Android example source code file (RequestQueue.java)

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

Java - Android tags/keywords

activepool, android, connectionthread, content, eventhandler, httphost, inputstream, internet, linkedlist, map, net, network, request, requesthandle, requestqueue, string, stringbuilder, syncfeeder, util, webaddress

The RequestQueue.java Android example source code

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * 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.
 */

/**
 * High level HTTP Interface
 * Queues requests as necessary
 */

package android.net.http;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Proxy;
import android.net.WebAddress;
import android.os.Handler;
import android.os.Message;
import android.os.SystemProperties;
import android.text.TextUtils;
import android.util.Log;

import java.io.InputStream;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.ListIterator;
import java.util.Map;

import org.apache.http.HttpHost;

/**
 * {@hide}
 */
public class RequestQueue implements RequestFeeder {


    /**
     * Requests, indexed by HttpHost (scheme, host, port)
     */
    private final LinkedHashMap<HttpHost, LinkedList mPending;
    private final Context mContext;
    private final ActivePool mActivePool;
    private final ConnectivityManager mConnectivityManager;

    private HttpHost mProxyHost = null;
    private BroadcastReceiver mProxyChangeReceiver;

    /* default simultaneous connection count */
    private static final int CONNECTION_COUNT = 4;

    /**
     * This class maintains active connection threads
     */
    class ActivePool implements ConnectionManager {
        /** Threads used to process requests */
        ConnectionThread[] mThreads;

        IdleCache mIdleCache;

        private int mTotalRequest;
        private int mTotalConnection;
        private int mConnectionCount;

        ActivePool(int connectionCount) {
            mIdleCache = new IdleCache();
            mConnectionCount = connectionCount;
            mThreads = new ConnectionThread[mConnectionCount];

            for (int i = 0; i < mConnectionCount; i++) {
                mThreads[i] = new ConnectionThread(
                        mContext, i, this, RequestQueue.this);
            }
        }

        void startup() {
            for (int i = 0; i < mConnectionCount; i++) {
                mThreads[i].start();
            }
        }

        void shutdown() {
            for (int i = 0; i < mConnectionCount; i++) {
                mThreads[i].requestStop();
            }
        }

        void startConnectionThread() {
            synchronized (RequestQueue.this) {
                RequestQueue.this.notify();
            }
        }

        public void startTiming() {
            for (int i = 0; i < mConnectionCount; i++) {
                ConnectionThread rt = mThreads[i];
                rt.mCurrentThreadTime = -1;
                rt.mTotalThreadTime = 0;
            }
            mTotalRequest = 0;
            mTotalConnection = 0;
        }

        public void stopTiming() {
            int totalTime = 0;
            for (int i = 0; i < mConnectionCount; i++) {
                ConnectionThread rt = mThreads[i];
                if (rt.mCurrentThreadTime != -1) {
                    totalTime += rt.mTotalThreadTime;
                }
                rt.mCurrentThreadTime = 0;
            }
            Log.d("Http", "Http thread used " + totalTime + " ms " + " for "
                    + mTotalRequest + " requests and " + mTotalConnection
                    + " new connections");
        }

        void logState() {
            StringBuilder dump = new StringBuilder();
            for (int i = 0; i < mConnectionCount; i++) {
                dump.append(mThreads[i] + "\n");
            }
            HttpLog.v(dump.toString());
        }


        public HttpHost getProxyHost() {
            return mProxyHost;
        }

        /**
         * Turns off persistence on all live connections
         */
        void disablePersistence() {
            for (int i = 0; i < mConnectionCount; i++) {
                Connection connection = mThreads[i].mConnection;
                if (connection != null) connection.setCanPersist(false);
            }
            mIdleCache.clear();
        }

