http断点续传简单实现（java)

/* f4R1$(<  
**SiteFileFetch.java w'd.;  
*/ +d=~LQ}*  
package NetFox; 2[.5oz`  
import java.io.*; R @"`~#$$  
import java.net.*; >[K0=nA  
mDZ=Due1  
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public class SiteFileFetch extends Thread { ~Y% : 3  
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SiteInfoBean siteInfoBean = null; //文件信息Bean /[0F6  
long[] nStartPos; //开始位置 gC0;2  
long[] nEndPos; //结束位置 =Wj{]&`  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 O-Dc[t%  
long nFileLength; //文件长度 gyC^K3}  
boolean bFirst = true; //是否第一次取文件 HH7[tGF  
boolean bStop = false; //停止标志 -eUV`&[4  
File tmpFile; //文件下载的临时信息 _=uviMuE  
DataOutputStream output; //输出到文件的输出流 %=BtOM_2  
. /Y&\<  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） m+H%g"Zj  
public SiteFileFetch(SiteInfoBean bean) throws IOException :#Ty^-"]1  
{ _~PO  
siteInfoBean = bean; hPcS, p{%  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 1c'79YU  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 5KK{%6#f\  
if(tmpFile.exists ()) "rVU4F)  
{ T4eWbNSs  
bFirst = false; kr#I{gF  
read_nPos(); ~fBex_.o*  
} j13riI3A  
else Ex6o=D2  
{ &%6NQWW  
nStartPos = new long[bean.getNSplitter()];
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nEndPos = new long[bean.getNSplitter()]; t7&Dwmck9  
} sqT^t!  
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} A$Wx#r7)  
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public void run() =9(tsB gTX  
{ X\kjAMuW/*  
//获得文件长度 NK~PcdGl  
//分割文件 k9l^6#<?  
//实例FileSplitterFetch 4x(F&0  
//启动FileSplitterFetch线程 bhn5Lz$z  
//等待子线程返回 o,J^ e_  
try{ {(%~i37  
if(bFirst) !\ZcOk2  
{ ":V%(c  
nFileLength = getFileSize(); B.}cB'|  
if(nFileLength == -1) V(r`.75  
{  ER_ 3'  
System.err.println("File Length is not known!");
 b)Tl*  
} >zFD$  
else if(nFileLength == -2) B_cgWJ*4  
{ :Z[(A"dA  
System.err.println("File is not access!"); ~U9q-/(J/  
} 4Ppop  
else &;s<dDQK  
{ SAy{YOLtl  
for(int i=0;i<nStartPos.length;i++) s047"Q  
{ LaclC]yLU  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); %uua_&#)  
} zXjwnep  
for(int i=0;i<nEndPos.length-1;i++) ^@K WYAAW5  
{ 8]HY. $E  
nEndPos = nStartPos[i+1]; Si]X rub  
} gn^!"MN+g  
nEndPos[nEndPos.length-1] = nFileLength; `4skwvS=  
} p=vV4C:  
} 'aZASPn[  
S_$nCyaH2  
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//启动子线程 r,0@~;zA  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 8A!'I<S1  
for(int i=0;i<nStartPos.length;i++) 2Y$  
{ :kt/$S^-  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Iqx84  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), L/%Y#  
nStartPos,nEndPos,i); )O&z5n7t4s  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); @gEr+O1K(  
fileSplitterFetch.start(); xvB8YW"  
} q=+wI"[  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .'&V#D0  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); "Vx6 #u@}  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 6`Lc
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nEndPos = " + nFileLength); >O3IfS(l  
// fileSplitterFetch[nPos.length-1].start(); PV(4$I}  
k/@Tr
:  
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//等待子线程结束 =-5[Hn%  
//int count = 0; @i{]4rk lv  
//是否结束while循环 i&*<lff  
boolean breakWhile = false; 50*@.!^*  
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while(!bStop) ,WGc7NN`  
{ %0zS  
write_nPos(); S}b~_}  
Utility.sleep(500); 6uqUiRs()  
breakWhile = true; 9$wAm89  
##GY<\",;  
{m'AY)  
for(int i=0;i<nStartPos.length;i++) p(?g-
  
{ vzG ABP  
if(!fileSplitterFetch.bDownOver) 5D L,U(Y  
{ 8gAu7\p}  
breakWhile = false; {:$NfW  
break; XfDX:b1p  
} tH,sql)  
} B$j' /e-Zk  
if(breakWhile) GL`tOD:P"  
break; 0#^Bf[Dn  
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`,P >mp)uU  
//count++; N8QH*FX/F1  
//if(count>4) x9D/s`!  
