http断点续传简单实现（java)

/* v^_]W3K  
**SiteFileFetch.java 'N ::MN  
*/ c$:=d4t5$  
package NetFox; |0R%!v(,  
import java.io.*; ND1%s &  
import java.net.*; :wmf{c  
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public class SiteFileFetch extends Thread { 7h&`BS  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 4?M3#],'h  
long[] nStartPos; //开始位置 B5H&DqWzr  
long[] nEndPos; //结束位置 wK`ieHmp  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 xYVjUb(,X  
long nFileLength; //文件长度 vek:/'sj3p  
boolean bFirst = true; //是否第一次取文件 T1!Gr!=  
boolean bStop = false; //停止标志 y{I[}$k  
File tmpFile; //文件下载的临时信息 seU^IC<  
DataOutputStream output; //输出到文件的输出流 o]jP3 $t;  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） (Cd{#j<  
public SiteFileFetch(SiteInfoBean bean) throws IOException u6Qf*_-K  
{ Li-(p"  
siteInfoBean = bean; =_m9so  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); SM /ykk  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); fxoi<!|iGY  
if(tmpFile.exists ()) T<e7(=  
{ P&%eIgAOL  
bFirst = false; o|;eMO-  
read_nPos(); !MJe+.  
} 9+8!xwR:  
else 6;[/9  
{ =e!l=d|/  
nStartPos = new long[bean.getNSplitter()]; H9san5{  
nEndPos = new long[bean.getNSplitter()]; uJam $
V  
} >g>`!Sf  
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} euj8p:+X  
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public void run() rx6-~0!eI=  
{ %t`SSW7I  
//获得文件长度 4OOn,09  
//分割文件 pPyvR;NJ  
//实例FileSplitterFetch b WbXh
$  
//启动FileSplitterFetch线程 '-PMF~~S  
//等待子线程返回 .-KtB(t  
try{ C3\E.u?  
if(bFirst) jH&_E'XMX  
{ t`Y!"l  
nFileLength = getFileSize(); W[>iJJwz  
if(nFileLength == -1) *K,hrpYR  
{ ) Kc%8hBv  
System.err.println("File Length is not known!"); 'cAc{\)  
} %/y`<lJz(  
else if(nFileLength == -2) Zgg'9E  
{ R>d@tr  
System.err.println("File is not access!"); C1T=O  
} AUxM)H  
else V@v1a@=W  
{ ,'C30A*p  
for(int i=0;i<nStartPos.length;i++) OpK.Lsd0y  
{ %-# qO  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); (rr}Pv%yb  
} w!WRa8C  
for(int i=0;i<nEndPos.length-1;i++) /}w#Jk4pD  
{ Zn@W7c,_I  
nEndPos = nStartPos[i+1]; !.3R~0b  
} 3a#PA4Ql  
nEndPos[nEndPos.length-1] = nFileLength; Sk/#J!T8{  
} !8Z2X!$m{<  
} 6X7s 4  
-]Q(~'a  
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//启动子线程 WY+(]Wkao  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 'lhP!E_)q  
for(int i=0;i<nStartPos.length;i++) / l".}S  
{ 4K9Rpm  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), FU
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), )Fqy%uR8  
nStartPos,nEndPos,i); 5M%,N-P^  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); >dpbCPJ9[  
fileSplitterFetch.start(); |l|_
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} =-$!:W~  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Bx(yu'g|a  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); -IBO5;2_  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", +w"_$Tj@;  
nEndPos = " + nFileLength); aSOU#Csx  
// fileSplitterFetch[nPos.length-1].start(); `gBD_0<T7  
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//等待子线程结束 1~%o}+#-  
//int count = 0; I4)Nb WQ  
//是否结束while循环 rdO@X9z  
boolean breakWhile = false; ZCm1+Y$  
#gh p/YoTq  
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while(!bStop) &Hv;<  
{ 9Z&?R++?  
