http断点续传简单实现（java)

/* +NiCt S  
**SiteFileFetch.java <zAYq=IU  
*/ 6V#EEb  
package NetFox; )me`Ud
 
import java.io.*; 2Je]dj4  
import java.net.*; -_O jiQR  
i1bmUKZ8'L  
#ZP;] W  
public class SiteFileFetch extends Thread { }-u%6KZ   
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?a1pO#{Dg  
SiteInfoBean siteInfoBean = null; //文件信息Bean 6)20%*[  
long[] nStartPos; //开始位置 (qz)3Fa  
long[] nEndPos; //结束位置 7QoMroR  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 \F""G,AWq{  
long nFileLength; //文件长度 K5jeazasp  
boolean bFirst = true; //是否第一次取文件 8yH
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boolean bStop = false; //停止标志 7;&,LH  
File tmpFile; //文件下载的临时信息 Sn' +~6i  
DataOutputStream output; //输出到文件的输出流 ,g,Hb\_R)  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） pmO0/ty  
public SiteFileFetch(SiteInfoBean bean) throws IOException i` ay9J8N  
{ ,@Kn@%?$  
siteInfoBean = bean; ]e+&Pxw]e  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); XGjFb4Tw
7  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); QBN\wL8g  
if(tmpFile.exists ()) v53|)]V  
{ ~03M
H'  
bFirst = false; RAuVRm=E  
read_nPos(); w8 `1'*HG  
} #l3)3k*;  
else Tf?`_jL  
{
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nStartPos = new long[bean.getNSplitter()]; sH >zsc  
nEndPos = new long[bean.getNSplitter()]; rUAt`ykTmN  
}  _-9cGm v  
8%xBSob{j  
1-&L-c.  
{];-b0MS~  
} n+i=Ff  
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public void run() ErQ6a%~,  
{ UP%6s:>:  
//获得文件长度 hhFO,
  
