From how to submit the form apk file ?

This is from a form , I submit jpg, png, zip format so no problem , submit . apk format can not upload, What is the reason ? . apk not convert binary upload it ?
I will not let this control with uploadily upload the apk files compressed into rar, zip nor
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visual landlord struts, and do not set the file upload size. struts default upload file size is 2M.
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files will not be too big . You upload small to see. .
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do not upload an error message ? Stickers ah.
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404 can not enter directly the background , you can change the jpg pictures uploaded into the background
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I uploaded on the size of 3M

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set constant attribute it, this is about 10M
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this configuration where ah
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really is the problem, what can be set up thank
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really is this problem, what can be set up    thanks   get points slightly.