProperty("Content-Length", Integer.toString(bytes.length));
        for (Map props : requestProperties) {
            addRequestProperties(props, connection);
        }
        OutputStream outputStream = connection.getOutputStream();
        outputStream.write(bytes);
        outputStream.flush();
        return connection.getInputStream();
    }

    /**
     * @param inputStream
     * @param optionalCharsetName optional parameter
     * @return String with stream content
     */
    public static String inputStreamToString(InputStream inputStream, String... optionalCharsetName) {
        Scanner scanner = (optionalCharsetName == null) || (optionalCharsetName.length == 0) || (optionalCharsetName[0] == null) ? new Scanner(inputStream) : new Scanner(inputStream, optionalCharsetName[0]);
        // return scanner.useDelimiter("\\A").hasNext() ? scanner.next() : "";
        String content = scanner.useDelimiter("\\A").hasNext() ? scanner.next() : "";
        return content;
    }

    /**
     * Silently drop UTF8 BOM
     * @param source
     * @return data without UTF8 BOM
     */
    public static byte[] dropUTF8BOM(final byte[] source) {
        if (source == null) {
            return null;
        }
        if (source.length < 3) {
            return source;
        }
        if ((source[0] == (byte) 0xef) && (source[1] == (byte) 0xbb) && (source[2] == (byte) 0xbf)) {
            return Arrays.copyOfRange(source, 3, source.length);
        }
        return source;
    }

}