//分割文件 7T t!hf  
//实例FileSplitterFetch ]0j_yX  
//启动FileSplitterFetch线程 !]RSG^%s{  
//等待子线程返回 mZjpPlJ  
try{ xtLP4VL  
if(bFirst)
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{  _+(@?  
nFileLength = getFileSize(); ,|.}6\zl*{  
if(nFileLength == -1) ik;F@kdm`  
{ tV>qV\>  
System.err.println("File Length is not known!"); N]6t)Zv  
} e0otr_)3F  
else if(nFileLength == -2) %~PT7"4  
{ }&==;7,O  
System.err.println("File is not access!"); \j3dB tc  
} ?,8+1"|$A]  
else ju.pQ=PSX  
{ rPqM&&+  
for(int i=0;i<nStartPos.length;i++) a(D=ZKbVU  
{ 9
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); ~131|e`C  
} p8?v o?^  
for(int i=0;i<nEndPos.length-1;i++) ecR)8^1 '  
{ ]^>:)q  
nEndPos = nStartPos[i+1]; 6 .)Xeb"  
} 3
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nEndPos[nEndPos.length-1] = nFileLength; vLyazVj..  
}
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} 5Z5x\CcC3  
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//启动子线程 t8rFn  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; D|Wlq~IpQ  
for(int i=0;i<nStartPos.length;i++) Kfr1k  
{ kxJ[Bi#  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), j0V/\Ep)T<  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ;ko6igx)+  
nStartPos,nEndPos,i); )5gj0#|CG@  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 7')W+`o8eL  
fileSplitterFetch.start(); VuH ->  
} <JU3sXl  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), "k{so',7z  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); =WBfaxL}  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", TsGx2[  
nEndPos = " + nFileLength); Q~VM.G  
// fileSplitterFetch[nPos.length-1].start(); /kg#i&bP~  
u*rP8GuS  
(V]3w  
//等待子线程结束 P)J-'2{  
//int count = 0; js@L%1r#L  
//是否结束while循环 6Io}3}3  
boolean breakWhile = false; zB~<@  
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f.+1Ubq!5  
while(!bStop) WvSm!W  
{ V[KN,o{6  
write_nPos(); pt,L  
Utility.sleep(500); a !%,2|U  
breakWhile = true; ;l ZKgi8`  
Fb=uN   
N&?V=X  
for(int i=0;i<nStartPos.length;i++) 1gbFl/i6T  
{ *X
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if(!fileSplitterFetch.bDownOver) %A=/(%T>  
{ 6=;(~k&x9:  
breakWhile = false; ck5cO-1>6  
break; c@3 5\!9  
} oW6Hufu+o  
} t"q'"FX  
if(breakWhile) ?4Rd4sIM$u  
break; UU MB"3e  
wCruj`$  
|D"L!+J-$  
//count++; #?jsC)  
//if(count>4) )H{1Xjh-  
// siteStop(); 3IlVSR^py  
} L\:m)g,F.  
c {%mi  
40h$- VYT/  
System.err.println("文件下载结束！"); 80[# 6`  
} vk48&8  
catch(Exception e){e.printStackTrace ();} kwc Cf2  
} 3mo4;F,h9  
RO,TNS~  
7Y(Dg`8G  
//获得文件长度 \&;y:4&l8  
public long getFileSize() jTIG#J)  
{ A@)Q-V8*9s  
int nFileLength = -1; ['.])  
try{ 1ruI++P  
URL url = new URL(siteInfoBean.getSSiteURL()); aSX4~UYB=  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); i#t-p\Tcz  
httpConnection.setRequestProperty("User-Agent","NetFox"); )Ak#1w&q  
R^o535pozc  
nH6SA1$kW  
int responseCode=httpConnection.getResponseCode(); Sq ]gU  
if(responseCode>=400) a'?;;ZC-  
{ a(]&H "  
processErrorCode(responseCode); k1f<(@*`  
return -2; //-2 represent access is error cr{yy :D  
} 4A6Y \ZXI  
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JDJ  
o&Xp%}TI  
String sHeader; ~44u_^a  
az0=jou<Zl  
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for(int i=1;;i++) H/x0'  
{ S3Gr}N  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); @qp6Y_,E[  
//Utility.log(in.readLine()); `v``}8tm  
sHeader=httpConnection.getHeaderFieldKey(i); +u0of^}=  
if(sHeader!=null) r+E!V'{C  
{ |xFA}
  
if(sHeader.equals("Content-Length")) WF~BCP$OR  
{ z}u`45W+  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); WX?nq'nr  
break; 8^y=YUT  
} K
{v^Y,B  
} _Fa\y ZX  
else /-[vC$B"  
break; iIX%%r+  
} N{HAWB{  
} i~]
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catch(IOException e){e.printStackTrace ();} 9d#?,:JG  
catch(Exception e){e.printStackTrace ();} >*ls} q^  
w+ !c9  
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Utility.log(nFileLength); zP #:Tv'  
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return nFileLength; 0j!3\=P$  
} |nx3x  

