Author: lytsing

很久以前写过一篇《How to Use Android Downloads Provider》，到了Android 2.2(froyo)，Android 提供了更优雅的接口：

public static long startDownloadByUri(Context context,
                                      String url,
                                      String cookieData,
                                      boolean showDownload,
                                      int downloadDestination,
                                      boolean allowRoaming,
                                      boolean skipIntegrityCheck,
                                      String title,
                                      String notification_package,
                                      String notification_class,
                                      String notification_extras)

当然这些接口都是hide的，做ROM系统开发的才可以直接使用，用mmm方式编译。签于这个原因，一些国内第三方电子市场直接拿Downloads组件的代码修改成自己的提供使用。代码实现在：

[deli@violet frameworks]$ find . -type f -name Downloads.java
./base/core/java/android/provider/Downloads.java
./base/core/java/android/net/Downloads.java
还有 packages/providers/DownloadProvider

startDownloadByUri 即这个函数很容易理解，有网友给我发email说不知道如何使用，我贴出系统升级使用的代码片段，希望对大家有帮助。

[deli@violet update]$ cat Download.java

/*
 * Copyright (C) 2010 lytsing.org
 *
 * 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 com.google.android.gsf.update;

import com.google.android.gsf.R;

import android.content.Context;
import android.util.Log;
import android.net.Downloads;

public class Download {

    private final Context mContext;

    private String mNotificationClass;

    private String mNotificationPackage;

    public Download(Context context) {
        mContext = context;
        mNotificationPackage = context.getPackageName();
        mNotificationClass = SystemUpdateService.Receiver.class.getName();
    }

    public boolean downloadUpdate(String url, boolean showDownload, boolean allowRoaming) {
        removeAllDownloads();
        try {
            if (Downloads.ByUri.startDownloadByUri(
                        mContext,
                        url,
                        null,
                        showDownload,
                        2,
                        allowRoaming,
                        true,
                        mContext.getString(R.string.system_update_downloading_notification_title),
                        mNotificationPackage,
                        mNotificationClass,
                        null)== -1) {
                Log.w("update.Download", "Could not insert download entry into provider");
                return false;
            } 

            Log.i("update.Download",new StringBuilder()
                    .append("Started a new update download: ").append(url).toString());
        } catch (Exception e) {
            Log.e("update.Download", "Could not start update download", e);
            return false;
        }

        return true;
    }

    public Downloads.StatusInfo getStatus(String url) {
        return Downloads.ByUri.getStatus(mContext, url, 24 * 3600 * 1000);
    }

    public void removeAllDownloads() {
        Log.v("update.Download", "deleting all update downloads");
        try {
            Downloads.ByUri.removeAllDownloadsByPackage(mContext, mNotificationPackage,
                    mNotificationClass);
        } catch (Exception ex) {
            Log.e("update.Download", "Couldn\'t delete downloads", ex);
        }
    }
}