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Java example source code file (AbstractAuthenticationHandler.java)

This example source code file (AbstractAuthenticationHandler.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

abstractauthenticationhandler, authenticationexception, authscheme, authschemeregistry, collection, default_scheme_priority, formattedheader, header, http, illegalstateexception, list, malformedchallengeexception, map, string, util

The AbstractAuthenticationHandler.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.impl.client;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import org.apache.http.annotation.Immutable;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.FormattedHeader;
import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScheme;
import org.apache.http.auth.AuthSchemeRegistry;
import org.apache.http.auth.AuthenticationException;
import org.apache.http.auth.MalformedChallengeException;
import org.apache.http.client.AuthenticationHandler;
import org.apache.http.client.protocol.ClientContext;
import org.apache.http.protocol.HTTP;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.CharArrayBuffer;

/**
 * Base class for {@link AuthenticationHandler} implementations.
 *
 * @since 4.0
 */
@Immutable 
public abstract class AbstractAuthenticationHandler implements AuthenticationHandler {

    private final Log log = LogFactory.getLog(getClass());
    
    private static final List<String> DEFAULT_SCHEME_PRIORITY = 
        Collections.unmodifiableList(Arrays.asList(new String[] {
            "ntlm",
            "digest",
            "basic"
    }));
    
    public AbstractAuthenticationHandler() {
        super();
    }
    
    protected Map<String, Header> parseChallenges(
            final Header[] headers) throws MalformedChallengeException {
        
        Map<String, Header> map = new HashMap(headers.length);
        for (Header header : headers) {
            CharArrayBuffer buffer;
            int pos;
            if (header instanceof FormattedHeader) {
                buffer = ((FormattedHeader) header).getBuffer();
                pos = ((FormattedHeader) header).getValuePos();
            } else {
                String s = header.getValue();
                if (s == null) {
                    throw new MalformedChallengeException("Header value is null");
                }
                buffer = new CharArrayBuffer(s.length());
                buffer.append(s);
                pos = 0;
            }
            while (pos < buffer.length() && HTTP.isWhitespace(buffer.charAt(pos))) {
                pos++;
            }
            int beginIndex = pos;
            while (pos < buffer.length() && !HTTP.isWhitespace(buffer.charAt(pos))) {
                pos++;
            }
            int endIndex = pos;
            String s = buffer.substring(beginIndex, endIndex);
            map.put(s.toLowerCase(Locale.ENGLISH), header);
        }
        return map;
    }
    
    protected List<String> getAuthPreferences() {
        return DEFAULT_SCHEME_PRIORITY;
    }
    
	public AuthScheme selectScheme(
            final Map<String, Header> challenges, 
            final HttpResponse response,
            final HttpContext context) throws AuthenticationException {
        
        AuthSchemeRegistry registry = (AuthSchemeRegistry) context.getAttribute(
                ClientContext.AUTHSCHEME_REGISTRY);
        if (registry == null) {
            throw new IllegalStateException("AuthScheme registry not set in HTTP context");
        }
        
        @SuppressWarnings("unchecked")
        Collection<String> authPrefs = (Collection) context.getAttribute(
                ClientContext.AUTH_SCHEME_PREF);
        if (authPrefs == null) {
            authPrefs = getAuthPreferences();
        }
        
        if (this.log.isDebugEnabled()) {
            this.log.debug("Authentication schemes in the order of preference: " 
                + authPrefs);
        }

        AuthScheme authScheme = null;
        for (String id: authPrefs) {
            Header challenge = challenges.get(id.toLowerCase(Locale.ENGLISH)); 

            if (challenge != null) {
                if (this.log.isDebugEnabled()) {
                    this.log.debug(id + " authentication scheme selected");
                }
                try {
                    authScheme = registry.getAuthScheme(id, response.getParams());
                    break;
                } catch (IllegalStateException e) {
                    if (this.log.isWarnEnabled()) {
                        this.log.warn("Authentication scheme " + id + " not supported");
                        // Try again
                    }
                }
            } else {
                if (this.log.isDebugEnabled()) {
                    this.log.debug("Challenge for " + id + " authentication scheme not available");
                    // Try again
                }
            }
        }
        if (authScheme == null) {
            // If none selected, something is wrong
            throw new AuthenticationException(
                "Unable to respond to any of these challenges: "
                    + challenges);
        }
        return authScheme;
    }

}

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