LockFileEx
內(nèi)容
VB聲明 |
||
Declare Function LockFileEx Lib "kernel32" Alias "LockFileEx" (ByVal hFile As Long, ByVal dwFlags As Long, ByVal dwReserved As Long, ByVal nNumberOfBytesToLockLow As Long, ByVal nNumberOfBytesToLockHigh As Long, lpOverlapped As OVERLAPPED) As Long |
||
說(shuō)明 |
||
與LockFile相似，只是它提供了更多的功能 |
||
返回值 |
||
Long，非零表示成功，零表示失敗。會(huì)設(shè)置GetLastError |
||
參數(shù)表 |
||
參數(shù) |
類型及說(shuō)明 |
|
hFile |
Long，欲鎖定文件的句柄 |
|
dwFlags |
Long，指定下述一個(gè)或兩個(gè)常數(shù) |
|
LOCKFILE_FAIL_IMMEDIATELY |
指出如鎖定失敗，函數(shù)應(yīng)返回一個(gè)錯(cuò)誤。否則，應(yīng)用程序線程就會(huì)暫時(shí)掛起，并一直等待，直到能進(jìn)行鎖定為止 |
|
LOCKFILE_EXCLUSIVE_LOCK |
指出鎖定區(qū)域不可由另一個(gè)線程或進(jìn)程讀寫(xiě)。否則這個(gè)區(qū)域就只能防范“寫(xiě)”——其他進(jìn)程仍然能夠讀取鎖定區(qū)域的內(nèi)容 |
|
dwReserved |
Long，未使用，設(shè)為零 |
|
nNumberOfBytesToLockLow |
Long，鎖定區(qū)域包含字符數(shù)的低32位 |
|
nNumberOfBytesToLockHigh |
Long，鎖定區(qū)域包含字符數(shù)的高32位 |
|
lpOverlapped |
OVERLAPPED，包含了文件中相對(duì)于鎖定區(qū)域起始處的偏移量 |
|
注解 |
||
鎖定區(qū)域不可重疊操作（即多個(gè)進(jìn)程同時(shí)操作） |
||