http断点续传简单实现（java)

/* Q"KH!Bu%P  
**SiteFileFetch.java x\lua  
*/ &"=inkh  
package NetFox; v+Hu=RZE  
import java.io.*; 6d,"GT  
import java.net.*; f?)qZ
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public class SiteFileFetch extends Thread { ~&g:7f|X  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Mb-C DPT  
long[] nStartPos; //开始位置 tU
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long[] nEndPos; //结束位置 3N?uY2  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 #+XKfumLk  
long nFileLength; //文件长度 f"/NY
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boolean bFirst = true; //是否第一次取文件 I;=}@]9  
boolean bStop = false; //停止标志 p0b&CrALx  
File tmpFile; //文件下载的临时信息 uu HWN|  
DataOutputStream output; //输出到文件的输出流 tP`,Egf"g  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） h)sc-e
 
public SiteFileFetch(SiteInfoBean bean) throws IOException G'!Hc6OZ  
{ VXC_Y  
siteInfoBean = bean; *<J**FhcMu  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ?k/Uw'J4u/  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ?(F~9V  
if(tmpFile.exists ()) Ltc>@  
{ RP6QS)|  
bFirst = false; q0Fy$e]u  
read_nPos(); t1xX B^.M{  
} Fm:Ri$iT  
else g8^$,  
{ qz?9:"~$C  
nStartPos = new long[bean.getNSplitter()]; k9a-\UIMet  
nEndPos = new long[bean.getNSplitter()]; $H?v  
} 
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th !Gc  
} Ta~Ei=d^  
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public void run() d^4!=^HN  
{ V;9.7v  
//获得文件长度 &6h,'U  
//分割文件 }6`#u:OZ  
//实例FileSplitterFetch `g3H;E  
//启动FileSplitterFetch线程 hX8;G!/  
//等待子线程返回 yYF%U7N/n  
try{ I~EJctOG  
if(bFirst) "H6DiPh.E  
{ .F |yxj;I7  
nFileLength = getFileSize(); @N34 Q-l  
if(nFileLength == -1) ho 4~-xmN  
{ )%P!<|s:5  
System.err.println("File Length is not known!"); ZfoI7<?33  
} &!_>J0  
else if(nFileLength == -2) nD|Bo 9  
{ ?z p$Wz;k  
System.err.println("File is not access!"); (;\JCeGA  
} !Vy/-N  
else o[aRG7C  
{ fE,\1LK4  
for(int i=0;i<nStartPos.length;i++) ^k/@y@%  
{ dCN4aY[d  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); K%)u zP  
} (zte'F4  
for(int i=0;i<nEndPos.length-1;i++) ] vQn*T"^  
{ kk& ([xqU  
nEndPos = nStartPos[i+1]; <$R'y6U:  
} \vsfY   
nEndPos[nEndPos.length-1] = nFileLength; "p0e6Z=  
} ?$%#y u#.  
} wm_xH_{F  
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//启动子线程 /U+0T>(HS  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; PIl:z?q({  
for(int i=0;i<nStartPos.length;i++) g=Rl4F]  
{ ;X*I,g.+H  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), :.J Ad$>P  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), =HH}E/9z  
nStartPos,nEndPos,i); s: pmB\  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); .liVlo@  
fileSplitterFetch.start(); "`s{fy~mV  
} e+Vn@-L;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), PVLLuv  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); c7Jfo x V  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", V9bn  
nEndPos = " + nFileLength); _ 5nLrn,~  
// fileSplitterFetch[nPos.length-1].start(); v*U OD'tk  
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//等待子线程结束 imC>T!-7  
//int count = 0; I82GZL  
//是否结束while循环 ~x4]^XS  
boolean breakWhile = false; M8(N9)N  
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while(!bStop) =*>ri  
{ )
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write_nPos(); gwO]U=Y  
Utility.sleep(500); +~Wg@  
breakWhile = true; clyZD`*  
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for(int i=0;i<nStartPos.length;i++) fAYp\k  
{ wkc)2z   
if(!fileSplitterFetch.bDownOver) }xJ ).D  
{ )&Af[mS  
breakWhile = false; =jz [}5  
break; )jm!bR`  
} yGj'0c::  
} b v5BV  
if(breakWhile) @|N{EI  
break; 2Kwr
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//count++; 29z$z$l4  
//if(count>4) E&G]R!  