write_nPos(); YgCc|W3{  
Utility.sleep(500); [?-]PZ  
breakWhile = true; R0%?:! F  
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9  
for(int i=0;i<nStartPos.length;i++) ibvJWg  
{ BBcj=]"_
 
if(!fileSplitterFetch.bDownOver) Bn\l'T  
{ eY T8$  
breakWhile = false; mA&=q_gS  
break; LI[ ?~P2\  
} Qh\YR\O  
} wG+=}1X  
if(breakWhile) vF"c  
break; [*<.?9n)or  

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Rho5s@N7  
//count++; hp*<x4%*a"  
//if(count>4) t\8&*(&3F  
// siteStop(); Vt'L1Wr0v  
} 80Ag  
L[rpb.'FG  
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System.err.println("文件下载结束！"); ~;[&K%n  
} 8x9Rm  
catch(Exception e){e.printStackTrace ();} !#?8BwnaZ  
} Qm< gb+  
(^LS']ybc  
i3\~Qj;1  
//获得文件长度 D}w<84qX  
public long getFileSize() rj3YTu`  
{ y0<Uu  
int nFileLength = -1; Zd[OWF  
try{ |Ab{H%  
URL url = new URL(siteInfoBean.getSSiteURL()); 2
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); bp#fyG"  
httpConnection.setRequestProperty("User-Agent","NetFox"); ~AQ>g#|%  
[(|^O>k8c  
3[r";Wt#  
int responseCode=httpConnection.getResponseCode(); fD{II+T  
if(responseCode>=400) s"i~6})K<$  
{ B oqJ   
processErrorCode(responseCode); }p=g*Zo*C;  
return -2; //-2 represent access is error EWA;L?g|A  
} )Vg2Jix,]  
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n  
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String sHeader; %hc'dZ  
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for(int i=1;;i++) Cp^g'&  
{ fywvJ$HD]L  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); `XW*kxpm  
//Utility.log(in.readLine()); y])).p P  
sHeader=httpConnection.getHeaderFieldKey(i); \vCGU>UY  
if(sHeader!=null) h*3{6X#(/  
{ WS:5MI,OL  
if(sHeader.equals("Content-Length")) 1{
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{ 7)^:8I(  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); h%TLD[[/jr  
break; WhFS2Jl0  
} @*(4dt:V  
} ZYcd.?:6  
else ~zF2`.  
break; l}rS{+:wK  
} J R$r!hX  
} R^%e1K
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catch(IOException e){e.printStackTrace ();} f8'MP9Lv  
catch(Exception e){e.printStackTrace ();} v$Uhm</|19  
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Utility.log(nFileLength); __I/F6{ 9V  
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return nFileLength; dlDki.  
} .VM3D0aV  
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brSi<  
//保存下载信息（文件指针位置） \?Mf_  
private void write_nPos() -.iNNM&a  
{ L9FHgl?  
try{ }gGkV]  
output = new DataOutputStream(new FileOutputStream(tmpFile));
^$-Ye]<  
output.writeInt(nStartPos.length); {Dr@HP/x=s  
for(int i=0;i<nStartPos.length;i++) A&,,9G<  
{ l&W;b6L  
// output.writeLong(nPos); WR#0<cz(  
output.writeLong(fileSplitterFetch.nStartPos); a{'Z5ail  
output.writeLong(fileSplitterFetch.nEndPos); B=X,7  
} 4woO;
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output.close(); lA^+Flh  
} &(blN.2  
catch(IOException e){e.printStackTrace ();} .lNs4e  
catch(Exception e){e.printStackTrace ();} ~n?>[88"  
} ^"i~DC  
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//读取保存的下载信息（文件指针位置） vq!uD!lr  
private void read_nPos() &:5\"b  
{ fuX'~$b.fA  
try{ "D][e'  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); &dR=?bz-A  
int nCount = input.readInt(); [/ M`  
nStartPos = new long[nCount]; M4m$\~zf  
nEndPos = new long[nCount]; ymN!-x8q>'  
for(int i=0;i<nStartPos.length;i++) jrMe G.e=D  
{ e3(/qMl  
nStartPos = input.readLong(); IQH[Q9%  
nEndPos = input.readLong(); o[1yl
zk}+  
} EU-]sTJLF  
input.close(); atF?OP|{,w  
} wJ+Aw  
catch(IOException e){e.printStackTrace ();} 57,dw-|xi  
catch(Exception e){e.printStackTrace ();} 7KjUW\mN2Z  
} 0?0Jz  
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private void processErrorCode(int nErrorCode) 58V[mlW)O0  
{ x@>&IBiL  
System.err.println("Error Code : " + nErrorCode); -&2B@]
]  
} V5`^Y=X(%  
*|#T8t,}n  
>~nF=  
//停止文件下载 kAA>FI6  
public void siteStop() OJAIaC\  
{ (C;I*cv  
bStop = true; wzCUZ1N9q  
for(int i=0;i<nStartPos.length;i++) %G3(,Qz  
fileSplitterFetch.splitterStop(); I5m][~6.?  
