【我的Android进阶之旅】 解决bug: Expected file scheme in URI: content://downloads/my_downloads/12

一、错误描述

今天测试MM用HTC手机测试某个模块的时候crash了，抓log后发现是使用DownloadManager下载apk安装包然后自动安装的时候，抛了异常：java.lang.IllegalArgumentException: Expected file scheme in URI: content://downloads/my_downloads/12

具体crash错误信息如下所示：

11-30 09:24:21.933 28279 28279 E AndroidRuntime: FATAL EXCEPTION: main
11-30 09:24:21.933 28279 28279 E AndroidRuntime: Process: com.xtc.watch, PID: 28279
11-30 09:24:21.933 28279 28279 E AndroidRuntime: java.lang.RuntimeException: Error receiving broadcast Intent { act=android.intent.action.DOWNLOAD_COMPLETE flg=0x10 pkg=com.xtc.watch (has extras) } in
com.xtc.watch.service.compatible.VersionCompatibleUpdateService$DownloadCompleteReceiver@33fa7ec
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:934)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at android.os.Handler.handleCallback(Handler.java:739)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at android.os.Handler.dispatchMessage(Handler.java:95)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at android.os.Looper.loop(Looper.java:168)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at android.app.ActivityThread.main(ActivityThread.java:5885)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at java.lang.reflect.Method.invoke(Native Method)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)
11-30 09:24:21.933 28279 28279 E AndroidRuntime: Caused by: java.lang.IllegalArgumentException: Expected file scheme in URI: content://downloads/my_downloads/12
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at java.io.File.checkURI(File.java:223)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at java.io.File.<init>(File.java:175)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at com.xtc.watch.service.compatible.VersionCompatibleUpdateService.a(Unknown Source)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at com.xtc.watch.service.compatible.VersionCompatibleUpdateService.a(Unknown Source)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at com.xtc.watch.service.compatible.VersionCompatibleUpdateService$DownloadCompleteReceiver.onReceive(Unknown Source)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:915)
11-30 09:24:21.933 28279 28279 E AndroidRuntime:        ... 7 more
11-30 09:24:21.939  1785  3503 E ActivityManager: App crashed! Process: com.xtc.watch

二、错误分析

进入File.java查看代码，

/**
* Constructs a new File using the path of the specified URI. {@code uri}
* needs to be an absolute and hierarchical Unified Resource Identifier with
* file scheme and non-empty path component, but with undefined authority,
* query or fragment components.
*
* @param uri
*            the Unified Resource Identifier that is used to construct this
*            file.
* @throws IllegalArgumentException
*             if {@code uri} does not comply with the conditions above.
* @see #toURI
* @see java.net.URI
*/
public File(URI uri) {
// check pre-conditions
checkURI(uri);
this.path = fixSlashes(uri.getPath());
}

checkURI(URI uri)的源代码如下：

private static void checkURI(URI uri) {
if (!uri.isAbsolute()) {
throw new IllegalArgumentException("URI is not absolute: " + uri);
} else if (!uri.getRawSchemeSpecificPart().startsWith("/")) {
throw new IllegalArgumentException("URI is not hierarchical: " + uri);
}
if (!"file".equals(uri.getScheme())) {
throw new IllegalArgumentException("Expected file scheme in URI: " + uri);
}
String rawPath = uri.getRawPath();
if (rawPath == null || rawPath.isEmpty()) {
throw new IllegalArgumentException("Expected non-empty path in URI: " + uri);
}
if (uri.getRawAuthority() != null) {
throw new IllegalArgumentException("Found authority in URI: " + uri);
}
if (uri.getRawQuery() != null) {
throw new IllegalArgumentException("Found query in URI: " + uri);
}
if (uri.getRawFragment() != null) {
throw new IllegalArgumentException("Found fragment in URI: " + uri);
}
}

原来就是下面这一段代码抛出的异常，如果uri不是以file开头的就抛异常IllegalArgumentException(“Expected file scheme in URI: ” + uri)，

if (!"file".equals(uri.getScheme())) {
throw new IllegalArgumentException("Expected file scheme in URI: " + uri);
}