Q
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+?U[362>  
//保存下载信息（文件指针位置） z:f&k}(  
private void write_nPos() s_NY#MPz[  
{ 6LCtWX  
try{ n~ad#iN  
output = new DataOutputStream(new FileOutputStream(tmpFile)); n!/0yR2S  
output.writeInt(nStartPos.length); |w|c!;,  
for(int i=0;i<nStartPos.length;i++) +a.2\Qt2A  
{ q<q IT  
// output.writeLong(nPos); !\R5/-_UU  
output.writeLong(fileSplitterFetch.nStartPos); q*&H  
output.writeLong(fileSplitterFetch.nEndPos); auK9wQ%\  
} {im?tZ,  
output.close(); %akW43cE  
} TF:
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catch(IOException e){e.printStackTrace ();} D=z~]a31!  
catch(Exception e){e.printStackTrace ();} VU,G.eLW  
} q"2APvsvp  
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//读取保存的下载信息（文件指针位置） ZDmL?mC  
private void read_nPos() >B0AJW/u  
{ zb9G&'7  
try{ M@{?#MkS%  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); n<8WjrK  
int nCount = input.readInt(); ,:(s=JN+  
nStartPos = new long[nCount]; L'{W|Xb+  
nEndPos = new long[nCount]; qBBCnT  
for(int i=0;i<nStartPos.length;i++) A|f6H6UUx  
{ hxL?6mhY  
nStartPos = input.readLong(); "ZGP,=?y2  
nEndPos = input.readLong(); ,EEAxmf  
} +S4>}2N33  
input.close(); &f.|MNz;  
} 3Y38lP:>h  
catch(IOException e){e.printStackTrace ();} rq3f/_#L!O  
catch(Exception e){e.printStackTrace ();} r=n{3o+  
} 17KQ  
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private void processErrorCode(int nErrorCode) 5]Rbzg2t  
{ akyMW7'3V<  
System.err.println("Error Code : " + nErrorCode); bp9R
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} >p
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 6a,8t  
n%F _3`  
//停止文件下载 ,K,st+s|  
public void siteStop() s>6h]H  
{ jXA/G%:[  
bStop = true; uluAqDz`  
for(int i=0;i<nStartPos.length;i++) pCIS82L  
fileSplitterFetch.splitterStop(); 0R)x"4Ww  
Bz }nP9  
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} DK?aFSf\  
} (o|bst][S  
//负责部分文件的抓取 BZW03e8|  
**FileSplitterFetch.java phu,&DS!  
*/ 8HKv_vl  
package NetFox; 
o
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s*
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import java.io.*; N0S^{j,i  
import java.net.*; ;VKWY  
*?t$Q|
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public class FileSplitterFetch extends Thread { DehjV6t  
s_y8+BJaV  
vcu@_N1Dc  
String sURL; //File URL KuJ9bn{u!C  
long nStartPos; //File Snippet Start Position {BJ>x:2  
long nEndPos; //File Snippet End Position p48enH8CO  
int nThreadID; //Thread's ID
_ VuWo  
boolean bDownOver = false; //Downing is over 0
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boolean bStop = false; //Stop identical WCsf_1  
FileAccessI fileAccessI = null; //File Access interface GrG'G(NQ  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException rB".!b  
{ 1+*sEIC"  
this.sURL = sURL; 5/nL[4Z  
this.nStartPos = nStart;
'l5
  
this.nEndPos = nEnd; &6s&nx  
nThreadID = id; )$S=
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 ![B|Nxq}@  
} rNV3-#kU  
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<?B3^z$  
public void run() hdw.S`~}%  
{ #l}Fk
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while(nStartPos < nEndPos && !bStop) ljK?2z>  
{ `]W9Fj<1j  
:-jbIpj'  
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try{ OS#aYER~/  
URL url = new URL(sURL); >G|RVB  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); B$rhsK
%  
httpConnection.setRequestProperty("User-Agent","NetFox"); Sa<(F[p`  
String sProperty = "bytes="+nStartPos+"-"; =.8n K y  
httpConnection.setRequestProperty("RANGE",sProperty); B<EqzP*#  
Utility.log(sProperty); 9 3)fC  
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2*75*EQCH  
InputStream input = httpConnection.getInputStream(); *>W<n1r@]  
//logResponseHead(httpConnection); ]|!|3lQ  
nPvys~D  
Q*<KX2O  
byte[] b = new byte[1024]; t>"`rcg  
int nRead; 8/>.g.]  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) EY"of[p  
{ gf>H-718F  
nStartPos += fileAccessI.write(b,0,nRead); 0+iRgnd9?  
//if(nThreadID == 1) #,z-Pj?O!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); &V*MNi,4Z  
} mQ`atFz:Z  
wY ItG"+6  
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Utility.log("Thread " + nThreadID + " is over!"); R*bx&..<  
bDownOver = true; sPQjB[  
//nPos = fileAccessI.write (b,0,nRead); S~:uOm2t\  
} r2#G|/=@  
catch(Exception e){e.printStackTrace ();} lUjZ=3"'
 
