http断点续传简单实现（java)

/* @TX@78fWz=  
**SiteFileFetch.java |yzv o"3  
*/ Il(o[Q>jJ3  
package NetFox; 96
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import java.io.*; CSq|R-@<U  
import java.net.*; ksuePMIK  

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public class SiteFileFetch extends Thread { r jxkgd  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Ip=QtNW3\  
long[] nStartPos; //开始位置 LL)t)  
long[] nEndPos; //结束位置 %"fO^KA.h]  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 DI2e%`$  
long nFileLength; //文件长度 ls!A'@J  
boolean bFirst = true; //是否第一次取文件 !Ko>   
boolean bStop = false; //停止标志 T]tu#h{ a  
File tmpFile; //文件下载的临时信息 w?^[*_Y  
DataOutputStream output; //输出到文件的输出流 (w5cp!qW9J  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ID!S}D  
public SiteFileFetch(SiteInfoBean bean) throws IOException <)T~_s  
{ _@[W[=|H  
siteInfoBean = bean; b7I0R;Zj  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); J5HK1  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); !6RDq`  
if(tmpFile.exists ()) hfyU}`]  
{ !K}W.yv,  
bFirst = false; QRBx}!:NZ#  
read_nPos(); knph549  
} N[Ei%I  
else rxyeix  
{ a%si:_  
nStartPos = new long[bean.getNSplitter()]; -WF((s;<#  
nEndPos = new long[bean.getNSplitter()]; ~yw]<{?  
} ~D4l64  
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} ]H}2|~c  
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public void run() ?Z
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{ x4L3Z__  
//获得文件长度 Z
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//分割文件 >(.|oT\Tb  
//实例FileSplitterFetch =#y;J(>~|  
//启动FileSplitterFetch线程 PQSmBTs.  
//等待子线程返回 {cIk-nG-_  
try{ EK"/4t{L_  
if(bFirst) OW\vbWX  
{ 4m91XD  
nFileLength = getFileSize(); (B\ UZb  
if(nFileLength == -1) :Hm'o}  
{ JJ_Z{  
System.err.println("File Length is not known!"); -aok]w m  
} gH'hA'  
else if(nFileLength == -2) S\A0gOL^  
{ 6fo"k+S  
System.err.println("File is not access!"); H{=G\N{  
}
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else &;P\e  
{ {2P18&=  
for(int i=0;i<nStartPos.length;i++) @
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{ Y3&,U  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); sRT H_]c  
} EwFq1~  
for(int i=0;i<nEndPos.length-1;i++) KhB775  
{ ZSe30Rl\  
nEndPos = nStartPos[i+1]; *P`wuXn}  
} $o5i15Oy.  
nEndPos[nEndPos.length-1] = nFileLength; 0LL0
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} O(8CrKYY  
} np6G~0Y`  
.qZz'Eq[  
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//启动子线程 !0Nf`iCQ(  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; jF}kV%E  
for(int i=0;i<nStartPos.length;i++) 'hBnV xd&  
{ $u~ui@kB  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), U{oM*[  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), {._'Q
[  
nStartPos,nEndPos,i); S 4 17.n  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 87l*Y|osP  
fileSplitterFetch.start(); A~a 3bCX+"  
} b:Zh|-  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), [y'blCb  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 1#_pj eG  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", bs~P  
nEndPos = " + nFileLength); h>GbJ/^  
// fileSplitterFetch[nPos.length-1].start(); 2 >O[Y1  
X0P +[.i  
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//等待子线程结束 6X h7Bx1  
//int count = 0; v(.mM9>  
//是否结束while循环 =oL:|$
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boolean breakWhile = false;

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#9DJk,SP  
while(!bStop) hui #<2{  
{ 
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write_nPos(); 0:[A4S`X  
Utility.sleep(500); 0/f|Z
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breakWhile = true; ,(x`zpp _  
}>BNdm"Er  
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for(int i=0;i<nStartPos.length;i++) Ka(B&.  
