InitCustomMaker

function	interface	available implemented components	the default components	description
database	FileDownloadDatabase	DefaultDatabaseImpl	DefaultDatabaseImpl	the customized database component, what is used for storing data
okHttpClient	okHttpClient	okHttpClient	okHttpClient	the customized okHttpClient，what isused for downloading file
outputStreamCreator	FileDownloadOutputStream	FileDownloadRandomAccessFile、FileDownloadBufferedOutputStream、FileDownloadOkio	FileDownloadRandomAccessFile	the customized output stream, what isused for writing the input stream to the file for downloading.
maxNetworkThreadCount	-	-	3	the maximum count of the network thread, what is the number of simultaneous downloads