// siteStop(); <aSjK#  
} 1K\zamBg  
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System.err.println("文件下载结束！"); 4fSGc8  
} o@2Y98~Q}  
catch(Exception e){e.printStackTrace ();} \8Y62  
} &uP,w#  
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//获得文件长度 xaI)d/  
public long getFileSize() .:r l<.  
{ [$]qJ~kz  
int nFileLength = -1; Yc^;?n`x  
try{ 6
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URL url = new URL(siteInfoBean.getSSiteURL()); Xnc?o
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); erlg\-H
 
httpConnection.setRequestProperty("User-Agent","NetFox"); YUjKOPN  
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;
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int responseCode=httpConnection.getResponseCode(); wNvq['P  
if(responseCode>=400) D4Z7j\3a
 
{ 1EiSxf  
processErrorCode(responseCode); ({$>o]<h  
return -2; //-2 represent access is error 9w!PA-) L  
} ~`yO@f;D  
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String sHeader; ,76Q*p  
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=[do([A  
for(int i=1;;i++) adY ,Nz  
{ %_(Xn  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); {&TP&_|H  
//Utility.log(in.readLine()); 9s4>hw@u  
sHeader=httpConnection.getHeaderFieldKey(i); br;~}GR_h
 
if(sHeader!=null) .C|dGE?,  
{ yU|=)p5  
if(sHeader.equals("Content-Length")) fL(_V/p^  
{ Q3<ctd\]Y  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); >zX`qv&>  
break; dt5`UBvUg  
} &0x;60b  
} VV-%AS
6;  
else Qa#Em1co  
break; |BEoF[1  
} ]kdU]}z  
} ?Gx-q+H  
catch(IOException e){e.printStackTrace ();} U+G8Hs/y  
catch(Exception e){e.printStackTrace ();} ovk^  
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Utility.log(nFileLength); P" aw--f(  
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return nFileLength; n#PXMD*  
} K |^OnM  
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//保存下载信息（文件指针位置） ZFC&&[%-sG  
private void write_nPos() @rE+H 5  
{ @yNCWa~N  
try{ ~Dbu;cqR@  
output = new DataOutputStream(new FileOutputStream(tmpFile)); RPw1i*  
output.writeInt(nStartPos.length); a|-B#S  
for(int i=0;i<nStartPos.length;i++) m$`4.>J  
{ ffy,ds_7  
// output.writeLong(nPos); t=IM"ZgfL  
output.writeLong(fileSplitterFetch.nStartPos); 0ZJrK\K;  
output.writeLong(fileSplitterFetch.nEndPos); th|'t}bWV  
} &[t} /+)  
output.close(); )1/J5DI @8  
} _};T:GOT  
catch(IOException e){e.printStackTrace ();} jwp?eL!7  
catch(Exception e){e.printStackTrace ();} Bq~?!~\?.  
} CqLAtS X7  
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//读取保存的下载信息（文件指针位置） =>*9"k%m  
private void read_nPos() LG vPy  
{ *5mJA -[B+  
try{ T5eJIc3a"  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); H,(4a2zx  
int nCount = input.readInt(); LHMA-0$?)  
nStartPos = new long[nCount]; Mk/ZEyq^  
nEndPos = new long[nCount]; :M$8<03>F  
for(int i=0;i<nStartPos.length;i++) Q"k #eEA  
{ _|>bOI  
nStartPos = input.readLong(); i\zN1T_  
nEndPos = input.readLong(); MZt&HbD-  
} Na.)!h_Kn'  
input.close(); b v4  
} :+<GJj_d+  
catch(IOException e){e.printStackTrace ();} Ai~d  
catch(Exception e){e.printStackTrace ();} i9^m;Y)^I  
} a/Cc.s   
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private void processErrorCode(int nErrorCode) \tfhF#'  
{ 6C- !^8[f  
System.err.println("Error Code : " + nErrorCode); T#3`&[  
} /mQ9}E4X  
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//停止文件下载 9u1Fk'cxG,  
public void siteStop() Wdp4'rB  
{ ]4[^S.T=  
bStop = true; #{~3bgY  
for(int i=0;i<nStartPos.length;i++) gcF V$  
fileSplitterFetch.splitterStop(); ;m}o$`  
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} ?mh0^G  
} M5{vYk>,1Q  
//负责部分文件的抓取 +IM6 GeH  
**FileSplitterFetch.java XBos^Q  
*/ iI@(Bl
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package NetFox; TnLblkX  
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import java.io.*; &P(vm@*  
import java.net.*; 9=G dj!L  
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public class FileSplitterFetch extends Thread { k(wJ6pc  
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String sURL; //File URL wi S8S{K5  
long nStartPos; //File Snippet Start Position [KsVI.gn  
long nEndPos; //File Snippet End Position J:2Su1"ODh  
int nThreadID; //Thread's ID nEh^{6  
boolean bDownOver = false; //Downing is over hJGWa%`  
boolean bStop = false; //Stop identical Iq(;?_  
FileAccessI fileAccessI = null; //File Access interface o[>p  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException MJ~)CiKgN  
{ dMoN1
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this.sURL = sURL; *Bx'g| u  
this.nStartPos = nStart; o88Dz}a  
this.nEndPos = nEnd; YL@d+ -\  
nThreadID = id; \?NT,t=3J  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ?]2OT5@&s  
} mG+hLRTXP  
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public void run() WyJXT.  