{ '{ =F/q  
if(!fileSplitterFetch.bDownOver) P`Ku. ONQ  
{ Fh)xm* u(  
breakWhile = false; jH<Sf: Y(  
break; SEzjc ~@3  
} ,ESli/6  
} f]%SFQ+  
if(breakWhile) h?n?3x!(  
break; 3R%JmLM+R9  
w(ZZTVW-  

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//count++; O[MFp  
//if(count>4) RNB&!NC  
// siteStop(); }9\6!GY0  
} 61kSCu  
BI)C\D3[  
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System.err.println("文件下载结束！"); vPYHM2  
} %4!^AA%  
catch(Exception e){e.printStackTrace ();} #*CMf.OCh  
} ^ei[1#  
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BE@(| U  
//获得文件长度 X+A@//,7  
public long getFileSize() Posz|u<x  
{ J
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int nFileLength = -1; -d4v:Jab  
try{ 7SJ=2  
URL url = new URL(siteInfoBean.getSSiteURL()); 6?M/71
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); '62_q8:  
httpConnection.setRequestProperty("User-Agent","NetFox"); =L#&`s@)_  
tP! %(+V  
5Q8 H8!^  
int responseCode=httpConnection.getResponseCode(); +fboTsp% H  
if(responseCode>=400) M}11 tUl  
{ |A*4Fuc&  
processErrorCode(responseCode); 7=?!B#hm!  
return -2; //-2 represent access is error
G5U?]& I8  
} Ar>JQ@0  
%zGv+H?  
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String sHeader; 7M~/ q.  
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for(int i=1;;i++) 71[?AmxV  
{ ~3gazTe9  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 9;{(.K  
//Utility.log(in.readLine()); c8mh
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sHeader=httpConnection.getHeaderFieldKey(i); .gC.T`/m  
if(sHeader!=null) iLBORT!;  
{ &)Qq%\EP4  
if(sHeader.equals("Content-Length")) #OM'2@  
{ MCibYvc[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); P2jh[a%  
break; dcmf~+T  
} Wu{_QuAB  
} 7$%G3Q|)L  
else $dI mA  
break; &UnhYG{A  
} [5IbR9_  
} Co(N8>1  
catch(IOException e){e.printStackTrace ();} Wm-$l  
catch(Exception e){e.printStackTrace ();} %D#&RS  
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Utility.log(nFileLength); M.y!J  
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return nFileLength; 9b=0 4aWHm  
} Z|*#)<|~  
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zT)cg$8%fY  
//保存下载信息（文件指针位置） .>TG{>sH  
private void write_nPos() Ua|iAD1  
{ :X}SuM?c  
try{ S{l)hwlE  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Q.Nw#r+m  
output.writeInt(nStartPos.length); :atd_6   
for(int i=0;i<nStartPos.length;i++) %.`u2'^  
{ &Cj~D$kDEu  
// output.writeLong(nPos); !\{2s!l~  
output.writeLong(fileSplitterFetch.nStartPos); -7w}+iS  
output.writeLong(fileSplitterFetch.nEndPos); bl>W
i@GL  
} fh)eL<I  
output.close(); E-Xz  
} 9[VYd '  
catch(IOException e){e.printStackTrace ();} XZ.D<T"  
catch(Exception e){e.printStackTrace ();} iP9]b&  
} XYP RMa?  
iT{4-j7|P4  
`.JW_F)1  
//读取保存的下载信息（文件指针位置） j~\FDcG*ed  
private void read_nPos() H?;+C/-K`_  
{ dpS@:  
try{ x*F-d2D  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Mx,5  
int nCount = input.readInt(); /q>ExXsEC  
nStartPos = new long[nCount]; bf.+Ewb(  
nEndPos = new long[nCount]; ,8Q0AkG  
for(int i=0;i<nStartPos.length;i++) QChWy`x  
{ 9*FA=E  
nStartPos = input.readLong(); (@*|[wN  
nEndPos = input.readLong(); p<dw C"z  
} vjGJRk|XED  
input.close(); =/a`X[9vI  
} b*S,8vE]  
catch(IOException e){e.printStackTrace ();} ] +%`WCr9  
catch(Exception e){e.printStackTrace ();} z6M5'$\y  
} Y1r'\@L w  
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private void processErrorCode(int nErrorCode) gh[q*%#  
{ .4E24FB[f?  