// siteStop(); d#8e~  
} jqtVpNwM  
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lC4PKmno  
System.err.println("文件下载结束！"); bJ6p,]g  
} YD9!=a$  
catch(Exception e){e.printStackTrace ();} X.eB ;w/}  
}
.`+yo0O:  
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5NFRPGYX  
//获得文件长度 7f r>ZY^  
public long getFileSize() 0MrN:M2B  
{ (0}j]p'w  
int nFileLength = -1; #D0 ~{H  
try{ |T y=7d,  
URL url = new URL(siteInfoBean.getSSiteURL()); G1[(F`t>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); p#=;)1  
httpConnection.setRequestProperty("User-Agent","NetFox"); EZ{\D!_Y  
s[T{c.F  
/B[}I}X  
int responseCode=httpConnection.getResponseCode(); (l_:XG)7~b  
if(responseCode>=400) x,uBJ  
{ rs_h}+6"s  
processErrorCode(responseCode); `2e_ L  
return -2; //-2 represent access is error t}~UYG(h~  
} @,e8t BL  
#9,=Owup  
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String sHeader; ~bGC/I;W>  
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for(int i=1;;i++) ,J&9kYz  
{ 7>&1nBh. f  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); }LQ\a8]<
 
//Utility.log(in.readLine()); $Elkhe]O %  
sHeader=httpConnection.getHeaderFieldKey(i); R{`gR"*  
if(sHeader!=null) QTE:K?  
{ 
I^:F)a:  
if(sHeader.equals("Content-Length")) 3HKxYvc C  
{ *IqVY&  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); s`1^*Dl%+  
break; /=/ HB  
} t)'dF*L  
} .pW o>`"  
else  Fs)  
break; qRl/Sl#F  
} LuL$v+`  
} q)k{W>O  
catch(IOException e){e.printStackTrace ();} Gk 6fO  
catch(Exception e){e.printStackTrace ();} Y;g% e3nu  
}Aw47;5q;  
&
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Utility.log(nFileLength); 7H#2WFQ7  
@ t|3gF$X  
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return nFileLength; x=vK EyS@  
} l=NAq_?N\  
70=(.[^+  
Bj=@&;  
//保存下载信息（文件指针位置） =]d^3bqN  
private void write_nPos() `-u7 I  
{ :*cHA  
try{ gi1j/j7  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Oq}ip  
output.writeInt(nStartPos.length); q<EEb  
for(int i=0;i<nStartPos.length;i++) gb(#DbI  
{ Bj8<@~bX:L  
// output.writeLong(nPos); `V@z&n0P6  
output.writeLong(fileSplitterFetch.nStartPos); 1lsLG+Rpxi  
output.writeLong(fileSplitterFetch.nEndPos); O:,=xIXR  
} \j:AR4  
output.close(); xG w?'\  
} wonYm27f  
catch(IOException e){e.printStackTrace ();} 0$QIfT)  
catch(Exception e){e.printStackTrace ();} IX.sy  
} N3Z@cp  
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//读取保存的下载信息（文件指针位置） 3>M.]w6{  
private void read_nPos() }7Jp :.qk  
{ >>j+LRf*  
try{ #4N >d~  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); p {?}g
'  
int nCount = input.readInt(); XECikld>  
nStartPos = new long[nCount]; s6/cL|Ex  
nEndPos = new long[nCount]; 4]EvT=Ro  
for(int i=0;i<nStartPos.length;i++) Rf?%Tv
0\  
{ O{nC^`X  
nStartPos = input.readLong(); g}YToOs  
nEndPos = input.readLong(); B*2{M  
} >]-<uT_  
input.close(); p7$3`t6u  
} *w|iu^G  
catch(IOException e){e.printStackTrace ();} P8IRH#ED  
catch(Exception e){e.printStackTrace ();} wx./"m.M  
} #w;;D7{@m  
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private void processErrorCode(int nErrorCode) yi|:}K$  
{ s&0*'^'O[S  
System.err.println("Error Code : " + nErrorCode); AoIc9ElEX  
} u]0!|Jd0  
{zu/tCq?  