{ Ge4tc  
while(nStartPos < nEndPos && !bStop) +( V+XT  
{ R,ddH[3  

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try{
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URL url = new URL(sURL); fa;GM7<e)  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); <>K@#|%Y&  
httpConnection.setRequestProperty("User-Agent","NetFox"); gfAVxMg  
String sProperty = "bytes="+nStartPos+"-"; TkV$h(#!f&  
httpConnection.setRequestProperty("RANGE",sProperty); g bwg3$!9  
Utility.log(sProperty); !Mk:rO-L  
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InputStream input = httpConnection.getInputStream(); o)IcAqN$H  
//logResponseHead(httpConnection); vh6#Bc)i%w  
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byte[] b = new byte[1024]; 9{5 c}bX  
int nRead; /pDI \]  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) dM3V2TT  
{ 0B[eG49  
nStartPos += fileAccessI.write(b,0,nRead); sTGe=}T8  
//if(nThreadID == 1) /yj-^u\R  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); .
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} 7<c&)No
;  
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Utility.log("Thread " + nThreadID + " is over!"); <jRs/?1R  
bDownOver = true; Gq
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//nPos = fileAccessI.write (b,0,nRead); ]qk/V:H:  
} G.c@
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catch(Exception e){e.printStackTrace ();} ?4}EhXR(  
} r.;(Kx/M  
} =m=utd8  
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//打印回应的头信息 =.Q|gZ   
public void logResponseHead(HttpURLConnection con) zwKm;;v8  
{ "RJf2~(ZX  
for(int i=1;;i++) ))>)qav  
{ ZW|VAn'>  
String header=con.getHeaderFieldKey(i); ^#L?HIM  
if(header!=null) |d1%N'Ll  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); R!.HS0i.  
Utility.log(header+" : "+con.getHeaderField(header)); c~UYs\  
else _;+N=/l0  
break; U-EX)S^T[{  
} 0IEFCDeCO  
} ^R4eW|H  
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public void splitterStop() nNff~u)I  
{ W[3)B(Vq<E  
bStop = true; `N"fsEma  
} tEl4 !vA  
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} 'yM)>]u"  
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/* cuP5cL/Y  
**FileAccess.java S:"t]gbF =  
*//文件访问(定位，写) N{G+|Wm
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package NetFox; UI:{*N**Z  
import java.io.*; eMvb*X6  
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public class FileAccessI implements Serializable{ c#e_Fs  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 0fPqO2  
RandomAccessFile oSavedFile; %?EOD=e=  
long nPos; *<
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public FileAccessI() throws IOException c])b?dJ*  
{ 5Ffz^;i  
this("",0); %zyMWC  
} soZw""|v  
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public FileAccessI(String sName,long nPos) throws IOException >M^ 1m(  
{ 0n,5"B  
oSavedFile = new RandomAccessFile(sName,"rw"); Sh]x`3 ).  
this.nPos = nPos; ~&~%qu  
oSavedFile.seek(nPos); z[S,hD\w  
} S~F:%@,*  
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public synchronized int write(byte[] b,int nStart,int nLen) ]T(O;y*m   
{ "=<lPi  
int n = -1; UUY-EC7X  
try{ k&DHQvfB  
oSavedFile.write(b,nStart,nLen); bYdC.AE  
n = nLen; "ngYh]Git$  
} KW&&AuPb}  
catch(IOException e) r[Q$w>  
{ n a2"Sy=Yi  
e.printStackTrace (); &bj :,$@  
} =tH+e7it  
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return n; RQ{w`>K  
} S/d})8~.  
