在項目中需要用
FileSystemWatcher對單個文件內容進行監視，文件中每添加一行則需要Fire相應的事件，代碼如下
???
public
?
class
?CommandWatcher
????
{
????
????????
public
?
event
?EventHandler
<
CommandEventArgs
>
?CommandHandler;
??????
????????
Fields
?Fields
????????
public
?CommandWatcher(
string
?cmdfile)
????????
{
????????????
this
.fileName?
=
?cmdfile;
????????????isChangeImmediate?
=
?
true
;
?????????
????????}
????????
????????
//
????????
//
?Summary:
????????
//
?????Raises?the?System.IO.FileSystemWatcher.Changed?event.
????????
//
????????
//
?Parameters:
????????
//
???e:
????????
//
?????A?System.IO.FileSystemEventArgs?that?contains?the?event?data.
????????
protected
?
void
?OnChanged(
object
?sender,?FileSystemEventArgs?e)???
????????
{
????????????ReloadFile();
????????}
????
????????
//
????????
//
?Summary:
????????
//
?????Raises?the?System.IO.FileSystemWatcher.Error?event.
????????
//
????????
//
?Parameters:
????????
//
???e:
????????
//
?????An?System.IO.ErrorEventArgs?that?contains?the?event?data.
????????
protected
?
void
?OnError(
object
?sender,?ErrorEventArgs?e)
????????
{
????????}
????????
//
????????
//
?Summary:
????????
//
?????Raises?the?System.IO.FileSystemWatcher.Renamed?event.
????????
//
????????
//
?Parameters:
????????
//
???e:
????????
//
?????A?System.IO.RenamedEventArgs?that?contains?the?event?data.
????????
protected
?
void
?OnRenamed(
object
?sender,?RenamedEventArgs?e)
????????
{
????????}
????????
///
?
<summary>
????????
///
?Hook?up?for?the?currently?selected?monitoring?method.
????????
///
?
</summary>
????????
public
?
void
?Start()
????????
{
????????????
if
?(isChangeImmediate)
????????????
{
????????????????
//
?stop?timer?if?running
????????????????ClearTimer();
????????????????
//
?If?a?file?is?set?and?the?watcher?has?not?been?set?up?yet?then?create?it
????????????????
if
?(
null
?
!=
?fileName?
&&
?
null
?
==
?watcher)
????????????????
{
????????????????????
string
?path?
=
?Path.GetDirectoryName(fileName);
????????????????????
string
?baseName?
=
?Path.GetFileName(fileName);
????????????????????
//
?Use?the?FileSystemWatcher?class?to?detect?changes?to?the?log?file?immediately
????????????????????
//
?We?must?watch?for?Changed,?Created,?Deleted,?and?Renamed?events?to?cover?all?cases
????????????????????watcher?
=
?
new
?System.IO.FileSystemWatcher(path,?baseName);
????????????????????FileSystemEventHandler?handler?
=
?
new
?FileSystemEventHandler(OnChanged);
????????????????????watcher.Changed?
+=
?handler;
????????????????????watcher.Created?
+=
?handler;
????????????????????watcher.Deleted?
+=
?handler;
????????????????????watcher.Renamed?
+=
?OnRenamed;
????????????????????
//
?Without?setting?EnableRaisingEvents?nothing?happens
????????????????????watcher.EnableRaisingEvents?
=
?
true
;
????????????????}
????????????}
????????????
else
????????????
{
????????????????
//
?On?a?timer?so?clear?the?watcher?if?previously?set?up
????????????????ClearWatcher();
????????????????
int
?numSeconds?
=
?
5
;
???????????????
????????????????
if
?(
null
?
!=
?timer)
????????????????
{
????????????????????
//
?Timer?is?already?running?so?just?make?sure?the?interval?is?correct
????????????????????
if
?(timer.Interval?
!=
?
1000
?
*
?numSeconds)
????????????????????
{
????????????????????????timer.Interval?
=
?
1000
?
*
?numSeconds;
????????????????????}
????????????????}
????????????????
else
????????????????
{
????????????????????
//
?Fire?up?a?timer?if?the?user?entered?a?valid?time?interval
????????????????????
if
?(
0
?