System.err.println("Error Code : " + nErrorCode); :9(kU  
} \6a' p Q,  
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JE:LA+ (  
//停止文件下载 |*J;X<Vm  
public void siteStop() .
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{ }OcrA/  
bStop = true; ?+=,t]`!m  
for(int i=0;i<nStartPos.length;i++) 0&NM=~  
fileSplitterFetch.splitterStop(); R?lTB3"  
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} "dv\ 9O  
} 7^rT-f07  
//负责部分文件的抓取 @eBo7#Zr  
**FileSplitterFetch.java L T`T~|pz  
*/ 9HN&M*}  
package NetFox; :tFcPc'  
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import java.io.*; ]6v7iuvI  
import java.net.*; xv$fw>  
@(=?x:j  
 K%%Ow  
public class FileSplitterFetch extends Thread { 3`SH-"{j%  
%jj-\Gz!  
)ZLj2H<  
String sURL; //File URL +K'YVB U}  
long nStartPos; //File Snippet Start Position (L4C1h_]9  
long nEndPos; //File Snippet End Position ?$A)lWk(  
int nThreadID; //Thread's ID S`
mB1(h  
boolean bDownOver = false; //Downing is over n=d#Fm0<  
boolean bStop = false; //Stop identical d<ES  
FileAccessI fileAccessI = null; //File Access interface <<qzZ+u  
[8tpU&J  
o\W>$$EXD  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 3VMaD@nYa  
{ _]'kw [  
this.sURL = sURL; ~yXDN4s  
this.nStartPos = nStart; R=R]0  
this.nEndPos = nEnd; S]fkA6v  
nThreadID = id; }3Ke  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 VrT-6r'Y  
} U%1M?vT/  
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public void run() wH=7pS"s  
{ QrSO%Rm1*  
while(nStartPos < nEndPos && !bStop) h Ks  
{ K(MZ!>{  
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try{ 23=wz%tF  
URL url = new URL(sURL); v%`k*n':  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); L*Ffic  
httpConnection.setRequestProperty("User-Agent","NetFox"); *}HDq(/>w  
String sProperty = "bytes="+nStartPos+"-"; F@t\D?  
httpConnection.setRequestProperty("RANGE",sProperty); B[w.8e5  
Utility.log(sProperty); 4M>]0%3.D  
mrsN@(X0  
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InputStream input = httpConnection.getInputStream(); It3@ Cd>  
//logResponseHead(httpConnection); mDwuJf8}  
8EiS\$O-  
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byte[] b = new byte[1024]; BB1_EdoG  
int nRead; 0V"(}!=2a  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) s&WE'  
{ Vfq-H/+  
nStartPos += fileAccessI.write(b,0,nRead); 3M[d6@a  
//if(nThreadID == 1) g(jn /Cx  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); lnMU5[g{  
} kJ.7C  
HCktgL:E=  
I)%bOK]  
Utility.log("Thread " + nThreadID + " is over!"); [ot+EA  
bDownOver = true; 6x!iL\Y~  
//nPos = fileAccessI.write (b,0,nRead); FDGzh/  
} I L&PN`#  
catch(Exception e){e.printStackTrace ();} u[wDOw  
} ZZxt90YR'5  
} QRdtr  
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(i<\n`h1K  
//打印回应的头信息 ZLP0SCkuR  
public void logResponseHead(HttpURLConnection con) i-95>ff
  
{ 8*VQw?{Uee  
for(int i=1;;i++) ,Wd+&|Q  
{ NS
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String header=con.getHeaderFieldKey(i); )TNG0[  
if(header!=null) qMO(j%N
5  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); .UK`~17!  