]3iH[,KU3  
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} @A<PkpNL  
} MrRaU x6z  
//负责部分文件的抓取 R&f^+0%f  
**FileSplitterFetch.java 2";SJF'5\  
*/ @`36ku  
package NetFox; "Z=5gj  
9=X)ung9  
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import java.io.*; o=J9  
import java.net.*; ufV!+$C)is  
txgQ"MGA%  
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public class FileSplitterFetch extends Thread { _ *f  
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String sURL; //File URL _PFnh)o  
long nStartPos; //File Snippet Start Position q@hzo>[  
long nEndPos; //File Snippet End Position 1BHG'
y  
int nThreadID; //Thread's ID [BBEEI=|r  
boolean bDownOver = false; //Downing is over 8I;XS
14Q  
boolean bStop = false; //Stop identical EZ;"'4;W  
FileAccessI fileAccessI = null; //File Access interface $Fkaa<9;P  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException eB>s=}|  
{ ` |IUGz  
this.sURL = sURL; azQD>  
this.nStartPos = nStart; XW{>-PBg:  
this.nEndPos = nEnd; FGWN}&K  
nThreadID = id; 0+Ta%
H{  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ~S,p?I  
} G7!W{;@I  
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public void run() *Xo]-cKL0  
{ )SryDRT  
while(nStartPos < nEndPos && !bStop) ez]tAW  
{ "tjLc6Xl^  
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try{ ;Gx)Noo/>  
URL url = new URL(sURL); /sM~Uq?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); xx{!3 F  
httpConnection.setRequestProperty("User-Agent","NetFox"); 2{-ZD ,(u7  
String sProperty = "bytes="+nStartPos+"-"; nOx4<Wk&  
httpConnection.setRequestProperty("RANGE",sProperty); ~qe%Yq  
Utility.log(sProperty); F  
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InputStream input = httpConnection.getInputStream(); Y!iZW  
//logResponseHead(httpConnection); HbP!KVHyk1  
_@S`5;4x  
qW:HNEiir  
byte[] b = new byte[1024]; (=D&A<YX  
int nRead; sf&]u;^D
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Zo1,1O  
{ Ookh<ES>  
nStartPos += fileAccessI.write(b,0,nRead); 4DZ-bt'  
//if(nThreadID == 1) ]smkTo/  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); uqz]J$
 
} D}8EERb  
CLvX!O(~  
|5Xq0nvCe  
Utility.log("Thread " + nThreadID + " is over!"); >pUtwIP  
bDownOver = true; *m?/O}R  
//nPos = fileAccessI.write (b,0,nRead); {(r6e  
} D %Xo&V[  
catch(Exception e){e.printStackTrace ();} &0f5:M{P  
} McB[|PmC  
} q, O$ %-70  
h=;{oY<V)?  
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//打印回应的头信息 (vT+IZEI  
public void logResponseHead(HttpURLConnection con) 4apL4E"r  
{ ;b-XWK=  
for(int i=1;;i++) J:V?EE,\-  
{
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String header=con.getHeaderFieldKey(i); I? ,>DHUX  
if(header!=null) Lemui)  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); M4as  
Utility.log(header+" : "+con.getHeaderField(header)); e7w
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else ZP
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break; 9B;{]c  
} t!RiUZAo  
} {<<U^<6}  
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public void splitterStop() -GxaV #{  
{ -'6Dg  
bStop = true; 2}8v(%s p  
} XI^QF;,  
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} 1I:+MBGin  
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/* eA<0$Gs,h  
**FileAccess.java -B +4+&{T  
*//文件访问(定位，写) nr<4M0tIp  
package NetFox; M3.do^ss  
import java.io.*; FJMrs[  
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public class FileAccessI implements Serializable{ 3W N@J6?  
7Op>i,HZk\  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 s7F.s
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RandomAccessFile oSavedFile; $&=S#_HQS  
long nPos; c Vc-  
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public FileAccessI() throws IOException *WuID2cOI  
{ ueUuJxq)  
this("",0); w(L4A0K[  
} Abc)i7!.,.  
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> ;*b|Ik  
public FileAccessI(String sName,long nPos) throws IOException HAa;hb  
{ y gz6C  
oSavedFile = new RandomAccessFile(sName,"rw"); .6Pw|xu`Pw  
this.nPos = nPos; vw9@v`k  
oSavedFile.seek(nPos); x<ZJb  
} Tc? $>'  
Vh4X%b$TV  
~nay"g:  
public synchronized int write(byte[] b,int nStart,int nLen) 'd9INz.  
{ 8]9%*2"!  
int n = -1; $|@ (  
try{ ZpQ)IHA.  
oSavedFile.write(b,nStart,nLen); 2fL;-\!y(  
n = nLen; glDu2a,Q  
} , K~}\CR  
catch(IOException e) U2W|:~KM  
{ MDnua  
e.printStackTrace (); 7fZDsj:  
} gi1^3R[  
[<@.eH$hU/  
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return n; [_EZhq  
} I=`U7Bis"  
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} #V~me  
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&i6),{
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/* s Z].8.  
