http断点续传简单实现（java)

/* yAU[A  
**SiteFileFetch.java 9b@L^]Kg  
*/ 4wX{N   
package NetFox; C<r7d[  
import java.io.*; @z#;O2  
import java.net.*; `i8osX[&p  
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public class SiteFileFetch extends Thread { ~7Kqc\/H&I  
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SiteInfoBean siteInfoBean = null; //文件信息Bean hc5M)0d  
long[] nStartPos; //开始位置 &}nU#)IX  
long[] nEndPos; //结束位置 }5RfY| ;  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 i^G/)bq  
long nFileLength; //文件长度 W*QD'  
boolean bFirst = true; //是否第一次取文件 `mQY%p|  
boolean bStop = false; //停止标志 ^uW](2  
File tmpFile; //文件下载的临时信息 _YWw7q  
DataOutputStream output; //输出到文件的输出流 yX,2`&c  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 3uwu}aw  
public SiteFileFetch(SiteInfoBean bean) throws IOException 1Z'cL~9  
{ 9hHQWv7TgK  
siteInfoBean = bean; FviLlly6  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); -TU7GCb=  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Nb>|9nu O  
if(tmpFile.exists ()) r[vMiVb  
{ X, <
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bFirst = false; W=j/2c/  
read_nPos(); wp-5B= #:{  
} )pjd*+V  
else S5
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{ 9qIUBHe  
nStartPos = new long[bean.getNSplitter()];  $Tfq9  
nEndPos = new long[bean.getNSplitter()]; ZwAX
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} yHurt>
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} D
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public void run() _U1~^ucV  
{ W,`u5gbT  
//获得文件长度 J#L-Slav%  
//分割文件 u6'vzLmM  
//实例FileSplitterFetch @CP"AYB #  
//启动FileSplitterFetch线程 {:IO
Ty  
//等待子线程返回 GxLoNVr  
try{ 9
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if(bFirst) n!|K#  
{ 4))u*c/,  
nFileLength = getFileSize(); 4};!nYey!  
if(nFileLength == -1) *#+d j"  
{ @es}bKP  
System.err.println("File Length is not known!"); /"- k ;jz  
} $|C%G6!s?@  
else if(nFileLength == -2) yUq,9.6Ig  
{ *ys@'Ai?  
System.err.println("File is not access!");
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} 79~,KFct  
else I}puN!  
{ yv9~  
for(int i=0;i<nStartPos.length;i++) d0>V^cB'?  
{ UIvTC S  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); n4 KiC!*i0  
} -WB?hmx  
for(int i=0;i<nEndPos.length-1;i++) ~2 T_)l?  
{ G-G!c2o  
nEndPos = nStartPos[i+1]; Z_iu^Q  
} iv?'&IU
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nEndPos[nEndPos.length-1] = nFileLength; i6kW"5t  
} Y)N(uv6  
} yrdJX  
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//启动子线程 weT33O"!1  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; >f^&^28  
for(int i=0;i<nStartPos.length;i++) nUQcoSY#  
{ J{@gp,&e  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), X;w1@4!  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),  &{7n  
nStartPos,nEndPos,i); ::dLOf8o  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `-D6:- ,w  
fileSplitterFetch.start(); ?#qA>:2,  
} ~4U[p 50  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), '# "Z$  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); C:h
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", >L$y|8O  
nEndPos = " + nFileLength); s^^X.z ,  
// fileSplitterFetch[nPos.length-1].start(); F] +t/
 
+#6WORH0S  
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//等待子线程结束 YZ7rs]A  
//int count = 0; 5u:+hB  
//是否结束while循环 r4gkSwy  
boolean breakWhile = false; doFp53NhV  
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while(!bStop) EX>>-D7L  
{
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write_nPos(); A%"XNk  
Utility.sleep(500); Eof1sTpA  
breakWhile = true; "]LNw=S  
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for(int i=0;i<nStartPos.length;i++) enF.}fo]  
{ hEl)BRJ  
if(!fileSplitterFetch.bDownOver) ?fXg_?+{'g  
{ p[0Ws460  
breakWhile = false; $sU?VA'h  
break; |^S[Gr w  
} gET& +M  
} J,;;`sf  
if(breakWhile) 9*[!uu  
break; 3HO4h\mp  
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//count++; XEfTAW#7  