Utility.log(header+" : "+con.getHeaderField(header)); [e|9%[.V  
else %&'[? LXD  
break; aJs! bx>K  
} A i#~Eu*  
} FhEfW7]0,  
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,4,./wIq  
public void splitterStop() @Ko}Td&E(  
{ ! v%%_sRV  
bStop = true; dt=M#+g  
} lH,/N4r*&  
[m<8SOMG(  
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} n;.
);  
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/GNm>NSK  
/* O+DYh=m*p  
**FileAccess.java T}'*Gry  
*//文件访问(定位，写) d<cQYI4V  
package NetFox; |mw3v>  
import java.io.*; oBPm^ob4  
w0.;86<MV  
+I.{y  
public class FileAccessI implements Serializable{ )5diX + k  
IS{>(XT{  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 *MCkezW7{  
RandomAccessFile oSavedFile; tg2+Z\0)4g  
long nPos; kf' 4C "}  
0}>p)k3&A  
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public FileAccessI() throws IOException *2m{i:3  
{ #("E)P  
this("",0); wX@g>(  
} ~P-^An^  
8hX/~-H  
SmP&wNHQf  
public FileAccessI(String sName,long nPos) throws IOException @Rqn&tA8  
{ =#I/x=
L:  
oSavedFile = new RandomAccessFile(sName,"rw"); KW3
6nY\7  
this.nPos = nPos; :{#w-oC>6P  
oSavedFile.seek(nPos); a0wpsl iF  
} vWYU'
_=  
^{O1+7d[.  
_6sSS\  
public synchronized int write(byte[] b,int nStart,int nLen) V$MMK  
{ Ez^wK~  
int n = -1; R{Me~L?  
try{ ML1/1GK*i+  
oSavedFile.write(b,nStart,nLen); R8, g^N  
n = nLen; cEPqcy *  
} 2B=BRVtSs  
catch(IOException e) QyEoWKu;  
{ pc](  
e.printStackTrace (); `jGG^w3  
} ZlL]AD@  
Z~g7^,-t  

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return n; _$gP-J  
} S1*xM  
@$|bMH*1:  
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} M
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/* KA9v?_@{F  
**SiteInfoBean.java D;oX*`  
*/ 14 hE<u  
package NetFox; ShU1RQk  
5k<0>6;XH  
pJ@D}2u(  
public class SiteInfoBean { '!XVz$C  
|)YN"nqg  
YGCBDH%6  
private String sSiteURL; //Site's URL rn-CQ2{?  
private String sFilePath; //Saved File's Path =zwn3L8fL  
private String sFileName; //Saved File's Name ?Lquf&`vP  
private int nSplitter; //Count of Splited Downloading File eh6=-  
6"U$H$i.G  
`R_;n#3F0  
public SiteInfoBean() 2?(dS  
{//nSplitter的缺省值为5 z~RE}k  
//default value of nSplitter is 5 Nb/Z+  
this("","","",5); ~d=Y98'xS  
} a`;nB E  
^[hx`Rh`t  
03dmHg.E!E  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) jtQ}   
{ _h P7hhR  
sSiteURL= sURL; 7^]KQ2fF 8  
sFilePath = sPath; &]1gx#  
sFileName = sName; 2Afg.-7EP  
this.nSplitter = nSpiltter; zXv2plw(  
)SWLX\b  
![aa@nOSa  
} 8/ PS#dM\  
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:z%q09.)  
public String getSSiteURL() %1kIaYZ  
{ <2fgao&-n  
return sSiteURL; 78t:ge eX  
} yo!