} _<f%== I'  
} [4#HuO@h  
>;9g`d  
q`p0ul,n  
//打印回应的头信息 )]q Qgc&  
public void logResponseHead(HttpURLConnection con) X(/fE?%;  
{ VX8rM!3  
for(int i=1;;i++) 1_{e*=/y  
{ }i^
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String header=con.getHeaderFieldKey(i); *~P| ? D'  
if(header!=null) =aB+|E  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); >/\TG8t,f  
Utility.log(header+" : "+con.getHeaderField(header)); Crc6wmp  
else NTq_"`JjZ  
break; s~Ivq+ipr;  
} k-jFT3b$  
} S6M7^_B4F  
^&&Wv'7XQ  
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public void splitterStop() _k]R6V:  
{ bxYSZCo*  
bStop = true; mQ1  
} TXM/+
sd  
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O$,
 
} \\ItN  
* ;sz/.  
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/* %pjY^tM/  
**FileAccess.java @,oc%m  
*//文件访问(定位，写) 3q`f|r  
package NetFox; MD$W;rk(Hn  
import java.io.*; mRAt5a#is  
k(RKAFjY  
j_,/U^Ws|f  
public class FileAccessI implements Serializable{ E8av/O VUd  
lfb+)s  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 #akJhy@m$  
RandomAccessFile oSavedFile; Xbmsq,*]  
long nPos; Z{vc6oj  
u:J(0re  
T"htWo{v>  
public FileAccessI() throws IOException JZ`u?ZaJ/s  
{ l@SV!keQ  
this("",0); 0#Gm# =F  
} "gNi}dB<]  

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public FileAccessI(String sName,long nPos) throws IOException Dn<3#V  
{ )
6%*=-  
oSavedFile = new RandomAccessFile(sName,"rw"); e=h-}XRC  
this.nPos = nPos; T\Xf0|y  
oSavedFile.seek(nPos); #xx.yn(7  
} T\.~!Q
  
+fY@q,`  
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public synchronized int write(byte[] b,int nStart,int nLen) -flcB|I`  
{ f{2UL ?y  
int n = -1; +a,#
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try{ dpE^BWv3  
oSavedFile.write(b,nStart,nLen); h{"SV*Xpk/  
n = nLen; D8! Y0  
} Pi1LOCq  
catch(IOException e) - s'W^(  
{ Q'jGNWep  
e.printStackTrace (); f9UDH8X  
} ~rI2 RJ  
6wpu[  
fk15O_#3  
return n; fX:q]  
} 9[\do@  
:I"22EH  
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} k;<@2C  
g:~q&b[q6  
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/* RLex#j  
**SiteInfoBean.java 13 L&f\b  
*/ 2V;{@k  
package NetFox; >q?{'#i /  
Iu0GOy*[  
 +fM8  
public class SiteInfoBean { G"3KYBN>  
\nyqW4nTm  
2sgp$r  
private String sSiteURL; //Site's URL lAG@nh^  
private String sFilePath; //Saved File's Path wvisu\V  
private String sFileName; //Saved File's Name @$kzes\  
private int nSplitter; //Count of Splited Downloading File a5m[ N'kah  
~Fo2MwE2~  
id+EBVHAd  
public SiteInfoBean() :I/9j=@1  
{//nSplitter的缺省值为5 HZ!<dy3  
//default value of nSplitter is 5 z|],s]F>G  
this("","","",5); -]}#Z:&  
} lmUCrs37  
XySkm2y  
f'"PQr^9  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) /T {R\  
{ ~C>;0a;<:  
sSiteURL= sURL; `K@N\VM  
sFilePath = sPath; ' xaPahx;  
sFileName = sName; IAUc.VH  
this.nSplitter = nSpiltter; wAu]U6!  
M`Wk@t6>  
q},,[t  
} %L)QTv/  
BE&8E\w  
)mAD<y+  
public String getSSiteURL() JgHYuLB  
{ dg*xo9Xi`  
return sSiteURL; EJz!#f~  
} . WJ  
jR:
\D_:  
R$IsP,Uw  
public void setSSiteURL(String value) e\aW~zs2  
{ ;B2&#kot7  
sSiteURL = value; 0H%zkJ>Q  
} ro?.w  
S{F\_'%  
[V8^}s}tF  
public String getSFilePath() ^; U}HAY  
{ \Js*>xA  
return sFilePath; Nk%$;
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} (p'/a.bn  
wZCboQ,  
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public void setSFilePath(String value) Jb9@U/<\  
{ I)jAdd
 
