http断点续传简单实现（java)

/* I,`D&  
**SiteFileFetch.java (Db*.kd8,  
*/ NIXcib"tG  
package NetFox; V]CK'   
import java.io.*; VgC9'"|  
import java.net.*; fSQ3 :o  
-
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uN?O*h/(  
public class SiteFileFetch extends Thread { "n2xn%t{  
*M\i4FO8  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ^VLUZ  
long[] nStartPos; //开始位置 O]4 x;`)  
long[] nEndPos; //结束位置 i+ &lMgh  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 /{#_Um0.  
long nFileLength; //文件长度 #t9=qR~"  
boolean bFirst = true; //是否第一次取文件 bZ@53  
boolean bStop = false; //停止标志 piM11W}|/  
File tmpFile; //文件下载的临时信息 LZAj4|~,m  
DataOutputStream output; //输出到文件的输出流 4Xb}I;rM  
;hRpAN  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） F~0%j}ve  
public SiteFileFetch(SiteInfoBean bean) throws IOException fKK-c9F  
{ #+DmH  
siteInfoBean = bean; kBQenMm  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); )V =K#MCK  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ]bU'G$Qm&s  
if(tmpFile.exists ()) lO[jf6gB  
{ < $?}^ 0R  
bFirst = false; hZ/  
read_nPos(); 3
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} Rb>RjHo S  
else %Fm;LQa ]  
{ ZK_@.O+]  
nStartPos = new long[bean.getNSplitter()]; u:u 7|\q  
nEndPos = new long[bean.getNSplitter()]; p'c<v)ia  
} Ch&]<#E>`  
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} ydFhw}1>  
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public void run() G?1V~6  
{ F0^~YYRJV  
//获得文件长度 =4\~M"
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//分割文件 7Mg7B
  
//实例FileSplitterFetch !U~#H_  
//启动FileSplitterFetch线程 5i-;bLm  
//等待子线程返回 *RE-K36m|u  
try{ zZ0V6T}
  