,O2q+'&  
//停止文件下载 $YPQC  
public void siteStop() #r(a~  
{ A(NEWO  
bStop = true; wa2~C [  
for(int i=0;i<nStartPos.length;i++) Hva{A #  
fileSplitterFetch.splitterStop(); a}w&dE$!-  
pJn>oGeJ&  
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} ]o `
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} 7> )l{7  
//负责部分文件的抓取 HwM/}-t  
**FileSplitterFetch.java leR"j  
*/ ]a=l^Pc(xN  
package NetFox; PB@-U.Z  
.jCk#@+  
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import java.io.*; t9]r  
import java.net.*; =^by0E2  
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public class FileSplitterFetch extends Thread { ONNW.xHp  
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so'eZ"A:  
String sURL; //File URL TZkTz P[  
long nStartPos; //File Snippet Start Position pIL`WE1'  
long nEndPos; //File Snippet End Position *6'_5~G  
int nThreadID; //Thread's ID hl}dgp((  
boolean bDownOver = false; //Downing is over /lru"R D  
boolean bStop = false; //Stop identical x7Eeb!s0f,  
FileAccessI fileAccessI = null; //File Access interface n
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IG>>j}  
^T=5zqRD  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException bnIf}ut-G  
{ ,I=O"z>9  
this.sURL = sURL; 6B /Jp  
this.nStartPos = nStart; 6mX:=Q  
this.nEndPos = nEnd; 8XgVY9]Qm  
nThreadID = id;  eMztjN  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 =g1D;  
} 1/!nV  
ddl3fl#f  
W%w82@'  
public void run() aL{EkiR  
{ 5t TLMZ`o  
while(nStartPos < nEndPos && !bStop) hY)YX,f=S  
{ WtMcI>4w  
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try{ N{|[R   
URL url = new URL(sURL); &MBOAHhze  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); I)qKS@  
httpConnection.setRequestProperty("User-Agent","NetFox"); j^:b-:F  
String sProperty = "bytes="+nStartPos+"-"; A-}PpH~.Z  
httpConnection.setRequestProperty("RANGE",sProperty); +ESX.Vel  
Utility.log(sProperty); CRP
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InputStream input = httpConnection.getInputStream(); H)-L%l|9  
//logResponseHead(httpConnection); Q^\{Zg)p  
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byte[] b = new byte[1024]; l@(t^68OD  
int nRead; Z(#XFXd  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) _ak.G
=  
{ /%c+ eL}l  
nStartPos += fileAccessI.write(b,0,nRead);
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//if(nThreadID == 1) ^a: Saq-}  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); }x>}:"P;W  
} bwv/{3G,Ys  
`W6:=H  
Be'?#Qe   
Utility.log("Thread " + nThreadID + " is over!"); _Jt_2o%G  
bDownOver = true; ]KfghRUH  
//nPos = fileAccessI.write (b,0,nRead); "87O4 #$  
} a>#d=.  
catch(Exception e){e.printStackTrace ();} EG8%~k+R  
} Fa Qu$q  
} ytuWT
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*)2x&~T*|  
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//打印回应的头信息 })h'""i&xn  
public void logResponseHead(HttpURLConnection con) Djg1Qh  
{ |E>v~qD8I  
for(int i=1;;i++) e-YGuWGN7  
{ |s)VjS4@  
String header=con.getHeaderFieldKey(i); R;5QD`  
if(header!=null) ?
Yynd  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); /r#b  
Utility.log(header+" : "+con.getHeaderField(header)); U0lqGEZ  
else ]0at2  
break; My`josJ`Pb  
} $fq-wl-=  
} n3-GnVC][  
(Q*2dd>  
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public void splitterStop() T +|J
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{ >"2\D|-/  
bStop = true; 'US8"83  
} )eIz{Mdp=  
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j  
} 3}.mp}K5  
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>n@>h$]  
/* 3M`hn4)K  
**FileAccess.java uaZ"x&oZ#  
*//文件访问(定位，写) *)}Ap4[  
package NetFox; =N[V{2}q  
import java.io.*; 8 RzF].)  
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public class FileAccessI implements Serializable{ Rz])wBv e  
J7&.>y1%  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 o{
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RandomAccessFile oSavedFile; ~]m@k'n  
long nPos; dd @COP?  