//if(count>4) j*I0]!-  
// siteStop(); B
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} ]gIXG`  
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System.err.println("文件下载结束！"); m,K\e  
} H5,{Z  
catch(Exception e){e.printStackTrace ();} =V"ags  
} 8!3+Obj  
@IB8(TZ5I  
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//获得文件长度 j6/ 3p|E  
public long getFileSize() {AO3o<-h  
{ |QAmN>7U  
int nFileLength = -1; 8<^[xe  
try{ }.NR+:0  
URL url = new URL(siteInfoBean.getSSiteURL()); 18}L89S
>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ;1NZY.pyc  
httpConnection.setRequestProperty("User-Agent","NetFox"); ppR_y  
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3 V8SKBS  
int responseCode=httpConnection.getResponseCode(); _L_SNjA_  
if(responseCode>=400) &m'O :ZS2  
{ PX?tD:,[-  
processErrorCode(responseCode); YCh!D dy  
return -2; //-2 represent access is error 9`{Mq9J  
} &VR<'^>  

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String sHeader; To}L%
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for(int i=1;;i++) 5G(y  
{ 2EG"xA5%  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); bkmX@+Pe  
//Utility.log(in.readLine()); )09_CC!a  
sHeader=httpConnection.getHeaderFieldKey(i); k
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if(sHeader!=null) `WWf
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{ 4yQ4lU,r  
if(sHeader.equals("Content-Length")) VY=~cVkzS  
{ ~ZG>n{Q   
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); K._1sOw'"Y  
break; &|9mM=^  
} r\@"({q}_-  
} /W:}p(>4a  
else Jfo|/JQ  
break; )lB-D;3[_  
} |g8 ]WFc  
} d>@{!c-  
catch(IOException e){e.printStackTrace ();} .a;-7|x  
catch(Exception e){e.printStackTrace ();} I #1_  
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}9Y='+.%^  
Utility.log(nFileLength); dam.D.o"  
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return nFileLength; +(PtOo.  
} at7/KuY!~  
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+ZizT.$&  
//保存下载信息（文件指针位置） #g~~zwx/N  
private void write_nPos() @{+*ea7M(`  
{ ut3jIZ1]  
try{ wKk  
output = new DataOutputStream(new FileOutputStream(tmpFile)); .IF dJ  
output.writeInt(nStartPos.length); _qE2r^o"B  
for(int i=0;i<nStartPos.length;i++) <u->hT  
{ b.YQN'  
// output.writeLong(nPos); k^R>xV  
output.writeLong(fileSplitterFetch.nStartPos); ot_jG)  
output.writeLong(fileSplitterFetch.nEndPos); kZUuRB~om  
} ;1(OC-2>d  
output.close(); DgClN:Hw  
} fQOaTsyA  
catch(IOException e){e.printStackTrace ();} %6Hn1'7+v  
catch(Exception e){e.printStackTrace ();} 
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} 1;? L:A  
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//读取保存的下载信息（文件指针位置） `q$DNOrS  
private void read_nPos() +Tq _n@  
{ %}'sFum`  
try{ F4bF&% R  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); <=A&y5o  
int nCount = input.readInt(); 3vrQY9H>  
nStartPos = new long[nCount]; eRVu/TY  
nEndPos = new long[nCount]; ~Ja>x`5  
for(int i=0;i<nStartPos.length;i++) jVfC4M7 ,  
{ 1/HPcCsHb  
nStartPos = input.readLong(); uA}asm  
nEndPos = input.readLong(); ZJR{c5TE  
} yMo@ka=v  
input.close(); b#82G`6r  
} >V;<K?5B`W  
catch(IOException e){e.printStackTrace ();} !p0FJ].g,  
catch(Exception e){e.printStackTrace ();} @M,KA {e  
} Bm~>w`1wK  
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private void processErrorCode(int nErrorCode) HnOF_Twq  
{ w`!Yr:dU  
System.err.println("Error Code : " + nErrorCode); _`D760q}  
} ef!I |.FW  
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N3x}YHFF  
//停止文件下载 ^.-P]I]  
public void siteStop() rWbL_1Eq  
{ JpSS[pOg  
bStop = true; d%]7:  
for(int i=0;i<nStartPos.length;i++) 3FX`dZ  
fileSplitterFetch.splitterStop(); N>]u;HjH  
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} ]}'WNy6c&x  
} EEkO[J[=  
//负责部分文件的抓取 !knYD}Rxd  
**FileSplitterFetch.java %>JqwMK  
*/ v- {kPc=:#  
package NetFox; `P# h?tZ  
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OW #pBeX99  
import java.io.*; Y61E|:fV!  