if(bFirst) yl+)I  
{ 3S|;yOl#X  
nFileLength = getFileSize(); 4O"kOEkKT>  
if(nFileLength == -1) tnbs]6  
{ MxA'T(Ay  
System.err.println("File Length is not known!"); UNLNY,P/!)  
} 4J2F>m40  
else if(nFileLength == -2) gbv[*R{<%  
{ W_n.V" hN  
System.err.println("File is not access!"); 72.IhBNtT  
} r&~iEO|?\  
else kAQZj3P]  
{ _q}%!#4  
for(int i=0;i<nStartPos.length;i++) {+mkXp])R  
{ 4$w-A-\t  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); h#;K9#x6  
} 
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for(int i=0;i<nEndPos.length-1;i++) vszAr
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{ `mTxtuid{  
nEndPos = nStartPos[i+1]; RWcQT`  
} 69[k ?')LM  
nEndPos[nEndPos.length-1] = nFileLength; vXZz=E AH  
} 3;gtuqwD$  
} &b8D'XQu  
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2Yjysn  
//启动子线程 j!n> d  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; +~]g&Mf6o  
for(int i=0;i<nStartPos.length;i++) e(N <Mf  
{ gZSi\m>  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 3goJ(XI  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), B\w`)c  
nStartPos,nEndPos,i); H;L&G|[  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); a{.n(M  
fileSplitterFetch.start(); _( Cp   
} ->{WO+6(  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), CU&,Kq@  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ,gD i)]  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 2p[3Ap  
nEndPos = " + nFileLength); ^yZEpQN_  
// fileSplitterFetch[nPos.length-1].start(); h /Nt
92  
]gk1h=Y~h  
}PuO$ L  
//等待子线程结束 >GR
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//int count = 0; :UciFIa  
//是否结束while循环 ((q(Q9(F  
boolean breakWhile = false; 7NEn+OI4  
c:TP7"vG  
aoX$,~oI5  
while(!bStop) C"WZsF^3  
{ yp/*@8%_E  
write_nPos(); J6P Tkm}^  
Utility.sleep(500); /Qy0vAvJ  
breakWhile = true;
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for(int i=0;i<nStartPos.length;i++) x N)Ck76  
{ N"y4#W(Z@  
if(!fileSplitterFetch.bDownOver) "(GeW286k  
{ _>I5Ud8(-  
breakWhile = false; GK+w1%6)  
break; @RW%EXKt  
} 4Rq"xYGXh  
} `Fr$q1qae{  
if(breakWhile) ;GSj}Nq  
break; *uR'eXW  
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cyyFIJj]  
//count++; jT',+  
//if(count>4) ?=&*6H_v  
// siteStop(); j*}xe'#  
} 'z/hj>B<  
Jjv&@a}  
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System.err.println("文件下载结束！"); Sb.;$Be5g  
} 10(N|2'q  
catch(Exception e){e.printStackTrace ();} 1)y}.y5S  
} r>\.b{wI  
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&/p9+gd  
//获得文件长度 }J1#UH_E  
public long getFileSize() gC.T
5,tn  
{ 9L,T@#7  
int nFileLength = -1; KC'{>rt7  
try{ .E(Ucnz/  
URL url = new URL(siteInfoBean.getSSiteURL()); h.NA$E?7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); \Uiw: ,  
httpConnection.setRequestProperty("User-Agent","NetFox"); TQE_zOa:  
3c)xNXq m  
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int responseCode=httpConnection.getResponseCode(); gueCP+a_  
if(responseCode>=400) }tN"C 3)@  
{ udMq>s;  
processErrorCode(responseCode); wbTw\b=  
return -2; //-2 represent access is error t V</x0#  
} WD<M U ]  
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;IyQqP#,<  
String sHeader; /KkUCq2A  
7y!{lr=n  
:v#3;('7  
for(int i=1;;i++) ^+88z>  
{ U:H*b{`TU  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ~_Aclm?  
//Utility.log(in.readLine()); [1Rs~T"  
sHeader=httpConnection.getHeaderFieldKey(i); z
@2NAC  
if(sHeader!=null) ^c*'O0y[D  
{ WE\V<MGS/  
if(sHeader.equals("Content-Length")) u7K0m! jW  
{ 3LG)s:p$/  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); @>?&Mw\c  
break; V<b"jCXI  
} IsI\T8yfc  
} r>Vgo):s  
else MOXDR  
break; -g~$HTsGm  
} vq|W&  
} Y:O%x
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catch(IOException e){e.printStackTrace ();} (fC [Y  
catch(Exception e){e.printStackTrace ();} *x$\5;A  
?g1%-F+  
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Utility.log(nFileLength); *+5AN306  
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return nFileLength; @X:P`?("^  
} e(sQgtM6  
;sDFTKf  
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//保存下载信息（文件指针位置） tJc9R2  
private void write_nPos() ^8DC W`V  
{ _rOKif?5  
try{ ZhW>H  
output = new DataOutputStream(new FileOutputStream(tmpFile)); &q>=6sQvf  
output.writeInt(nStartPos.length); ~b*f2UVs  
for(int i=0;i<nStartPos.length;i++) VHJOj  
{ UW!!!  
// output.writeLong(nPos); n>{>3?  
output.writeLong(fileSplitterFetch.nStartPos); D{~I  
output.writeLong(fileSplitterFetch.nEndPos); 42mdak}\  
} ):1NeJOFF  
output.close(); A~u-Iv(U  
} i!9yN:m0  
catch(IOException e){e.printStackTrace ();} ;kY'DKL(  
catch(Exception e){e.printStackTrace ();} pno]Bld'z  
} zGF_c9X  
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//读取保存的下载信息（文件指针位置） !q mnMY$  
private void read_nPos() m z) O  
{ Mz_*`lRN  
try{ 1d,;e:=j  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); crG+BFi
 
int nCount = input.readInt(); ew
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nStartPos = new long[nCount]; se2ay_<F+  
nEndPos = new long[nCount]; t[|^[%i  
for(int i=0;i<nStartPos.length;i++) $5Jo%K%  
{ *%bQp  
nStartPos = input.readLong(); u?r=;:N|y  
nEndPos = input.readLong(); C;QIp6"1  
}  `C9/=  
input.close(); g4^=Q'j-  
} |hk?'WGc`0  
catch(IOException e){e.printStackTrace ();} %#7Yr(&
 