        /* Linear lookup -- okay for small thread counts.  Might use
           private HashMap<HttpHost, LinkedList mActiveMap;
           if this turns out to be a hotspot */
        ConnectionThread getThread(HttpHost host) {
            synchronized(RequestQueue.this) {
                for (int i = 0; i < mThreads.length; i++) {
                    ConnectionThread ct = mThreads[i];
                    Connection connection = ct.mConnection;
                    if (connection != null && connection.mHost.equals(host)) {
                        return ct;
                    }
                }
            }
            return null;
        }

        public Connection getConnection(Context context, HttpHost host) {
            host = RequestQueue.this.determineHost(host);
            Connection con = mIdleCache.getConnection(host);
            if (con == null) {
                mTotalConnection++;
                con = Connection.getConnection(mContext, host, mProxyHost,
                        RequestQueue.this);
            }
            return con;
        }
        public boolean recycleConnection(Connection connection) {
            return mIdleCache.cacheConnection(connection.getHost(), connection);
        }

    }

    /**
     * A RequestQueue class instance maintains a set of queued
     * requests.  It orders them, makes the requests against HTTP
     * servers, and makes callbacks to supplied eventHandlers as data
     * is read.  It supports request prioritization, connection reuse
     * and pipelining.
     *
     * @param context application context
     */
    public RequestQueue(Context context) {
        this(context, CONNECTION_COUNT);
    }

    /**
     * A RequestQueue class instance maintains a set of queued
     * requests.  It orders them, makes the requests against HTTP
     * servers, and makes callbacks to supplied eventHandlers as data
     * is read.  It supports request prioritization, connection reuse
     * and pipelining.
     *
     * @param context application context
     * @param connectionCount The number of simultaneous connections 
     */
    public RequestQueue(Context context, int connectionCount) {
        mContext = context;

        mPending = new LinkedHashMap<HttpHost, LinkedList(32);

        mActivePool = new ActivePool(connectionCount);
        mActivePool.startup();

        mConnectivityManager = (ConnectivityManager)
                context.getSystemService(Context.CONNECTIVITY_SERVICE);
    }

    /**
     * Enables data state and proxy tracking
     */
    public synchronized void enablePlatformNotifications() {
        if (HttpLog.LOGV) HttpLog.v("RequestQueue.enablePlatformNotifications() network");

        if (mProxyChangeReceiver == null) {
            mProxyChangeReceiver =
                    new BroadcastReceiver() {
                        @Override
                        public void onReceive(Context ctx, Intent intent) {
                            setProxyConfig();
                        }
                    };
            mContext.registerReceiver(mProxyChangeReceiver,
                                      new IntentFilter(Proxy.PROXY_CHANGE_ACTION));
        }
        // we need to resample the current proxy setup
        setProxyConfig();
    }

    /**
     * If platform notifications have been enabled, call this method
     * to disable before destroying RequestQueue
     */
    public synchronized void disablePlatformNotifications() {
        if (HttpLog.LOGV) HttpLog.v("RequestQueue.disablePlatformNotifications() network");

        if (mProxyChangeReceiver != null) {
            mContext.unregisterReceiver(mProxyChangeReceiver);
            mProxyChangeReceiver = null;
        }
    }

    /**
     * Because our IntentReceiver can run within a different thread,
     * synchronize setting the proxy
     */
    private synchronized void setProxyConfig() {
        NetworkInfo info = mConnectivityManager.getActiveNetworkInfo();
        if (info != null && info.getType() == ConnectivityManager.TYPE_WIFI) {
            mProxyHost = null;
        } else {
            String host = Proxy.getHost(mContext);
            if (HttpLog.LOGV) HttpLog.v("RequestQueue.setProxyConfig " + host);
            if (host == null) {
                mProxyHost = null;
            } else {
                mActivePool.disablePersistence();
                mProxyHost = new HttpHost(host, Proxy.getPort(mContext), "http");
            }
        }
    }

    /**
     * used by webkit
     * @return proxy host if set, null otherwise
     */
    public HttpHost getProxyHost() {
        return mProxyHost;
    }