import java.net.*; F." L{g  
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public class FileSplitterFetch extends Thread { BA-n+WCWJ  
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{ ET+V  
String sURL; //File URL :;7qup  
long nStartPos; //File Snippet Start Position qa%g'sB-b  
long nEndPos; //File Snippet End Position CdEJ/G:  
int nThreadID; //Thread's ID %mxG;w$  
boolean bDownOver = false; //Downing is over $}HSU>,%  
boolean bStop = false; //Stop identical W?6RUyMC$T  
FileAccessI fileAccessI = null; //File Access interface [q(7Jv  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException :!r_dmJ  
{ wz:wR+  
this.sURL = sURL; i5_gz>  
this.nStartPos = nStart; d}WAP m  
this.nEndPos = nEnd; re^1fv  
nThreadID = id; u9GQ)`7Z@  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 .@[+05Yw  
} y<#y3M!\  
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public void run() QTP1u  
{ ?;i6eg17<  
while(nStartPos < nEndPos && !bStop) RS$:]hxd>_  
{ hVR=g!e#X  
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try{ x$A5Ved  
URL url = new URL(sURL); YSZz4?9\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Ymn0?$,D1=  
httpConnection.setRequestProperty("User-Agent","NetFox"); 8ALYih7"W  
String sProperty = "bytes="+nStartPos+"-"; *_^AK=i  
httpConnection.setRequestProperty("RANGE",sProperty); nQ/El&{  
Utility.log(sProperty); o#6j+fo!n  
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InputStream input = httpConnection.getInputStream(); 8{h:z 9]J  
//logResponseHead(httpConnection); y~W6DL}  
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byte[] b = new byte[1024]; Bj\0RmVa1  
int nRead; %tpt+N?  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) h#`qEK&u  
{ %=_Iq\lC  
nStartPos += fileAccessI.write(b,0,nRead); #_Tceq5  
//if(nThreadID == 1) .CmwR$u&  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ogQbST  
} B)Gm"bLCOZ  
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Utility.log("Thread " + nThreadID + " is over!"); -i 6<kF-W  
bDownOver = true; WE
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//nPos = fileAccessI.write (b,0,nRead); RAxA H  
} 1?mQ fW@G  
catch(Exception e){e.printStackTrace ();} Y&+<'FA  
} C' ny 2>uA  
} `Y$LXF~,Om  
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//打印回应的头信息 9C`Fd S  
public void logResponseHead(HttpURLConnection con) L$Ss]Ar=  
{ +mH Kk  
for(int i=1;;i++) f? ko%c_p  
{ *<BasP  
String header=con.getHeaderFieldKey(i); XhTp'2,]  
if(header!=null) ~>+}(%<,  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 0y6nMI  
Utility.log(header+" : "+con.getHeaderField(header)); 2MJ0[9  
else $~U_VQIA^  
break; yyBfLPXZ  
} 18|H  
} oIf-s[uH  
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public void splitterStop() rTK/WZ
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{ unP7("A0D  
bStop = true; N?R1;|Z]  
} R3.tkFZq]  
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} iF<VbQP=X^  
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/* MiS$Y  
**FileAccess.java C8aYg  
*//文件访问(定位，写) 4qiG>^h9  
package NetFox; ]<{BDXIGIE  
import java.io.*; a0y;c@pkO  
5\qoZs*e  
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public class FileAccessI implements Serializable{ Rl$NiY?2  
ud!iy  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 y%3Yr?]  
RandomAccessFile oSavedFile; [@.%6aD  
long nPos; Qt!l-/flh  
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public FileAccessI() throws IOException ")cdY)14"  
{ {:'eH  
this("",0); ?%;)> :3N  
} m#DC;(Pn  
\
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public FileAccessI(String sName,long nPos) throws IOException Z]"ktb;+[  
{ `2Ff2D^ ?  
oSavedFile = new RandomAccessFile(sName,"rw"); =yvyd0|35  
this.nPos = nPos; 2hu;N  
oSavedFile.seek(nPos); :DQHb"(  
} (x#4BI}L9)  
;^t<LhN:  
QH#|R92:  
public synchronized int write(byte[] b,int nStart,int nLen) @P[Tu; 4  
{ qnruatA  
int n = -1; 4l>/6LNMF  
try{ PNc^)|4^Q  
oSavedFile.write(b,nStart,nLen); m {wMzsQ  
n = nLen; obS|wTG~  
} iK'bV<V&7  
catch(IOException e) \q%li)  
{ H@5:
x8  
e.printStackTrace (); )2u=U9  
} QvjsI;CQ-  
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=f=MtH?0y  
return n; 9C3q4.$D  
} +7d%)t  
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} 7S1 Y)  
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/* ,Q >u N  
**SiteInfoBean.java zVJwmp^  
*/ xHe<TwkI  
package NetFox; uRwIxT2  
{i`BDOaL  
Y <Ta2H  
public class SiteInfoBean { Yb6(KT  
fg+Q7'*Vq  
Z!7#"wO9+V  
private String sSiteURL; //Site's URL 8H3|^J  
private String sFilePath; //Saved File's Path ZrXvR`bsw  
private String sFileName; //Saved File's Name Ah)_mxK  
private int nSplitter; //Count of Splited Downloading File .B_)w:oF  
3($%AGKJ  
:Y~fPke  
public SiteInfoBean() Y(W>([59  
{//nSplitter的缺省值为5 RY&Wvkjh  
//default value of nSplitter is 5 ;' YM@n  
this("","","",5); ZGe+w](  
} * t{A=Wk  
&*/8Ojv)9  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) oq(um:m  
{ Bp>%'L  
sSiteURL= sURL; L]9uY
  
sFilePath = sPath; 9<}d98  
sFileName = sName; C3hnX2";  
this.nSplitter = nSpiltter; cAV9.VS<L  
2*F["E  
_ B",? }  
} e*Sv}4e=.  