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public FileAccessI() throws IOException 8H
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{ kOlI?wc  
this("",0); P5ESrZ@f  
} @ B}c4,  
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public FileAccessI(String sName,long nPos) throws IOException .yHHogbt  
{ ID{Pzmt-  
oSavedFile = new RandomAccessFile(sName,"rw"); 8O;rp(N.n  
this.nPos = nPos; hCOy\[2$  
oSavedFile.seek(nPos); 
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} H8=vQy  
/(WX!EEsB  
4IGQ,RTB  
public synchronized int write(byte[] b,int nStart,int nLen) HC<BGIgL  
{ \|b1s @c8  
int n = -1; M25z<Y  
try{ f0fqDmn  
oSavedFile.write(b,nStart,nLen); XyKKD&j  
n = nLen; s1*WK&@  
} xYzcV%-Pm  
catch(IOException e) t0AqGrn  
{ $HR(|{piZ  
e.printStackTrace (); (0+GLI8  
} OA8b_k~  
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%l]rQjV-  
return n; G+\~rl  
} !]jNVg  
* zJiii  
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} R;Ix<y{U  
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b$$L]$q2  
/* 6r-<XNv)0  
**SiteInfoBean.java  zxynEdO  
*/ 9O0  
package NetFox; j{Qbzczy,  
&&QDEDszp  
hnfrnYH  
public class SiteInfoBean { ?6l,   
3vvFF]D5k  
_`Yvfz3  
private String sSiteURL; //Site's URL #dn%KMo2r  
private String sFilePath; //Saved File's Path "l2N_xX;  
private String sFileName; //Saved File's Name [7Kj$PB3  
private int nSplitter; //Count of Splited Downloading File `- uZv  
3 v,ae7$U&  
uBL~AC3>O  
public SiteInfoBean() xr7<(:d  
{//nSplitter的缺省值为5
:O@,Z_"  
//default value of nSplitter is 5 X:} 5L>'  
this("","","",5); SJ|.% gn  
} 5IF~]5s  
>=q!!'$:  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) %_X[{(  
{ %~v76;H<  
sSiteURL= sURL; bMK'J  
sFilePath = sPath; MdTd$ 4J3  
sFileName = sName; )*QTxN  
this.nSplitter = nSpiltter;  "lnk  
+ 1%^c(3  
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} q'8@0FT0  
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public String getSSiteURL()
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{ ~>-;(YU"t  
return sSiteURL; gu%'M:Xe  
} AZ Lt'9UD  
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public void setSSiteURL(String value) f`";
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{ ,9j:h)ks?  
sSiteURL = value; =rtA{g$)+  
} / )u,Oa  
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public String getSFilePath() OQb9ijLeK  
{ ;cHI
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return sFilePath; fyoB]{$p8  
} ((IBaEq  
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^Th"`Av5  
public void setSFilePath(String value) L"^366M!  
{ 0 Ln5e.&  
sFilePath = value; 1R~
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} 25@j2K(  
L}S4Zz18  
O?J:+L(  
public String getSFileName() M{k
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{ 2]3Jb{8FI>  
return sFileName; JGNxJ S<]  
} xwp?2,<  
Wa
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public void setSFileName(String value) qO3BQ]UF  
{ r0uXMr=Z96  
sFileName = value; wdDHRW0Y  
} JY8"TQ$x  
%[CM;|?B4  
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public int getNSplitter() HaN_}UMP  
{ \B ^sJ[n  
return nSplitter; tNf" X!  
} A =#-u&l  
hBSJEP  
scEQDV  
public void setNSplitter(int nCount) r{jD,x2  
{ 1E_Ui1[  
nSplitter = nCount; g~D6.OZU  
} Gv3Fg[MA@c  
} /g7?,/vnZ  
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/* P&`r87J  
**Utility.java ~TR|Pv  
*/ {hP&P  
package NetFox; Ujzz`!mz  
]BBgU[O) !  
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public class Utility { +((31l  
Yf`.Cq_:  
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public Utility() __%E!*m"<_  
{ \k-juF80  
_%%"Y}  
(>`SS#(T!  
} x`l; ;  
{YTF]J$  
//线程睡眠 Bzt`9lg  
public static void sleep(int nSecond) E}j8p_p  
{ zFQkUgb  
try{ Y rnqi-P  
Thread.sleep(nSecond); ]H7Mx\  
} /\I%)B47^9  
catch(Exception e) l#.,wOO{  
{ RteTz_z{  
e.printStackTrace (); |CqJ2  
} M.^A`  
} `bF;Ew;  
=_6h{f&Q  
//日志 ?O Nw*"9  
public static void log(String sMsg) rM.<Gi05Qe  
{ cHct|Z u  
System.err.println(sMsg); )Dpt<}}\  
} ^{bEq\5&  
[ [CXMbD`*  
M 7$4KFNp  
public static void log(int sMsg) g$LwXfg  
{ &JM;jSz  
System.err.println(sMsg); }Cg~::,"  
} N0hU~|/  
} )B4c;O4t  
=nZd"t'p|  
!\4FIs&Qv  
/* Bz~h-  
**TestMethod.java BQg]$Tr?  
*/ HNT8~s.2  
package NetFox; e/\_F+jyc  
RyD$4jk+T"  
H2cc).8"  
public class TestMethod { Isb^~c_P  
2MeavTr  
[ Ulo; #P  
public TestMethod() X+@,vCC  
{ ///xx/weblogic60b2_win.exe ^`?> Huu<w  
try{ HE'8  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); y@JYkp>I  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); XjU;oh4:.  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 1]`HX=cl  
fileFetch.start(); k@U`?7X  
} [nD4\x+  
catch(Exception e){e.printStackTrace ();} )zV5KC{{  
9%6`ZS~3  
X jN.X  
} Q6>( Z  

5Vqvb|  
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public static void main(String[] args) Jl ?Q}SB  
{ KL`>mJo$  
new TestMethod(); v}D!  
} *?&O8SSBH  
} iK:]Q8b  
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