而我们的uri 是通过下面代码获取而来的

Uri downloadFileUri = manager.getUriForDownloadedFile(downId);
File file = new File(new URI(downloadFileUri.toString()));

得到的uri信息为

content://downloads/my_downloads/12

因此就抛了该异常出来。

getUriForDownloadedFile(long id)源代码如下：

/**
* Returns the {@link Uri} of the given downloaded file id, if the file is
* downloaded successfully. Otherwise, null is returned.
*<p>
* If the specified downloaded file is in external storage (for example, /sdcard dir),
* then it is assumed to be safe for anyone to read and the returned {@link Uri} corresponds
* to the filepath on sdcard.
*
* @param id the id of the downloaded file.
* @return the {@link Uri} of the given downloaded file id, if download was successful. null
* otherwise.
*/
public Uri getUriForDownloadedFile(long id) {
// to check if the file is in cache, get its destination from the database
Query query = new Query().setFilterById(id);
Cursor cursor = null;
try {
cursor = query(query);
if (cursor == null) {
return null;
}
if (cursor.moveToFirst()) {
int status = cursor.getInt(cursor.getColumnIndexOrThrow(COLUMN_STATUS));
if (DownloadManager.STATUS_SUCCESSFUL == status) {
int indx = cursor.getColumnIndexOrThrow(
Downloads.Impl.COLUMN_DESTINATION);
int destination = cursor.getInt(indx);
// TODO: if we ever add API to DownloadManager to let the caller specify
// non-external storage for a downloaded file, then the following code
// should also check for that destination.
if (destination == Downloads.Impl.DESTINATION_CACHE_PARTITION ||
destination == Downloads.Impl.DESTINATION_SYSTEMCACHE_PARTITION ||
destination == Downloads.Impl.DESTINATION_CACHE_PARTITION_NOROAMING ||
destination == Downloads.Impl.DESTINATION_CACHE_PARTITION_PURGEABLE) {
// return private uri
return ContentUris.withAppendedId(Downloads.Impl.CONTENT_URI, id);
} else {
// return public uri
String path = cursor.getString(
cursor.getColumnIndexOrThrow(COLUMN_LOCAL_FILENAME));
return Uri.fromFile(new File(path));
}
}
}
} finally {
if (cursor != null) {
cursor.close();
}
}
// downloaded file not found or its status is not 'successfully completed'
return null;
}

三、错误解决

将之前查找下载好的apk文件的代码

Uri downloadFileUri = manager.getUriForDownloadedFile(downId);

File file = new File(new URI(downloadFileUri.toString()));

改为通过downId来查询DownloadManager下载的数据库的记录，然后查找本地文件的路径，如下所示：

Cursor c = manager.query(new DownloadManager.Query().setFilterById(downId));
if(c != null){
c.moveToFirst();
int fileNameIdx = c.getColumnIndex(DownloadManager.COLUMN_LOCAL_FILENAME);
String fileName = c.getString(fileNameIdx);
File file  = new File(fileName);
LogUtil.d(TAG, "安装文件：" + file.getAbsolutePath());
c.close();
}

安装apk的代码由

//自动安装apk
Intent install = new Intent(Intent.ACTION_VIEW);
install.setDataAndType(downloadFileUri, "application/vnd.android.package-archive");
install.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(install);

改为

//自动安装apk
Intent install = new Intent(Intent.ACTION_VIEW);
//install.setDataAndType(downloadFileUri, "application/vnd.android.package-archive");
install.setDataAndType(Uri.parse("file://" + fileName.toString()), "application/vnd.android.package-archive");
install.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(install);

这样通过查询本地真实的下载好apk的真实本地路径，然后再进行安装的话就不会报异常了。

参考文章：

http://blog.csdn.net/q445697127/article/details/40537945

http://www.xuebuyuan.com/2163407.html

http://www.2cto.com/kf/201502/376975.html

作者：欧阳鹏 欢迎转载，与人分享是进步的源泉！

转载请保留原文地址：http://blog.csdn.net/ouyang_peng/article/details/53404379