&ZClv"6  
{&,a)h7&  
public String getSSiteURL() !7P 1%/  
{ V[uB0#Lp  
return sSiteURL; %}x/fq  
} r,!7TuBl  
c+Ejah+  
-Q<3Q_  
public void setSSiteURL(String value) ]?/[& PP,  
{ G!L=W#{  
sSiteURL = value;  #/MUiV  
} p4bQCI  
&5)Kg%r  
srw5&s(3X  
public String getSFilePath() 9{^:+r  
{ M g1E1kXe  
return sFilePath; u&mB;:&  
} `.>2h}op  
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public void setSFilePath(String value) Jou~>0,/j  
{ m .l
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sFilePath = value; 1 nIb/nY  
} BO5F6lyQ0P  
=YR/X@&  
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public String getSFileName() 7-nwfp&|$  
{ ,H'O`oV!1E  
return sFileName; A d=NJhz
l  
} 9<W0'6%{/  
i:ZpAo+Z{  
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public void setSFileName(String value) {UT^pIP\  
{ :%{MMhbx  
sFileName = value; O\q|b#q}/  
} p>96>7w  
ac p-4g+j  
%19TJn%J$  
public int getNSplitter() O|O#T.Tg  
{ ahU\(=  
return nSplitter; !6'j W!  
} +D&W!m  
s,\!@[N  
K)`,|q* \  
public void setNSplitter(int nCount) ;sT7c1X^!  
{ A?06fo,  
nSplitter = nCount; l[fU0;A  
} 1;i[H[hNY  
} wBTnI>l9[  
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/* GE\@mu *pO  
**Utility.java 2v0lWO~c7z  
*/ N0,.cd]y`  
package NetFox; d/k&f5  
7N+No.vR.  
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public class Utility { Y4YA1F  

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public Utility() ~T|?!zML  
{ JM0'V0z  
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} EGf9pcUEO&  
rQC{"hS1  
//线程睡眠 f`*Ip?V-  
public static void sleep(int nSecond) *6cP-Vzd  
{ C
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try{ 4Cr|]o'  
Thread.sleep(nSecond); {a-p/\U  
} S^HuQe!#  
catch(Exception e) I $!Y  
{ 4E}]>  
e.printStackTrace (); r5xu#%hgp;  
} r]iec{ ^  
} _'JKPD[  
iqig~fjK~  
//日志 U{gJn#e/.  
public static void log(String sMsg) ]7}2"?J4v  
{ ]xBQ7Xqf
|  
System.err.println(sMsg); ^EdY:6NJ=A  
} &Y;z[+(P  
r in#lu&N  
&]iX>m.  
public static void log(int sMsg) o /AEp)8  
{ 'KMyaEh.u  
System.err.println(sMsg); -
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} uli,@5%\  
} /Li?;H  
u~=>$oT't  
,~`R{,N`  
/* qd6XKl\5  
**TestMethod.java '9>z4G*Td  
*/ xV @X%E  
package NetFox; {wiw]@c8  
f'Dl*d  
v?F~fRH  
public class TestMethod { 6H\3  
id8a#&t]  
LSv0zAIe/  
public TestMethod() j yR9a!  
{ ///xx/weblogic60b2_win.exe I:Wrwd  
try{ MQ9 9fD$  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); $rD&rsx6  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 7 [N1Vr(1  
SiteFileFetch fileFetch = new SiteFileFetch(bean); OWT5Bjl  
fileFetch.start(); 3#}5dO  
} '\Z54$  
catch(Exception e){e.printStackTrace ();} cd)yj&:?Bt  
%Ak"d+OH4  
X!V@jo9?  
} /xj^
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public static void main(String[] args) c&z@HEzV7  
{ vG`R.  
new TestMethod(); _ #288`bU  
} .YKqYN?y4  
} @6w\q?.s  
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