!=
?numSeconds)
????????????????????
{
????????????????????????timer?
=
?
new
?System.Windows.Forms.Timer();
????????????????????????timer.Interval?
=
?
1000
?
*
?numSeconds;
????????????????????????timer.Tick?
+=
?timerTick;
????????????????????????timer.Start();
????????????????????}
????????????????}
????????????}
????????????
this
.ReloadFile();
????????}
????????
void
?timerTick(
object
?sender,?EventArgs?e)
????????
{
????????????UpdateBasedOnFileTime();
????????}
????????
///
?
<summary>
????????
///
?Update?the?log?file?if?the?modified?timestamp?has?changed?since?the?last?time?the?file?was?read.
????????
///
?
</summary>
????????
private
?
void
?UpdateBasedOnFileTime()
????????
{
????????????
if
?(
null
?
!=
?fileName)
????????????
{
????????????????
//
?This?returns?"12:00?midnight,?January?1,?1601?A.D."?if?the?file?does?not?exist
????????????????DateTime?newLastModifiedTime?
=
?File.GetLastWriteTime(fileName);
????????????????
if
?((newLastModifiedTime.Year?
<
?
1620
?
&&
?newLastModifiedTime?
!=
?lastModifiedTime)
????????????????????
||
?newLastModifiedTime?
>
?lastModifiedTime)
????????????????
{
????????????????????
//
OnLogFileChanged();
????????????????????ReloadFile();
????????????????}
????????????}
????????}
????????
///
?
<summary>
????????
///
?Read?the?log?file.
????????
///
?
</summary>
????????
///
?
<remarks>
If?the?user?has?some?text?selected?then?keep?that?text?selected.
</remarks>
????????
private
?
void
?ReloadFile()
????????
{
????????????
if
?(reloadingFile)?
return
;?
//
?already?busy?doing?this
????????????reloadingFile?
=
?
true
;
????????????
try
????????????
{
????????????????
if
?(
null
?
==
?fileName)
????????????????
{
???????????????????
//
?textBoxContents.Text?=?"";
????????????????}
????????????????
else
????????????????
{
????????????????????
string
?newFileLines?
=
?
""
;
????????????????????lastModifiedTime?
=
?File.GetLastWriteTime(fileName);?
//
?Remember?when?we?last?read?in?this?file
????????????????????
long
?newLength?
=
?
0
;??
//
?will?be?set?properly?later?if?all?is?well
????????????????????
bool
?fileExists?
=
?File.Exists(fileName);
????????????????????
bool
?needToClear?
=
?
!
fileExists;
????????????????????
if
?(fileExists)
????????????????????
{
????????????????????????
//
?It?is?possible?the?file?will?be?in?use?when?we?read?it?(especially?if?using?Immediate?mode)
????????????????????????
//
?So,?we?will?try?up?to?5?times?to?access?the?file
????????????????????????
int
?count?
=
?
0
;
????????????????????????
bool
?success?
=
?
false
;
????????????????????????
while
?(count?
<
?
5
?
&&
?
!
success)
????????????????????????
{
????????????????????????????
try
????????????????????????????
{
????????????????????????????????
//
?Open?with?the?least?amount?of?locking?possible
????????????????????????????????
using
?(FileStream?stream?
=
?File.Open(fileName,?FileMode.Open,?FileAccess.ReadWrite,?FileShare.ReadWrite))
????????????????????????????????
{
????????????????????????????????????newLength?
=
?stream.Length;
????????????????????????????????????
if
?(newLength?
>=
?lastFileSize)
????????????????????????????????????
{
????????????????????????????????????????stream.Position?
=
?lastFileSize;??
//
?Only?read?in?new?lines?added
????????????????????????????????????}
????????????????????????????????????
else
????????????????????????????????????
{
????????????????????????????????????????needToClear?
=
?
true
;
????????????????????????????????????}
????????????????????????????????????
using
?(StreamReader?reader?
=
?
new
?StreamReader(stream))
????????????????????????????????????
{
????????????????????????????????????????newFileLines?
=
?reader.ReadToEnd();
????????????????????????????????????????
if
?(newFileLines?
!=
?
string
.Empty)
????????????????????????????????????????