    /**
     * Queues an HTTP request
     * @param url The url to load.
     * @param method "GET" or "POST."
     * @param headers A hashmap of http headers.
     * @param eventHandler The event handler for handling returned
     * data.  Callbacks will be made on the supplied instance.
     * @param bodyProvider InputStream providing HTTP body, null if none
     * @param bodyLength length of body, must be 0 if bodyProvider is null
     */
    public RequestHandle queueRequest(
            String url, String method,
            Map<String, String> headers, EventHandler eventHandler,
            InputStream bodyProvider, int bodyLength) {
        WebAddress uri = new WebAddress(url);
        return queueRequest(url, uri, method, headers, eventHandler,
                            bodyProvider, bodyLength);
    }

    /**
     * Queues an HTTP request
     * @param url The url to load.
     * @param uri The uri of the url to load.
     * @param method "GET" or "POST."
     * @param headers A hashmap of http headers.
     * @param eventHandler The event handler for handling returned
     * data.  Callbacks will be made on the supplied instance.
     * @param bodyProvider InputStream providing HTTP body, null if none
     * @param bodyLength length of body, must be 0 if bodyProvider is null
     */
    public RequestHandle queueRequest(
            String url, WebAddress uri, String method, Map<String, String> headers,
            EventHandler eventHandler,
            InputStream bodyProvider, int bodyLength) {

        if (HttpLog.LOGV) HttpLog.v("RequestQueue.queueRequest " + uri);

        // Ensure there is an eventHandler set
        if (eventHandler == null) {
            eventHandler = new LoggingEventHandler();
        }

        /* Create and queue request */
        Request req;
        HttpHost httpHost = new HttpHost(uri.mHost, uri.mPort, uri.mScheme);

        // set up request
        req = new Request(method, httpHost, mProxyHost, uri.mPath, bodyProvider,
                          bodyLength, eventHandler, headers);

        queueRequest(req, false);

        mActivePool.mTotalRequest++;

        // dump();
        mActivePool.startConnectionThread();

        return new RequestHandle(
                this, url, uri, method, headers, bodyProvider, bodyLength,
                req);
    }

    private static class SyncFeeder implements RequestFeeder {
        // This is used in the case where the request fails and needs to be
        // requeued into the RequestFeeder.
        private Request mRequest;
        SyncFeeder() {
        }
        public Request getRequest() {
            Request r = mRequest;
            mRequest = null;
            return r;
        }
        public Request getRequest(HttpHost host) {
            return getRequest();
        }
        public boolean haveRequest(HttpHost host) {
            return mRequest != null;
        }
        public void requeueRequest(Request r) {
            mRequest = r;
        }
    }

    public RequestHandle queueSynchronousRequest(String url, WebAddress uri,
            String method, Map<String, String> headers,
            EventHandler eventHandler, InputStream bodyProvider,
            int bodyLength) {
        if (HttpLog.LOGV) {
            HttpLog.v("RequestQueue.dispatchSynchronousRequest " + uri);
        }

        HttpHost host = new HttpHost(uri.mHost, uri.mPort, uri.mScheme);

        Request req = new Request(method, host, mProxyHost, uri.mPath,
                bodyProvider, bodyLength, eventHandler, headers);

        // Open a new connection that uses our special RequestFeeder
        // implementation.
        host = determineHost(host);
        Connection conn = Connection.getConnection(mContext, host, mProxyHost,
                new SyncFeeder());

        // TODO: I would like to process the request here but LoadListener
        // needs a RequestHandle to process some messages.
        return new RequestHandle(this, url, uri, method, headers, bodyProvider,
                bodyLength, req, conn);

    }

    // Chooses between the proxy and the request's host.
    private HttpHost determineHost(HttpHost host) {
        // There used to be a comment in ConnectionThread about t-mob's proxy
        // being really bad about https. But, HttpsConnection actually looks
        // for a proxy and connects through it anyway. I think that this check
        // is still valid because if a site is https, we will use
        // HttpsConnection rather than HttpConnection if the proxy address is
        // not secure.
        return (mProxyHost == null || "https".equals(host.getSchemeName()))
                ? host : mProxyHost;
    }