catch(Exception e){e.printStackTrace ();} |]y]K%  
} Ksr.'  
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private void processErrorCode(int nErrorCode) O0[.*xG  
{ bxLeQWr6  
System.err.println("Error Code : " + nErrorCode); gTa6%GM>  
} ~H`~&?  
{N!Xp:(<7_  
qVjl8%)  
//停止文件下载 U51C /A  
public void siteStop() EFSln*|  
{ lB3@jF  
bStop = true; g:V8"'  
for(int i=0;i<nStartPos.length;i++) ?Zu2=<DU  
fileSplitterFetch.splitterStop(); no).70K  
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} i^`]TOP  
} x=]PE}<E  
//负责部分文件的抓取 F6,[!.wl  
**FileSplitterFetch.java !0p_s;uu,W  
*/ *c<0cHv*  
package NetFox; e!BablG[  
]w*w@:Zk  
6'E3Q=}d  
import java.io.*; _ljdo`j#N  
import java.net.*; >AFX}N#  
33/aYy  
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public class FileSplitterFetch extends Thread { j6@5"wx  
98"/]ER
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String sURL; //File URL "'i" @CR  
long nStartPos; //File Snippet Start Position wX7|a/|@  
long nEndPos; //File Snippet End Position \l$gcFXb  
int nThreadID; //Thread's ID ~Q4 emgBD  
boolean bDownOver = false; //Downing is over mV\QZfoF  
boolean bStop = false; //Stop identical T;{M9W+  
FileAccessI fileAccessI = null; //File Access interface 35>VCjCw0  
#I]5)XT  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 8~q%H1[I\N  
{ !w+A3Z>V  
this.sURL = sURL; D`|.%  
this.nStartPos = nStart; =~7%R.U([e  
this.nEndPos = nEnd; L!fiW`>0G  
nThreadID = id; 39j "z8n  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 #a :W  
} 8+gti*C?\  
@#wBK3Ut^  
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public void run() zzq7?]D  
{ *C>B-j$  
while(nStartPos < nEndPos && !bStop) w"p,6Ew
 
{ EKwA1,Xz  
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try{ OB-2xmZW  
URL url = new URL(sURL); ^Md
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); jSY&P/[xb  
httpConnection.setRequestProperty("User-Agent","NetFox"); Woo2hg-ti  
String sProperty = "bytes="+nStartPos+"-"; SHM ?32'  
httpConnection.setRequestProperty("RANGE",sProperty); KZK9|121  
Utility.log(sProperty); }4 p3m]  
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InputStream input = httpConnection.getInputStream(); S}0W<H P  
//logResponseHead(httpConnection); W>ZL[B
Q  
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hJ)>BeH0  
byte[] b = new byte[1024]; F0cde  
int nRead; ?zypF 5a  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) \ow3_^Bk  
{ QH_0U`3  
nStartPos += fileAccessI.write(b,0,nRead); aFZu5-=x  
//if(nThreadID == 1) $?38o6  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8XwZJ\5  
} 0zSRk]i.f  
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Utility.log("Thread " + nThreadID + " is over!"); tcovMn'  
bDownOver = true; .Pp;%  
//nPos = fileAccessI.write (b,0,nRead); OHz>B!`  
} P>*g'OK^!G  
catch(Exception e){e.printStackTrace ();} :'\4%D=w  
} aD2+9?m  
} M"q]jeaM  
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yM
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//打印回应的头信息 `5y+3v~"  
public void logResponseHead(HttpURLConnection con) Qv3g 4iJ  
{ NPN*k].  
for(int i=1;;i++) 5<%]6cx}  
{ n@3(bl
5{  
String header=con.getHeaderFieldKey(i); /F>\-    
if(header!=null) qDOJ;>I  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); l7rGz2:?  
Utility.log(header+" : "+con.getHeaderField(header)); 9u3~s<  
else (kECV8)2  
break; x#mZSSd  
} n+5X*~D  
} O@.afk"{  
410WWR&4_  
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public void splitterStop() wm3fd7T  
{ c$<7&{Pb  
bStop = true; %-zAV*>  
} /}~; b#t  
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} !&~8j7{  
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/* J- %YmUc)  
**FileAccess.java "@xF(fyg  
*//文件访问(定位，写) /]/3)@wT  
package NetFox; jGB2`^&d  
import java.io.*; 9]Q\Pr\Ub$  
"HWl7c3q  
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public class FileAccessI implements Serializable{ ulnG|3A9  
_8Si8+j  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 >$gWeFu  
RandomAccessFile oSavedFile; t7VXW{3  
long nPos; C[j'0@~V:B  
>x%Z^U  
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public FileAccessI() throws IOException wW4/]soM  
{ "%+C@>`(  
this("",0); Q+ ;6\.#r  
} A9lnQCsJ  
a#X[V5|6Q  
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public FileAccessI(String sName,long nPos) throws IOException
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{ H<dOh5MFh  
oSavedFile = new RandomAccessFile(sName,"rw"); ;9,<&fe
 
this.nPos = nPos; mw<LNnT{8  
oSavedFile.seek(nPos); V@jR8zv|_  
} I71kFtvcy*  
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public synchronized int write(byte[] b,int nStart,int nLen) ^s25z=^t  
{ umXa  
int n = -1; <C\snB  
try{ &Y"u*)bm  
oSavedFile.write(b,nStart,nLen); ^ N]u  
n = nLen; ya]CxnKR3  
} H"4^  
catch(IOException e) P@'<OI  
{ >JVZ@ PV H  
e.printStackTrace (); V7u;"vD  
} ' }rUbJo  
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return n; f>
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} QK-_~9V  
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} Le"$ksu>  
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/* ^-T!(P:  
**SiteInfoBean.java #KZ6S9>@
 
