本文主要介绍如何修改Android系统下载管理，以支持更多的功能及部分bug修改和如何编译生效。目前内容包括暂停下载、继续下载、通知设置NotiExtra和NotiClass、wifi切换到3g自动暂停、Bug修改。
更多下载相关开源项目可见 Android 下载。
PS: 很多童鞋不是自己做rom，所以就算修改了系统源码编译出来的包在其他系统上也不通用
这里推荐DownloadProvider@Github(并不是我的开源项目，我的项目为TrineaAndroidCommon@Github，包含图片缓存，下拉刷新，静默安装等，欢迎关注)，系统下载管理的独立版，可整合进自己的应用，感谢@DONG童鞋提供地址。
下面需要修改的DownloadManager.java所在目录为frameworks/base/core/java/android/app
DownloadInfo.java, DownloadProvider.java,DownloadThread.java文件所在目录为packages/providers/DownloadProvider/src/com/android/providers/downloads
1、暂停、继续下载功能
(1) DownloadProvider类修改
Java
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public int update(final Uri uri, final ContentValues values, final String where, final String[] whereArgs) |
函数，修改后代码如下(只增加了一行有效代码)：
Java
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if (Binder.getCallingPid() != Process.myPid()) { filteredValues = new ContentValues(); copyString(Downloads.Impl.COLUMN_APP_DATA, values, filteredValues); copyInteger(Downloads.Impl.COLUMN_VISIBILITY, values, filteredValues); Integer i = values.getAsInteger(Downloads.Impl.COLUMN_CONTROL); if (i != null) { filteredValues.put(Downloads.Impl.COLUMN_CONTROL, i); startService = true; } // trinea BEGIN, added by trinea@trinea.cn 2013/03/01 copyInteger(Downloads.Impl.COLUMN_STATUS, values, filteredValues); // trinea END copyInteger(Downloads.Impl.COLUMN_CONTROL, values, filteredValues); copyString(Downloads.Impl.COLUMN_TITLE, values, filteredValues); copyString(Downloads.Impl.COLUMN_MEDIAPROVIDER_URI, values, filteredValues); copyString(Downloads.Impl.COLUMN_DESCRIPTION, values, filteredValues); copyInteger(Downloads.Impl.COLUMN_DELETED, values, filteredValues); } else { |
其中以// trinea BEGIN开头，// trinea END结尾为修改部分，下面代码示例同样如此。因为DownloadProvider安全策略对非该进程id的修改会过滤掉COLUMN_STATUS状态，所以我们需要添加该行。
(2) DownloadThread类修改
Java
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private void setupDestinationFile(State state, InnerState innerState) |
函数中这个注释掉一个else if，如下：
Java
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// trinea BEGIN, noted by trinea@trinea.cn 2013/03/01 //} else if (mInfo.mETag == null && !mInfo.mNoIntegrity) { // // This should've been caught upon failure // if (Constants.LOGVV) { // Log.d(TAG, "setupDestinationFile() unable to resume download, deleting " // + state.mFilename); // } // f.delete(); // throw new StopRequestException(Downloads.Impl.STATUS_CANNOT_RESUME, // "Trying to resume a download that can't be resumed"); // trinea END |
上面一段代码表示一个验证过程，可以去掉。
mETag为数据库中的etag字段值，代码中没有解释，感觉是一个验证值，类似hashcode。
mNoIntegrity为数据中no_integrity字段值，表示启动下载的应用程序能否验证下载的文件的完整性。不过坑爹的是对于etag和no_integrity都没有提供设置的接口
(3) DownloadManager类中添加对外接口
DownloadManager中添加暂停、继续接口
Java
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/** * pause download, added by trinea@trinea.cn 2013/03/01 * * @param ids the IDs of the downloads to be paused * @return the number of downloads actually paused */ public int pauseDownload(long... ids) { if (ids == null || ids.length == 0) { // called with nothing to remove! throw new IllegalArgumentException("input param 'ids' can't be null"); } ContentValues values = new ContentValues(); values.put(Downloads.Impl.COLUMN_CONTROL, Downloads.Impl.CONTROL_PAUSED); values.put(Downloads.Impl.COLUMN_STATUS, Downloads.Impl.STATUS_PAUSED_BY_APP); if (ids.length == 1) { return mResolver.update(ContentUris.withAppendedId(mBaseUri, ids[0]), values, null, null); } return mResolver.update(mBaseUri, values, getWhereClauseForIds(ids), getWhereArgsForIds(ids)); } /** * resume download, added by trinea@trinea.cn 2013/03/01 * * @param ids the IDs of the downloads to be resumed * @return the number of downloads actually resumed */ public int resumeDownload(long... ids) { if (ids == null || ids.length == 0) { // called with nothing to remove! throw new IllegalArgumentException("input param 'ids' can't be null"); } ContentValues values = new ContentValues(); values.put(Downloads.Impl.COLUMN_CONTROL, Downloads.Impl.CONTROL_RUN); values.put(Downloads.Impl.COLUMN_STATUS, Downloads.Impl.STATUS_RUNNING); if (ids.length == 1) { return mResolver.update(ContentUris.withAppendedId(mBaseUri, ids[0]), values, null, null); } return mResolver.update(mBaseUri, values, getWhereClauseForIds(ids), getWhereArgsForIds(ids)); } |
无论是暂停还是继续我们都是同时把Downloads.Impl.COLUMN_CONTROL和Downloads.Impl.COLUMN_STATUS字段进行修改，因为在DownloadInfo的private boolean isReadyToStart(long now)函数中,会对COLUMN_CONTROL字段进行判断，如果是用户手动暂停的话，是不会自动继续的，部分代码如下：
点击展开代码
之后我们直接调用DownloadManager的pauseDownload和resumeDownload接口即可
PS：也可以试试不做第二步的修改，而将第一步DownloadProvider的update函数修改变为
Java
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// trinea BEGIN, added by trinea@trinea.cn 2013/03/01 copyInteger(Downloads.Impl.COLUMN_STATUS, values, filteredValues); copyInteger(Downloads.Impl.COLUMN_NO_INTEGRITY, values, filteredValues); // trinea END |
第二步修改变为在public int resumeDownload(long… ids)加入
Java
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values.put(Downloads.Impl.COLUMN_CONTROL, Downloads.Impl.CONTROL_RUN); values.put(Downloads.Impl.COLUMN_STATUS, Downloads.Impl.STATUS_RUNNING); values.put(Downloads.Impl.COLUMN_NO_INTEGRITY, true); |
没有亲自试，不过按照逻辑应该也可以。
2、通知栏可以设置NotiExtra和NotiClass
(1) DownloadProvider类中修改private void checkInsertPermissions(ContentValues values)函数
Java
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values.remove(Downloads.Impl.COLUMN_IS_VISIBLE_IN_DOWNLOADS_UI); values.remove(Downloads.Impl.COLUMN_MEDIA_SCANNED); // BEGIN, added by trinea@trinea.cn 2013/03/01 values.remove(Downloads.Impl.COLUMN_NOTIFICATION_CLASS); values.remove(Downloads.Impl.COLUMN_NOTIFICATION_EXTRAS); // trinea END |
在DownloadProvider insert之前会调用checkInsertPermissions检查不能被插入的字段插入，这里我们需要允许这两个字段存在。
(2) DownloadManager.Request添加对外接口
DownloadManager.Request支持setNotiClass、setNotiExtras
在Request中添加接口以及允许字段修改。通过允许设置NotiExtra和NotiClass，我们可以给系统传递更丰富的参数，在通知栏点击相应或是DownloadUi中通过broadcast将这些参数传递出来方便应用调用。
3、wifi切换到3g自动暂停
(1) 修改DownloadInfo.java
Java
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private int checkIsNetworkTypeAllowed(int networkType) { if (mIsPublicApi) { final int flag = translateNetworkTypeToApiFlag(networkType); final boolean allowAllNetworkTypes = mAllowedNetworkTypes == ~0; if (!allowAllNetworkTypes && (flag & mAllowedNetworkTypes) == 0) { return NETWORK_TYPE_DISALLOWED_BY_REQUESTOR; } // trinea BEGIN if (mStatus == Downloads.Impl.STATUS_WAITING_FOR_NETWORK && flag != DownloadManager.Request.NETWORK_WIFI) { return NETWORK_TYPE_DISALLOWED_BY_REQUESTOR; } // trinea END } return checkSizeAllowedForNetwork(networkType); } |