    /**
     * @return true iff there are any non-active requests pending
     */
    synchronized boolean requestsPending() {
        return !mPending.isEmpty();
    }


    /**
     * debug tool: prints request queue to log
     */
    synchronized void dump() {
        HttpLog.v("dump()");
        StringBuilder dump = new StringBuilder();
        int count = 0;
        Iterator<Map.Entry> iter;

        // mActivePool.log(dump);

        if (!mPending.isEmpty()) {
            iter = mPending.entrySet().iterator();
            while (iter.hasNext()) {
                Map.Entry<HttpHost, LinkedList entry = iter.next();
                String hostName = entry.getKey().getHostName();
                StringBuilder line = new StringBuilder("p" + count++ + " " + hostName + " ");

                LinkedList<Request> reqList = entry.getValue();
                ListIterator reqIter = reqList.listIterator(0);
                while (iter.hasNext()) {
                    Request request = (Request)iter.next();
                    line.append(request + " ");
                }
                dump.append(line);
                dump.append("\n");
            }
        }
        HttpLog.v(dump.toString());
    }

    /*
     * RequestFeeder implementation
     */
    public synchronized Request getRequest() {
        Request ret = null;

        if (!mPending.isEmpty()) {
            ret = removeFirst(mPending);
        }
        if (HttpLog.LOGV) HttpLog.v("RequestQueue.getRequest() => " + ret);
        return ret;
    }

    /**
     * @return a request for given host if possible
     */
    public synchronized Request getRequest(HttpHost host) {
        Request ret = null;

        if (mPending.containsKey(host)) {
            LinkedList<Request> reqList = mPending.get(host);
            ret = reqList.removeFirst();
            if (reqList.isEmpty()) {
                mPending.remove(host);
            }
        }
        if (HttpLog.LOGV) HttpLog.v("RequestQueue.getRequest(" + host + ") => " + ret);
        return ret;
    }

    /**
     * @return true if a request for this host is available
     */
    public synchronized boolean haveRequest(HttpHost host) {
        return mPending.containsKey(host);
    }

    /**
     * Put request back on head of queue
     */
    public void requeueRequest(Request request) {
        queueRequest(request, true);
    }

    /**
     * This must be called to cleanly shutdown RequestQueue
     */
    public void shutdown() {
        mActivePool.shutdown();
    }

    protected synchronized void queueRequest(Request request, boolean head) {
        HttpHost host = request.mProxyHost == null ? request.mHost : request.mProxyHost;
        LinkedList<Request> reqList;
        if (mPending.containsKey(host)) {
            reqList = mPending.get(host);
        } else {
            reqList = new LinkedList<Request>();
            mPending.put(host, reqList);
        }
        if (head) {
            reqList.addFirst(request);
        } else {
            reqList.add(request);
        }
    }


    public void startTiming() {
        mActivePool.startTiming();
    }

    public void stopTiming() {
        mActivePool.stopTiming();
    }

    /* helper */
    private Request removeFirst(LinkedHashMap<HttpHost, LinkedList requestQueue) {
        Request ret = null;
        Iterator<Map.Entry> iter = requestQueue.entrySet().iterator();
        if (iter.hasNext()) {
            Map.Entry<HttpHost, LinkedList entry = iter.next();
            LinkedList<Request> reqList = entry.getValue();
            ret = reqList.removeFirst();
            if (reqList.isEmpty()) {
                requestQueue.remove(entry.getKey());
            }
        }
        return ret;
    }

    /**
     * This interface is exposed to each connection
     */
    interface ConnectionManager {
        HttpHost getProxyHost();
        Connection getConnection(Context context, HttpHost host);
        boolean recycleConnection(Connection connection);
    }
}