{
????????????????????????????????????????????
if
?(
this
.CommandHandler?
!=
?
null
)
????????????????????????????????????????????????
this
.CommandHandler(
this
,?
new
?CommandEventArgs(newFileLines));
????????????????????????????????????????}
??????????????????????????????????????
????????????????????????????????????????
//
string?[]tmp?=?newFileLines.Split(seprater,?StringSplitOptions.RemoveEmptyEntries);
????????????????????????????????????}
????????????????????????????????}
????????????????????????????????success?
=
?
true
;
????????????????????????????}
????????????????????????????
catch
?(IOException)
????????????????????????????
{
????????????????????????????????System.Threading.Thread.Sleep(
50
);?
//
?Give?a?little?while?to?free?up?file
????????????????????????????}
????????????????????????????
++
count;
????????????????????????}
????????????????????}
????????????????????
//
?Remember?the?current?file?length?so?we?can?read?only?newly?added?log?lines?the?next?time?the?log?file?is?read
????????????????????lastFileSize?
=
?newLength;
????????????????????
if
(lastFileSize?
>
?
1024
?
*
?
1024
?
*
?
2
)
????????????????????
{
????????????????????????File.Delete(fileName);
????????????????????????File.Create(fileName);
????????????????????}
???????????????????
???????????????
????????????????????
if
?(
0
?
!=
?newFileLines.Length)
????????????????????
{
????????????????????????
//
?See?if?this?log?file?has?proper?cr/lf?and?if?not?convert
????????????????????????
int
?lastCr?
=
?newFileLines.LastIndexOf(
'
\n
'
);
????????????????????????
if
?(
-
1
?
!=
?lastCr?
&&
?
0
?
<
?lastCr)
????????????????????????
{
????????????????????????????
if
?(newFileLines[lastCr?
-
?
1
]?
!=
?
'
\r
'
)
????????????????????????????
{
????????????????????????????????
//
?OK,?this?file?only?has?Cr?and?we?need?to?convert?to?CrLf
????????????????????????????????newFileLines?
=
?newFileLines.Replace(
"
\n
"
,?
"
\r\n
"
);
????????????????????????????}
????????????????????????}
????????????????????}
????????????????????
???????????????????
????????????????}
????????????}
????????????
finally
????????????
{
????????????????
//
?Put?clearing?this?flag?in?a?finally?so?we?know?it?will?be?cleared
????????????????reloadingFile?
=
?
false
;
????????????}
????????}
????????
///
?
<summary>
????????
///
?Cleanup?the?
<see?cref="Timer"/>
????????
///
?
</summary>
????????
private
?
void
?ClearTimer()
????????
{
????????????
if
?(
null
?
!=
?timer)
????????????
{
????????????????timer.Tick?
-=
?timerTick;
????????????????timer.Dispose();
????????????????timer?
=
?
null
;
????????????}
????????}
????????
///
?
<summary>
????????
///
?Cleanup?the?
<see?cref="FileSystemWatcher"/>
????????
///
?
</summary>
????????
private
?
void
?ClearWatcher()
????????
{
????????????
if
?(
null
?
!=
?watcher)
????????????
{
????????????????FileSystemEventHandler?handler?
=
?
new
?FileSystemEventHandler(OnChanged);
????????????????watcher.Changed?
-=
?handler;
????????????????watcher.Created?
-=
?handler;
????????????????watcher.Deleted?
-=
?handler;
????????????????watcher.Renamed?
-=
?OnRenamed;
????????????????watcher.Dispose();
????????????????watcher?
=
?
null
;
????????????}
????????}
????}
更多文章、技術交流、商務合作、聯系博主
微信掃碼或搜索：z360901061
微信掃一掃加我為好友
QQ號聯系： 360901061
您的支持是博主寫作最大的動力，如果您喜歡我的文章，感覺我的文章對您有幫助，請用微信掃描下面二維碼支持博主2元、5元、10元、20元等您想捐的金額吧，狠狠點擊下面給點支持吧，站長非常感激您！手機微信長按不能支付解決辦法：請將微信支付二維碼保存到相冊，切換到微信，然后點擊微信右上角掃一掃功能，選擇支付二維碼完成支付。
【本文對您有幫助就好】元