表示等待网络时始终只等待wifi
(2) 修改DownloadReceiver.java
Java
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} else if (action.equals(ConnectivityManager.CONNECTIVITY_ACTION)) { NetworkInfo info = (NetworkInfo) intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO); if (info != null && info.isConnected()) { startService(context); } } else if (action.equals(Constants.ACTION_RETRY)) { |
修改为：
Java
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} else if (action.equals(ConnectivityManager.CONNECTIVITY_ACTION)) { NetworkInfo info = (NetworkInfo) intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO); // trinea BEGIN /** * modified by trinea@trinea.cn @2013/04/01, resume download only when network type is wifi */ if (info != null && info.isConnected() && info.getType() == ConnectivityManager.TYPE_WIFI) { // trinea END startService(context); } } else if (action.equals(Constants.ACTION_RETRY)) { |
表示只有连接wifi时才唤醒service去检查是否下载
(3) 修改DownloadThread.java
Java
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/** * Check if the download has been paused or canceled, stopping the request appropriately if it * has been. */ private void checkPausedOrCanceled(State state) throws StopRequestException { synchronized (mInfo) { if (mInfo.mControl == Downloads.Impl.CONTROL_PAUSED) { Xlog.i(Constants.DL_ENHANCE, "DownloadThread: checkPausedOrCanceled: user pause download"); throw new StopRequestException( Downloads.Impl.STATUS_PAUSED_BY_APP, "download paused by owner"); } if (mInfo.mStatus == Downloads.Impl.STATUS_CANCELED) { throw new StopRequestException(Downloads.Impl.STATUS_CANCELED, "download canceled"); } } // if policy has been changed, trigger connectivity check if (mPolicyDirty) { // trinea BEGIN /** * add by trinea@trinea.cn @2013/04/01, when switched from wifi to 3g, pause all download */ NetworkInfo info = mSystemFacade.getActiveNetworkInfo(mInfo.mUid); if (info != null && !info.isConnected()) { mInfo.mStatus = Downloads.Impl.STATUS_WAITING_FOR_NETWORK; } // trinea END checkConnectivity(); } } |
表示如果网络变化并且表示网络断开时，下载状态变为等待网络。
4、Bug修改
(1) 当存储空间不足时，利用DownloadManager下载，只显示通知栏提示，在下载管理UI中不显示
DownloadManager的Cursor runQuery(ContentResolver resolver, String[] projection, Uri baseUri)函数修改如下：
Java
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if ((mStatusFlags & STATUS_RUNNING) != 0) { parts.add(statusClause("=", Downloads.Impl.STATUS_RUNNING)); // trinea BEGIN parts.add(statusClause("=", Downloads.Impl.STATUS_INSUFFICIENT_SPACE_ERROR)); // trinea END } |
DownloadManager的CursorTranslator类的private int translateStatus(int status) 函数修改如下：
Java
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// trinea BEGIN case Downloads.Impl.STATUS_INSUFFICIENT_SPACE_ERROR: // trinea END case Downloads.Impl.STATUS_RUNNING: return STATUS_RUNNING; |
5、编译安装
修改后是需要重新编译的，需同时编译framweork和DownloadProvider。
framework编译命令为：./makeMtk model mm frameworks/base/core/
编译后apk所在路径为out\target\product\model\system\framework\secondary_framework.jar，之后push到system/framework重启即可。编译命令中model为机型，非mtk平台命令有所不同
DownloadProvider编译命令为./makeMtk model mm packages/providers/DownloadProvider/
编译后apk所在路径为out\target\product\model\system\app\DownloadProvider.apk，之后push到system/app即可(可能需要先删除/system/app/目录下的DownloadProvider.odex)