sFilePath = value; 8?'=Aeo  
} ;){ZM,Ox  
]fh(b)8_,  
t]v
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public String getSFileName() o*d(;  
{ +7lr#AvU/  
return sFileName; vd^Z^cpip  
} Xg
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{Z
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1)~9Eku6K  
public void setSFileName(String value) n/BoK6g  
{
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sFileName = value; WSU/Z[\`H  
} dpge:Qhr  
Zn*W2s^^{  
(}T},ygQ  
public int getNSplitter() |V}tTx1  
{ ?qHQ#0 @y]  
return nSplitter; =<#++;!I  
} S}Z@g  
ghkV^ [  
X?u=R)uG  
public void setNSplitter(int nCount) xrNe:Aj  
{ &F;bg  
nSplitter = nCount; n^55G>"0|  
} {fEb>  
} j~+(#|  
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|z@AvS[  
/* Y)(w&E>1  
**Utility.java -!T24/l
 
*/ }a UQ#x  
package NetFox; y'oH>l+n  
\ ux{J  
|Q%nnN  
public class Utility { f/.f08  
!)J$f_88D  
)"tM[~e`  
public Utility() PbxQ \.  
{ - ?  i  
z~2;u5S&  
S;#7B?j  
} VggSDb  
J5f}-W@  
//线程睡眠 KxhWZ3  
public static void sleep(int nSecond) UpQda`rb  
{ g^=Ruh+  
try{ Ya<V@qd  
Thread.sleep(nSecond); ,k@iNid  
} "ZNy*.G|[  
catch(Exception e) ?< Ma4yl</  
{ |Zo36@s  
e.printStackTrace (); &`]T#">  
} 'c/8|9jX  
} M3d%$q)<rW  
x FvKjO)  
//日志 dgByl-8Q  
public static void log(String sMsg) 8{&.[SC7  
{ %l%2 hvGZ  
System.err.println(sMsg); |w>b0aY  
} CNWA!1n^Hy  
i}
|jHlv  
@o<B>$tbu4  
public static void log(int sMsg) VGCd)&s  
{ &[PA?#I`  
System.err.println(sMsg); E3CwA8)k  
} KNF{NFk  
} < jX5}@`z  
*xx)j:Sc2  
r0\C2g_X  
/* {8;}y[R  
**TestMethod.java B1Z;  
*/ [ 'B u  
package NetFox; ]h`d>#Hw!  
1
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3;  
qckRX+P`  
public class TestMethod { %82:?fq  
OwDwa~  
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public TestMethod() Efpju(   
{ ///xx/weblogic60b2_win.exe anKflt3  
try{ ?ZhBS3L  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); TOvsW<cM
 
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); !b$~Sm)  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Z#kB+.U  
fileFetch.start(); G;pc,\MF  
} LS-_GslE7\  
catch(Exception e){e.printStackTrace ();} F+D e"^As  
e!k4Ij-]  
YQ1rS X3  
} 9D?JzTsyg  
\z@:OR,  
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public static void main(String[] args) :hf%6N='kI  
{ x97L>>|  
new TestMethod(); W:}t%agis  
} ATV|M[B  
} 0@ vzQ$  
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