*/ ppIMaP  
package NetFox; l>)0OP]  
-~eNC^t;W  
vINm2%*zJ  
public class SiteInfoBean { |4BS\fx~N  
6/B"H#rN  
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private String sSiteURL; //Site's URL %qR
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private String sFilePath; //Saved File's Path XRVE8v+  
private String sFileName; //Saved File's Name TI:-Y@8  
private int nSplitter; //Count of Splited Downloading File MIasCH>r  
xlF$PpRNM  
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public SiteInfoBean() JnH>L|G{;%  
{//nSplitter的缺省值为5 6rMGlzuRo  
//default value of nSplitter is 5 FQ>KbZ
h  
this("","","",5); !'(bwbd  
} =@;uDu:Q  
s QfP8}U  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Q+gd|^Vc9  
{ ^il'
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sSiteURL= sURL; <SmXMruU  
sFilePath = sPath; BO<I/J~b  
sFileName = sName; w+gA3Dg  
this.nSplitter = nSpiltter; 5mdn77F_  
"WR)a`$UR  
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} k!Nl#.j  
'}4LHB;:  
!q;EC`i#  
public String getSSiteURL() % \Nfj)9  
{ =z^v)=uhp  
return sSiteURL; V|xKvH  
} 2[: *0 DV#  
!Vl>?U?AN  
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public void setSSiteURL(String value) 9{\eE]0
  
{ xTNWT_d  
sSiteURL = value; 6O8'T`F[  
} [xq"[*Evv  
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public String getSFilePath()
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{ JnE
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return sFilePath; ';4DUhp  
} \TqKm  
)]~'zOE_  
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public void setSFilePath(String value) ~E&drl\  
{ Rdao  
sFilePath = value; 'eg?W_zu  
} a}eM ny  
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public String getSFileName() pn?c6KvO  
{ TWE$@/9)g  
return sFileName; xo/[,rR  
} SOQm>\U'i  
h3Kv0^{  
wZN<Og+;  
public void setSFileName(String value) xB"o 7,  
{ Q| > \{M  
sFileName = value; |Z}uN!Jm  
} q5J6d+  
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public int getNSplitter() g(m3 &  
{ b$)b/=2  
return nSplitter; M?pu7wa  
} NidG|Yg~Z  
8_WFSF^  
tkU"
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public void setNSplitter(int nCount) R4=n">>Q  
{ Rg~ ~[6G>  
nSplitter = nCount; -#T?C]}  
} DPR=Xls  
} }l{r9ti  
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<*u[<  
/* hp?hb-4l  
**Utility.java >AIkkQT  
*/ gf2<dEff  
package NetFox; @A6P[r  
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public class Utility { >(+g:p  
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public Utility() .z7%74p  
{ @WVpDhG  
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} @mM'V5
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,&$=2<Dx  
//线程睡眠 c0M=T  
public static void sleep(int nSecond) 3]Rb2$p[=  
{ 4r5trquC  
try{ f%ude@E3  
Thread.sleep(nSecond); b#cXn4<3D  
} m }I@:s2  
catch(Exception e) $OU,| D  
{ !}fq%8"-  
e.printStackTrace (); o!6gl]U'y9  
} p<IMWe'tP  
} ??Zh$^No:  
NU>={9!  
//日志 9A0wiKp  
public static void log(String sMsg) :^".cs?g  
{ Lk{ES$  
System.err.println(sMsg); "bZ{W(h  
} x#z}A&  
7u/_3x1  

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public static void log(int sMsg) 6}bUX_!&s  
{ ?g*#ld()  
System.err.println(sMsg); 3dm lP2  
} 1I< <`7'  
} fW^\G2Fk  
[]R`h*#  
];X[xs  
/* lt 74`9,f  
**TestMethod.java c\.Hs9T >  
*/ D90m..\w  
package NetFox; %\OG#36  
)Zx;Z[  
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public class TestMethod { O/EI8Qvm  
os/_ObPiX  
@64PdM!L  
public TestMethod() 0N02E  
{ ///xx/weblogic60b2_win.exe y"4Nw]kU  
try{ D*!p8J8Ku  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); :ryyo$  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); nff X  
SiteFileFetch fileFetch = new SiteFileFetch(bean); OhUEp g[  
fileFetch.start(); Jo%5NXts4  
} dUAZDoLi  
catch(Exception e){e.printStackTrace ();} Z!\xVCG"q  
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} D vG9(Eh  
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public static void main(String[] args) ?LE\pk R  
{ ;+pS-Zb 6  
new TestMethod(); ySC;;k
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} 6:Eu[PE~w  
} /F#_~9JXG  
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