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} gH\r# wy|  
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/* #G.3a]p}"  
**SiteInfoBean.java 2a=WT`xf?  
*/ %T6#c7U_  
package NetFox; ''BP4=r5n  
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public class SiteInfoBean { d0 V>;Q  
:/%Vpdd@  
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private String sSiteURL; //Site's URL h;4g#|,  
private String sFilePath; //Saved File's Path |7`Vw Z  
private String sFileName; //Saved File's Name Uzb"$Ue4  
private int nSplitter; //Count of Splited Downloading File M:`hb$k:  
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public SiteInfoBean() C3@.75-E  
{//nSplitter的缺省值为5 F`I-G~e  
//default value of nSplitter is 5 sjTsaM;<  
this("","","",5); $xu?zd"  
} ;wQWt_OtuJ  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) j5'Jp}  
{ fr#lH3  
sSiteURL= sURL; `8dE8:#Y  
sFilePath = sPath; Xp} vJl   
sFileName = sName; ~#a1]w  
this.nSplitter = nSpiltter; @IiT8B  
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} dWqFP  
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public String getSSiteURL() iQ9#gPk_9  
{ U[A*A^$c}  
return sSiteURL; Ab2g),;c  
} gv[7h'}<  
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public void setSSiteURL(String value) V
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{ [QZ~~(R  
sSiteURL = value; zt,-O7I'1  
} n~&R_"mv(  
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public String getSFilePath() }qD.Ek  
{ _yWH\5@  
return sFilePath; Y$ChMf  
} W;N/Y3Lb  
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public void setSFilePath(String value) Eq8
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{ <;6])  
sFilePath = value; 40#KcbMa|  
} 7 YK+TGmU^  
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public String getSFileName() kQ#eWk J,  
{ *c AoE l  
return sFileName; `>sqP aD  
} DYWC]*  
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public void setSFileName(String value) R&4E7wrdP  
{ ]~qN<x  
sFileName = value; 6gKOpa  
} m_(hCY=Q$  
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public int getNSplitter() s
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{ \9}5}X_x.  
return nSplitter; @qC:% |>  
}
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s{k\1P(G}  
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public void setNSplitter(int nCount) xF/DYXC{8  
{ .HQ<6k:  
nSplitter = nCount; 'QS"4EvdD  
} ltrSTH,kL  
} eurudl  
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/* 5i^vN"J  
**Utility.java tbPPI)lu  
*/ p&4n3%(R@  
package NetFox; >o} ati  
s =5H.q%PV  
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public class Utility { bvgD;:Aj  
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public Utility() >ek%P;2w>  
{ od}x7RI%m  
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} yo.SPd="Vx  
,>UmKrYo  
//线程睡眠 {T.Vu]L80  
public static void sleep(int nSecond) ->hxHr`!%a  
{ m6x. "jG  
try{ Yy)a,clZ*$  
Thread.sleep(nSecond); `_'Dj>  
} 3kQ^f=Wd  
catch(Exception e) ^d9
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{ gkz#kiGF  
e.printStackTrace (); LgNNtZ&F  
} 4:@|q:DR  
} B<XPu=|  
3b
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//日志 E)hinH  
public static void log(String sMsg) +=h!?<*C8  
{  >Y'yM4e*  
System.err.println(sMsg); jp^WsHI3  
} FqsjuU@l  
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na3kHx@  
public static void log(int sMsg) @L!#i*> 9  
{ W[>TqT63  
System.err.println(sMsg); |I}+!DDuv  
} SU'1#$69F  
} YhT1P fl  
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/* (<C%5x
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**TestMethod.java 6h_k`z  
*/ 'Xl>,\'6  
package NetFox; 0:Y`#0qK  
<u?hdwW\  
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public class TestMethod { Gr@{p"./z  
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)Zf}V0!?+  
public TestMethod() N
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{ ///xx/weblogic60b2_win.exe _Af4ct;ng  
try{ :3>yr5a7-  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); L[G\+   
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 5SL>q`t.bd  
SiteFileFetch fileFetch = new SiteFileFetch(bean); pInWKj[y1  
fileFetch.start(); ePRMv  
} {}o>nenx\  
catch(Exception e){e.printStackTrace ();} ')<FLCFwT  
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} r)5\3j[P  
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public static void main(String[] args) 7oe@bS/Z  
{ M y"!j,Up  
new TestMethod(); .(1j!B4^  
} 0^&R7Rv c  
} xnQGCw?S&}  
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