This bug include the below improvement when import and export table data
(1)when import data, if use the XLS or XLSX file , will probably cause that the memory is not enough.
By investigate, find two cause. one is that the JXL or POI API, when use these API, will load the all data into the memory.
other is coding, when import data by multi-thread, every thread will load a copy of the data.
The first problem can not be solved. the second problem is solved. And when memory is not enough, will pop up the tip.
(2)When export data, if use XLS, will probably cause the memory is not enough, the root cause is that JXL API only can write once.
the solution is when memory is not enough, popup the tip dialog.
(3)When export data, if use XLSX, the temp files are not deleted after export data.
the solution is that after export data, delete these temp file.
Hence, when import data, at best use CSV format file. when export data, at best use CSV and XLSX format file.