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kuo!}QFL  
rc7^~S]5  
public void setSSiteURL(String value) *L#\#nh7  
{ mBg$eiGTB  
sSiteURL = value; yey]#M[y  
} ~y8KQ-1n"  
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}9 I,p$  
public String getSFilePath() G57c 8}\4  
{ h~u|v[@{J  
return sFilePath; vW`[CEm^X  
} +E }q0GV  

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MW|:'D`  
public void setSFilePath(String value) DAx
1  
{ |sPUb;&~  
sFilePath = value; Yp;?Zq9  
} J42/S [Rt  
Apc!!*7  
. MH;u3U  
public String getSFileName() )i$KrN6  
{ \MB$Cwc  
return sFileName; RZqou|ki  
} 6l&,!fd  
(A\\s$fE/1  
L_R(K89w  
public void setSFileName(String value) Z6IWQo,)Rh  
{ DN;3VT.-  
sFileName = value; z?'z{+HY  
} "g&hsp+i"A  
i^"!"&tW#  
Nh"U~zlh  
public int getNSplitter() g0:{{w  
{ zx;~sUR;  
return nSplitter; U,7}VdO  
}  /J[s5{  
QEc4l[^{.B  
sff4N>XAl<  
public void setNSplitter(int nCount) J3_Ou2cF`  
{ sk7]s7  
nSplitter = nCount; E$USam  
} r&Qq,koE  
} 8Cw3b\ne  
}mOo=)C!  
yVgHu#?PM  
/* (W+aeB0  
**Utility.java kt7x}F(?<  
*/ EjP9/VG@=  
package NetFox; l9f%?<2D  
|H>;a@2d  
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public class Utility { I9*BTT]  
3_ko=& B$  
(ty&$  
public Utility() 5+
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{ J7+[+Y  
=TJ9Gr/R&:  
hr3<vWAD  
} puox^  
$) m$c5!  
//线程睡眠 '+7"dHLC;  
public static void sleep(int nSecond) 1G)I|v9R  
{ w/csLi.O  
try{ 2 :wgt  
Thread.sleep(nSecond); 4O
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} %{
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catch(Exception e) #|=Q5"wU  
{ /cZTj!M  
e.printStackTrace (); }/MmuPp  
} 8~y&"  \  
} ew<_2Xy"<  
cc0Tb  
//日志 'PWA  
public static void log(String sMsg) @S1Z"%S  
{ Ty}Y/jW  
System.err.println(sMsg); 'zOB!QqA`v  
} HYl~)O>  
4`Lr^q}M+  
ZP'0=  
public static void log(int sMsg) HJJ;gTj  
{ O~mQ\GlW  
System.err.println(sMsg); 8^sh@j2L  
} 17-B'Gl!<%  
} ; *\xdg{d  
y%O^Zm1  
;.=]Ar}  
/* gF
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**TestMethod.java @D>qo=KPM  
*/ I>{o]^xw-D  
package NetFox; U7HfDDh  
+QP(ATdM  
oSIP{lfp2Q  
public class TestMethod { EVP{7}K1  
"r1 !hfIYf  
2}15FXgN  
public TestMethod() '3?-o|v@D  
{ ///xx/weblogic60b2_win.exe nf1O8FwRb  
try{ hDXaCift  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); [9G=x[  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); .q1y)l-^Z  
SiteFileFetch fileFetch = new SiteFileFetch(bean); %<fs \J^k  
fileFetch.start(); >R5A@0@d5  
} 8Oz9 UcG  
catch(Exception e){e.printStackTrace ();} 6sG5n7E-A  
&hih p"  
m|3Q'  
} 88l1g,`**  
u;+8Jg+xH/  
d:"7Tw2v+  
public static void main(String[] args) yhrjML2K  
{ HuR774f[  
new TestMethod(); M4(57b[`  
} (I/iD.A  
} ]-_ ma  
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