upload file docs api

upload file docs api

Hi
I am developing java application and i need a hint to how using post method to upload file  https://www.zoho.com/docs/zoho-docs-api.html#upload
Parameter Value Description
filename string Mandatory. Name of the file to be uploaded
fid string Optional. id of the folder where files to be uploaded to a folder
wsid string Optional. id of the workspace where files to be uploaded to a workspace
content string Mandatory. Actual document content to be uploaded
content here is string value not  FileInputStream as in  https://www.zoho.com/crm/help/api/uploadfile.html
so i need to know how to upload file using java.