**SiteInfoBean.java yPb"V  
*/ VY7[)  
package NetFox; Yi.N&&o  
I&x=;   
!Dn,^  
public class SiteInfoBean { +nFu|qM}  
_Tm3<o.  
'-Vt|O_Q  
private String sSiteURL; //Site's URL V_.5b&@  
private String sFilePath; //Saved File's Path rlOAo`hd  
private String sFileName; //Saved File's Name +%h8r5o1  
private int nSplitter; //Count of Splited Downloading File _@ qjV~%Sy  
~:s>aQ`!  
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public SiteInfoBean() w;4<h8Wn5  
{//nSplitter的缺省值为5 <L8'!q}  
//default value of nSplitter is 5 *k.G5>@  
this("","","",5); ;n*.W|Uph  
} TrEu'yxy8*  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) NJWA3zz   
{ u}macKJmp\  
sSiteURL= sURL; ^@s1Z7  
sFilePath = sPath; *av<E  
sFileName = sName; %K=?@M9i  
this.nSplitter = nSpiltter; B"1c  
y.mda:$~=  
[}E='m}u9+  
} U]H#MiC!  
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public String getSSiteURL() H)kwQRfu  
{ BLQ6A<  
return sSiteURL; X9W@&zQ  
} :^6y7&o[  
O:;w3u7;u  
y}" O U  
public void setSSiteURL(String value) ?jv
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{ &R'c.  
sSiteURL = value; O`IQ(,yef  
} P^~yzI  
& p  
*5C7d*'  
public String getSFilePath() ;#W2|'HD  
{ e5ZX
 
return sFilePath; JzQ_{J`k  
} oM>l#><nq  
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[Gb. JO}X  
public void setSFilePath(String value) {T$9?`h~M  
{ $f <(NM6?  
sFilePath = value;
MS~(D.@ZS  
} RLjc&WhzXu  
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public String getSFileName() ?=Z?6fw  
{ KxJ!,F{>H  
return sFileName; oq
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} HAdg/3Hw  
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*aM=Z+  
public void setSFileName(String value) hR?{3d#x2  
{ <`=j^LU  
sFileName = value; `KoV_2|  
} zj{pJOM06  
AlaW=leTe  
]m3HF
&  
public int getNSplitter() oWT3apGO  
{ IVY]EkEG~  
return nSplitter; Qz1E 2yJ  
} vm8eZG|  
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public void setNSplitter(int nCount) -$ls(oot  
{ y'q$|  
nSplitter = nCount; ~Fcm[eoC  
} ~!d\^Z
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} +Mb.:_7'  
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kS);xA8s]  
/* D;*SnU(9L  
**Utility.java m=:9+z  
*/ +{.WQA}z\  
package NetFox; %YscBG  
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H/ HMm{4  
public class Utility { ~TD0zAA&  
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public Utility() oJz^|dW  
{ Q(?#'<.#  
4xje$/_d  
O,f?YJ9S  
} j</: WRA`]  
.|70;  
//线程睡眠 =8. ,43+  
public static void sleep(int nSecond) T.BW H2gRP  
{ aB&&YlR=n<  
try{ AQvudx
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Thread.sleep(nSecond); k="i;! Ge  
} F^;ez/Gl  
catch(Exception e) |u<7?)mp  
{ R&k<AZ  
e.printStackTrace (); Ow,w$0(D  
} &j"?\f?  
} eq;uO6[  
!l8PDjAE  
//日志 ##>H&,Dp[  
public static void log(String sMsg) ^hM4j{
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{ 29.h91  
System.err.println(sMsg); @qAS*3j  
} O_7|C\]  
aX'*pK/-  
?N9u
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public static void log(int sMsg) JK5gQ3C[  
{ mz0X3  
System.err.println(sMsg); ?CPahU  
} }19\.z&J  
} iqWQ!r^  
]N?kG`[  
)3EY;  
/* w<(pl%  
**TestMethod.java !Wnb|=j  
*/ 2E'UZ m  
package NetFox; 8<Av@9 *}  
-FaJ^CN~  
/*
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public class TestMethod { @:#eb1<S  
s.C_Zf~3  
A3/k@S-R2  
public TestMethod() (O3nL.  
{ ///xx/weblogic60b2_win.exe x7[BK_SY  
try{ eeB{c.#  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); /PIcqg  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); zK@@p+n_#.  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 3 Za}b|  
fileFetch.start(); [{,1=AB  
} ~Mxvq9vaD  
catch(Exception e){e.printStackTrace ();} wbl&  
$ddCTS^  
*$g-:ILRuZ  
} t b}V5VH  
"4{r6[dn  
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public static void main(String[] args) &tj!*k'  
{ k9L;!TH~1K  
new TestMethod(); ]c'A%:f<  
} ew4U)2J+  
} H4+i.*T#  
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